Author Archives: Philip van der Matten

Tandberg TD 20 A

I have recently acquired a Tandberg TD 20 A. This model was on my list of decks that I always wanted to own. It is a very good sounding deck, and received wonderful reviews in it’s days. It was compared once to a Philips N4520 and a Teac X-2000R in a magazine article and it came out 1st in some of the sections. I can not find the article at the moment, if I find it I will post the link here.

It is a deck from Tandberg, a Norwegian company. Not many decks came from Scandinavia, apart from B&O and some others. This deck is also available in 2 tracks, maybe I will come across one someday, I hope.

This deck came as ‘mechanical defect, does not run but signal in/output is good.’ So it will be a challenge to get it working. It also came with 2 very special Tandberg NAB adapters.
First it will need a good cleaning. Especially the front aluminum is yellow-ish.

Cleaning

First I took the deck out of its casing. Then I took of the knobs and the front plates. The knobs were cleaned, and fortunately on the front plate the lettering does not come off! The black upper plate looks nicer now too.

1st checks

It powers on: good. It winds: good.
But it does not play. It appears the pinch roller, or better the arm on which the pinch roller is located, is stuck. This looks like a bad case of stuck grease. 

After disassembling some parts, including removing a split-pen, I was able to remove the arm. I removed the rubber roller and put it into a detergent solution for a night to revive it. I cleaned the axle from old grease and lubricated it. Now it moves again effortlessly. I checked, cleaned and regreased all moving parts. Also the gears on the 4th motor, that manages the tape handling, were stuck. Cleaned and lubricated that as well.

Then another issue presented itself: the left reel dish was scraping against the brake. I readjusted that table so that it is in the correct position again.

Cleaned the tape path and the heads, made sure the tape guides were smooth in their movement.

provisional play test

Then I put a tape on: it was working! This deck has a very smooth tape handling when starting and stopping. It is a delight to see this in action. Also the music on the tape was playing, so playback circuit was working too. This keeps getting better and better.

provisional record test

I noticed something odd: the erase head is not in the position that it should be: it is slanted and it’s position is too low on the tape path. Apparently the construction on which it is mounted was dented once. This is an issue for later. Now I will just use my bulk eraser to erase a tape and record on that.

I put on some Agfa pe36 (which is not a very high end tape, but als not budget – a kind of ‘well, ok’ -tape) and the difference between source and tape was almost non-existent!. This is a very good deck as-is even without the maintenance, adjustment and calibration that I will perform on it.

NAB adapters

The matching NAB adapters have 2 peculiarities:

  • they haven’t got a clamp en turn mechanism like the ones from Teac and Philips etc. Nevertheless it works well: the outer ring covers the NAB hole in the reel, and the trident from the deck grabs the whole tight to the reeltable. Looking at it this way you could say that the other manufacturers have come up with a far too complicated construction 😀
  • using the large 26cm reels with these adapters, the reels are too deep relative to the tape path and the tape scratches the rim of the reels. This is mentioned in the manual: a disc is to be used to lift the reels a few mm. When I use the other brand’s adapters, there is no problem.

The tape guide arms can be adjusted to bring the tape lower to the reels, but I will not do that as I suspect trouble with 7 inch reels.

erase head problems

There is a strange thing going on with the erase head. This is the very first time that I experience a skewed erase head. And it is not only skweded but it is also too low.It looks like it has been pushed down. The construction is weird: the head is mounted on top of a kind of tincan strip which is Ω omega shaped. And that is dented. And while pushing it up again, one side broke.

What I did was load some blank tape, and by that I mean see-through tape, and line up the erase head. I put some nuts and ring under the plate until it was level with the tape. After adjusting the other mounting screws of the head my erase head was level again and at the right height etc. I tested it with erasing and it seems to work just fine. And I could always use the deck for playback only. Or first bulk erase the tape before recording with this deck when it won’t work after all.:)

measuring

After all the mechanical adjustments were made, the unit was cleaned, lubricated, demagged, etc etc I ran some tests to determine how well the deck was performing.

Wow & Flutter, 19 cm/s 9,5 cm/s:
flutter:             0,1         0.15
wow:               0.03       0.08
unweighted:    0.1         0.06
weighted:        0.05       0.15

DIN measured. The values still match the specs quite well!

Distortion: 1kHz 1,2V input:
0.14 % with DUT on ‘source’
0.5 % with DUT on ‘play’ but still on ‘source’
0.75% with DUT on ‘tape’

Tape is Maxell UDXL 19 cm/s. Around 0dB on VU meters.

frequency sweep

Then I proceeded to measure the frequency response. Although the deck sound very good, what I saw on the screen I wasn’t very happy with:

Yellow line is the source sweep, from 20-20kHz and measured through the deck in ‘source’ mode, and the green line is what comes back from that same sweep in ‘tape’ mode.

calibration tapes

I was sure that could be improved upon, but I wasn’t sure what was going on. It could be that recording was the problem, or playback, or both. So I mounted not one, but two (!) calibration tapes to examine the playback frequency curve. The result was this:

The red line is a BASF Bezugsband and the white line is a brand new MRL tape. Apart from the difference in levels, which is solely for the purpose of the graph, the frequency run is fairly identical. There is fall off in the higher frequencies on both tapes. So there is a problem with playback at the least.

REMARK: the BASF tape is IEC, the MRL is a NAB tape.

head alignment

I continued to go through the complete Service Manual of the deck. Starting with heads alignment, that already gave some better high frequency response because you not only align the playback but also the rec head.

After that I followed the rest of the service manual and calibrated the levels, the bias and the freq. curve. After I was done, the result was spectacular:

This is a recorded signal played back. The sweep is almost straight. At least as straight as I will (can) get it. The image comes from a new program that I found called BAUDLINE. It runs on linux and is very fast. I use the ‘peak smoothing’ feature to create a sort of peak-hold.

listening tests

After that was done, all the work I planned to do on it and that was necessary on it was done. The subsequent listening tests were a revelation: the deck sounds so good that even my trusty old Philips N4520 was left a bit behind. May need to rework that one as well sometime 🙂

 

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Measuring (baselining) with my new National Distortion Meter

I like measuring. So I bought a National Distortion Meter. It is the VP-7701a.

This device is capable of measuring the distortion of an sine audio signal. And can be useful to calibrate vintage audio equipment.

Baselining

To be able to make any meaningful measurements, I need to do some baselining, meaning that I want to measure the distortion when the device is not measuring anything at all. If that makes any sense to you. It does to me anyway 😀
When the base distortion levels are extremely low, I can measure devices and discard the base distortion. But when the base distortion levels are significant, then I would have to subtract these levels from the measurement each time I do a measurement. Which I do not want, because it is a hassle.

So in order to do that I need a pure sine wave for input. The device does not provide that, at least not one that is available to the user. The device measures the distortion by subtracting its own sine waveform from the one that is being measured, and the result should be zero. But only if the supplied waveform is 100% equal to the internal sine waveform. My search for a matching waveform therefor brought me to 3 sources:

  • a pure sinewave provided by my soundcard from the computer, created in audacity
  • a test CD made for this purpose which I bought 20 odd years ago
  • a test CD that I created myself with pure sine waves created by audacity and burned to a CD

This is the test CD that I once (’90-s) bought:

It has all kinds of tests on it: frequency sweep, fase checks etc and also sine wave tones across the audio spectrum.

Result

This is the result of my base line tests:

The results show that both my soundcard and the commercial testCD are useless for my measurements. The CD that I made myself is a lot better. It performed marginally better on my Technics SL-P777than on my Philips DVD 963SA player (SACD). The result is such that I think that the base distortion is low enough to not take it into account when I start to measure real equipment. So I will be using this CD as my source for sine waves.

One side note: my CD is recorded at 0dB level, so the player outputs 2,5V which is rather high. I may have to make a second CD where the levels are lower, like -10 or -20 dB.

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My personal checklist for upgrading from openSUSE Leap 42.1 to 42.2 using online update (zypper dup)

** update — also tested ok on 42.2 -> 42.3 **

This is my personal checklist for upgrading from openSUSE Leap 42.1 to 42.2 using online update (zypper dup). This may or may not include all the steps necessary for YOUR system.

You may not need all the steps. So be careful. Read it carefully, and make sure that you understand each step. Use it as an aid. Use it at your own risk.
Remember, always update 1 versionnumber at a time, so go from 42.1 -> 42.2 -> 42.3 and do not go from 42.1 to 42.3 !!

For the full (very good) documentation, see: https://doc.opensuse.org/documentation/leap/startup/book.opensuse.startup_color_en.pdf

Preparations:

  1. Check your repos.
    1. Remove all repos that you no longer need, like I have the ‘kde updated apps’ repo.
    2. It is most preferable to leave only base (oss & non-oss), update(oss & non-oss) & packman repos.
    3. # zypper verify
      to remove cache files from the repos you deleted. Saves lots of disk space beforehand.
  2. If necessary, but this may be not for you, enable packet locks on packages that you need. For instance, I still need createrepo and KDirStat and I don’t want the upgrade to delete these packages. This step may not be for you.
    1. # zypper al createrepo
    2. # zypper al kdirstat
  3. update your system to the latest patch level just before the upgrade.
    1. # zypper up
  4. IMPORTANT!! Make sure that you have enough free diskspace, >4GB is recommended. (probably in /var/cache but i’m not sure) <– yes, confirmed

To change the repos:

  1. go to the repo directory
    1. # cd /etc/zypp/repos.d/
  2. change all references from 42.1 to 42.2 (or whatever version number you need)
    1. # sed -i ‘s/42.1/42.2/g’ *.repo
  3. check if the repo files are correct now
    1. # grep base * | cut -d”:” -f2-
      and check the output
  4. check to make sure that these new repos all exist and are accessible
    1. # zypper ref -f

To start the update:

  1. please read step 4.3 below first.
  2. I like to start the update not in an X session, so either:
    1. init 3 :to switch to runlevel 3, or
    2. CTRL-ALT-F1 to start a root session on tty1. This has the benefit that a graphical console is still available during the update. (press CTRL-ALT-F7 to switch)
      but his is not a necessary step. You can skip this if you want.
  3. I like to download the files in advance, so I don’t end up with a broken system when something goes wrong during the process. Please check for >4GB free disk space beforehand.
    1. # zypper dup – -download-in-advance
      Otherwise just leave the download-in-advance option out.
  4. Really, really check the output good before giving it a go.
    1. Check especially the section on ‘downgraded packages’ and ‘removed packages’ . Check if there aren’t any packages that you know you want to keep.
    2. To check the downgraded packages, I have a little tip: type ‘v’ at the promt where zypper is asking for ‘yes or no’, and the list will be repeated but now with version numbers!
    3. This step may be difficult to do on tty1, so you might want to do a test run of this command in the graphical console first, where you have a large scroll-back buffer. So check and then simply answer no at the end will do. Then repeat the command in the tty1, where you will answer yes of course.
  5. Once you answered ‘y’, the download will start. For me, it was ~4000 packages, ~2.1GB download. How long this will take depends on your internet connection.
  6. After the download, the installation of the packages will start. How long this will take depends on the speed of your processor and disk system.
  7. then you can reboot
    # reboot

After the upgrade to 42.2, my server performed its functions (database, webserver, nfs, smb etc.) perfectly. However I had a slight issue with the KDE-desktop. The taskbar would not come up and the desktop was inaccesible.
To solve that, I had to issue the following command:
# zypper in -t pattern “kde_plasma”

That command installed some packages that were probably missing. After that, I could use the desktop as normal again.

Have a lot of fun!

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Cleaning contacts in audio equipment

file_342_9To clean contacts in audio equipment, I do the following:

  1. clean the contact with Kontakt 60
    this will dissolve the corrosion and is slightly acidic. Follow up with 2 & 3.
  2. clean the contact with Kontakt WL or IPA
    this will rinse the contact clean and evaporate completely
  3. protect the contact with Kontakt 61
    this will put a protective layer on the contacts to prevent corrosion and wear so that you won’t have to do this again next year 🙂

For potentiometers don’t use 60, this will erode the internals. Use Kontakt 390 or Kontakt Tuner(600). Tuner works very well.

Kontakt 390 is an old Philips recipe and should be an all-in-one solution. I have not used it yet.

Don’t use contactspray!

Good luck!

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AEG Magnetophon AW-2

A very good acquaintance gave me some recorders recently. Among them was this beauty: The AEG Magnetophon AW-2.

aeg_1

As you can see, this recorder is from 1951 and is more than 65 years old! This particular device that I have was used in cinemas for sound reproduction. It sits in a suitcase for easy carrying around. It is quite heavy though. It uses platters and pancakes.

aeg_2

aufname und wiedergabe switch

aeg_3

on/off-volume and play/rewind switch

It is in a very reasonable condition. So far nothing seems to be broken beyond repair. My goal is to try to restore it so that it plays tapes again. I have not turned it on yet, it first needs a lot of TLC.
It appears that when used with ‘modern’ tape, this unit will nowadays produce stunning results that would exceed what would have been achieved back then.

For instance, there are three very heavy duty belts in this one motor machine. And with belt I mean like belt from a car engine. They are not in a condition to be used again, so these will have to be replaced. Also some of the electronic components, like capacitors and rectifiers are way beyond their normal operating life so they will have to go too. And then everything else that I will run into. Hopefully the tubes, there are a few, still work.

I have started to open the device up and clean it.
p1040011

p1040012

Immense belt

p1040019

fltr: erase, r/w head capstan and pinchroller

the heads:

p1040018

somewhere in this shell is the head

p1040017

erase head before cleaning

p1040022

oil’s well!

There are of course a lot of electrical components as well that need to be replaced. The first and foremost candidates are the capacitors, as there are certain types that don’t last for so long.


The device contains some paper-oil capacitors, like this one:

 

This will certainly have to be replaced before I can switch it on. I am told that ones like this will probably be ok:

The device is really beautifully made. When I ventured inside I fell in love with it more and more. But there are a few ‘minor’ issues to be resolved, like: where is this supposed to be connected?

I was told that this rectifier could go up in (probably very nasty) smoke:

So I will need to figure out how to replace it.

Fortunately I have got the electrical diagram:

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Philips N4522 (twice) and another N4520: new arrivals!

I recently went on a road trip and came back with:

  • a Philips N4522 2-track. This machine is in very good condition and has recently been serviced in Germany.
  • another N4522 2-track, but this one is going to need some TLC. There are some issues with it, although none of them are serious problems. But I just like to fix it as much as possible.
  • another N4520 4 track. I already have one, but this new arrival is not recording well. This has probably something to do with the levels, but I have not looked into it yet.

So now a have a total of 4 Philips N452X machines and that looks like this:

The two on the left with the white VU meters are the 2 track stereos, and the two on the right are the 4 track stereo machines.

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Wow! What speed flutter!

Why speed measurement

For some reason I got interested in the speed of my tape decks. Why, you ask? I really don’t know. I was fiddling around with my vintage Philips multimeter, which is capable of measuring the frequency of a tone, when I thought it would be cool to use that meter to measure the 1kHz tone which is a the beginning of my (generic) calibration tapes. If the tape runs too fast, the measured frequency would be over 1000Hz, and if the speed was too low, it would be under 1000Hz. Suddenly I was fascinated by the fact whether my decks were running at the exact speed or not, or if not, how much deviation it had.

Now, you have to understand that I do a lot (well, actually not that much) calibrations of decks, but I never ever calibrated the speed. I never bothered before. I never had a problem with speed before. I never had the need to adjust the speed of a deck. So whatever I measured now, it would be the ‘default’ speed, untouched.

So I loaded the test tape onto all of my decks, connected the multimeter, and did my measurements.

The results were sometimes surprising, sometimes more or less expected.

Merk/Type speed %
Akai GX77 980 98
Revox PR99 994,5 99,45
Teac X7R 995 99,5
Philips N7300 998 99,8
Teac X2000R 998 99,8
Philips N4520 1000 100
Tascam 34B 1000 100
Studer A80 1000 100
Teac A3440 1002 100,2
Teac X7 1011 101,1

And a graph says more than words, so:

What can we conclude from this?

  • The Akai GX-77 really runs too slow

  • almost all decks run within +/- 0,5% of the correct speed, which is within the DIN norm

  • only 3 decks run a EXACT the correct speed: the Philips N4520, the Tascam 34B, and the Studer A80.

    • the Philips N4520 is know for its quartz/PLL like control, so this is no surprise

    • the Tascam 34B is a professional deck, but this result still surprised me

    • the Studer A80…..well…….need I say more?

enter the wow and flutter

So that has been a very interesting experience. But then I started thinking about variations of the speed, also known as ‘wow’ and ‘flutter’.

Wow is the slow variation in speed, with a period below 6 Hz.
Flutter is the fast change in speed, with a frequency above 6 Hz.

One can experience wow then playing a record where the hole is not centered, and the speed goes up and down all the time.

Flutter is more difficult to hear because it is so fast. It can be measured however. Flutter is created by faulty mechanics: a capstan here, a roller there, dirt, bearings, the overall construction etc. It would appear that less flutter makes for a more tight and clean sound.

There is always wow and flutter. No mechanical system is without them. It is just a matter of reducing it as much as possible.

causes of W&F

what are the causes of W&F? There can be many. The capstan or axis involved might not be perfectly round. The bearing idem. The system may not be perfectly lubricated. There may be dirt on tape guides, causing jerky tape motion (on a microscopic scale). Tape may not be slit evenly. Etc. etc. etc. There really are too many to mention here.

Remember: There is always wow and flutter. No mechanical system is without it. Realize that.

measuring wow and flutter

Now there I had a problem. To measure W&F you need a special device called a ‘wow and flutter meter’. Of course, you can rely on Philips that they had such a product back in the days. They did. It is this one:

But unfortunately I don’t own one. It is on my wanted list though. They are relatively rare, and sometimes expensive. If you have one, or one like this, and you would like to sell it to me, please let me know.

software to the recue

What to do now? Fortunately I found an interesting program on the web that is supposed to measure W&F. It’s called WFGUI. Here is a screenshot of the program in action:

That looks impressive, right? It can measure DIN 45507, wow < 6Hz, and flutter >6Hz. According to the documentation provided with the program it has been tested against some real life hardware W&F meters and the results were very very comparable. Good!

Now I had a different challenge with this program, as it runs on windows, and I only have Linux. But, I soon found out that it runs perfectly fine in Wine! Yeah!

You can select between the 2 most used frequencies in calibration: 3000 and 3150 Hz. (It also shows the measured frequency for your convenience.) Then there are 3 values to take notice of:

  1. RMS (%): this shows the root mean square value in % of the current measurement
  2. Peak: this shows the current peak in % using a nice needle display
  3. maximum value of RMS and Peak in % during the last 10 seconds
  4. and it also produces a nice waveform of the current fluctuation measurement (this is NOT the input or output sinewave)

Now, this is where it gets interesting. The program has different settings so it can measure different values. It can measure:

  1. DIN (Deutsche Industrie Norm), or more specifically DIN 45507
  2. wow: measure variations between 0,3 Hz and 6 Hz
  3. flutter: measure between 6 Hz and 200 Hz

Now I will not go into too much detail here, but take it from me that the DIN norm is a sort of average between the 2nd and 3rd setting, i.e. it takes a little bit of both. If you want to know more, you can read the documentation that comes with the program, that has some nice graphs that show it all. That will explain everything. For my measurements I used all three settings (DIN, wow and flutter), and I measured all 3 values (RMS, Peak and Max RMS)

calibration tape

The problem I had is that measuring these kinds of W&F is traditionally done with a tone of either 3000 or 3150 Hz. And, more specifically, you need a special (and expensive) speed calibration tape with that tone on it recorded in a very precise manner.
Guess what, I do not own such a tape. They are quite rare actually, although you can still buy them at MRLtapes.com I presume. My regular Bezugsband (German for calibration tape) has a 1kHz tone at the beginning, but that is used foor reference level measurements.

making my own test tape (huh?)

So I thought about it a bit and I knew I was never going to buy that special speed calibration tape (>€130). What if I took my trusted tone generator and used that to record and immediately playback a 3kHz tone? Of course that would be an imperfect recording, because it would contain W&F, but wasn’t that just what I wanted to measure? And if you play back that recording on the same deck, doesn’t that give a good indication of the performance of that deck? The more I thought about it, the more sound (pun intended!) the idea seemed to be.
Doing that would mean that I could not refer to a know calibrated source anymore. But I’m not interested in those figures. I can now compare the performance of my decks between themselves, see who stands out, either way.

Some people may argue that one can not make his or her own test tape. Of course that is true. But that is not the purpose. I want to measure the W&F of a deck. I was going to use the deck itself to record a tone and play it back at the same time.
Some may argue that that is not a good way to measure W&F. I disagree. I will explain.

When you record the test tone on the DUT (device under test), it wil will be recorded with wow and flutter. That is clear. So it will be an imperfect recording. So what. That is what I want to measure, so that seems ok to me. Let’s assume that the recorded tone will contain at the maximum an amount of W&F of n. If you would examine the tape in a laboratory you would find max n W&F. The DUT obviously has a W&F value of n. So at some points in time the value would be 0 (zero), at some points in time the value would be n (the max value) and most of the times some value in between. This will vary constantly, and it will vary very quickly.
Now I play back this tape on that same deck that has that W&F reading of max n. So again, some of the time that tape will play back with no W&F, and some of the time it will play back with the maximum value of n, and most of the time some value in between. The resulting W&F will be 2*n at the most, to be exact that would occur when a piece of the tape that was recorded at that moment with n W&F value will be played back at a moment that the deck plays back with a W&F value of n.

testing

So again I dragged all my decks to the test bench and hooked them up one by one. Now reading the values from the program proved to be quite a challenge, because the readings vary a lot and change very quickly. So i took a sort of ‘observed average’ , as I would call it.

I did the measurement all at 19 cm/s, because that is the common speed all my decks have. I have noted where I used an other speed, like 38 cm/s.

 So what are the first results?

  • the kind of tape used for the test has a great influence on the end result. At first, I used an older tape and got very different (much much worse) result that when I later used a brand new tape of the same type. This was kind of shocking!
  • tape speed has a great influence on the stability as well. All deck produce much better results on 38 cm/s than on 19 cm/s. A few quick test at 9,5 cm/s were even worse.
  • I did not find any difference when using the beginning, the middle or the end of the tape, but I have not tested that on every deck. I suppose if a deck has too much or too little tension, the position on the tape would matter

After a lot of testing I had a spreadsheet full of values that were very difficult to interpret. So I made a graph out of all the numbers and this is the end result:

This may seem overwhelming and confusing at first, but it really isn’t. Let me clarify for you.

  • On the X-axis (lower) you see the three different measuring methods for each deck: DIN, wow and flutter.
  • Each deck has an corresponding line in the graph for these 3 values.
  • Lower values (lower lines) are better.
  • Legend is on the right, showing which line corresponds to which deck. It is a bit crowded but bear with me.

Here are the conclusions:

  • the most upper line, meaning the worst deck, is the Teac A-3440 at both speeds. This is one of my oldest decks.
  • for fun I included one turntable, my Technics SL1900. That is the blue dotted line. I found that I had a test record with a 3kHz tone on it, so I could actually do the measurement. I was surprised to see that the values produced were in the same range as the tape decks. However, unlike all decks, the wow is the worse value of the three.
  • the best deck is the Studer A80 @ 38 cm/s. Of course, Studer was famous for their mechanics and always paid special attention to the tape path. Studer used the best available bearings and even had special lubricant that had to be used.
  • a very positive measurement is the Philips N7300, the light blue line in the lower part.
  • in general, the newer decks (Philips N7300, AKAI GX-77 and Teac X-2000R) are in the better part of the graph. Maybe it is because when they were manufactured, the W&F was better under control, or it is simply because they are fewer used.
  • the ReVox PR99 (also a Studer brand), the dark blue line, is giving the A80 a run for his money.
  • the results for the dual capstan decks that I have (Teac X7, X7-R, and X2000-R) are not as I expected. Yes, they are good, but they are beaten by single capstan decks. The whole idea of the dual-capstan system is that that would eliminate (well, minimize) W&F values. I think the system fails to deliver. And on top of that, it introduces a lot of unwanted negative side effects, that are most notable after all these years when the decks age.
    The result of playing in the reverse direction were mostly comparable to the forward direction, so no real diffrerence here.

There you have it. I hope you liked my article. If you have any comments, please leave them below.

-edit  31 may 2016-

I have recently purchased a ‘real’ wow and flutter meter, the B+K Precision wow and flutter meter 1035. 
I have used this meter to check some results from the softwareprogram above, and the results fortunately match. Great!

A80@19 RMS Peak max RMS
DIN 0,0225 0,04 0,0294
wow 0,013 0,019 0,0166
flutter 0,0406 0,029 0,0484
a80@38 RMS Peak max RMS
DIN 0,0093 0,019 0,0136
wow 0,007 0,01 0,009
flutter 0,0368 0,059 0,0398

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Re-capping a vintage quadraphonic amplifier: JVC MCA-V7E (quadrophonic)

JVC MCA V7E closeup

For some reason I wanted to do a recap job of my vintage quadraphonic amplifier, the JVC MCA-V7E that you see above. This unit is actually in very good shape, so the reason for me to do this is also unclear to me, really! But sometimes my ways are inscrutable.

recap

A recap job means that you replace all the old, worn out electrolytic capacitors that are >40years old with new ones, preferably audio-grade types. Electrolytic capacitors are known to dry out when they get older. And then they lose their characteristics. Worst case is that they short out, or that they start acting as a coil or as a resistor. These are all things that you do not want in your amplifier. Or in any other device, for that matter. Also, the original caps were never the same quality as the ones that you can buy today just because manufacturing, tolerance and materials have become so much better in 40 years. So in theory this should enhance the performance of the unit.

Also, it is not a question if an electolytic caps will fail, but when. So after the recap your equipment will be good for at least another 40 years, but probably a whole lot longer.

Panasonic FC series

If you are gonna do it, you want to do it good. Then you go for the audio-grade caps.

These black caps are available at sometimes crazy prices of several euros a piece, but there is a very good capacitor at a very reasonable price. So all audio enthousiasts like me that do not have a money tree in the backyard use these FC series caps, as you will probably need a good bunch of them. In this case I used around 50-60 of them, but I have not counted them exactly.  I ordered them from farnell.nl  they have the complete range of values at good prices. The only problem is the minimum order amount of 50 euros.

The works

This is what the unit looked like before I started:

before

Basically all the grey capacitors that you see here had to be replaced. This consists of the Power Supply board, the tone/preamp board, the mainamp board, and the phono board which is located on the underside

I started with the PSU (power supply). These contained some big ones.

psu_done

PSU after

psu_before

PSU before

Note the difference in size. The new ones are a lot smaller. They have the same value nevertheless. After I had done the power supply, and the amplifier still worked (!!) 🙂 I tackled the phono board.

phono_before

phono before

And then the preamp.

tone_preamp_done2

premp done

tone_pre_before

preamp before

And then the main amp:

halfway2

halfway

amplifier_print_before

before

All_done2

all done

After all the works was done, it was time to turn the power on. Exiting! Nothing exploded and no component was getting very hot, so I connected an input signal on the four inputs and turned up the volume. Channel 3 was not working. Hmmm. I remembered a problem I had when removing the large capacitor from the third channel, when the copper strip had come loose from the board. On closer examination I saw that it indeed was not making contact properly anymore, so that was easily fixed. Now the 3rd channel worked ok!
The sound from the ‘new’ amplifier is very crisp, someone called it ‘clean’. I think that is an apt description. I turned the JVC up quite a bit, and experienced no problems. So I am very happy with that.

Testing & measuring

Next up is a bit of testing and especially measuring. Because I wanted to test some new type of transistors, I have installed them in the channel 2 pre-amp. I want to see how they stack up against the original ones. I am especially interested in distortion and overall performance. If they don’t perform well, I will re-install the old ones. Maybe the amp needs to be biased as well, but I’m not sure yet.
I also turned up the calibration on the meters quite a bit, so now the needles are showing signal even at normal volume levels, that was not so before. Previously they just lingered around in the left corner doing mostly nothing.

I have provided here a simple drawing of the electrolytics on both amplifier boards for your convenience, if you should decide to do the recapping as well. Good luck!

JVC_MCA_V7E_elcolayout_mainamp

JVC_MCA_V7E_elcolayout_preamp

(view count: 277)

Another Akai: GX-77

Today I picked up a mint condition Akai GX-77

3779855926_a41e21b91b_z

This photo is from the internet; I will upload a real photo later.

The unit does not work; the two pinch rollers won’t come down all the way and the tape loader roller in the middle is stuck at the top so I will have to fix that. The middle roller is necessary for tape loading and unloading.

auto reverse

This unit is a real beauty. It is an auto-reverse deck, and is capable of playback AND recording in both directions. Therefore it has 6 heads and two capstans. The capstans are always spinning, in opposite directions and only the pinch roller associated with the current playing direction is engaged. The result of this is that switching tape direction takes only 0,4 seconds.

other features and specs

  • It has user adjustable bias through a dial on the front
  • capable of using EE tape (chrome)
  • L+R recording level knobs have a 3rd ‘master’ knob which controls both channels
  • output level is adjustable from the front
  • digital tape counter with optional backup adapter

Here are the full specs:

  • Track system: auto reverse, 4-track, 2-channel, stereo system
  • Heads: 2 x GX record, 2 x GX playback, 2 x erase
  • Motor:
    • 1x FG servo direct-current capstan motor
    • 2x direct-current reel motor
  • Reel size: up to 7 inch reel
  • Tape speeds: 3 3⁄4 7 1⁄2 ips
  • Wow and flutter: 0.03% (7 1⁄2 ips)
  • Fast forward rewinding time: About 80 seconds
  • Frequency response:
    • 25Hz to 33kHz ±3dB (19 cm/s) 
    • 25Hz to 25kHz ±3dB (9.5 cm/s)
  • Signal to Noise Ratio: 63dB
  • Total harmonic distortion: 0.5%
  • Input: 70mV (line), 2mV (DIN)
  • Output: 0.775V (line), 0.3V (DIN)
  • Dimensions: 440 x 244 x 227mm
  • Weight: 17kg
  • Power consumption: 28W

work begins

The first thing I did after opening up the unit was checking the belts. It has three: one capstan belt and two for the spooling motors. The capstan belt was ok, it was still feeling like it should, but it was probably a little stretched because it didn’t feel very tight to me. I ordered a new set which included the 2 spool motor belts for €12,-

Once I had the belts replaced, it still would not engage the middle roller. It is supposed to go up and down.

akai gx-77 with the roller stuck in top position

akai gx-77 with the roller stuck in top position

Searching on the internet I found that there is a large white gear wheel located behind the 2 flywheels which controls the up/down movement of the roller. When I manually engaged this wheel, everything worked. Tape was loading fine. But I had to help it every time. So what could cause this?

old dried out grease

The answer is: old grease. Old grease is grease that, over the course of 35+ years, has started to dry out and instead of lubricating, it starts clogging things. So I had to take the unit further apart to the point where every gear wheel is removed and cleaned.

gear

gear

akai gx-77 plunger arm dried out grease

akai gx-77 plunger arm dried out grease

This plunger arm was very slow returning to it’s default position and probably missed the next turn when the hook had to engage. So I fixed that.

Also the right flywheel (as seen from the back) has a gear on it. This was also very loose on the spindle and could be turned quite easy. I put it in a ultrasonic bath and tried to clean it with IPA. Now it moves a lot rougher.

flywheel with gear

So after almost completely removing all moving parts and cleaning and re-lubing them I carefully put the unit back together to try a cautious test. Here is the result:

As you can see the unit works smoothly now. At the moment the deck is still mostly disassembled but I will put it back together again and then start the mechanical adjustments and followed by the electrical calibration.

Akai gx-77 weer in elkaar

As you can see the beauty is put together again and is recording and playing like new. Very happy with it!

(view count: 544)

A Quadraphonic 8-track player: National Panasonic RS-845us

The JVC, my first 8-track

jvc ed-1240     IMG_20141125_161052

I possess one JVC 8-track player, the JVC ED-1240, a very nice and featureful deck.

The main reason I am interested into the 8-track world is, of course, the fact that aside from 4 track reel to reel tape, this is the only format that has discrete quadraphonic. I realise that the quality of the sound is not up to par like the Studer, or even a normal tape deck, but it will have to do 🙂

The first time I heard this 8-track deck i was very disappointed with the sound. So I found myself a challenge at hand. I have cleaned it, repaired it, refurbished the motor, changed the belt, demagnetized it, changed all the caps on the power board etc. etc. and eventually it performs quite well.teaser

tapes

I cleaned and repadded the 8-track cassettes that I have. I even found it necessary to lube the inside axis a little bit to prevent squeaking and to lower the rumbling and the mechanical noises from the cassettes while playing. The end result is quite pleasing I must say.

But there are still some issues with the player, so if anyone has the schematics, or the service manual, please contact me!

Quadraphonic 8-track

But this post is not about this deck. The JVC is just stereo. This post is about a new one I just bought. A few weeks ago I ran, quite to my surprise, into a quadraphonic 8-track player from National Panasonic, the RS-845us.

Here it can be seen on top of my JVC. At the moment the picture was taken, it was playing a quad tape as you can see by the ‘4 channel’ indicator light. In this mode there are only 2 programs, not 4 as you would find with a stereo tape.

problems ahead

But, alas, this player also came with its problems. I tested it before I bought it, and it was ok as far as I could test it at the time. Coming home, when I could test it for a longer period, I found the same issues I had with the JVC, like irregular tape speed etc. Also the sound was not as good as I was used to from the JVC.

So I did my usual fixup things, like cleaning everything, oiling etc. No good. I quickly found out that the voltage over the motor was dropping several volts at times. I suspected the power circuit board. So i tested the diodes, they were ok. I tested the caps and replaced them all nevertheless, although they were not really out of spec. Unfortunately, that did not help much. New belt. There was some improvement, yes. But still the voltage drop at times, from 12-13V all the way down to 6-7V. The motor would almost stop turning then. And it would squeak a lot.

motor fix

The solution would be to open up the motor and fix it there. That is always a bit tricky but I did it before and I therefore have some experience with the procedure. It went surprisingly well. There was some dust (powder) from the magnets and from carbon brushes. I also scraped clear the spaces between the 3 parts of the rotor (I think it’s called) so there would not be any more shortage. I reassembled a clean motor and lubricated it. When I tested it it it ran very smooth and silent. Cool! The tape speed is also a lot more constant than before. Also the sound seems to have some more punch to it. Maybe it has to do with improved tape-head contact, or with a more stable power supply to the audio board due to the changed caps.

audio fix

But I also have the capacitors ready for a complete overhaul of the audio prints. So somewhere in the next few days I hope I will find time to replace them and see if that will fix the muffled sound. I don’t expect a lot from that action, but hey, that’s what this hobby is all about.

[Update:]

Yesterday I did the recapping of one of the 2 audioprints, i.e. the print for the front channels. This is the result:

When I tested the audio after the process, I found that there was very little, if any at all, change in sound quality. I had made a ‘before’ recording so I could compare the sound.

So I am a little disappointed about that, but I guess the 8-track format was never intended for good audio quality, At least I didn’t break it. 🙂

So while I have all the caps here to replace the rear print also, I will not do that; too much trouble for little or no result…..

Anyway the unit is reassembled now and it playing happily.

(view count: 391)

spotify on openSUSE

 

Hello all,

If you’re looking for a binary to install Spotify on your openSUSE installation, you can download a linux client from the spotify site, but that is a .deb file for debian/ubuntu.

I recompiled this client for openSUSE (tested on 13.2). So I build it for you and you can download it here. (binary from march 2015: spotify-client-0.9.11.27.g2b1a638.81-1.x86_64.rpm)

 

(view count: 118)

Studer A80-R

So, the inevitable has happened.
I have bought a Studer A80-R.

Studer A80

Studer A80

Studio

This is a beast. The unit is 70x60x84 cm, and is the size of a washing machine. And it weighs around 100kg. That is even heavier than a washing machine. It has wheels though. So you can roll it around.
This is the studio recorder that the artists from the seventies used to record their material on. It came in several configurations, from 1/8” (cassette tape) to 2” (24 track). Mine is the A80-R (for ‘rundfunk’ i think) 1/4” 2 track, speeds 7½ and 15 IPS (19 & 38 cm/s). Every studio in the world had one, or several. The most prominent artists that used the Studer A80 are Pink Floyd, Alan Parsons, etc.
I came in contact with someone who has access to professional studio equipment and repairs them on a regular basis, often in his spare time. Sometimes studios get rid of these machines that are in the way, and then he takes them in and repairs and refurbishes them.
I have visited him to look at the machine that I would buy and the second time I went there, the machine was all done and I took it home. Which was not a simple task. It fitted the back of my car fortunately.
After I got it home I wheeled it inside, where it would stay in the living room for the time being. It was simply impossible to get it upstairs.

Here is a short clip:

Challenges

The Studer gave me some challenges. First, the inputs and outputs are the balanced XLR type. I already have adapters to/from RCA which I used for my Revox PR99, but the problem is the line level. My other equipment is home use stuff, so it’s line level is -10dBV. The Studer, being a professional piece of equipment, uses +4dBu. This box fixes the level conversion and the physical connections.

xlr-rca lveveller
Second, the Studer was simply too heavy to carry up the stairs to the first floor where my audio room is. So it sat in the living room, happily enjoying the family life. And, between you and me, it sounds so good in the room.

Caps

Unfortunately, after a few weeks, the left motor, the supply motor, was giving problems because the tension was not there in play. Also, rewind was not possible anymore. A search on the net and my supplier both revealed that on the board 1.080.383 there are 2 transistors that control the 2 motors.P1010315

They are BC141-16 with heatsink on them. On my deck the one for the supply (left) motor was broken. I replaced him twice, but that was not the cause of the problem. The problem was elsewhere. The transistor blows as a result of that other problem.
Further investigation revealed that there could be problems with the tension potmeters that control the tape tension (the A80 has a sophisticated tension control system) or with the motor capacitors that could be faulty after 30+ years. I tested the potentiometer and I could not find anything wrong with it. So I removed and tested all the motor caps (9 pcs.) and found they were not entirely up to spec anymore.

A80 rear - motor caps

A80 rear – motor caps

I replaced them all, and installed a new BC141 just tot be sure. And so far, it works flawlessly again. Fingers crossed.

mechanical calibration

So now that all the caps were replaced, i though that the tape tension was a bit off. So i grabbed the service manual and started the mechanical calibration of the deck. This involves setting the (emergency) brakes, the tape path, the capstan pinch roller, and of course the tape tension and edit mode characteristics back to the desired specification. I have bought spring scales just for this! It was fun to do and the end result is here:

Heavyweight

So I had a Studer A80 in my living room. Now who can say that? It was always clear that it would have to be moved to the upstairs room eventually. When my brother-in-law heard about my problem, he thought it would be a challenge to get it upstairs. So one day he showed up on my doorstep. Long story short, an hour later it was done. Actually, it took almost an hour to do the preparations like attaching the rope appropriately (and carefully!), and it took just 10 seconds to go from the bottom of the stairs to the top of the stairs! So now it has reached its final destination, my “audio room”.

Testing

Being hooked up to some good sounding equipment, my trusty Technics amp and my new KEF Q700 speakers, and using my Philips SACD player as source, I made test recordings and played them back. My tape of choice was BASF 911 and SM900. The results were nothing short of spectacular! The level of OEMPF that his recorder is able to put on tape is astounding! And, those of you who are familiar with analog recording equipment will know that there is always noise (tape noise, vinyl groove noise, FM-noise, cassettes!) when working with these machines. Not so with the Studer! It is so quiet! And that is a piece of equipment that was made around 1970. Incredible.

I am still enjoying this beast. I am tempted to do the technical calibration as well to calibrate it for BASF 911 or 900, but it sounds so good already i’m not sure it would get much better, and there is always the risk of f***ing it up. So for now, i think I’m good.

(view count: 1068)

Latest server uptime record

The last uptime record of one of my linux servers was around 350 days. Today I found another server that has even more uptime: 428 days. Another new record!!

The screendump is as follows:

filezilla:~ # uptime
16:01pm up 428 days 6:48, 1 user, load average: 0.13, 0.10, 0.10

-edit-

Today I found that the server is still up and going strong!! Updated screendump:

filezilla:~ # uptime
 15:29pm  up 697 days  6:15,  2 users,  load average: 0.30, 0.19, 0.15
filezilla:~ #

-edit-

I found another one that is still going strong!!

[root@cygnus2 ~]# uptime
 14:14:19 up 833 days,  4:09,  2 users,  load average: 0.02, 0.01, 0.00

(view count: 139)

A Quadraphonic Akai 1730D-SS

My new addition to the collection is already a few months old, but here is the blogpost anyway.

It is an AKAI 1730D-SS Quadraphonic tape deck that I received from the first owner.

[picture shamelessly stolen from the internet]

When picking it up I tested the deck and only 2 of the 4 channels worked. Only the REAR. Strange. And one of those 2 channels failed intermittently.  When I got home I opened up the deck and had a look at it. I put on one of the many quadraphonic tapes that came with the deck. Quickly I found out that cleaning and fixing the 2ch-4ch switch solved that problem. That was easy.

But the FRONT channels still did not work. At all. No sound, no noise, no click when the deck was powered up, no nothing. I sure hope the playback amp hasn’t died. It appeared there are 4 audioprints in the machine, see picture. At the left of the picture you see the 2 playback prints, at the right the record prints. Each print is stereo. FRONT at the top, REAR at the bottom.


[picture showing the 2 right audio prints removed from their slots]

By turning the pot on the prints I found out wich print was unresponsive (I am going to recalibrate it anyway, so that did not matter). I took it out of its slot for further inspection.



Unfortunately I could not find anything wrong with the print or the components. No burned components, fused caps, burn marks, loose contacts, nothing. I was beginning to feel that I was reaching the end of my knowledge because I have not got expert knowledge of electronics.

When I was going to put the print back into its slot, I noticed something odd about the slot. The slot is a kind of very crude ISA-style slot type, like in the first IBM PC. I saw that the plastic of the slot was broken! That caused the print to not make good contact with the pins in the slot. See the pictures.





When I carefully with my hand pressed the slot so that the print made contact, everything started working! Eureka! ‘There, I found it.’ 

Now how to fix it. Glueing was no option. I soon thought of a tight tie-wrap, that might do the trick. I pulled the tie-wrap as tight as I could. See the pictures.



Then came the next issue. The deck did not want to record at all. I soon found out that the other slots were damaged too (duh). So another set of tie-wraps to the rescue. I put tie-wraps around everything and reconnected it all.

It worked ok, but not reliable. Even when just looking at the recorderprints weird effects on the signal were noticable. First I doubted my tie-wraps, but that solution DID work reliably at the playback prints. Just to be sure I sanded the contacts on the prints and voilá: everything worked flawlessly! So I put the print in and secured them thoroughly. ‘There, I fixed it again’

This is a machine from the early seventies, that has been idle for who knows how long, and I’m surprised at the audio quality.

Now I need to demag it, and calibrate it. Then it will probably sound even better!

[edit]
Although it sounded good at first hearing, further test revealed there was noise in the left front channel ,even when it was not playing. Same on the right rear.

So I replaced the 2sc458 transistors on all the audio prints. After that, I eagerly turned on the machine.

No signal at all!

Remember that I am only doing this as a hobby, I am not a professional guy and I know very little about electronics.

Searching and searching and searching again I found out that the new transistors I had ordered, had a different pin-out than the ones that came of the print. I had put the new ones in with the same orientation as the old ones, that seemed logical but that was incorrect. :) They simply needed to be turned around, so that was relatively simple. I did not need to cross their legs.

After that it worked again, fortunately! Apparently these guys can withstand some rough handling haha. And the best part is, that the deck is silent again now, the noise is gone. I recalibrated it and it sound great!

(view count: 1561)

A problematic Teac X-2000R

2014-03-31 18.59.39

 

 

 

 

 

 

 

 

 

 

 

 

Recently I obtained, for a fair price, a Teac X-2000R. It is a stereo reverse deck, with 6 heads, which means it will record also in reverse. It has dbx built-in, and it can use (chromium) EE tape. A digital counter in hours, minutes and seconds and bias fine tuning on the front panel is also provided. It has 9,5 and 19 cm/s speeds.

Dual capstan

Another prominent feature that is has, however proved to be a very problematic one. The deck is equipped with 2 capstans. This feature was introduced into the later tape deck models, almost towoards the end of the tapedeck-era, to further improve tape-head contact and wow&flutter. These assumptions are correct, and they work well when the deck is in new condition and everything is well calibrated and up to specifications.

On this deck however, things were not new and not up to specs. The dual capstan design is a challenge in itself, but things are further complicated by the fact that it has to function in reverse as well. On this unit that is accomplished by a belt that ‘travels’ across different parts of the flywheel that varies in diameter.

Problems

After the initial cleaning, optical and technical/mechanical, it soon became apparent that the tape handling was not up to par. Sometimes the tape would ‘run away’ from the heads a bit, resulting in loss of audio or worse: tape jam. Things were even worse when playing in reverse. I soon found out (through the service manual) that there were adjustments to be made to the tape tension.

Tape tension

But the increased tape tension was not the solution. When it was ok in forward play, it was bad in reverse. Or vice versa. Or it differed when loading large reels (26 cm) compared to 18 cm reels. Or it was different with different brands of tape. And that wasn’t even reproducible across sessions. And the next day it would be different again.

Solution

Of course the first thing I did was to change the belt. I have a blog of that action, but it is in dutch. So here it is, sorry only in dutch:

====== BEGIN OF DUTCH TEXT ======

Nou, de siem-snaar was snel binnen, en vanochtend was het toch regenachtig, dus aan de slag gegaan met het vervangen van de Teac X-2000R snaar.

Ik heb de uitbouw gedaan volgens de foto’s in deze thread, daar heb ik heel veel aan gehad:

http://www.audiokarma.org/forums/showthread.php?t=59729


Daar wordt behandeld een X-1000R, en die blijkt toch niet helemaal hetzelfde van binnen. Ik kwam meteen al een grote print tegen die in de weg zat, deze is er niet in een X-1000.
Hierdoor kon ik niet bij de bovenste schroeven komen van de plaat waar de capstanmotor op vast zit. De print moest dus los en daarna omhoog gelift worden, er zitten helaas te veel kabels aan vast om hem compleet uit de weg te krijgen.







Na wat kabelbomen losgeknipt te hebben, kon ik de print opbeuren en omhooghouden met een plakbandrol.





Hierna kon ik er wel goed bij.





Nog even de plaat losknippen van de motor zelf:



Er zitten alsnog wat kabels in de weg, maar die zitten gelukkig vast met connectoren. Loshalen die hap dus.





Eindelijk uitgebouwd. De 2 vliegwielen in de achtergrond:



De 2 vliegwielen verwijderen. Goed links en rechts uit elkaar houden.



Overigens viel me meteen op het grote verschil tussen de snaren: de oude is een stuk langer dan de nieuwe. Dus of de oude was wat uitgerekt, ondanks dat het rubber nog vers aanvoelde, of de nieuwe is ietsje te krap. Of allebei.

Toen heb ik alles losgehaald en schoongemaakt en opnieuw gesmeerd: de vliegwielen, de aandrukrollen en het aandruk mechanisme. Oud vet verwijderd, nieuw vet er op. 

Alles zeer grondig schoongemaakt. Vliegwielen er weer op, meteen de washers aan de voorkant weer over de capstans gedaan. Nieuwe snaar er op:



En toen alles in omgekeerde volgorde weer vast. Het was een beetje pielen om de snaar weer over de motor te krijgen, maar het ging uiteindelijk wel. Als laatste de print weer laten zakken en vastgezet.

====== END OF DUTCH TEXT ======

Unfortunately this was not the solution that fixed it completely, although the situation improved a bit. Even increasing the tape tension to incredible heights (or incredible lows) did not fix it. So I went online to find a solution.

Several fora messages suggested that everything in the tape path was relevant to my problem. From tape guides, to the rubber idle rollers, to lubrication of the tension rollers, to the state of the rubber of the pinch rollers. From the tape tension to the smoothness of the tape in question. It seems that everything was related to weather the dual capstan principle would function correctly.
So I soaked the pinch rollers in detergent for one night. The rubber was much softer and grippier after that treatment. Again, a little improvement, but no permanent fix.
I switched the pinch rollers from left to right, to see if that would improve the situation. No way.
I lubricated all the moving parts, I installed the little O-rings that were required for the rollers to function correctly (expensive little buggers!). Still there was no definitive solution that worked all the time.

Meeting

In April I went to a meeting of fellow tape deck enthusiasts where there was an opportunity to work on decks. I tagged the deck along, and fortunately there was an expert who was willing to take a look at the Teac. Immediately he found one problem: I had put the tape tension way too high. We measured more than 100 gr. when 50 was required. He used a Tentelometer, a very rare instrument which he posesses. It looks like this:

After we adjusted the tension to 50 grams, the tape handling was still not good. In fact, it was worse. Then, the guy helping me thought the problem might be in the capstan motor, of which the carbon brushes would have degraded over the years resulting in less powerful drive. So, on the fly he opened the capstan motor, removed the old brushes and (he had them available) installed new ones.20140412_145008 20140412_144659After this, still no good. But I had new carbon brushes! Jeey!

At the meeting we came to the conclusion that maybe the new belt I had put in was not an original Teac spare part but a fake. So I went to an official Teac repair center and got myself an original Teac approved belt. After I installed that belt, still not any better. Grrrr.

The solution!

Eventually, as a sort of last resort, I took the Service Manual and went through all the mechanical adjustments mentioned there. Some I could do, some I couldn’t. For instance, I haven’t got a spring scale necessary to measure torque. And then, finally, after I adjusted the pinch roller pressure to a much lower value, it suddenly all seemed to come together.
When I adjusted for a very, very low pressure of the pinch rollers on the capstans, even to the extend that I could very easily stop the tape when playing, the tape would indeed run fine along the heads and reverse play was no problem. So I adjusted for a little more pressure but anyway now it works great and I haven’t got any more tape issues.

Great sound

After that, I planned to calibrate the deck. This also proved to be not as easy as I thought. The service manual mentions a lot of steps and I think I did them all 4 or 5 times. The problem was that the record calibration required EE or Chrome tape, which I did not have. Fortunately I could borrow a Maxell XLII tape from a friend.
Bu after I calibrated the deck using the EE tape, it did not sound good. The level was way too low. And when I recorded at a higher level, the amount of distortion was unbearable. Something was not right here. After advice given to me on my favorite forum, I used normal tape to do the calibration. It still wasn’t to my expectation. I’m not sure what fixed it, but I repeated the calibration procedure several times, and after that I found the recording to be very good!

EE (chrome) tape

So the deck was performing as it should, reversing as it should, handling tape as it should and now I was to test it with EE tape and with the dbx noise reduction and dynamic expander on.
The result was, well, as close tot the original sound as you can hope for. The high tones were beautiful, and the sound was quiet as a CD. Out of nowhere the music starts. This is tape technology at it’s finest. I am very happy with my new tape deck.

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Installing new Ortofon 2m red cartridge in the Technics SL-1900

Yesterday I received my new cartridge: the Ortofon 2m red. It came with a brush, some screws and a little screwdriver. All in the package for €84,-

2M Red Verso hifisiteI couldn’t wait for a day off to try it so I installed it yesterday evening. I have never before installed a cartridge, and I must admit the thought of doing so was a bit daunting.

I had read a lot about installing and adjusting phono cartridges in the past few weeks so I understood the basics. I had downloaded the Technics protractor from vinylengine.com, printed it and checked the scale of the print. But now it was time to put the theory into practice.

headshell_old

My old-style head shell

I soon realized that this new cartridge wouldn’t fit in the headshell I had designated for it. This is an old style Technics head shell with one screw on the top.

Although only one screw is visible in the picture, it has an additional mounting bracket underneath that should fit the 2 screws necessary to mount normal cartridges. But my Ortofon needs to have the heads of the screws on the topside and that is not supported in this headshell.

new style headshell

new style headshell

But fortunately I have two headshells, the other one is the newer type which has the normal two screwholes at the top. Using the screws which were provided in the package I was able to quickly attach the cartridge provisionally to the headshell.

So that was fairly easy. Next was the task of adjusting the ‘contraption’ 😀 I took my protractor and put it on the turntable on top of a record.

I soon learned that when I moved the cartridge all the way to the front of the shell that the needle followed the ‘arc’ on the protractor perfectly. Yes!

IMG_20131219_212926

using the protractor

But when I tested the alignment of the cartridge on the two gridline patterns on the protractor, I found that it was not perfect in line. So I adjusted it very slightly to the point that it was in line on both patterns and then secured the screws. Pfew! Job done!

 

 

yes-90125

Yes – 90125

 

Then came the testing. I must admit I was a little but afraid, or better anxious. I tried it out with a record from Yes – 90125.

I put the needle down very very carefully.

I put on my headphones.

But as soon as the first tones from the song (Owner Of A Lonely Heart) were played, I relaxed. It sounded very very good!

IMG_20131219_212756

The Ortofon happily playing in my sl-1900

There is a lot of definition in the sound. There is also a lot of ‘punch’, which I like. HF tones are also ok. Bass is tight and well defined. Overall, I have never ever heard a record sound so clear. True, in the past I have not had good quality turntables. In fact, they were rubbish. But I never thought a record could sound like this. It is so close to a CD. I’m also very glad that I treated my records carefully in the past, I didn’t play them a lot (I immediately recorded them onto tape) so that I now have old, but ‘like new’ records that sound wonderful!

I continued to listen to albums from ELO, Marillion, Tchaikovsky and 12-inch’s from Chaka Khan, Unique (What I Got IS What You Need). Those were the first records I found for grabs. It was a good experience. I am pleased. In the coming evenings I will listen to some other albums.

I was surprised how quickly and how easily an inexperienced person like myself could do this task. It took me a little over an hour including the adjustments. I can recommend it to everyone.

Coming up next: cleaning the records with a LP cleaner

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New arrival: Technics SL-1900 turntable

This week I picked up a Technics SL-1900 turntable

1900

Technics SL-1900 (image borrowed from internet)

I was actually looking for a more high end model, like the Technics SL-1600Mk2, SL-1700Mk2, 1800Mk2 or even an SL-5300. But, those are hard to find, and when found, are very expensive and could cost more than €200,-. I found a very inexpensive SL-1900. It still had the original Technics 270 cartridge installed. And it came with an additional 270 cartridge without a needle. So I thought ‘oh, what the heck’, and I went to get it.

I was not disappointed. Not at all. In fact, I was very impressed. For the last years I have used a Dual cs-607, so that was my reference. And although the Dual has more definition, this one is more agreeable to listen to because….well, it has less definition. It doesn’t reveal all the noises and scratches and clicks and pops from the record so much as the Dual does. Compared to the Dual it lacks highs though.

UPDATE:

Please read the next post on how I installed an Ortofon Red cartridge in this turntable. http://pvdm.xs4all.nl/blog/?p=364

Some information from internet:

Description

The Technics SL-1900 is a 2-speed, direct-drive turntable with fully automatic single disc playback. A one-chip IC, incorporating 321 elements, controls motor speed for superb accuracy with servo control. The tonearm mechanism gives convenient automatic set-down, lift-off and stop. Memo-repeat control permits up to six repeated plays of the record, or continuous play. The heavy monolithic bas and isolator system protects against external vibrations. The SL-1900 comes complete with an EPC-270C-II moving magnet phono cartridge.

Some specs:

  • Brand: Technics
  • Model: SL-1900
  • Manufacturing year: 1977
  • Made in: Japan
  • Colour: Braun
  • Power: 4,5 Watt
  • Dimensions: 137 x 430 x 334mm
  • Weight: 7,2 kg
  • Original price ca.: $400,-
  • Direct Drive
  • Fully automatic operation
  • Platter: 310mm aluminium diecast
  • Speeds: 33 and 45rpm
  • Wow and flutter: 0.03% WRMS
  • Rumble: -73dB
  • Tonearm: universal, static balanced
  • Effective length: 230mm
  • Overhang: 15mm

und auf Deutsch:

Technische Daten

  • Antrieb: Direktantrieb
  • Motor: Gegenelektromotorische-Kraftfrequenz-Generator Servo Gleichstrommotor
  • Drehzahl: 33 1/3 und 45 U/min
  • Gleichlaufschwankungen: 0,03% WRMS (JIS C5521), ±0,042% bewertet Null-zu-Spitze (DIN 45507)
  • Rumpelgeräuschabstand:
    • DIN 45539A: 50 dB
    • DIN 45539B: 73 dB
  • Plattenteller: Aluminium-Spritzguss, 310 mm
  • Betriebsart: Automatisch oder manuell
  • Pitch: ±5%
  • Tonarm: Rohrarm, statisch balanciert
    • Nadelauflage: 0 – 3 g
    • effektive Achslänge: 230 mm
    • Überhang: 15 mm
    • Kröpfungswinkel: 21,5°
    • Reibung: 7mg (horizontal und vertikal)
    • Spurfehlwinkel: Innerhalb + 3 (145mm vom Mittelpunkt), + 1 (55mm von Mittelpunkt)
    • Gewichtsbereich für Tonabnehmer: 5,5 – 9,5 g
    • Gewicht des Tonarmkopfes: 9,5 g
  • Tonabnehmer: Technics EPC-270 C-II (MM)

Besondere Ausstattungen

  • Aufsetztpunkt: Einstellbar für 12″,10″ und 7″ Schallplatten
  • Memo-Repeat: wiederholtes Abspielen von ein- bis sechsmal, oder dauernd wiederholendes Abspielen einstellbar
  • Schwergewichts-design: Schweres Polymer-Unterchassis auf Viscoelastisch gedämpften Stahlfedern
  • Motor-Rotor ist direkt mit dem Plattenteller verbunden (war damals von Technics entwickelt worden)
  • Elektronisch gesteuert mit damals revolutionärem One-Chip-IC AN 630
  • hochempfindlicher Tonarm mit Kardan-Aufhängung in Präzisionszapfenlagern. Damals ebenso aussergewöhnlich.
  • Viscogedämpfte Tonarmsteuerung und Anti-skating – damals ein Novum ebenso wie die dicken, kapazitätsarmen Phonokabel.

Information about the cartidge:

Allgemein

  • Hersteller: Technics
  • Modell: EPC-270C-II
  • Baujahre: zum 1976
  • Hergestellt in:
  • Farbe:
  • Gewicht: 6,0 g
  • Neupreis ca.:

Technische Daten

  • Prinzip: MM
  • Frequenzgang: 20 – 15.000 Hz (±2 dB)
  • Kanaltrennung:
  • Kanalbalance: 2 dB (1 kHz)
  • Übersprechdämpfung: 25 dB (1 kHz), 20 dB (10 kHz)
  • Ausgansspannung:
    • 1 kHz, Höchstamplitude: 3,2 mV
    • DIN 45500: 6,4 mV
  • Abschlusswiderstand: 47 kOhm – 100 kOhm
  • Induktion:
  • Nadeltyp: Diamant elliptisch
  • Empfohlene Auflagekraft: 1,75 ±0,25 g
  • Nadelnachgiebigkeit: 12x 10^-6 cm/dyn

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Checking out dbx encoded discs (vinyl)

The other day I received two dbx encoded 7″ singles, demonstration discs by Technics. These are supposed to have superior dynamic range and almost no noise/hiss/rumble whatsoever.

IMG_20131203_151004

IMG_20131203_150842

IMG_20131203_150830

First some background:

dbx was also used on vinyl records, from 1973 until around 1982, and over 1100 albums were released with dbx encoding, which were known as dbx discs. When employed on LPs, the dbx Type-II system reduced the audibility of dust and scratches, reducing them to tiny pops and clicks (if they were audible at all) and also completely eliminated record surface noise. dbx encoded LPs had, in theory, a dynamic range of up to 120db.[3] In addition, dbx LPs were produced from only the original master tapes, with no copies being used, and pressed only on heavy, virgin vinyl. Most were released in limited quantities with premium pricing. [wikipedia][

Well, the accompanying sheet suggest that you hook your equipment up to a dbx capable (cassette) deck, but I didn’t. Instead, I connected my dbx model 150 unit. Better!

On all 4 sides was music, mostly jazz-like. On side A of the first disc was an impressive dynamic piece with flute and big drums. I was very surprised when the drums reached full power! And they go very loud! It is an extremely dynamic experience. Even on headphones.

Clicks and pops  and other vinyl noise are so unnoticeable, the whole listening experience is very, very enjoyable. Even the dropping of the needle was hardly audible. Now, I need to find me some other dbx encoded discs!

edit: while writing this down, I’m thinking about what would happen if I record this on a tapedeck with dbx encoding.
Or better: skip the decode and encode step, and record the disc as-it-is on tape, and the play it back through my dbx unit….interesting experiment. I should try that some time.

-Philip

 

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A few months after my purchase of the Philips N4520 tapedeck, it developed a nasty fault: during playback there would be cracking sounds coming through the music, or even when not playing at all. Also when touching the knobs, there would be pops and clicks.

An intensive internet search revealed that there were more decks affected with the same symptom. Fortunately, a remedy was also given: replace the transistors on the main circuit board with new ones. Gulp. All 19 of them.

I have some experience with soldering, but this was a completely new level for me. I happen to be in possession of a very good soldering station with temperature control, and I have used litz wire once or twice, to remove solder of the component you want to remove.

IMG_20131101_171351IMG_20131101_171428So, I ordered the necessary components on-line:

 7x BF245A : TS2 TS5/TS105 TS4/TS104 TS3/TS103
 1x BC547 : TS11
 4x BC548 : TS8 / TS108 TS9 / TS109
 2x BC549 : TS1/101
 1x BC557 : TS10
 2x BC546A : TS6/106
 2x BC556A : TS7/107
IMG_20131101_135434

My new friends

Total number of transistors: 19 pcs.
Total cost: around € 10,- excl. transport.

Then, the scary part started.

Taking apart the biggest monster in taperecorders known to mankind.

 

 

 

Well, almost. And, as I found out, the bottom part slides out fairly easy to the front. And it is connected to the rest of the machine with connectors. So in the end you have the bottom part which contains the ‘mainboard’ as I call it as a separate unit on your workbench.
IMG_20131101_135115
IMG_20131101_135124

 

 

 

 

 

Locating the components on the printboard was difficult, but doable. Then soldering started. Using the litze wire to remove the solder from the board, I was able to remove the components.

IMG_20131101_135219

Don’t shake!

IMG_20131101_171544

My old friends. Well, not my friends anymore!

Working methodically through all components, I replaced all 19 of them. Double-checked the joints for good contact. Cut away the excess pins. And I was left with this:Then it was time to test. To do that, the mainboard had to be reinserted into the recorder and reconnected.
And?

It worked! Yeaj! I now have a N4520 that plays back and records beautifully! It took about an afternoon’s work and about ten euro’s, but Then you have successfully restored a very very nice machine.

IMG_20131101_150513

The glorious Philips N4520 in action 

See a video of this beast in action on my YouTube channel:  http://youtu.be/UTS9aYsIH2k

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Servicing the new ReVox PR99 with new VU lamps and roller bearing

Hello all,

Today I have been busy servicing my new ReVox PR99. This deck is built like a tank (to use an too often heard metaphor regarding tape decks) and it is working well. It is a 2 track deck which is designed for heavy use, like in studios and broadcast facilities. It is world famous for that.

But when I received it – actually I fetched it from way across Holland – I immediately noticed three small things wrong with it:

  • the VU meter lights were not working
  • the left tape guide roller bearing was making noise
  • and the infrared tape sensor incorrectly identified tape as being leader tape and switches off. This happens with some tapes that are apparently too thin 🙂

So I ordered and received 2 spare bulbs (from a webshop) and one new roller bearing (from ebay Germany) and opened the unit up.

P1020831

P1020832
rear view

 

 

P1020841 P1020842 P1020843 P1020844 P1020845 P1020846 P1020847 P1020848 P1020849 P1020850

 

 

without case

 

 

 

 

 

 

First I removed the siderails and the frontplate knobs

 

 

 

Then I removed the face plate all together.

 

 

 

 

 

Get the meters and the controls out

 

 

 

 

Remove old and insert new bulb

 

 

 

 

Testing….yes! Part 1 is done!

 

 

 

 

Remove the bits around the heads.
Also a good time to do some cleaning.

 

 

 

 

Remove the old roller bearing

 

 

 

 

And put the new one in place. Part 2 done!

 

 

 

 

 

Also put the unit on 240 Volts

P1020834new

 

 

 

 

This is the test point where the tape sensor should be measured

 

 

 

 

And this is the potentiometer that should be adjusted.

 

 

P1020852

 

 

All done! There is light in the dark!

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New arrivals: Philips N4520 & Teac X-300

New decks

All of a sudden the tape recorders are pouring in. At almost the same time I got hold of a Teac X-300, a small 18 cm reel deck from one of the last series made by Teac around 1987, and a Philips N4520 from around 1978, which is THE kick-ass deck to have from Philips if you want to do serious business. It is really monstrous.

Philips N4520

The Philips N4520 has some unique features not found on other decks or only on very expensive studio decks, like

  • bias adjustable from the front panel
  • wind speed is adjustable on the front panel
  • electronic tape counter in 1/10 meters
  • Selectable equalization (at 38 cm/s) after NAB or IEC
  • cue buttons for fast winding&play without using the stop button
  • peak hold (yes, on analog VU meters!!) with peak leds as well
  • mini input mixing console with master fader
  • constant tape tension, so no reel size switch needed. Even when winding!

Listening

After listening to my first test recording on the 4520 with new and fresh SM911 tape through my Sennheiser HD-600 I was really blown away by the depth of the sound! It appears the 4520 has a build-in headphone amplifier that is very very good! It adds a lot of OEMPF to the sound. I did not know a good phone-amp was that that important to the overall sound. Also the sound quality on the line level is astonishing. The only difference when comparing the recording to the original is the tape noise, which is by the way very low. But that can be solved by using my newly bought (I haven’t told you yet. Sorry about that) DBX units.

Mods

Anyway, this Philips is the top of the line from all Philips tape decks. Among audio enthusiasts it is a very sought after model. It has some weaknesses, but mine has been under repair and is now ready for use. Also some modifications only found on later produced machines have been done. Sonically, I think it is my best sounding machine. But a comparison between my Tascam 34B and this baby will probably happen in the not so near future.

Teac X-300

Not forgetting the other new deck, the Teac X-300. It is a compact built unit, as it only carries 18 cm reels. It is one of the last series built by Teac, and it shows. It has a plastic look and feel, however, when you operate it it feels very robust. It is capable of handling the new EE tapes (or chrome) with superior audio characteristics which unfortunately have not been very successful when they came out in the mid 80-s. I do not own such a tape, so I can not test it.

This unit came very cheap, only €50. It is in e very new state. I don’t think it has many hours on it. Everything on the deck feels new and fresh, like the brakes and the controls etc. When comparing the sound quality using SM911 with the new N4520 it came sooo close, I was really surprised. This is definitely a keeper, if I can live with the small reel limitation.

Tomorrow I will add some photos to this article

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Some simple math…..proving 0,999999999 equals 1

I am going to prove to you, using standard algebra, that

0,99999999999….. equals 1.

Now I know that if you have even a basic understanding of maths you say: ‘I know for sure that’s not true’, but I will show you otherwise.

So here is the breakdown:

    1. let’s start by substituting 0,99999999999….. with the letter a, so

a = 0,99999999999….. 

That is easy huh?

 2. now say 10 times a would mean

10a = 9,99999999999…..

that is still right, right? I don’t believe that there is any need for discussion here.

3. if we substract a from that, of course you have to do that on both sides of the equal sign, we get:

10a – a = 9,99999999999…..  – a

still a correct formula.

4. 10a – a is of course 9a, so:

9a = 9,99999999999…..  – a

 5. but since a = 0,99999999999 the right side of the formula could be written as 9

9a = 9

6. and that means that a must be 1

a = 1

7. combining step 1 and step 6 I have proven to you that

0,9999999999….. = 1

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The surprising Teac A-3340S

From a friend of mine I recently received a Teac A-3340S in good condition. Here is a picture of it:

IMG_20130802_090644

Teac A-3340S in good condition

My friend had just acquired it and asked me to take a look at the levels and to do an overall adjustment of the deck for him. This is I believe the first 4-track quadro deck by Teac, introduced in 1973. The deck is very very heavy and very very well built. This particular deck is also very well kept, there are no signs of usage and it looks like it has just come out of the shop. Remarkable as this deck was in production from 1973 until 1978.

IMG_20130802_090704 IMG_20130802_090722

 

 

 

 

 

 

 

 

 

 

 

After I serviced it, it sounded wonderful! It was a pity I had to return it to my friend, but well, it was his deck.

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I found a fine new tapedeck: Philips N7300

A few weeks ago I found an interesting tape deck online. It was a deck from Philips. It was close by so I immediately e-mailed the seller and after some conversation I fetched it with the car. It was a good price. Although Philips are not well known for the quality of their consumer decks (whereas their professional decks ARE good) I was interested because this was their last model that they made before production stopped because of the changed market conditions, everyone wanted a cassettedeck.

I believe it was produced in 1983, so it is fairly modern in its technique. It has controlled tape tension amongst other things.3 speed: 4,75 & 9,5 & 19 cm/s. It takes the BIG reels. Pitch control.

P1020407The problem with this deck is that it is entirely made of plastic. And I mean not just the front and the chassis, but even the cog wheels and everything inside. The result is that it is very light, especially compared to some of my Teacs and Tascams. So far nothing has broken. This would be a big problem as it seems to happen a lot and the plastic parts are, well, impossible to find or replace. Fingers crossed! The only thing that didn’t work was the on/off switch, but I managed to secure it in the ‘on’ position and I just unplug the unit to switch it off. Works for me!

Philips N7300 with tone generator

Philips N7300 with tone generator

So, after the holidays I managed to find time to do my adjusting and tuning. The Service Manual was quickly found on the net and then I started work. Unfortunately the SM is, well somewhat vague in some parts. It was quite the struggle I must confess. I could put my new oscilloscope (also from Philips BTW!) to good use. In the process I found out I still need to learn to use the scope better. But I managed.

I just finished the work recently and did some tests with test signals and some music. I must say that the results are very, very good. Did I mention that this is a very good sounding deck? Switching between source and tape it is very hard to hear any difference at all. I use new BASF LPR35 tape. Especially at the middle speed of 9,5 cm/s it performs remarkably, delivering very close to the same audio quality as at the highest speed. I was really surprised.

Even at the slow speed, at 4,75 cm/s it was very acceptable. One could use that for parties where the music will not be played loud, for background use. A full reel 26 cm with 35 micrometer tape has 1100 meters on it, giving a playing time of almost 6 1/2 hours! Using the thinner tripleplay tape of 25 micrometer gives even longer playing time of 8 1/2 hours.

Overall I am very pleased with it. This will probably become my main deck for 4 track stereo recordings, where the TASCAM 34B is the main deck for 4 track quad recording.

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koolmees

English text follows below:

Hier een filmpje van onze huiskoolmezen. Eigenlijk zijn het geen echte koolmezen, maar een andere mezensoort. Welke dat is, dat weten we niet 🙁 Ze hebben een kuifje….

Sinds enkele weken hebben we jonkies in ons vogelhuisje. Op dit moment staan ze op het punt van uitvliegen. Ik heb hiervan een filmpje:

English text:

This is a clip of our domestic tomtits. They’ve got a tuft….

For some weeks now they are in our birdhouse. At the moment they are on the verge of fledging. I have got a clip of this:

 

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Another server uptime record!!

The last uptime record of one of my servers was around 300 days. Today I found that the server still hasn’t rebooted and that has even more uptime: 353 days. Another new record!!

The screendump is as follows:

fotoserver:~ # uptime
 08:35am up 353 days 16:55, 1 user, load average: 0.14, 0.05, 0.06

(view count: 367)

New project: Sony TC-378

Sony TC-378

Sony TC-378

This is my new project, the Sony TC-378. This is the ’tilted’ tape recorder, the front plate is hanging back, although is is not very visible in the pictures. The message given to me when I got it was that it worked ok and the pause button was missing.

Well that is both true. It plays nice and the pause button is indeed missing. It is possible to use the pause function however. This unit has the nice feature of a pinch roller that is moving out of the way when the tape is not playing. That is very clever because the tape path is clear when loading the tape. No fiddling the tape in between the capstan and the pinch roller. How this construction will last over the years is of course another question. And pinch roller pressure is of course also an issue.

TC-378 open

TC-378 expanded

The only thing that is in need of fixing at the moment is the supply reel. When rewinding, it makes a screaming sound that is impossible to bear. I guess there is something wrong with the bearings. I will have to look into that.

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Finally calibrated my Tascam 34B

Teac A-3440

The ‘older’ Teac A-3440

 

This past week I finally got round to working with my recently bought Tascam 34B. Ever since I got it a few months ago, I haven’t been satisfied with the sound at all. And surely not for this kind of machine. The tape transports are ok, very good exactly. The overall look and feel is excellent, working with it is an absolute joy.

But the sound was not ok. The sound was a little bit muffled, and some highs were absent. My older Teac A-3440 sounds a lot better. But of course, that deck I have already tackled. Using some other decks I finetuned my skills over the last few months, and now I felt the time was right to take on the big mighty TASCAM 34B.

Fortunately I had the service manual (recently purchased on the internet for a few euros, it was not freely available) so I used that as a guide. Other tools I used were my trusty calibration tape, a blank tape of LPR35, my old Philips scope (which will be replaced by a better scope, more on that later), my Philips analogue voltmeter PM2505, and software called Visual Analyser (for spectrum).

On the workbench, my 34B looked like this:

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TASCAM 34B with face plate removed

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TASCAM 34B bottom view. Notice the adjustment ‘knobs’

So, after a lot of fiddling with the potentiometers, measuring levels, changing tapes, etc. etc. I was done. So I eagerly recorded my first music onto it, played it back and …………..

Wow!

The sound was really, really great! I used CD recordings of Dire Straits, Donald Fagen, and 4-track surround (quad) music of Pink Floyd, The Doors, Doobie Brothers and Queen – Bohemian Rhapsody to test, and I could hardly, if at all, distinguish between de CD and the tape.

This is truly amazing. I did not know a tape recorder could reproduce sound this good. As you can notice, I’m happy with the modifications I have done.
I don’t think this baby will go anywhere anytime soon, it will stay with me.
tascam 34b small

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