Lets Talk Belts

I'm fairly new to this forum and wanted to share my experience as far as belts are concerned. As most of you guys are aware, a belt change on a unit is the core of your sound experience. I have found this out the hard way, trying to figure out why I'm still getting loads of W&F after a full stripdown and reassemble replacing all the rubber and oil/grease etc along the journey.

So I wanted to start a chat along the lines of belts and what you guys think/recommend, as a starter this is what I have found -

I personally buy most of my belts from CPC, but they don't have lower than 0.9 square and even then they are limited size. However, I have found they are the best for being uniform and therefore reduces W&F massively. Even if I have to put oversized belts on a unit I will do it because if it fits, the pros outweigh the cons. Decktech and fixyouraudio are good but some times the belts are hit and miss and seem expensive but I may be being picky. I had a chat once to fixyouraudio about uniformity they just said they do their best as production can be difficult and I do still buy from them because sometimes you can't get them anywhere else. Another place that's good for belts is https://www.donberg.co.uk but you have to put a big order before they will deal with you, however, the belts are great no problems at all, and they have sub 1mm belts too.. So if I were to rank belt quality and buying order it would be
1) CPC
2) donberg
3) Decktech
4) Fixyouraudio..

What do you guys think ? ..

BTW Don't you just hate when you open a unit and the rubber belt has turned to black tar goo! it gets everywhere, nasty stuff..

 

There are 2 sources that I would recommend regarding belts: fixyouraudio.com and Deck Tech on ebay. Have no experience regarding CPC and donberg, so cannot say anythig about them.
Keep in mind that thicker belts are easier to be made more uniform than thin belts. However, many units (I'm reffering to walkmans in particular here) that were designed to be used with a thin belt will work better with such a belt, even if it's not as uniform as an oversized belt.
Please post some wow&flutter measurements using different belts on the same units, I would be curious to see what the difference is between manufacturers.

I bought a lot belts from Marian (fixyouraudio.com) and did not experience what you are saying. In fact, all of them were made to high standards.
They are a little expensive, but I can guarantee you they're one of best ones available and also the newest ones regarding date of manufacture.
Other members of this forum have the same experience regarding Marian's parts.

If you are looking at the belt when running and can see minor cross section differences, that does not necesssarily mean they are bad. You need to measure the wow&flutter.
For example, on a WM-EX5, that uses a very thin belt, I can see minor cross section differences when the unit is running, however the wow&flutter is 0.2% WRMS.
And wow&flutter is influenced by other things, like rotating parts not moving freely, dry capstan bearings, dirt inside the pulley grooves, etc.

I also used belts from DeckTech and can say they're good quality, but some of them are a little old. The good part is they have belts specifically made for a lot of rare units.

In general, I prefer to use a belt that is specifically made for a particular walkman or deck, as that's the ideal solution.

You can read a more complete post about wow&flutter I made recently. I recommend reading the entire thread, as there's plenty of useful information.
https://stereo2go.com/forums/threads/wow-and-flutter-my-know-how.19/

My question to you would be: what figure of wow&flutter do you consider acceptable ?
In my opinion, walkmans that do not have a spec for that and obtain 0.2% are good enough. A deck that uses a flat belt might get to 0.1%, but I would not expect much lower than that. 0.05% is already a spec for a direct-drive quartz-locked unit.

 

To my ears, 0.2% WRMS is usable for lot of pop-rock stuff, but the second you try something with slow strings or piano you hear it is not good enough. 0.15% is ok for listening to most stuff. 0.25% is unusable.

A component deck with more than 0.1% WRMS is garbage despite that it is listenable. One must take into account that distortion on recording and playback adds up. A decent deck has it at 0.05% or less.

DIN values are approximately twice larger.

 

Hi Valentin, thanks for your reply, I have amended my original post it didn't read right, and I don’t what to upset anyone. I have loads of belts and parts from all the suppliers and they are all excellent, but I just wanted to share my experiences and get a discussion going.

I did write the post after being puzzled for hours on a unit (WM-FX50) why I was getting so much wow&flutter, I had a new belt on there and ignored it as a cause, then I noticed after a while the variation in size while running, so I changed it out 3 times till I got a good one and this really solved the issue, so I guess I was a little frustrated.

I always make sure like you said “check for rotating parts not moving freely, dry capstan bearings, dirt inside the pulley grooves, etc”. I Normally use watch oil and/or lithium grease and use pointed cotton buds and/or a small toothbrush dipped in IPA ( not beer) to clean the pullies.

I will definitely do a comparison as you recommend with oversized belts and different supplies that's such a great idea. I will post the results here.

 

@CDV The values I am talking about are based on measurements I have done myself using a non-professional test tape (in reality the values are lower, but I don't expect a huge difference). I intend to buy a professional test tape to see the real values.
If we look at service manual specifications, 0.05% is a spec that is only found in either: direct-drive decks or disc drive portable recorders such as the TC-D5M. For instance, even the Revox-B215, which is a high end deck has a spec of only 0.05% WRMS.
What I want to say is this: if we set 0.05% as the standard, then it would mean most decks and walkmans will fall short of this standard.

Something that is also worth mentioning is the cassette shell itself: it can play a significant role in the wow&flutter. Some tape spools are deformed and the tape threads unevenly, creating a periodic friction. The friction material used between the shell and tape also plays a role.
This is especially true on pre-recorded tapes that usually don't have the best quality shells.

@Simon Green A comparison would clearly bring more light into this matter. I am personally satisfied with the figures I have posted above. Some of the units that I have refurbished were sold and the customers were very happy with the results. Of course, that does not mean things cannot be improved.
I am also interested in your opinion about what wow&flutter value should be considered good and what is the threshold above which it's considered unacceptable.

 

This is a budget Technics RS M24 — 4 belts (3 for main mecha, 1 for the counter). Check the specs below, click the image for larger size. I have a variant of this deck that uses the same exact mecha and has the same specs, a Panasonic 635 a.k.a. M205. I measured 0.07% WRMS using a non-professional tape on a 40-year old machine that has probably never been serviced (there is a grinding noise when it plays, a bearing? I probably need to lubricate it before it stops working).



Many highly regarded decks have middling or crappy specs including W&F, see the specs from 1992-93 Stereo Review's buying guide along with the TEAC W-1200 numbers (both as spec'd and as measured by several users). Most machines from that period priced between $200 and $500 have W&F within 0.04%-0.08% WRMS, and super-expensive machines are not much better.

I find it hilarious how owners of Nakamichis or Revoxes looked down at "black plastic crap" machines only to find that the TEAC W-1200 is in fact usable if all they want is to play pre-recorded cassettes, which have very little residual W&F. This just tells enough about these people: they are snobs, they do not have "golden ears", and their equipment may carry a fancy brand name but have middling performance.

To me up to 0.15% WRMS for an inexpensive play-only device (walkman or small boombox) is ok. It is unfortunate that my favorite cheap walkman has W&F too high to listen lots of music, not necessarily classical, for example I clearly hear wobble when I play Enigma or Sarah McLahlan. I expect better performance from an expensive machine. I would be very unhappy if I bought an expensive "serviced" or "repaired" machine with W&F higher than 0.15% WRMS, no matter a component deck or a walkman.

For a standalone deck that will be used for recording it should be below 0.1% WRMS, which is why the current offerings from ION/MarantzPro/Pyle/TEAC are all garbage. At least the first three are priced more reasonably, but they also seem to have actual performance significantly worse than spec'd — Mike Rivers measured 0.25% WRMS on a Marantz Professional, what horror! The TEAC machines perform better than specified, but seriously, 0.1%-0.15% for a $500 component deck is a pitiful performance, and 0.25% WRMS as specified would be unacceptable even for a boombox back in 1980s.

 

That's interesting... I would be curious to make more measurements on different units using a professional tape. 0.07% is pretty low for a belt-driven deck. I measured 0.05% on a Technics RS-BX606 (direct drive). The 2 seem very close to each other...
On walkmans, I have only measured below 0.1% in disc drive units: the WM-D6C, the WM-D3 and the TC-D5M. They were all between 0.05-0.08%. And the interesting parts is they're the only ones which have a spec for wow&flutter. I don't think that's a coincidence.

I saw your video regarding the TEAC W-1200 deck and also VWestlife's. Your opinion is clearly very different than his. Personally, as I stated in the thread comparing DAT with metal tape, the compact cassette has some inherent disadvatages and wow&flutter is one of them.
That's why I may not have such high standards. For example, if I compare the same music piece played on a DAP and on a belt-driven walkman, then I can clearly hear the difference. But otherwise, what's below 0.2% is ok to my ears (in reality it is lower due to the non professional tape).

Let's see what @Simon Green will measure. I'm really curious about his measured values.

 

I wonder which personal stereos, not necessarily Sony's, have W&F between 0.1% and 0.15% WRMS in your testing? Also, the EX6XX to EX9XX Sony models if you measured them.

 

Let me state some: the SONY WM-3, SONY WM-7, SONY WM-EX5, SONY WM-B603, AIWA HS-PC202 MKIII, Toshiba KT-4176, Toshiba KT-S3, Panasonic RQ-S25, Infinity Intimate, JVC CQ-1K, Sanyo MGP33 and others.

All the above-mentioned have been completely restored, meaning: disassembly, cleaning of old grease, lubricating the shafts of all rotating parts, cleaning of pulley grooves, lubricating the motor, new belts, new pinch rollers when needed.
All of them measured somewehere between 0.15%-0.22%. The TC-D5M measured 0.05%, the WM-D6C measured 0.04% and the WM-D3 measured 0.08% (this one I stated on the restoration topic when you asked me).
Regarding the WM-EX6XX and EX9XX I have not measured any in that series and don't have any in my collection to make a measurement at this point.

Do you have belt driven walkmans which perform considerably better than what I have stated ? If so, what have you done in order to achieve that figure ?

 

The best portable (not a boombox) cassette player I have is a Sony WM-FX435. This is a 1995 model. I've done nothing to it. Haven't opened it. Everything works except for autostop, such a bummer. It has about 0.15% WRMS and the speed is a bit high, I need to double-check whether I can adjust the speed without taking it apart.

I have a small Sony cassettecorder (boombox) that has astounding 0.07% WRMS.

 

I see. In general, I would expect decks and boomboxes to have better wow&flutter due to one particular reason: they tend to have bigger and hence heavier flywheels. Also, the mechanism that use flat belts have lower w&f than the ones which use square belts.

What model is that boombox with 0.07% WRMS ?

 

Sony CFM-130.

 

Being honest, I did not expect that. It seems a very basic boombox. It leads to the possibilty that the original belts may be of much better quality than many replacements that are available today, as Simon stated in his first post.
However, many walkmans have their belts turned to goo, cracked or loose. So keeping the original one is not always an option. Does your WM-FX435 has the original belt or was it replaced at some point ?

I recently repaired 2 SONY WM-3s, which both started at about 0.55% WRMS before doing anything. After the restoration, the w&f went down to 0.2%, which I think is a considerable improvement.
I start to wonder what a new WM-3 w&f should really be. I clearly won't expect anything below 0.1%, but maybe it can be better than 0.2%.

Also keep in mind that you need to repeat the test a couple of times by starting and stopping the unit (eventually winding the tape in a different position), because if the variations recorded on the test tape happen to be out of phase with the mechanism variations,
they will cancel each other out, giving the impression of a lower value than the real one. They will only add up if they're in phase.

 

As a matter of interest what W&F software are you using, i use wfgui , but don't get the graphs you do ? I just , I thnk any walkman @ 0.2 wrms and below sound fine to me..

 

@Valentin, I believe the FX435 has never been opened. I looked at the seams, and they are clean. It is almost impossible to open these players without leaving marks.

@Simon Green, I use WfGUI. If you leave the dropdown selector in "DIN" position, then "Peak to Peak" is W&F according to DIN 45500, and RMS numbers are values calculated according to JIS standard. And because they are weighted per JIS standard, they are effectively W. RMS.

 

I have found 2 reviews made by @walkman archive and seems that his TPS-L2 (also restored) is on par with my measurements: 0.219% WRMS. http://www.walkman-archive.com/gadgets/walkman_sony_01_tps-l2_eng_v3.htm
One of the best walkmans at the time, the AIWA HS-P08 measured 0.186% WRMS, which could be rounded to ~0.19%. Very close to the 0.2%. http://www.walkman-archive.com/gadgets/walkman_aiwa_02_p08_eng_v3.htm

I mean, yes they're not great in that regard, as Hugo notices that himself, but for a belt driven walkman I think it's more than reasonable. Of course, disc drive units will easily go below 0.1%, but it's a different type of mechanism.

Other members which have the TPS-L2/WM-3 are invited to do some wow&flutter measurements to have some more reference. But given the review, I tend to believe that the recently restored WM-3s are within original specification.

 

Can somebody measure the ZX-7, the only boombox (to date) we have captured in the DD line overview?

 

What can I say, 0.2% WRMS is too much for something I would want to pay real money. I cannot believe that there is such a big chasm between 0.04%-0.08% of quartz-controlled DD models and 0.2% of everything else. If anything, the last cheap generation of Sony walkmans seem to provide reasonable numbers around 0.15%, although I would prefer something closer to 0.1%. I need to look for W&F tests of slim aluminum clamshell models that were so common to the Japanese market, but seldom reached other countries. It would be a revelation and a shock to me, if these expensive slick machines have the same W&F as a $25 plastic almost disposable walkman. I think I want a big old chunky one like D3 or D33, and a super-slim metal one. Just two of them. I will maybe keep the FX407. Everything else I have will go on eBay.

As for belts, I bought from Marian several times, and I bought from some guys that sell generic belts which are thicker. In almost every case Marian's belt improved W&F compared to a thicker belt by 0.2%-0.5% WRMS. In one case there was no difference, in another case I preferred a thicker belt, because I think I did not clean the gunk well enough, so a thinner belt would fall deep into the groove, where all the remaining gunk was, so the walkman would squeal. Or maybe this early walkman from 1990-1999 series was simply designed for a thicker belt.