Working CD-4 (software) Demodulator!

[DanielTheGreat]

... I did want to comment that I have cleaned my entire collection via ultrasonic cavitation and cannot recommend it highly enough. It can really get the crud out.

Matt,

Could you please share some information about the specific ultrasonic machine you used to clean your discs? On recently looking into this method, I learned that there are really two 'classes' of ultrasonic cleaners for vinyl records: those purpose-designed and built just for record cleaning, and those that use an off-the-shelf general-purpose ultrasonic cleaner and adapt it with a mechanism on top to dunk and rotate the disc(s) in the cleaning solution. The former type seem to cost $thousands, while the latter go for 'only' several hundred $.

The purpose-built manufacturers make claims that theirs work better than the 'DIY' types because of the location/direction/power of the ultrasonic transducers. I've also seen some manufacturers specify a cleaning solution that contains alcohol (horrors!)! Does yours?

Thanks,
Daniel

 

[bigbillquad]

Matt,

Could you please share some information about the specific ultrasonic machine you used to clean your discs? On recently looking into this method, I learned that there are really two 'classes' of ultrasonic cleaners for vinyl records: those purpose-designed and built just for record cleaning, and those that use an off-the-shelf general-purpose ultrasonic cleaner and adapt it with a mechanism on top to dunk and rotate the disc(s) in the cleaning solution. The former type seem to cost $thousands, while the latter go for 'only' several hundred $.

The purpose-built manufacturers make claims that theirs work better than the 'DIY' types because of the location/direction/power of the ultrasonic transducers. I've also seen some manufacturers specify a cleaning solution that contains alcohol (horrors!)! Does yours?

Thanks,
Daniel

Hi. DanielTheGreat

I think that the companies that would say these things is to put off buying a "DIY" unit, which are professionally put together and a ultrasonic cleaner is a ultrasonic cleaner I have bought this unit ( https://www.alibaba.com/product-det...rasonic-vinyl-record-cleaner_60548164575.html ) and I highly recommend this unit.
All record cleaners have formula which has 95 to 100 present pure alcohol & detergent in distilled water, the shop I bought my unit from said when they had tried these standard cleaning fluids found that they had to modify the fluid to work better using a ultrasonic cleaners.
And the shop owner showed me in the back of the shop in a clean room there was 6 of them units in use.

 

[DanielTheGreat]

Bill,

Thanks for the info about your US record cleaner. Looks like a good model, but sadly the postage from China (almost 2/3 the item cost) pushes it beyond what I'm prepared to pay. So I'll probably end up going a DIY route.

I would advise against using any sort of alcohol in the cleaning fluid, despite it being commonly recommended, and included in many commercial fluids. Some vinyl experts, including the CD-4 guru, the late Lou Dorren, say that alcohol removes some of the plasticiser (some use the term 'lubricant') from the vinyl, eventually leading to hardening and micro-cracking, which ultimately increases the surface noise.
https://www.quadraphonicquad.com/fo...n-a-new-cd-4-demodulator-archive.9035/page-19https://www.yoursoundmatters.com/is-it-safe-to-clean-vinyl-records-with-alcohol/
Distilled water and a surfactant (Photo Flo or similar) seem to be the recommended mix, perhaps with a little ethylene glycol.

Daniel

 

[bigbillquad]

Hi. DanielTheGreat

Thanks for your feed back on cleaning fluids.....

 

[Soundfield]

I would advise against using any sort of alcohol in the cleaning fluid.....

Distilled water and a surfactant (Photo Flo or similar) seem to be the recommended mix, perhaps with a little ethylene glycol.

Unfortunately, ethylene glycol is an alcohol.

Not that it makes much difference if you were to use it, since Kodak's Photo Flo 200 is just two other alcohols and water anyway (!), their data sheet states :
2. COMPOSITION/INFORMATION ON INGREDIENTS
Weight % - Component - (CAS Registry No.)
60-70 Water (007732-18-5)
25-30 Propylene glycol (000057-55-6)
5-10 p-tert-octylphenoxy polyethoxyethyl alcohol (009002-93-1)

 

[DanielTheGreat]

Ethylene glycol is not an alcohol, though they are related.

After further research, I agree Kodak's Photo-flo is NOT recommended for vinyl records. Instead you should use Ilford's Ilfotol Wetting Agent, which is a different formulation, safe for vinyl.

Daniel

 

[DanielTheGreat]

OK, looks like Ethylene glycol is an alcohol – sorry, chemistry is not my forte. So let's drop that and just stick to distilled water with 5% (by volume) of Ilfotol added, for wetting.

Daniel

 

[Brice]

For the best reference when it comes to cleaning all records: acetates, 78s, and LPs you have to go back a long way, to the end of the nineteen-fifties, to a report by a team working for the US Library of Congress under a research grant from the Rockefeller Foundation.

Preservation and Storage of Sound Recordings. Pickett, A.G.; Lemcoe, M.M. (US) Library of Congress Report 1959

This is a master work of real science. But, of course, it's too early to cover ultrasonic cleaning.

In any cleaning activity, a surfactant is needed and a non-ionic surfactant like Ilfotol is good. Domestic dish-soap (washing-up liquid), like Dawn in the USA or Fairy Liquid in the UK, are not the most suitable detergents for record cleaning because they consist of powerful anionic surfactants which do nothing to neutralise the negative electrical charge present on the PVC disc, and may contribute to it.

However, Ilfotol does have some nasty chemicals in it (Methylisothiazolinone). There exist detergents (largely used for cleaning in hospitals and non-static environments) which are ideal and contain no nasty "added extras".

One such neutral detergent is Tergitol made by the Dow Chemical Company. The Library of Congress now employ Tergitol for record cleaning diluted to 0.05 percent in deionized water (ARSC Guide to Audio Preservation ed. Sam Brylawski, Maya Lerman, Robin Pike, Kathlin Smith. The Council on Library and Information Resources Publication 164. May 2015.)

Ultrasonic cleaning is endorsed by the Council on Library and Information Resources (op.cit.) as an approved method to clean records. However, sadly, a study of the microscopic effects of this cleaning method on records has never been published.

An important consideration for the record collector is that medical research (where ultrasonic cleaning is widely used) has shown that air-borne spores and mycelial fragments remain on the objects after ultrasonic cleaning, so this method is not effective against the suppression of fungal action which is one of the major factors Pickett and Lemcoe proved damage records long term.

 

[Soundfield]

OK, looks like Ethylene glycol is an alcohol – sorry, chemistry is not my forte. So let's drop that and just stick to distilled water with 5% (by volume) of Ilfotol added, for wetting.

Daniel

Are you aware that Ilfotol is a 3:1 mixture of 5-chloro-2-methyl-4-isothiazoline-3-one and 2-methyl-4-isothiazolin-3-one
and
C12-15 Ethoxylated Alcohol?

 

[fredblue]

i don't know if its suitable for ultrasonic cleaners but this is what i use in my Pro-Ject RCM;

https://www.hifix.co.uk/project-vc-s-wash-it-record-cleaning-concentrate
(said to be alcohol free. the cleaning solution that is, not the end user)

 

[Soundfield]

(said to be alcohol free. the cleaning solution that is, not the end user)

 

[DanielTheGreat]

Richard,

Thanks for that reference. I was going to mention in my next post that professional archivists use only pure water and a surfactant. Unfortunately Tergitol is not available in Australia, and importing it from the US would be prohibitively expensive. I think I'll just stick to Ilfotol, despite the small amount of alcohol (which becomes negligible when diluted to 5%).

I suggest we drop this subject now, it not being specifically quad, and having been discussed to death on many other record forums.

Daniel

 

[Brice]

Hi Daniel,

Yes, I Agree. We are off topic. I was expecting the Administrator to intervene soon anyway. In our defence, never has there even a medium more demanding than CD-4 records. It really is true to say that a prerequisite for a working (software) demodulator is clean discs. So, our sojourn hasn't been entirely unjustified.

But now, as the editor of the Times of London used sometimes to write on the letters page, "This correspondence now must cease".

Best wishes,

Richard

 

[kfbkfb]

CD-4 and Stylus Overhang (optimizing):

I bought an Akai AP-B110 turntable (in 1982-06), surprisingly, the manual specifically
mentions CD-4 and states that the turntable/tonearm is suitable for CD-4
(upon reading that, I thought "I'll never need that").

In 1992-12, I bought an SH-400 Demodulator.

I bought the 1992-03 issue of Hi Fi World specifically for the (cardboard) Stylus
Alignment Protractor (now lost), interestingly, this issue has a column entitled
"recorded message" by Richard Brice.

The Stylus Overhang I set using the Akai instructions worked OK for Stereo, but
not for CD-4, realigning with the cardboard Protractor resulted in CD-4 working
OK (Shure V-15 III).

Any recommendations for 3rd party Stylus Overhang Optimizing Device(s)?

Kirk Bayne

 

[Brice]

Hi Kirk,

Yes, "Recorded Message" was a regular column in Hi Fi World written by a (much younger!) me.

I have not been aware that there exists any definite dichotomy between a Stereo or CD-4 tonearm alignment (although see later). Only that CD-4 is definitely more critical; as it is of every other alignment. For example, it's easy to tolerate a few dB HF loss on one channel of the inner groove of a stereo record due to side-thrust misalignment. But the same misalignment will cause the CD-4 carrier to become unrecoverable.

The Stereo Lab help page regarding Tonearm Geometry might prove useful here.

http://pspatialaudio.com/tracking angle.htm
One point I would make is that Löfgren /Baerwald alignment MAY not be the ideal for CD-4. As a matter of record, we do not use this alignment on the turntable we use for most of our own CD-4 needle-drops.

Instead the alignment we adopt concentrates on minimising the tracking error near the innermost groove. This approach is sometimes attributed to Stevenson (after Stevenson, J.K., "Pickup Arm Design", Wireless World May, June 1966). It's a credible conjecture to propose this alignment for CD-4 because everything about CD-4 becomes more critical the nearer toward the centre of the record (as the tangential speed decreases). The Stevenson approach is explained in notes 7 & 8 of the page linked above.

Richard

 

[ArmyOfQuad]

Hi Kirk,

Yes, "Recorded Message" was a regular column in Hi Fi World written by a (much younger!) me.

I have not been aware that there exists any definite dichotomy between a Stereo or CD-4 tonearm alignment (although see later). Only that CD-4 is definitely more critical; as it is of every other alignment. For example, it's easy to tolerate a few dB HF loss on one channel of the inner groove of a stereo record due to side-thrust misalignment. But the same misalignment will cause the CD-4 carrier to become unrecoverable.

The Stereo Lab help page regarding Tonearm Geometry might prove useful here.

http://pspatialaudio.com/tracking angle.htm
One point I would make is that Löfgren /Baerwald alignment MAY not be the ideal for CD-4. As a matter of record, we do not use this alignment on the turntable we use for most of our own CD-4 needle-drops.

Instead the alignment we adopt concentrates on minimising the tracking error near the innermost groove. This approach is sometimes attributed to Stevenson (after Stevenson, J.K., "Pickup Arm Design", Wireless World May, June 1966). It's a credible conjecture to propose this alignment for CD-4 because everything about CD-4 becomes more critical the nearer toward the centre of the record (as the tangential speed decreases). The Stevenson approach is explained in notes 7 & 8 of the page linked above.

Richard

Maybe I'm overlooking something, I'm certainly not an expert at tone arm alignments, but I had decided not to use a Stevenson alignment for CD-4 because most CD-4s don't go as far to the inner grooves as a standard LP, making the alignment more ideal to the inner area of the record that is unused on a CD4.

 

[Brice]

Hi ArmyOfQuad,

That's a very good point. I had overlooked that. Did you go for the classic Löfgren /Baerwald alignment?

Richard

 

[ArmyOfQuad]

Yeah, I've been using a Baerwald.

 

[kfbkfb]

IMHO, it's virtually impossible to eyeball (as Akai instructs)
the correct stylus overhang setting.

I believe I lucked out because I was using a Shure HyperElliptical
(later MicroRidge) stylus which tended to mitigate the increased
inner groove distortion due to incorrect stylus overhang.

In 1991-11, I bought an (as is) Pioneer QX-747 at a Pawn Shop.

All of my CD-4 discs, played through the QX-747 Demodulator, had
"sandpaper Quad" sound. I thought the problem was either the
Demodulator or my stylus overhang adjustment.

My SH-400 gave the same "sandpaper Quad" sound on all my CD-4 discs,
I reset the stylus overhang with the Hi Fi World Protractor and
suddenly CD-4 worked OK (Shure V15 3, the 1972-12 Stereo Review
stated that a Shure V15 2 Improved worked for CD-4).

The Hi Fi World Protractor (checking the cover picture) has an inner
reference of 64mm, I don't know what "type" of alignment this is.


On a somewhat related note - is there a major difference in CD-4
sound quality when using a linear/straight line tracking tonearm as
opposed to a "properly" adjusted pivoting tonearm?

Kirk Bayne

 

[proufo]

My belief is that the correct rake angle is the most important thing for CD-4 playback, not overhang. Particularly when using a Shibata or similar stylus. The long mating surfaces must be perfectly aligned to get optimal tracking of the ultrasonic frequencies (and the rest).

Is there a way to view in an oscilloscope (ideally, PC-based and cheap) the carrier signal by itself? With the right tonearm you could micro-adjust the rake angle until the carrier is cleanest and/or loudest (a single, constant signal is easier to monitor).

Of course regular stereo tracking would be optimal too.