Finally Got CD-4 Working!

[kfbkfb]

AFAIK, only the 4DE-202 is faulty, all of the other CD-4 alignment records result in the correct Left and Right Front to Back channel separation.

(some later model Technics receivers w/CD-4 automatically adjust the Front to Back separation, I searched QQ at one time and didn't find any listening tests or measurements of these auto separation CD-4 decoders)


Kirk Bayne

 

[J. PUPSTER]

I'm using these and happy with them, Pup. Doesn't mean they're the end-all, be-all.
I'm vaguely aware that there are different types, with different features.
Trying one could be worth a shot? If it doesn't kill the noise you're experiencing, maybe a more sophisticated type could be found.

https://www.sweetwater.com/store/detail/M8x2--furman-m-8x2-power-conditioner

That Furman looks pretty good, it definitely is at a reasonable price point

 

[edisonbaggins]

That Furman looks pretty good, it definitely is at a reasonable price point

I bought 5!
If I'd be sad that a piece of gear got fried, it gets a line conditioner.

 

[jefe1]

There are many reviews on Amazon you can read

 

[Sonik Wiz]

OK, here's some of the test LPs I've got-

https://www.discogs.com/release/445...Present-CD-4-Channel-Demonstration-Quadradisc
https://www.discogs.com/release/3171839-Various-The-Fisher-Test-Performance-Standard-Quadradisc
https://www.discogs.com/release/154...-4-Quadradisc-4-Channel-2-Channel-Test-Record
and just for GP (Includes alignment protractor)-

https://www.discogs.com/release/3212139-No-Artist-Analogue-Test-LP
View attachment 90282

Unless you have an overtly defective one like Kirk pointed out they should all be done to JVC standards & work well. The exception might be if a particular cal disc is too well worn to be good.

Having said that the only one with Lou Dorren's name on it is the Soundbird label disc. That carries a lot of street cred to me.

As I pointed out to you elsewhere on side B there are musical slections that are used to demonstrate ch/speaker location. Maybe 30 secs each one. So if you want to try something other than test tones play left front while adjusting crosstalk cancellation in left back. Similar on the right side. Music tests for the rear chs to front have no adjustments of course. But it might be interesting check out crosstalk left back to left front, etc.

 

[fredblue]

I think his method was to listen to a song where you know there's supposed to be zero lead vocal in the rear (Carly Simon's "You're So Vain", for example), solo the rears and then tweak the seperation controls to get that vocal crosstalk as low as possible.

that's it!
i have to say though it's not my method, i nicked it from The Quadfather on here! lo and behold, it works!

 

[fredblue]

OK, here's some of the test LPs I've got-

https://www.discogs.com/release/445...Present-CD-4-Channel-Demonstration-Quadradisc
https://www.discogs.com/release/3171839-Various-The-Fisher-Test-Performance-Standard-Quadradisc
https://www.discogs.com/release/154...-4-Quadradisc-4-Channel-2-Channel-Test-Record
and just for GP (Includes alignment protractor)-

https://www.discogs.com/release/3212139-No-Artist-Analogue-Test-LP
View attachment 90282

that Fisher disc is "the one"

 

[barfle]

Actually I believe I'm good at this point, I've ruled everything else out after getting this (new to me) Panasonic SE-405. I really believe some of my issues may be with my home power; maybe some kind of grounding issue, but I just don't get any hum with newer gear like the Surround Master on the same power lines. I may need to call in a electrician to diagnose and nail down the problem.

I’m not there, of course, but if you have individual gear with hum issues, especially if that geat is old, my first thought is that the power supply filter capacitors are dried out and should be replaced. But maybe that’s already been addressed - IDK.

 

[J. PUPSTER]

I’m not there, of course, but if you have individual gear with hum issues, especially if that geat is old, my first thought is that the power supply filter capacitors are dried out and should be replaced. But maybe that’s already been addressed - IDK.

I wouldn’t know a “power supply filter capacitor” from a Tribble’s booger.

Possible I could record a piece of the hum and post it for others to hear, and maybe they might know a cause from that? I do know, usually if you crank up the volume you can hear faint voices in it!

 

[barfle]

I wouldn’t know a “power supply filter capacitor” from a Tribble’s booger.

Possible I could record a piece of the hum and post it for others to hear, and maybe they might know a cause from that? I do know, usually if you crank up the volume you can hear faint voices in it!

Typically, a power supply capacitor is round, and fairly large compared to other parts in the circuit. If you’re uncomfortable with troubleshooting electronics, I wouldn’t open the case, but since it’s a common problem, I’d address rhat before going on a 120VAC goose chase.

Good electronic repair shops are not easy to find these days, alas, and when you do find one, they tend to not be cheap. But vintage gear is usually worth the effort, IMNSHO.

 

[quadsearcher]

I wouldn’t know a “power supply filter capacitor” from a Tribble’s booger.

Possible I could record a piece of the hum and post it for others to hear, and maybe they might know a cause from that? I do know, usually if you crank up the volume you can hear faint voices in it!

I'd listen and report if it has any clues, if you want to do that. Faint voices sounds like poorly shielded RCA interconnect or perhaps a little corrosion, at least it was in my case once. I was a half block from a hospital and I suspect it was radio communication bleeding through. But I had a bunch of very cheap and old cables at the time.

 

[Sonik Wiz]

Typically, a power supply capacitor is round, and fairly large compared to other parts in the circuit. If you’re uncomfortable with troubleshooting electronics, I wouldn’t open the case, but since it’s a common problem, I’d address rhat before going on a 120VAC goose chase.

Good electronic repair shops are not easy to find these days, alas, and when you do find one, they tend to not be cheap. But vintage gear is usually worth the effort, IMNSHO.

I have not serviced Jeff's SE-405 but I may as well out myself as doing what I could with his Marantz 400-B. It also had a hum/noise problem that bothered him. I heard it too when I gave it a quick listen after receiving. Not bad but audible.

So that lead to replacing/upgrading 6 PS caps & 12 'lytic coupling caps. Checking after that it seemed the hum might be a little bit worse. But connecting to a proper cold water pipe earth ground made it all but vanish. I put the results that way because with almost any piece of audio gear, esp vintage, if you try hard enough there will always be some kinda hum+noise. In the Marantz case if I was not playing any music but cranked the volume to max on my Anthem pre-pro that it was plugged into I could definitely hear a bit of buzz hum. But of course if I was playing music at that level it would be deafening & any noise would be buried. Alas the Marantz still had unacceptable noise in use at the Pupster's which has lead to the purchase of the Panasonic. With better results. So, good on that.

I think part of the problem is the common use on audio gear to use wood cabinets that don't provide good shielding. And the Panasonic at least has a full metal enclosure that might help with that.

And as just a side note every CD-4 unit I've seen has a dedicated ground post. That makes me think that these demodulators are prone to hum/RFI and the mfg'ers did what the could to give users a way to reduce that.

 

[proufo]

The phono circuitry of the 405 has inductors which are simple wound cables (yellow), which is strange I guess. Are they prone to pick up hum?

Are those meant to be adjusted by fiddling with the wire loops?

Could the circuitry be improved with the use or a regular inductor?

TIA.

 

[J. PUPSTER]

apologies to Mr. Baggins, this has gotten to be too much discussion of my personal issues, not what this thread should be about.

I'll be re-addressing some of these issues over on this thread now -

https://www.quadraphonicquad.com/fo...-still-in-the-fight.32705/page-15#post-687959

 

[edisonbaggins]

apologies to Mr. Baggins, this has gotten to be too much discussion of my personal issues, not what this thread should be about.

I'll be re-addressing some of these issues over on this thread now -

https://www.quadraphonicquad.com/fo...-still-in-the-fight.32705/page-15#post-687959

Happy to discuss your issues in any thread!

 

[MidiMagic]

Actually I believe I'm good at this point, I've ruled everything else out after getting this (new to me) Panasonic SE-405. I really believe some of my issues may be with my home power; maybe some kind of grounding issue, but I just don't get any hum with newer gear like the Surround Master on the same power lines. I may need to call in a electrician to diagnose and nail down the problem.

Back now to CD-4 test LPs, I also have 2 or 3 different ones I plan on locating today and I'll post their discogs page here for others. I know some are better than others, and IINM it was @Doug G. that mentioned somewhere that one of those LPs has some incorrect tests on it?

The way I figure, the more we discuss CD-4 "fun" LOL we're having and solving problems for others here, we'll drive those CD-4 prices up with new users and it may make a small comeback like a CD-4 board in an upcoming Involve Master Pre-amp
View attachment 90277

I have become an expert on eliminating hum after 50 years of doing stereo repairs and live sound systems. There are many causes of hum. Here are some ideas for eliminating it:

Hum is caused by audio equipment picking up the 60 Hz or 50 Hz power line frequency (which one depends on where you are). The problem is that there are many ways for power line frequency to sneak in. Here are some of the ways:

- Defective power supply in a component (hum is always there with that component).
- Defective ground connection in the power cord to a component.
- Multiple paths to ground for the same component (ground loop acts as antenna).
- Missing ground connection between components.
- Missing or disconnected shield in signal cable.
- Circuitry picks up a hum field from a transformer or lamp ballast.
- Noise coming in on a power line (unlikely).
- Radio noise for other sources picked up by equipment.
- The pickup cartridge is in a hum field.
- The pickup cartridge has a bad internal connection.
- Another hum producer making a humming sound in the room.
- Open circuit in balanced line.

Here are some of the strangest solutions I have seen to hum problems:

1. A homemade cable had the signal and ground connections traded at both ends.
2. The cable used for signal was intended for speaker use and had no shield.
3. There was still hum with the system off. A new clock was on the other side of the wall.
4. An AC adaptor was placed next to the balanced line transformer for a guitar.
5. Adding a new component created a ground loop.

 

[proufo]

I have had hum issues with Zektor switches that went away by inverting the power transformer.

 

[Quad Linda]

I would be lying if I said "never had an issue with CD-4." I've had 2 belt drives and a DD turntable. It has always worked. Occasional sandpaper, but no other problems, unless I have a used disc. Most of mine were bought sealed and only played on AT & Ortofon Shibata and fine-line stylii. Yes, Ortofon MC will work, but needs precise setup.

JVC & Technics demods into B&K preamp or vintage Marantz & modern Denon receivers. I also have a Sansui QRX-6500 w/built-in CD-4 demod. Got it and a 5500 (no built-in demod) free from a GF when her Dad passed. Both pieces will be refurbished before I deploy them.

Badly worn or abused CD-4 LP's likely won't work well, if at all.
Demodulator not used in over 40 years? Get it checked out first.
All cables must be low capacitance.
Elliptical stylii will work half assed at best.
Too low a tracking force can be a nightmare and do damage. Too high can also damage the CD-4 carrier. Get in the proper range.
Cartridge alignment critical.
Cartridge and tonearm must be compatible. Groove compliance is best that way and limited by the lower compliance of the two.

Remember, no gear/system runs any better than the poorest part of the signal path.

 

[edisonbaggins]

Badly worn or abused CD-4 LP's likely won't work well, if at all.
Demodulator not used in over 40 years? Get it checked out first.

This excellent advice.
Any idea what kind of technician can check and restore them?

The reason I bought my 4th, and finally successful unit, the Technics SA-8000X, is that the seller claimed he got CD-4 working, and Reverb.com is no nonsense about refunds when an item shows up in a condition other than described, especially if shipping caused the change.

I had to replace fuses, but that's it.

 

[Quad Linda]

Panasonic & JVC were the big proponents and developers of CD-4. Controlling interest in JVC was (probably still is) owned by Matshushita (Panasonic.) JVC also patented VHS. JVC, as well as Technics & Panasonic didn't want to pay royalies to CBS & Sony for SQ, nor Sansui for QS. So, they used generic decoding circuits.

Here in Chicago, there was a repair shop in the city. Run by a husband and wife who possess EE degrees. They're in their 80's and gentrification has made the rent unsustainable. So, they retired recently. He knew Quad inside out. I bought a vintage Sony SQD 2020 refurbished from them for $100. Still works fine 20 years later.

Recommendation is to look for a used hi-fi shop. There are a couple vintage used hi-fi dealers in Chicago. Likely there are some in SF, East Bay, Castro Valley or somewhere your area. They may be able to repair or tweak them, or direct you to someone who does.

Large musical instrument stores might be able to help you. Sam Ash and Guitar Center are large stores here. One of the older folks like me may have a beat on a good tech. Start with the guys/gals in the amp/mixer/black box dept. Ash has a store within a store.

Surround yourself with good people, good music/ mixes and good gear. Then, relax and enjoy a microbrew, homebrew, kier royale, wine, single malt or whatever and ENJOY THE MUSIC!!