CD-4 Disc Demodulator JVC 4DD-5 . Please help.

I recently have acquired a JVC 4DD-5 Demodulator. I have never heard music from CD-4 format before, so I am unsure what to expect. I am very familiar with the sound of SQ/QS Matrix systems however - and i am generally happy with that. I played my CD-4 Quadradisc JVC demonstration record (RCA), and i'm really NOT happy! I did get some separation (like a badly recorded sq disc), but hardly anything I would call discrete.

Here's what I'm using:

• Grado Silver Prestige cartridge w/ eliptical stylus (frequency response goes up to 50,000).
• Technics sl-1200 turntable
• Accurately balanced tonearm with the correct skating and VT adjustments for the cartridge.

Note: The 'radar light' does come on when a cd-4 record is played.. But, hell, it goes on with any generic cartridge used. Don't know how to adjust the separation knobs on the back for L/R.. They seem to work like a volume gain. And, the KHZ tone switch on the bottom does nothing to affect sound or separation.

What am i doing wrong?? Is it possible my demodulator is defective?? @:

It's always possible that an old piece of electroinc equipment is defective \:^)

However, does your demonstration disc have adjustment tones on it?

I also don't know what you mean by a kHz tone switch on the bottom. I don't have a 4DD-5 demodulator. I have a Panasonic SE-405 and Technics SH-400 and they don't have anything like that.

Doug

Sounds to me like the demodulator is not set up properly. It takes about 10 minutes to do. Do you have the setup disc that came with your 4DD-5? If not, then you'll need to search through some threads here in the CD-4 section as to how to set up a demodulator.

Thanks for responding.

Doug G: The 'khz' switch reads "30 Khz Level" - it is located on the bottom of the demodulator. It looks like a flat-head screw with 10 stops.

Q-Eight: No, i don't have the setup disc. I have very recently acquired the "Fisher Test" Lp with the correct tones to adjust - it hasn't arrived yet. However, my JVC demo record has a section where a sound is supposed to be heard separately on all channels - and they don't seem to sound from the independent speakers.

I have the demodulator connected directly to an M-Audio Delta 1010LT - and Adobe Audition 2.0 software to hear and record the individual channels.

Well, when you get that setup disc, that will help.

Set the Carrier Level playing the Carrier Test Tone. Adjust for clearest signal with least distortion.

To set Separation Levels, sometimes it's best to play a music LP and adjust for best separation with least distortion. Play both front left and rear left and adjust for best results. Repeat with right channels.

OK, the "30 kHz level" control is the carrier level control. Adjust it like Q-Eight said.

I think it is much easier to adjust the separation controls using test tones from a setup disc. The way this works is there are tracks with tones recorded only on the front channels and you adjust the separation controls for minimum output from the back channels as the tones are played. This maximizes the separation.

You do this one side at a a time.

I like the Harman-Kardon test disc because there is a guy on the record itself announcing what is coming next. You have to read what is on each track with most other discs. Not a big deal though.

I'm sure that after you get the demodulator set up correctly, you will thrill to the spectacular sounds of CD-4!

One other question. Do you get clean signals at least? Without breakup or loud blatting noises? If so, that's a good sign that the cartridge is tracking the carriers well.

Doug

A regular elliptical diamond stylus won't work with CD-4 records. You need a Shibata or equivalent stylus.

Some Grado information http://www.vinylengine.com/cartridg...&dchi=&stid=&masslo=&masshi=&not=&prlo=&prhi=

Also see
https://www.quadraphonicquad.com/forums/showthread.php?10806-Generic-Replacements-for-CD-4-Styli

I used a Grado Prestige Blue for some time with mixed results; some records did well, others were barely listenable. I then switched to an Audio-Technica AT-440ML and got much better results, though the cartridge sounds a tad bright to me. The newer version is supposed to be better in that regard. I have the Fisher set-up disc, and the adjustment tracks do have announcements as to what the tones you are hearing are. I also have a 4DD-5 demodulator and I have a copy of the Service Manual, and I'll be glad to make a copy for you if you want it. It describes the parts and includes the schematic diagrams. Recently, I acquired an Audio-Technica AT-14Sa cartridge which needed a new stylus that I purchased from JICO and I'm getting the performance that I remember from back in the day. If you can afford to do so, I would recommend getting either and AT-15Sa or 20Sa, they were, in their day, top-of-the line cartridges and excellent performers even by modern standards. BTW, do you know if your Technics SL-1200 has the low-capacitance wiring? I had mine outfitted with the Cardas rewire from KAB, and I believe that is one reason that my CD-4 performance is so much better than on my old Sony turntable.

I generally agree with scifi's statement.

However, the critical things are the specifications, not so much the stylus shape.

If a cartridge with an elliptical stylus is, in fact, able to provide performance which results in signal retrieval able to be used by a demodulator to construct the four channels, it is entirely useable.

The critical specifications are frequency response and, and this is often overlooked, separation at the super sonic frequencies. Any shortcomings in the latter spec. will result in a less than desireable quadraphonic presentation because the demodulator will not receive separated difference information from each channel.

Of course, the whole reason behind the development of the Shibata stylus was because it was found that an elliptical stylus typically would not work well and the decreased scan contact radius and increased bearing contact radius of the Shibata provided maximum trace abilities combined with minimal groove wear.

So, yes, it is ideal to conform to the original developmental findings and use a stylus shape intended for CD-4 use. Shibata or modern line-contact.

Doug

There's some 4DD-5 information here:
http://www.grizwald.plus.com/quad/

There's a Grado G2 with an ellipsoid Shibata CD-4 stylus tip on this page
http://www.vinylengine.com/cartridg...&dchi=&stid=&masslo=&masshi=&not=&prlo=&prhi=

Thank you all for trying hard to help me out. I really do appreciate the time to reply. My main goal is to hear what CD-4 sounds like - without breaking the bank.. But, it seems like - i may have to now.:howl

I will reply back to all your questions, as best i can.

Doug G. said:

One other question. Do you get clean signals at least? Without breakup or loud blatting noises? If so, that's a good sign that the cartridge is tracking the carriers well.
Doug

Click to expand...

It distorts some when i try to adjust the L/R separation adjustments on the back. Keep in mind though, that the CD-4 records i have are not mint. The "best of Doors" has been played several times when i was a kid with my then linear tracking turntable and p-mount stereo cartridge. The "JVC Quad demo LP" is not in that great shape - and i don't know what was used to play that because it was bought used.

quadjoe said:

I used a Grado Prestige Blue for some time with mixed results; some records did well, others were barely listenable. I then switched to an Audio-Technica AT-440ML and got much better results, though the cartridge sounds a tad bright to me. The newer version is supposed to be better in that regard. I have the Fisher set-up disc, and the adjustment tracks do have announcements as to what the tones you are hearing are. I also have a 4DD-5 demodulator and I have a copy of the Service Manual, and I'll be glad to make a copy for you if you want it...

Click to expand...

Thanks Quadjoe. I have acquired a copy of the manual from another forum - the manual explains how to set-up the unit with the included set-up record (which i don't have). I'm happy to learn that the "Fisher Test" LP has proper announcements. Regarding the Grado - they have the basic eliptical stylus it seems. Would a shibata really be required?? I found a CD-4 cartridge online for 80 (US) dollars (Audio technica ed saunders model??).. Not sure, i want to go that route, and find that my demodulator is not working right..

quadjoe said:

BTW, do you know if your Technics SL-1200 has the low-capacitance wiring? I had mine outfitted with the Cardas rewire from KAB, and I believe that is one reason that my CD-4 performance is so much better than on my old Sony turntable

Click to expand...

What is low-capacitance wiring? Is that the type of RCA cable connections that go from the Turntable to the reciever? I'm going to guess my technics 1200 is standard wiring

scifi said:

There's some 4DD-5 information here:
http://www.grizwald.plus.com/quad/

There's a Grado G2 with an ellipsoid Shibata CD-4 stylus tip on this page
http://www.vinylengine.com/cartridg...&dchi=&stid=&masslo=&masshi=&not=&prlo=&prhi=

Click to expand...

Thanks Scifi! I will check out those links now.

surroundme33 said:

Thanks Quadjoe. I have acquired a copy of the manual from another forum - the manual explains how to set-up the unit with the included set-up record (which i don't have). I'm happy to learn that the "Fisher Test" LP has proper announcements. Regarding the Grado - they have the basic eliptical stylus it seems. Would a shibata really be required?? I found a CD-4 cartridge online for 80 (US) dollars (Audio technica ed saunders model??).. Not sure, i want to go that route, and find that my demodulator is not working right..



What is low-capacitance wiring? Is that the type of RCA cable connections that go from the Turntable to the reciever? I'm going to guess my technics 1200 is standard wiring

Click to expand...

Like I said, I used a Grado for a couple of years with acceptable results, but you will get better performance with a Shibata or Line-Contact type of stylus. The Ed Saunders cart isn't too bad IIRC, a few of the folks on this forum have used them, though I have no experience with his cartridges. Regarding the wiring issue, the CD-4 specification calls for impedance to be 100k ohms compared to the standard phono load of 47k ohms. How old is your Technics 1200? If it was made in the '70s, you are good to go, newer ones may or may not meet this requirement. I know that my old Sony turntable, a PSX-350LH, didn't have the correct wiring in the tonearm and I didn't have any serious demodulator problems, though I do use Monster phono cables to connect the turntable to the receiver (I now have a Lafayette LR-5000 with built-in CD-4), like these:

http://www.amazon.com/Monster-ULT-I...3?ie=UTF8&s=electronics&qid=1280451601&sr=8-3

I do know that the CD-4 specification requires the entire connection from cartridge to demodulator to have an impedance of 100k ohms. The Monster cables seem to fill the bill, as with standard cheap phono cables my CD-4 demodulator had trouble maintaining carrier lock. BTW, the Fisher disc was made to go with the Fisher CD-4 demodulator (which I originally owned until it died), which is identical to the JVC 4DD-5 in every way, so you will be able to get good adjustment with it. Just make sure you clean it very well before you use it.

Oh Wow! Look at this if you are reading this at 8:25 CDT:

http://cgi.ebay.com/MARANTZ-CD-400-...pt=Vintage_Electronics_R2&hash=item1e5d365f35

quadjoe said:

Like I said, I used a Grado for a couple of years with acceptable results, but you will get better performance with a Shibata or Line-Contact type of stylus. The Ed Saunders cart isn't too bad IIRC, a few of the folks on this forum have used them, though I have no experience with his cartridges. Regarding the wiring issue, the CD-4 specification calls for impedance to be 100k ohms compared to the standard phono load of 47k ohms. How old is your Technics 1200? If it was made in the '70s, you are good to go, newer ones may or may not meet this requirement. I know that my old Sony turntable, a PSX-350LH, didn't have the correct wiring in the tonearm and I didn't have any serious demodulator problems, though I do use Monster phono cables to connect the turntable to the receiver (I now have a Lafayette LR-5000 with built-in CD-4), like these:

http://www.amazon.com/Monster-ULT-I...3?ie=UTF8&s=electronics&qid=1280451601&sr=8-3

I do know that the CD-4 specification requires the entire connection from cartridge to demodulator to have an impedance of 100k ohms. The Monster cables seem to fill the bill, as with standard cheap phono cables my CD-4 demodulator had trouble maintaining carrier lock. BTW, the Fisher disc was made to go with the Fisher CD-4 demodulator (which I originally owned until it died), which is identical to the JVC 4DD-5 in every way, so you will be able to get good adjustment with it. Just make sure you clean it very well before you use it.

Oh Wow! Look at this if you are reading this at 8:25 CDT:

http://cgi.ebay.com/MARANTZ-CD-400-...pt=Vintage_Electronics_R2&hash=item1e5d365f35

Click to expand...

That was a great auction sale.. Too bad I missed it :howl

I have another turntable here that is much older.. It's a technics sl-1350. The wires that are also hot wired to the board (just like my Technics sl-1200 MK2) reads low stray capacity cord on the lead phono wires. So, i did a test with that one, and same results.. Blah.

My plan of action will be to wait for the 'fisher test' lp to arrive. Calibrate the demodulator using the record, as best as i can. If that fails, i will buy a cd-4 cartridge and try the tests again. If that still fails.. I will conclude that my demodulator is faulty, and purchase another one. If that fails.. I will conclude that I wasn't meant to listen to CD-4, and I will stick with Q8, and the SQ/ QS scripts.

Ok, i have managed to make a sample (about 1 minute) of chimes that supposed to ring in every speaker direction L, SL, SR, R ..

This is from the JVC CD-4 record. I have encoded it to a DTS-CD WAV. You can download it here.. http://sendshack.com/download/4htqi64

The critical specification for turntable wiring is the capacitance of the cables and this is measured in picofarads (pF)

The original specs, called for a total capacitance of 125 pF or less in each channel. It can be assumed that, if a turntable was sold as being CD-4 compatible, its cabling would meet the spec. This low capacitance is necessary to prevent attenuation of the super sonic signals before they get to the demodulator.

You are pretty much dependent on a manufacturers spec. for cabling since it's not that easy to measure accurately although you can if you have a good meter and knowledge of how to use it.

This spec, of course, relates to the wiring between the turntable and demodulator since after the demodulator there are no super sonic signals and standard shielded cable can be used.

The 100K impedance specification applies to the input impedance of the demodulator and this was also designed to minimize loss of super sonic signals from the turntable to the demodulator. You will find that the DC resistance of a typical stereo magnetic cartridge will be around 1000 - 1200 ohms whereas a typical quad cartridge will have a DC resistance of around 500 - 600 ohms.

There will be less high frequency signal loss with a 500 ohm source impedence working into a 100K load impedance than a 1200 ohm source impedance working into a 47K load impedance. The higher the load impedance and lower the source impedance, the less loss.

This spec. was eventually found to be less crtical than the cable capacitance spec. and, in reality you can usually use a cartridge meant for a 47K load in a CD-4 system, assuming it has a suitable stylus. Of course, it is still best to adhere to the strict orignal specifications.

Doug

Thank you Doug for the specifications. I must admit, it was a little too technical for me to understand. I think I generally understand that a turntable has to wired for quad to meet the original specifications. One turntable i know of (DUAL 1229 Q) comes to mind..

Thanks to everyone in trying to help me out with CD-4. I haven't given up entirely, yet. When I finally receive the CD-4 Test record, i will make a post announcing any improvements or lack of. I will also be investing into a CD-4 cartridge ( hopefully, a model that is not too pricey - under 100 would be ideal?).

Forgot to mention.. I read somewhere that Linear Turntables with p-mount cd-4 cartridges also work. If low-capacitance wiring is used to connect the turntable to the demodulator - would this be a viable option??

Yes. Theoretically, a linear arm is better because there is no tracking angle error (the stylus and cantilever are always tangent to the groove) and no skating force that has to be counteracted.

In practice, things aren't quite so rosy but there are many who use linear arms for CD-4 with success.

I have never tried one (even though I do have a linear tracking table...hmm, maybe I'll have to give it a try sometime) and my BIC 980 works very well for CD-4.

And as far as the technicalities of the whole thing, the main thing to remember is that the super sonic frequencies must reach the demodulator sufficiently strong enough for the demodulator to use. Otherwise, it can't construct the four discrete channels and you end up with poor separation. Keeping those signals strong enough (the regular audible frequencies are no problem, of course) is what all the electrical specifications are about.

The specifications for stylus type and tracking are to get the signals out of the grooves to begin with.

Doug

Hello Everyone. I want to update my post here. I have recently acquired an

Audio Technica 12Sa Phono Cartridge. It is NOS. It has a Shibata stylus. Here are the specs.

Specifications:
Generating element: Dual Moving Magnet
Frequency response: 15-45,000 Hz
Output (mv at 5 cm/sec): 2.7
Channel separation (dB at 1 kHz / 10 kHz): 26 / 20
Channel balance (dB): 1.0
Stylus shape: Shibata
Stylus construction: Bonded
Cantilever: Tapered
Tracking force (grams): .75-1.75

Here is a picture of it mounted on my technics sl-1350



So, I ran my CD-4 test using my JVC album (the fisher test LP still hasn't arrived).. Here is a wave view using Adobe Audition. Chimes ring in each channel Left Front.. then.. Left Rear.. then.. Right Rear and finally Right Front..



As you can see.. I have made no progress, and sound still bleeds from front to back. Perhaps, my JVC demodulator is not working.. Perhaps, CD-4 is not discrete as it so claims to be. :howl

surroundme33 said:

Hello Everyone. I want to update my post here. I have recently acquired an

Audio Technica 12Sa Phono Cartridge. It is NOS. It has a Shibata stylus. Here are the specs.

Specifications:
Generating element: Dual Moving Magnet
Frequency response: 15-45,000 Hz
Output (mv at 5 cm/sec): 2.7
Channel separation (dB at 1 kHz / 10 kHz): 26 / 20
Channel balance (dB): 1.0
Stylus shape: Shibata
Stylus construction: Bonded
Cantilever: Tapered
Tracking force (grams): .75-1.75

Here is a picture of it mounted on my technics sl-1350

View attachment 3248

So, I ran my CD-4 test using my JVC album (the fisher test LP still hasn't arrived).. Here is a wave view using Adobe Audition. Chimes ring in each channel Left Front.. then.. Left Rear.. then.. Right Rear and finally Right Front..

View attachment 3249

As you can see.. I have made no progress, and sound still bleeds from front to back. Perhaps, my JVC demodulator is not working.. Perhaps, CD-4 is not discrete as it so claims to be. :howl

Click to expand...

Looks like your front to back separation may need further adjustment, when you get your Fisher disc adjust the signal with the front channels turned all the way down and adjust the separation control until you can just barely hear the tone. Don't forget that you are not going to achieve the kind of separation you are used to with digital media, with analogue sources you should expect anywhere from 20-30 db, depending on the cartridge. This means that you may still hear some sound bleed, but you normally wouldn't listen to only one channel at a time. Now, I can't tell from the wave forms what you're hearing, but if you could post a a sample, I'd be interested in hearing how loud the sound bleed is. Also, don't forget that you are dealing with a piece of electronic equipment that is at least 35 years old and no doubt it may not be performing to spec. Let me ask you this: do the chimes seem like they are moving around you or does the bleed blur the image so much that you can't tell where it is coming from? Also, is the sound distorted? You may have a disc that has a damaged carrier signal, though in my experience that usually causes a "gritty" sound.