JVC CD-4 demodulator 4DD-10

[furui_suterioo]

It seems nobody has been able to find a schematic or manual for the 4DD-10, only this:

 

[amontass]

I have only, ever in my life, found one person who really knows what to do to make electronics work correctly and that is the "Save On Sound" place in Houston. This is a one man operation. He does not give it to some technician who might or might not really know the product. Everything I have taken in for observation and/or repair comes back perfect! My youngest son also has adequately repaired 2 JVC Add-5s because he has listened and watched Mr. Tran at Save On Sound. I will ask my son, Adam, why you may still be having a problem.

 

[furui_suterioo]

Got my Blue Jeans LC1 cables today, connected them from 2ch out on 4DD-10 to phono in on my kenwood receiver in order to compare with internal kenwood demodulator, distortion went away but did have to turn up the left and right carrier level pots about a quarter turn to get clean sound from the PLL lock tone on the Fisher test record (vs when connected without the 4DD-10 & BJ LC1). Other than that, problem solved, might even consider modifying my old pl12d with these cables but with smaller plugs though, had to scoot my setup forward to make enough clearance.

 

[Dan Tabacu]

I am not sure about the CD4 circuit into the SA 8000X, but if it is the same as their standalone cd4 decoder, it need a special cartridge (semiconductor).The 4dd10 works with all carts.

Hello!
I'm Dan and If you don't mind I have 2 questions:
1. Is it possible to get 4 channels from a stereo cd with a cd4 demodulator, or that is just for Phono (turntable)?
2. The 4 ch cartrige can be used also on a stereo turntable or just on a 4ch one?
I am fascinate by quad audition but the q reel tapes or vinyl records are too expensive, so I would like to converts my stereo musi into quad. So what should i use for stereo CDs and for stereo vinyl to convert it into quad?

 

[gvl_guy]

Hello!
I'm Dan and If you don't mind I have 2 questions:
1. Is it possible to get 4 channels from a stereo cd with a cd4 demodulator, or that is just for Phono (turntable)?
2. The 4 ch cartrige can be used also on a stereo turntable or just on a 4ch one?
I am fascinate by quad audition but the q reel tapes or vinyl records are too expensive, so I would like to converts my stereo musi into quad. So what should i use for stereo CDs and for stereo vinyl to convert it into quad?

A CD-4 demodulator only works with CD-4 records (AKA "quadradisc.") It takes a high frequency that's embedded on the vinyl and uses it to extract the 4 channels. What you would be looking for to "fake" 4 channels from 2 is a matrix decoder. They will take any stereo source, record, tape, CD or music file, and try to find information that is out of phase and turn it into quad. Some work well, others don't. Sometimes it's the music that the problem. (For example, I have a Hall & Oates album where a few songs actually sound like they were made for quadraphonic and some others that just don't decode well. It's just the way it was recorded.)

The 4 channel cartridge can be used on any turntable, but that turntable must have low capacitance phono cables. It is the only way to get that high frequency signal on the record to make it to the CD-4 demodulator for decoding.

I highly recommend the Surround Master from Involve Audio. They are out of Australia. It will do a fantastic job at extracting a quadraphonic signal from just about any source. Plus, if you ever purchase a quadraphonic matrix record, it will actually decode that record into the 4 channels as intended.

Hope this helps!

 

[Dan Tabacu]

A CD-4 demodulator only works with CD-4 records (AKA "quadradisc.") It takes a high frequency that's embedded on the vinyl and uses it to extract the 4 channels. What you would be looking for to "fake" 4 channels from 2 is a matrix decoder. They will take any stereo source, record, tape, CD or music file, and try to find information that is out of phase and turn it into quad. Some work well, others don't. Sometimes it's the music that the problem. (For example, I have a Hall & Oates album where a few songs actually sound like they were made for quadraphonic and some others that just don't decode well. It's just the way it was recorded.)

The 4 channel cartridge can be used on any turntable, but that turntable must have low capacitance phono cables. It is the only way to get that high frequency signal on the record to make it to the CD-4 demodulator for decoding.

I highly recommend the Surround Master from Involve Audio. They are out of Australia. It will do a fantastic job at extracting a quadraphonic signal from just about any source. Plus, if you ever purchase a quadraphonic matrix record, it will actually decode that record into the 4 channels as intended.

Hope this helps!

Thank you very much. I admit it's difficult to find someone experienced who to share the basic information with someone new but enthousiast in this domain. I shall read many times your message till i'll have a strong image for my future equipment investment. For the moment I owe a Teac Tascam 234 tape deck, a Toshiba which looks to be very smart with its plenty of buttons (unfortunately I can't find its user manual, the service manual I already bought not being too helpfull), 3 Teac reel-to-reel tape recorders (2 A 2340 sx and 1 A 3340) and a Dual quad turntable. The last one looks not to do its job working as it should. I am still for analog systems and I can understand that a demodutated signal is kind of fake, but as I already said, this hobby is really too expensive for my monthly budget and I mean the quad reel tapes or vynils

 

[barfle]

Hello!
I'm Dan and If you don't mind I have 2 questions:
1. Is it possible to get 4 channels from a stereo cd with a cd4 demodulator, or that is just for Phono (turntable)?
2. The 4 ch cartrige can be used also on a stereo turntable or just on a 4ch one?
I am fascinate by quad audition but the q reel tapes or vinyl records are too expensive, so I would like to converts my stereo musi into quad. So what should i use for stereo CDs and for stereo vinyl to convert it into quad?

Welcome aboard, Dan! @gvl_guy gave you good advice. Certainly, this hobby can get very expensive, and vintage vinyl is always risky to purchase, although I’ve had pretty good luck.

There are several ways to get a surround effect fairly cheaply, though. My first surround setup just had two very cheap speakers wired in parallel to the front speakers, and they sounded so different from the far better front speakers that it was a pretty pleasing effect. Of course, it wasn’t what the artists intended me to hear, but it was fine at the time.

 

[Doug G.]

Yes. My first "quad" setup was just a single speaker in the back hooked up with the Hafler circuit and even that limited configuration was a whole new added dimension. From then on, it was step-by-step (adding a pot to vary the volume of the back speaker and then, using two speakers in the back, etc.) until finally having an "official" quadraphonic system.

Welcome Dan.

Doug

 

[The Quadfather]

No such thing as a "quad TT"...to get good CD-4 performance you can use any model as long as it has short and low-capacitance cables. You do need a quad cartridge (with a shibata tip stylus) though. For CD-4 playback I use a Technics SL-1500 with a JVC 4MD-20x cartridge.

To properly use the demod you have to run the turntable wires into it, then run the 4 channel outs to a receiver. You then need a special adjustment record to properly tune the separation and carrier controls.

Actually, what is meant by a "quad turntable" is that the turntable is equipped with low capacitance cabling right up into the tonearm, not just from the terminal board to the RCA connectors that plug into the demodulator. Most high quality turntables from the quad era are designed with CD-4 quad in mind, especially Japanese made tables. And for SQ and QS or any other matrix quad format, it doesn't matter.

 

[The Quadfather]

Welcome aboard, Dan! @gvl_guy gave you good advice. Certainly, this hobby can get very expensive, and vintage vinyl is always risky to purchase, although I’ve had pretty good luck.

There are several ways to get a surround effect fairly cheaply, though. My first surround setup just had two very cheap speakers wired in parallel to the front speakers, and they sounded so different from the far better front speakers that it was a pretty pleasing effect. Of course, it wasn’t what the artists intended me to hear, but it was fine at the time.

A CD-4 demodulator only works with CD-4 records (AKA "quadradisc.") It takes a high frequency that's embedded on the vinyl and uses it to extract the 4 channels. What you would be looking for to "fake" 4 channels from 2 is a matrix decoder. They will take any stereo source, record, tape, CD or music file, and try to find information that is out of phase and turn it into quad. Some work well, others don't. Sometimes it's the music that the problem. (For example, I have a Hall & Oates album where a few songs actually sound like they were made for quadraphonic and some others that just don't decode well. It's just the way it was recorded.)

The 4 channel cartridge can be used on any turntable, but that turntable must have low capacitance phono cables. It is the only way to get that high frequency signal on the record to make it to the CD-4 demodulator for decoding.

I highly recommend the Surround Master from Involve Audio. They are out of Australia. It will do a fantastic job at extracting a quadraphonic signal from just about any source. Plus, if you ever purchase a quadraphonic matrix record, it will actually decode that record into the 4 channels as intended.

Hope this helps!

As the owner of the legendary Audionics Space and Image Composer, now defunct, I purchased a Surround Master from Involve Audio to replace it. I have to say that I am totally impressed with the Surround Master, and that it is an excellent replacement for the Audionics unit that served me so well for so many years. Plus, it also does QS decoding, which the Audionics did not do. It will also decode stereo records and divide the sound into four channels or 5.1 channels, (you choose) or any other stereo source for that matter. As previously stated, it does require a lively mix.

 

[Michaelteg24]

I'm in the process of building a CD4 Modulator.
It will feed proper left-right signals with a FM modulated 30 kilohertz carrier to a demodulator to be able to test it without a turntable.
The CD4 test records have very short test tracks that force you to play it over and over again to make measurements of the signals as it progresses through the system and make adjustments to the systems controls.
I like a good long steady
signal to allow me to troubleshoot a demodulator with problems!
So far I have I designed the Sum and difference circuitry and the RIAA pre emphasis and de emphasis circuitry, easy breezy!
The PLL for modulation is next on the list and will not be difficult ether.
When completed I will upload a schematic and parts list.
At any rate it's keeping me off the streets and out of trouble !

 

[kfbkfb]

It seems to me that an all software (PC/Windows based, for example) CD-4 encoder would be the easiest approach, even if the PC has to encode CD-4 at slower than real time (due to computational requirements), .wav format output files could be easily created.

edited: the word digital replaced by software


Might be helpful:
https://www.aes.org/e-lib/browse.cfm?elib=3385

"The RCA Quadulator"


Kirk Bayne

 

[Owen Smith]

It seems to me that an all digital (PC/Windows based, for example) CD-4 encoder would be the easiest approach, even if the PC has to encode CD-4 at slower than real time (due to computational requirements), .wav format output files could be easily created.

The ANRS noise reduction is difficult to do on a PC since it is level dependent and you don't know what gain the track was digitised at.

 

[Michaelteg24]

It seems to me that an all digital (PC/Windows based, for example) CD-4 encoder would be the easiest approach, even if the PC has to encode CD-4 at slower than real time (due to computational requirements), .wav format output files could be easily created.

Might be helpful:
https://www.aes.org/e-lib/browse.cfm?elib=3385

"The RCA Quadulator"


Kirk Bayne

Thanks for the info! The AES wants $33.00 for a copy of the paper.
It was published at about the same time as when I was working at Signetics in Sunnyvale CA.
I was working in the Analog Applications Dept and later on in the RF Design Group.
I learned a lot about PLLs, Dolby NR Chips, DSPs and such during my employment there.
It's true what you say about it.
Software Defined Circuitry is very interesting to me as is the old analog way of doing things.
It's true that feeding an analog (or digital for that matter) signal into a ADC and processing it with Software Defined Circuitry, and if desired outputting it to the outside world with a DAC, is all the rage these days.
However, I am retired and have time on my hands so I am going to build an Analog CD4 Modulator just for the fun of it!

 

[Michaelteg24]

The ANRS noise reduction is difficult to do on a PC since it is level dependent and you don't know what gain the track was digitised at.

Yes... and no...True... the analog processing that is/was done on the LPs is one of the subtle things that I will have to deal with in the design of an analog modulator. I will have to provide means of varying the parameters as needed for the ANRS depending on the frequency range and level of the audio that was used to modulate the 30khz carrier which determine the ANRS compression and expansion parameters. Even the amplitude of the 30khz signal was varied as needed for optimal Demodulator/playback characteristics.
The test records and entertainment LPs provide the information In the signals recorded on them that I need to build a Modulator.
It's a process of reverse engineering!

 

[kfbkfb]

I have the QSI-5022 CD-4 decoder IC application note scanned, I can email it to you if you give me your email (via the conversation option).

The schematic of the JVC 4DD-5 is online (somewhere, haven't found it yet) and should be useful to reverse engineer ANRS.

An all software CD-4 decoder was developed about 5 years ago (there could be some useful info in the thread):
https://www.quadraphonicquad.com/forums/threads/working-cd-4-software-demodulator.24900/


Kirk Bayne

 

[barfle]

It seems to me that an all software (PC/Windows based, for example) CD-4 encoder would be the easiest approach, even if the PC has to encode CD-4 at slower than real time (due to computational requirements), .wav format output files could be easily created.

edited: the word digital replaced by software


Might be helpful:
https://www.aes.org/e-lib/browse.cfm?elib=3385

"The RCA Quadulator"


Kirk Bayne

If you use an analog preamp, one issue you may well run into is the downgrading of the carrier by the RIAA EQ. Finding a linear preamp might be difficult, and running cartridge level signals to a computer could be a challenge as well.

Nothing that can’t be done, but those are some of the known challenges.

 

[Bruce00]

Good Morning all
I've joined the site to further my knowledge of the Quad scene, as I've been out of it for *gulp*, 50yrs!
I understand formats have come and gone since my days, and truthfully I don't understand the "mechanics" behind the working of 4 channel playback, but I know what I like.
Ive sent my Sanusi QXR 9001 to qxr restore for a full restoration, the Holy Grail, Cap upgrade and LED lighting. Probably spending way too much, but cry once and then enjoy is my motto. I also have a Marantz 6300 that has served me well and after using some DeoxIT D5 all functions are working

So my question to the experts, in 2024 what is the goto stylus for 4 channel playback that would work with my 6300
I use to use Shure products back in the 70's and ofcourse were inexpensive compared to todays market
So please share your opinions, as Iam still a few months from getting my ole girl back, which Iam patiently awaiting

 

[Owen Smith]

Do you want CD-4 playback or not? Makes a huge difference to what cartridges you can use.

 

[Bruce00]

Do you want CD-4 playback or not? Makes a huge difference to what cartridges you can use.

Yes
That's why I sent my Sanusi off for repair. I want to get my Marantz up to the standards of the Sanusi