CD-4 - The thin line between success and failure, but still in the fight!

QuadraphonicQuad

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jupp369

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Sandpaper distortion is actually the carrier detection circuit switching on and off as it gains and loses the carriers in rapid succession. It is not a function of that actual noise coming from the groove. It is a function of the demodulation process if it's not going right.

The "breaking pencils" or "explosions" aspect only happens if the CD-4 system is not set up correctly. Scratches or dirt sound no different from two channel records in my system. As I have stated elsewhere, I have heard the various CD-4 distortions and actually did have some of them in my system when I re-entered the CD-4 world many years ago, now, but they were corrected, mainly through tracking adjustments.

Doug
Hi Doug and all Sandpaper fans!

You're right with Sandpaper, the carrier goes out of limits. Even if there is a small buffer for small dropouts, if the carrier is always pending around the lower limit we will get the sandpaper.
Found a good example at the Doobie Brothers - Stampede.
I recorded all at the same level, only adjusting the horizontal angel to get the optimum.

Pic 1 shows the 30kHz at track 2 (or any other) beforre the the music and at the last track 5. Of course the switch (carrier sense = matrix on) got problems to handle that.
Pic 2 With Audacities's equalizer I added 8dB for the carrier to bring em up to normal volumen - than it plays well without any distortions.
Pic 3 I clip off the carrier in both recs at 20kHz to get the normal sound we hear. You see, there is is no difference in the volumen between a formerly low or high carrier in the sound.

Roberta Flack Suzanne is also an example: they reduced slowly the carrier from the 6th minute till end. so I added the 30kHz 1dB after 7min, 8min and 9minutes to keep em upright = everything OK.
 

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J. PUPSTER

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A shout out to @J. PUPSTER ... how's the CD-4 adventure coming along for you? Did you banish the buzz & hum gremlins?
I've been taking a little hiatus for now. Sadly, I tried ripping one a few days ago and the hum seems to be back. And yes, seems to be isolated to the Marantz. Then tried again with the Sansui (different surge suppressor) and I wasn't getting any sound out. So looks like I'm dead in the water for now.

If anyone has a good clean sounding Demodulator they want to sell, please PM me!
 

MidiMagic

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I'm sure the four different versions followed JVC's different versions. I don't know the exact differences but I know the first JVC version had either a track error having to do with adjusting separation on the two channels or the wording was incorrect.

JVC actually made the 45 RPM adjustment records for several different manufacturers.

Doug
Maybe that's because there are turntables that turn any 7-inch record at 45.
 

jupp369

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Joined
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Messages
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Location
Berlin
I've been taking a little hiatus for now. Sadly, I tried ripping one a few days ago and the hum seems to be back. And yes, seems to be isolated to the Marantz. Then tried again with the Sansui (different surge suppressor) and I wasn't getting any sound out. So looks like I'm dead in the water for now.

If anyone has a good clean sounding Demodulator they want to sell, please PM me!
There are endless possibilities for a good hum, I'm sure you've tried a lot and I'm not telling you so much new.
Hum Jam is a burden for all. Just before Janis Joplin starts singing I saw the big 50Hz on the record... you are never alone!
The housing of the Technics turntable is grounded via a separate cable to the amplifier instead via the common ground of the mag.head, if necessary you can also connect this to the grounding of the wall socket (if you have there a separate earthing like in europe).
With or without a mains filter doesn't matter, at most there are a few crackles every now and then.
In my basement I have long LED chains, when they are switched off they flash every 7 seconds, only short-circuiting with a relay helps....

It worked fine for me for years until I hooked up a computer. Only hum, because the small 3.5mm have poor contact with the ground. Then I connected the ground connections from the line in and out parallel and put an additional wire to ground of the amplifier (cynch outside). Everything helped a little.
Also had problems with the Cynch cables: measured everything was good, connected loose contact in the wire or on the plugs. to cry. And I had to pull the power plug of the laptop to run only on battery.
I now record with a Focusrite - Scarlett 3rd gereration! (US product) via USB: absolutely no more hum and clean 30kHz (needs the large 7.5mm jacks).


I still have a Panasonic SE-405 CD-4 demodulator laying around. Is no longer needed because I can now record on my both JVC 5436.
Transformer was broken, replaced by an external power pack: no more AC in the device. The switch for the EPC-45xx (semiconductor system, no more available) has spun: Conductors cut and firmly connected for a normal magnet system.
I reconnected the sockets for the additional Aux input as In and Out for recording. So I could record my CD-4 vinyls and play them back before the demodulator.
The box works well but just lies around.... ready for E-Bay
 

MidiMagic

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Sandpaper distortion is actually the carrier detection circuit switching on and off as it gains and loses the carriers in rapid succession. It is not a function of that actual noise coming from the groove. It is a function of the demodulation process if it's not going right.

The "breaking pencils" or "explosions" aspect only happens if the CD-4 system is not set up correctly. Scratches or dirt sound no different from two channel records in my system. As I have stated elsewhere, I have heard the various CD-4 distortions and actually did have some of them in my system when I re-entered the CD-4 world many years ago, now, but they were corrected, mainly through tracking adjustments.

Doug
That is certainly not what I got.

Maybe they improved demodulators since I gave up on CD-4, but I know the crashes were from dust ground into the grooves. I turned the demodulator switch to CD-4 and heard the crashes. I turned the switch to stereo and heard tiny clicks. And using a record cleaner removed some of the crashes, but not all of them. This was the setup record that came with the demodulator. But it had been used before I got it.

There was also the time I went into the stereo store and heard the crashes start when a woman put powder on her face using the mirror next to the turntable. The store manager was unable to remove the crashes by cleaning the record.

What adjustment cancels out boulders of dust (at CD-4 size)?
 

J. PUPSTER

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There are endless possibilities for a good hum, I'm sure you've tried a lot and I'm not telling you so much new.
Hum Jam is a burden for all. Just before Janis Joplin starts singing I saw the big 50Hz on the record... you are never alone!
The housing of the Technics turntable is grounded via a separate cable to the amplifier instead via the common ground of the mag.head, if necessary you can also connect this to the grounding of the wall socket (if you have there a separate earthing like in europe).
With or without a mains filter doesn't matter, at most there are a few crackles every now and then.
In my basement I have long LED chains, when they are switched off they flash every 7 seconds, only short-circuiting with a relay helps....

It worked fine for me for years until I hooked up a computer. Only hum, because the small 3.5mm have poor contact with the ground. Then I connected the ground connections from the line in and out parallel and put an additional wire to ground of the amplifier (cynch outside). Everything helped a little.
Also had problems with the Cynch cables: measured everything was good, connected loose contact in the wire or on the plugs. to cry. And I had to pull the power plug of the laptop to run only on battery.
I now record with a Focusrite - Scarlett 3rd gereration! (US product) via USB: absolutely no more hum and clean 30kHz (needs the large 7.5mm jacks).


I still have a Panasonic SE-405 CD-4 demodulator laying around. Is no longer needed because I can now record on my both JVC 5436.
Transformer was broken, replaced by an external power pack: no more AC in the device. The switch for the EPC-45xx (semiconductor system, no more available) has spun: Conductors cut and firmly connected for a normal magnet system.
I reconnected the sockets for the additional Aux input as In and Out for recording. So I could record my CD-4 vinyls and play them back before the demodulator.
The box works well but just lies around.... ready for E-Bay
YOU DON'T SAY.gif
 

par4ken

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There are endless possibilities for a good hum, I'm sure you've tried a lot and I'm not telling you so much new.
Hum Jam is a burden for all. Just before Janis Joplin starts singing I saw the big 50Hz on the record... you are never alone!
The housing of the Technics turntable is grounded via a separate cable to the amplifier instead via the common ground of the mag.head, if necessary you can also connect this to the grounding of the wall socket (if you have there a separate earthing like in europe).
With or without a mains filter doesn't matter, at most there are a few crackles every now and then.
In my basement I have long LED chains, when they are switched off they flash every 7 seconds, only short-circuiting with a relay helps....

It worked fine for me for years until I hooked up a computer. Only hum, because the small 3.5mm have poor contact with the ground. Then I connected the ground connections from the line in and out parallel and put an additional wire to ground of the amplifier (cynch outside). Everything helped a little.
Also had problems with the Cynch cables: measured everything was good, connected loose contact in the wire or on the plugs. to cry. And I had to pull the power plug of the laptop to run only on battery.
I now record with a Focusrite - Scarlett 3rd gereration! (US product) via USB: absolutely no more hum and clean 30kHz (needs the large 7.5mm jacks).


I still have a Panasonic SE-405 CD-4 demodulator laying around. Is no longer needed because I can now record on my both JVC 5436.
Transformer was broken, replaced by an external power pack: no more AC in the device. The switch for the EPC-45xx (semiconductor system, no more available) has spun: Conductors cut and firmly connected for a normal magnet system.
I reconnected the sockets for the additional Aux input as In and Out for recording. So I could record my CD-4 vinyls and play them back before the demodulator.
The box works well but just lies around.... ready for E-Bay
I think that I asked you this before, but years ago there was an internet post someplace where it showed just what you are talking about; recording from the CD-4 Demodulator and playing back through the demodulator. The post showed full pictures of the set up. The author burned special DVD-Audio discs to playback through the modified demodulator. I thought that it was very cool. I no longer have links to that post and doubt that the web page still exists. I've since searched for it without success. Was that your post? Pictures of the setup and modifications would be very cool!
 

jupp369

Member
Joined
May 9, 2021
Messages
36
Location
Berlin
I think that I asked you this before, but years ago there was an internet post someplace where it showed just what you are talking about; recording from the CD-4 Demodulator and playing back through the demodulator. The post showed full pictures of the set up. The author burned special DVD-Audio discs to playback through the modified demodulator. I thought that it was very cool. I no longer have links to that post and doubt that the web page still exists. I've since searched for it without success. Was that your post? Pictures of the setup and modifications would be very cool!
I posted befor a year:
CD-4 Recording? Very easy:

Solder the cable behind the RiAA output capacitor and record it with 192/24 (Audacity). (96/24 give triangels)
Feed in again at (almost) the same point via a capacity, but disconnect, cut, the RiAA out, i.e. before the resistor bridges and the CD4 demodulator.
Works great!
Small switch (2xUm) with 2 sockets Out, 2 sockets In via e.g. 4.7uF or so (Panasonic SEH 405 needs 2 resistors each channel about 22k for the DC voltage symmetry).
see schema from JVC5436

I had luck to have at once the right components on the whole line, now there are some new traps:
Computer: after XP there are frequency limiters for audio In and Out. They need to be set at 192/24. Win7 can't record at such frequency anymore, so I have to by a Focusrite - Scarlett 3rd gereration! (US product $150,-) via USB: absolutely no more hum and clean 30kHz (needs the large 7.5mm jacks).
HDMI: I was suprised, that it works fine at one TV, but not on a newer TV. The TV tells the sender via HDMI handshake: no more than 20kHz on all outputs. Use RGB cable and everything works fine. (or a RGB to HDMI converter, $15,-)

Now I rewired my "new" JVC GX500: all inputs to all Matrix/CD4 inputs, all Matrix/CD4 out to the Mode selector, and the SQ - CD4 is automatical switched by the CD4 radar.
Next year I will do that with the both 5436. Hope I can add then also an IR remote control for volume and direction. But this all needs a lot of work.
 

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edisonbaggins

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Just purchased a NOS Pickering D4500Q stylus replacement, for a smidge more than a JICO copy.
My theory is that my current stylus is worn. I hope that is it!

Question: I want to acquire a 2nd head shell, so I can dedicate the D4500Q cart/stylus to CD-4.
Do I need to be especially careful about the 2nd head shell choice? I guess I could use it for stereo/matrix quad records. My specific worry is if it's wiring doesn't meet the CD-4 standard.
 
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par4ken

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Just purchased a NOS Pickering D4500Q stylus replacement, for a smidge more than a JICO copy.
My theory is that my current stylus is worn. I hope that is it!

Question: I want to acquire a 2nd head shell, so I can dedicate the D4500Q cart/stylus to CD-4.
Do I need to be especially careful about the 2nd head shell choice? I guess I could use it for stereo/matrix quad records. My specific worry is if it's wiring doesn't meet the CD-4 standard.
Not much wire in a headshell, should not be a problem.
 
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