CD-4 adjustment question

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gvl_guy

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What you do is use your worst CD-4 album (if you have Cat Steven's Greatest Hits" that's a good one to use. Turn down your separation pots so that you only hear the subcarriers. It will sound hollow, that's normal. Play the record and adjust for the best fidelity. I would turn it up until it clears up and go no more. If you have trouble cleaning it up, adjust for the least distortion. If the clean area is wide, then find the edge points and go in between. Then bring up your separation pots and adjust for max separation. If it sounds clean over a wide range, then that's a good sign that you have a very good CD-4 cartridge/stylus.
Great advice. Any suggestions how to adjust the carrier level, too? I keep getting a crackling sound, no matter if I use the JVC or Shure cartridge.
 

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par4ken

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Great advice. Any suggestions how to adjust the carrier level, too? I keep getting a crackling sound, no matter if I use the JVC or Shure cartridge.
Make sure your phono cables are of low capacitance. Standard cables usually have much to high capacitance to ever allow CD-4 to work properly. Where to find them is another question? Keep them short as twice the length equals twice the capacitance.
 

Sonik Wiz

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Make sure your phono cables are of low capacitance. Standard cables usually have much to high capacitance to ever allow CD-4 to work properly. Where to find them is another question? Keep them short as twice the length equals twice the capacitance.
Good 'ol Blue Jeans Cable has them:

You can order to the exact length you want & other choices. I've never seen a TT with RCA out jacks on them; they are solder terminated internally. So you would have to open up the TT, unsolder the current cable & replace with new.
 

J. PUPSTER

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Good 'ol Blue Jeans Cable has them:

You can order to the exact length you want & other choices. I've never seen a TT with RCA out jacks on them; they are solder terminated internally. So you would have to open up the TT, unsolder the current cable & replace with new.
That’s the cables I’ve been buying recently, and the plugs are snug but not too tight. I’m considering a new TT to replace my old Technics 1500 with a 1200Mk7 and you can use your external cables on those, so we’ll see. And by the way, just got my QRX-8001 back in ;)
 

gvl_guy

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Make sure your phono cables are of low capacitance. Standard cables usually have much to high capacitance to ever allow CD-4 to work properly. Where to find them is another question? Keep them short as twice the length equals twice the capacitance.
I'm using my original Technics SL-1700 turntable, so they should be fine. I remember buying it years ago with CD-4 in mind. So I should be good there
 

J. PUPSTER

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I'm using my original Technics SL-1700 turntable, so they should be fine. I remember buying it years ago with CD-4 in mind. So I should be good there
I’ve often wondered if thin shielding on these old TT cables could introduce some noise, the Blue Jeans cables are also thick and are well shielded?
 

gvl_guy

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I’ve often wondered if thin shielding on these old TT cables could introduce some noise, the Blue Jeans cables are also thick and are well shielded?
Something tells me that the cables on the SL-1700 come right out of the body and can't just be unplugged and replaced. ☹
 

J. PUPSTER

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Great advice. Any suggestions how to adjust the carrier level, too? I keep getting a crackling sound, no matter if I use the JVC or Shure cartridge.
Do you get a crackling sound occasionally from other gear sources through your receiver?
I'm not an electronics expert like some of these guys here, but that's one of the reasons I sent my Sansui in for restoration, I'd occasionally get a crackling sound and figured it was some electronic part starting to fail.
 

gvl_guy

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Do you get a crackling sound occasionally from other gear sources through your receiver?
I'm not an electronics expert like some of these guys here, but that's one of the reasons I sent my Sansui in for restoration, I'd occasionally get a crackling sound and figured it was some electronic part starting to fail.
No. Only happens when I'm playing CD-4, no other source. It's like the record is crackling, except when I turn off the demodulator, it's fine. Maybe it's the demodulator is shot.
 

MidiMagic

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Great advice. Any suggestions how to adjust the carrier level, too? I keep getting a crackling sound, no matter if I use the JVC or Shure cartridge.
It's fine dust in the CD-4 groove. Larger dust particles make crashing sounds like people breaking pencils in half.

It is also possible that static electricity can make such sounds.
 

J. PUPSTER

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It's fine dust in the CD-4 groove. Larger dust particles make crashing sounds like people breaking pencils in half.

It is also possible that static electricity can make such sounds.
I’m leaning toward the static electricity; isn’t there some inexpensive device that removes that from LPs? I know I’ve seen a video of something like that 🤔
 

DuncanS

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I’m leaning toward the static electricity; isn’t there some inexpensive device that removes that from LPs? I know I’ve seen a video of something like that 🤔
Years ago I got an antistatic brush on its own 'tonearm' which was earthed, it got rid of most of the static but added its own 'rumbling sound' so I ditched it!
 

J. PUPSTER

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Years ago I got an antistatic brush on its own 'tonearm' which was earthed, it got rid of most of the static but added its own 'rumbling sound' so I ditched it!
I just added a dedicated thread to this issue to keep this thread on track:
 

MidiMagic

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Years ago I got an antistatic brush on its own 'tonearm' which was earthed, it got rid of most of the static but added its own 'rumbling sound' so I ditched it!
Use the brush first. Then play the record.

I just remembered the one time I recently saw a CD-4 system. When the owner used his cell phone, it acted up.
 

Doug G.

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If you get noises during CD-4 play, it is most likely due to either cables having too high capacitance and the carriers are getting attenuated before they get to the demodulator and the demodulator is losing control of the signals or, in an automatic model, the demodulator is switching in and out of demodulation which sounds like "crackles" or the infamous "sandpaper quad" when it happens.

Doug
 
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Circular Vibes

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I will add my personal experience and Aha moment with CD4. I tried a few NOS carts and all my turntables and nothing worked. I bought quite a few demogitators including a NOS 4DD5. My breakthrough was buying genuine Technics RCA cables and replacing the leads on 3 different turntables. Instant gratification with this and an AT440MLB. I bought the wires at Kabusa.com . Now all my internal demogitators in receivers work. I am not a fan of turntables that use removeable RCA cables as the extra jacks and plugs add capacitance. This is bad for most of us using CD4. I did also shorten the genuine Technics cables by 1 foot which also helped in my situation. That may not be realistic for all set ups though. All this chaatter of mine is only to say don't disregard the wiring. BTW, my copy of Cat Stevens Greatest Hits is a difficult tracker to set up BUT it is far from a bad pressing and sounds pretty good now. I must have been lucky. The difficult one I have is Barry Manilow 2. AoQ also had difficulty with a sealed copy. A later Barry title was even worse apparently. I haven't splurged on the other 2 Barry quad LPs....yet.
 
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