CD-4 (Quadro) LP-decoder/RIAA - diyAudio
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Old 13th November 2009, 07:40 PM   #1
Cobra2 is offline Cobra2  Norway
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Default CD-4 (Quadro) LP-decoder/RIAA

Has anybody built a 4-ch. decoder for analog? Is there any good designs worth copying? (Sony/Panasonic/Technics/JVC...?)

Arne K
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Old 16th November 2009, 07:49 PM   #2
oshifis is offline oshifis  Hungary
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I built an SQ decoder decades ago, but this technology just makes the soundfield confusing (perhaps this is why it has disappeared). CD-4 uses some kind of FM I think and it needs a special needle (Shibata?).
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Old 16th November 2009, 08:36 PM   #3
Cobra2 is offline Cobra2  Norway
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I know, I got several "CD-4-certified" cartridges/needles.
(AT/Grace/Empire)
But if I could build it myself, it would just be for the experiment.
I have seen decoders sold on epay, at stupid prices, and also heard that the sound-quality differs a lot...
-like a Technics model was much better than a Panasonic unit.

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Old 12th January 2010, 12:57 AM   #4
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I'd like to know what you find out as well. I have the Panasonic cartridge but no decoder.

Thanks,


GR
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Old 12th January 2010, 11:58 AM   #5
Ghianni is offline Ghianni  Greece
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Default Jan. 12

I remember that, about 30 years ago B&O had produced a Tangential tracking turntable, the Beogram 6000, which was equipped with such a decoder. You may ask for the company in DK to provide you a service manual of that turntable and you DY the decoder. As I remember the special cartridge was capable of "reading" up 45 kHz.

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Old 12th January 2010, 01:16 PM   #6
danzup is offline danzup  Romania
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Quote:
Originally Posted by Cobra2 View Post
Has anybody built a 4-ch. decoder for analog? Is there any good designs worth copying? (Sony/Panasonic/Technics/JVC...?)

Arne K
Why to build such an device when this days you do not have what source to play that is record for 4ch !
Or do you like funny fake sound stage ?
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Old 12th January 2010, 09:01 PM   #7
Cobra2 is offline Cobra2  Norway
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I have several records...and capable pickups...just wondered if it was worth trying..?
Or if I should buy an overpriced ebay-unit to try?

Arne K
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Old 28th February 2010, 04:53 AM   #8
fftulip is offline fftulip  United States
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I suggest that you try the QuadrophonicQuad Forums for ideas:
QuadraphonicQuad Forums
There is at least one design there (Dorren, under Discrete LP Formats) that uses up to date, near state of the art circuitry.

I have a vintage Panasonic CD4 decoder and matching cartridge ("semiconductor"), but I've only listened to it briefly so far. The decoder design is only what I would call "mid-fi", using mostly discrete parts plus a few old style op-amps (lots of Japanese parts probably obsolete nowadays, no audiophile grade caps, etc). I managed to pick it up for fairly cheap but if you want audiophile sound you can probably do a lot better using modern IC's and better quality parts. I've heard that the Technics version of the decoder is better quality than the Panasonic but have no first hand experience with it.

You don't really need a "special" needle for CD4, just a good cartridge that has extended high frequency response to well over 20KHz. A Shibata style tip will help do that, but it's not absolutely necessary.
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Old 28th February 2010, 08:33 AM   #9
Cobra2 is offline Cobra2  Norway
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I did register at the Quadra-forum, but never got the "activation" mail, and do not find anyway to contact admin...

Arne K
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Old 28th February 2010, 11:14 PM   #10
fftulip is offline fftulip  United States
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Originally Posted by Cobra2 View Post
I did register at the Quadra-forum, but never got the "activation" mail, and do not find anyway to contact admin...

Arne K
Arne, this is probably one of the forums that has problems with e-mails being blocked by certain mail servers. If you have an alternate e-mail address (like one at work), try using that for activation.
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