CD-4 (Quadro) LP-decoder/RIAA

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Cobra2

Cobra2

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Joined 2002
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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.

Arne K
 
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G

Ghianni

Member
Joined 2005
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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F

fftulip

Member
Joined 2010
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.
 
R-K Rønningstad

R-K Rønningstad

Member
Joined 2006
fftulip said:
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.
Click to expand...


The new Dorren CD-4 demodulator seems to be on hold, as Lou Dorren has not been active at the QQ forum for over half a year. I propose people should get some old 4DD-5 on ebay, and modify these according to some postings on the web. I do not have a link handy... Or maybe even implement a more modern front end. By that I mean replace the RIAA stage with something designed after 1972.
Or if the quad LPs from our youth maybe now are available on SACD, DVD-Audio or BluRay, and in surround, buy these instead. :spin:
 
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