Quaddities: This One's for You -- Barry Manilow (CD4) Listenable Copy?

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hmm.. wouldn't routing PC audio out into a demodulator cause problems?

i mean, the output from the PC would be line level and the demodulator would be expecting lower level phono signal from turntable..
 
I don't have much experience with PC sound cards, I don't
know if sound cards are available with an output frequency
range up to about 45kHz.

If the sound card has line level outputs, a simple 2 resistor
voltage divider could be used to lower it to phono level
(the PC wouldn't do any RIAA EQ, it would just pass through
the unEQ'd signal from the 1/2 speed input, but with all
frequencies doubled, i.e., back to normal).

There would need to be a 1 time setup:
Use a test record with a 1kHz tone, record at 1/2 speed,
play at normal speed and use the PC software to set the
output level to be the same as the 1kHz tone played at
normal speed.

Kirk Bayne

fredblue - Just curious - Do you have any Matrix Encoded
Compact Cassettes or DynaQuad or Electro-Voice Stereo-4
Matrix Encoded LPs?
 
hmm.. wouldn't routing PC audio out into a demodulator cause problems?

No. A simple attenuation cable should do the trick, the type designed to allow connecting a line-level signal to a mic input. There are many other options — long as they’re “low capacitance.” Haven’t used that term in like thirty years.

BTW, I’d always thought the ideal solution for demodulating CD-4 would be software. But Lou Dorren disagreed, saying hardware was better suited. I don’t recall him explaining why. He may have been wrong.
 
No. A simple attenuation cable would do the trick, the type designed to allow connecting a line-level signal to a mic input. There are many other options.

great stuff. hopefully this useful information will get back to the people running the project rather than little ol' me just trying to be helpful in his layman's way (y)
 
I don't have much experience with PC sound cards, I don't
know if sound cards are available with an output frequency
range up to about 45kHz.

If the sound card has line level outputs, a simple 2 resistor
voltage divider could be used to lower it to phono level
(the PC wouldn't do any RIAA EQ, it would just pass through
the unEQ'd signal from the 1/2 speed input, but with all
frequencies doubled, i.e., back to normal).

There would need to be a 1 time setup:
Use a test record with a 1kHz tone, record at 1/2 speed,
play at normal speed and use the PC software to set the
output level to be the same as the 1kHz tone played at
normal speed.

Kirk Bayne

fredblue - Just curious - Do you have any Matrix Encoded
Compact Cassettes or DynaQuad or Electro-Voice Stereo-4
Matrix Encoded LPs?

sorry Kirk, I'm afraid I don't have any matrix encoded cassettes or DynaQuad or EV-4 encoded LPs but i'm sure one of the helpful folks here who have been at this game a lot longer than me can help you in this endeavour :)
 
fredblue - You might consider loaning your copy of AQ-4090 to the developer(s)
of the (experimental) Stereo Lab (all software) CD-4 decoder, it seems like it would
be a good test disc for their CD-4 decoder (which, according to the latest info on
their website, has a alternate decode mode for "problem" CD-4 discs).

http://pspatialaudio.com/JVC_CD-4.htm

Kirk Bayne
 
fredblue - You might consider loaning your copy of AQ-4090 to the developer(s)
of the (experimental) Stereo Lab (all software) CD-4 decoder, it seems like it would
be a good test disc for their CD-4 decoder (which, according to the latest info on
their website, has a alternate decode mode for "problem" CD-4 discs).

http://pspatialaudio.com/JVC_CD-4.htm

Kirk Bayne

they can but I wouldn't recommend it, my copy of AQ-4090 is in really poor condition. I'm sure someone here has a copy in much better shape!
 
I'm sure someone here has a copy in much better shape!

I have one that I would loan out for that.
I believe it's NM.

The nice thing about this disc is it's not that hard to find a mint copy. Most including me only played it a few times because it decided so poorly on most equipment.
 
7D60F982-9C9B-4B84-BE7B-F447B28BBF40.jpeg


Looks like a top piece of gear.

I seem to recall somebody making a “professional”demodulator with a 1000 model number that cost a fortune.
Lots of knobs and dials.
Anyone?
 
I have one that I would loan out for that.
I believe it's NM.

The nice thing about this disc is it's not that hard to find a mint copy. Most including me only played it a few times because it decided so poorly on most equipment.

that's the QQ Dunkirk spirit! (y)
tbh i had the hardest time trying to find one the last couple of years and when i did was dismayed to find it turned up in pretty ropey condition.. oh well, maybe someday i'll find one of the many minty ones! :p
 
View attachment 33795

Looks like a top piece of gear.

I seem to recall somebody making a “professional”demodulator with a 1000 model number that cost a fortune.
Lots of knobs and dials.
Anyone?

drool.. that's just yummily to die for! :love:

if the Involve chaps could take this ultimate "holy grail" unit as their yardstick and develop their own spanky new demodulator, we'd have a real contender on our hands! (and a more readily available one at that!).. here's hoping they still have the will to do it! (y)
 
There was a JVC Laboratory Series CD4-1000, but I've only seen photos of it in one instance, outside of the original promotional material. Now, other discussions on the forum have been about upgrading a JVC CD4-10 to become a "studio" model, but that's circuitry modifications, with no additional external user buttons or knobs.
 
hmm.. wouldn't routing PC audio out into a demodulator cause problems?

i mean, the output from the PC would be line level and the demodulator would be expecting lower level phono signal from turntable..

No. A simple attenuation cable should do the trick, the type designed to allow connecting a line-level signal to a mic input.

You'd also have apply an inverse RIAA curve to the audio before outputting.
 
I don't have a CD-4 capable phono cartridge, I was hoping someone with
a suitable cartridge, PC and soundcard could try the 1/2 speed idea.

Kirk Bayne
 
IIRC, an article in the late 1970s in Audio magazine (USA) mentioned that a Quadradisc
release was cut about 2dB higher than the stereo release (wasn't AQ-4090).

I recently bought a used (stereo) copy of AL-4090 just to hear the songs.
I tried it through DPL, there's almost no out of phase content .

Has anyone compared the peak levels of AQ-4090 and AL-4090?

Kirk Bayne
 
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