Other Labels Quad Output & CD-4, QS & SQ Technical

[kfbkfb]

Drifting OT...

Stereo Lab - JVC CD-4 Decoding in software

JVC CD-4 decoding in software

www.pspatialaudio.com

An all software CD-4 decoder was developed in the last few years, these pages have some background info about CD-4, including some SEM photos of CD-4 record wear.


Kirk Bayne

 

[par4ken]

Oh, so a CD-4 LP plays back with unlimited high-frequency response when played in stereo, but the quad decoding is where the limitation is enforced. Ok, I don't do CD-4 decoding at home, and only study the records in stereo, or conversions others have done.

No wonder I've gotten some spectacular results capturing CD-4 LPs to stereo high-res digital.

Not really, the audio is still limited to 15 KHz, above that is the modulated FM carrier, it would sound as noise if audible at all.

 

[par4ken]

I noticed that polarity problem with Grado cartridges, and some Shure models when I was "experimenting" with some stereo cartridges. The Grados were all labeled as CD-4 capable.

I used Grados for years and never ran into that problem, I would suspect aftermarket styli. I never was able to get really good CD-4 until I switched to a moving coil cartridge. I did run into that problem though when I used a tube based pre-preamp with the moving coil (the pre-preamp inverts phase).

 

[4-earredwonder]

Never had any luck decoding CD~4 vinyl so out of frustration I invested in a TEAC 2340SX QUAD Open Reel Recorder with matching AN~300 Dolby B decoder! Problem was, Columbia Records, out of diehard commitment to their SQ matrix system, refused to release QUAD Open Reels [Only Q8] coupled with the fact that QR releases were sparse, at best and akin to the 70's QUAD 'revolution' likewise fizzled out prematurely.

And after hearing Rhino's recent Doobies Brothers QUADIO boxset on 192/24 BD~A, we, at QQ Forum, need to petition Warner/RHINO to release more of their excellent QUAD masters in that format because nothing, NOTHING approaches the sublime excellence of hearing those original QUAD analogue masters 'liberated' from all previous VINYL, QR, Q8 'limitations!'

TIME TO MAKE SOME NOISE, QQers!

 

[quicksrt]

It's done during the demodulating of the record, since the frequencies above 15 kHz could interfere with the demodulator's function. Remember, the center frequency of the carrier is 30 kHz, and harmonics of that frequency could play hell with the demodulator's ability to decipher the difference information in the carriers.

Not really, the audio is still limited to 15 KHz, above that is the modulated FM carrier, it would sound as noise if audible at all.

Then Jaybird is incorrect in his phrasing and actually means it is done in the encoding or mastering rather than done in the demodulating of the signals. "Demodulating to me means the decoding to four channels. As in a CD-4 demodulator > demodulates. And you are saying this is not where the 15k limiting is done. ok.

 

[par4ken]

Then Jaybird is incorrect in his phrasing and actually means it is done in the encoding or mastering rather than done in the demodulating of the signals. "Demodulating to me means the decoding to four channels. As in a CD-4 demodulator > demodulates. And you are saying this is not where the 15k limiting is done. ok.

It would have to be done in both places. You don't want the audio interfering with the modulated signal and you don't want the modulated signal fed to your speakers.

 

[quicksrt]

Drifting OT...

Stereo Lab - JVC CD-4 Decoding in software

JVC CD-4 decoding in software

www.pspatialaudio.com

An all software CD-4 decoder was developed in the last few years, these pages have some background info about CD-4, including some SEM photos of CD-4 record wear.


Kirk Bayne

Cool, does it work really well? Conversions specialists around these parts have experience with it?

 

[kfbkfb]

Cool, does it work really well? Conversions specialists around these parts have experience with it?

Several QQ members assisted with the development of these 2 CD-4 software decoders (suggestions, needledrops, listening evaluations etc.), more info:

Working CD-4 (software) Demodulator!

http://www.pspatialaudio.com/JVC_CD-4.htm ^^^ Please email them. Kirk Bayne

www.quadraphonicquad.com

also:

CD-4 in Hi-Fi World mag

http://71.248.165.151/Books-Mags/Hi-Fi%20World%20%E2%80%93%20October%202019.pdf ^^^ (been told link may not work) "What I heard is as good as, if not better, than vintage hardware decoders - which rely on obsolete and now-unobtainable chips." Kirk Bayne

www.quadraphonicquad.com

I don't know how the Stereo Lab decoder(s) compare with a JVC CD4-50 (for example) on problem discs (high baseband/sum signals).


Kirk Bayne

 

[fizzywiggs41]

They may have let one good one slip through.

Too bad they didn't release any of Lou Reed's Arista's , or Alan Parson Project.

 

[fizzywiggs41]

Never had any luck decoding CD~4 vinyl so out of frustration I invested in a TEAC 2340SX QUAD Open Reel Recorder with matching AN~300 Dolby B decoder! Problem was, Columbia Records, out of diehard commitment to their SQ matrix system, refused to release QUAD Open Reels [Only Q8] coupled with the fact that QR releases were sparse, at best and akin to the 70's QUAD 'revolution' likewise fizzled out prematurely.

In hindsight , it might have been a good idea for Columbia Records , EMI , ABC , and other matrix Companies to initiate the release of 2ch Matrix Quad Reels .
Equal to or better than most vinyl I'd reckon.


-fizzled out

 

[fizzywiggs41]

There is a copy of the Brazilian SQ for sale on Discogs for $120. I have the DVD-Video release of this. I don't remember how it sounds I'll have to pull it out to give it a try. The set includes the CD of the original album plus bonus tracks and the DVD with the Quad to 4.1 mix and the hi-rez stereo mix.

Thanks Ken , but I do have that quad dvd .
FWIW there are 3 or four ELO CD compilations with some SQ encoded tracks on each set. (Early Years , The Harvest Years , and etc)

 

[4-earredwonder]

In hindsight , it might have been a good idea for Columbia Records , EMI , ABC , and other matrix Companies to initiate the release of 2ch Matrix Quad Reels .
Equal to or better than most vinyl I'd reckon.


-fizzled out

NO pun intended, Fizzy but with the matrix decoders of the time, QUAD QR's would've still beat the pants off them. Chucky's SM was about 45 years too late!

 

[fizzywiggs41]

NO pun intended, Fizzy but with the matrix decoders of the time, QUAD QR's would've still beat the pants off them. Chucky's SM was about 45 years too late!

Oh I agree , but the cost of a QR (vs. 2Ch reel) was prohibitive for most Collectors.
I had a good friend in the UK that utilized 2ch Reel an awful lot.

Anyway just pondering the thought. What might have or could have .

BTW I thought I had read in 4 Quad/ Evolution or Quad Inc at one time , that .....
BARCLAY CROCKER issued 2ch Encoded Reels ?


Segue to Reels -
Which kinda brings me to another big question .....What the F is Sony/CBS Columbia , Vanguard , EMI , ABC/UMG -
etc , doing with all those SQ or QS 2ch Encoded Master Reels ?
I'm certain owners of Surround Masters , Tates , Sansuis' would love to get ahold of those reels either as a physical product or downloads.

 

[par4ken]

Oh I agree , but the cost of a QR (vs. 2Ch reel) was prohibitive for most Collectors.
I had a good friend in the UK that utilized 2ch Reel an awful lot.

Anyway just pondering the thought. What might have or could have .

BTW I thought I had read in 4 Quad/ Evolution or Quad Inc at one time , that .....
BARCLAY CROCKER issued 2ch Encoded Reels ?


Segue to Reels -
Which kinda brings me to another big question .....What the F is Sony/CBS Columbia , Vanguard , EMI , ABC/UMG -
etc , doing with all those SQ or QS 2ch Encoded Master Reels ?
I'm certain owners of Surround Masters , Tates , Sansuis' would love to get ahold of those reels either as a physical product or downloads.

I often wonder that myself, what about the encoded masters? A couple supposed SQ encoded CD's were released in Japan. I think that they turned out to be stereo versions, with SQ on the packaging! I have a couple of bootlegs but they are vinyl sourced.

OD did do a QS decode of (unreleased) Joe Walsh "So What" so he got a master tape copy from somewhere. I would of liked to get the original QS to decode myself vis QSD-1 and Involve.

 

[4-earredwonder]

Oh I agree , but the cost of a QR (vs. 2Ch reel) was prohibitive for most Collectors.
I had a good friend in the UK that utilized 2ch Reel an awful lot.

Anyway just pondering the thought. What might have or could have .

BTW I thought I had read in 4 Quad/ Evolution or Quad Inc at one time , that .....
BARCLAY CROCKER issued 2ch Encoded Reels ?


Segue to Reels -
Which kinda brings me to another big question .....What the F is Sony/CBS Columbia , Vanguard , EMI , ABC/UMG -
etc , doing with all those SQ or QS 2ch Encoded Master Reels ?
I'm certain owners of Surround Masters , Tates , Sansuis' would love to get ahold of those reels either as a physical product or downloads.

Have NO idea what Columbia/EMI/ABC/UMG is doing with all those SQ/QS encoded Master Reels but I did buy a slew of Barclay Crocker's Dolby B encoded Open Reel Tapes [ALL 7 1/2 ips] and had NO IDEA they were SQ encoded.

You learn something NEW every day @ QQ!

 

[quicksrt]

I have the CD-4 of Cat's Greatest Hits and, other than them maybe pushing the gain limit on the first track (Wild World), there really isn't anything wrong with it. In fact, it sounds great.

Doug

Not one fake quad track on the entire thing? Ok, good to know!

 

[fizzywiggs41]

OD did do a QS decode of (unreleased) Joe Walsh "So What" so he got a master tape copy from somewhere. I would of liked to get the original QS to decode myself vis QSD-1 and Involve.

I have that conversion(?) myself. But for all we know it could be a discreet upmix that was encoded , OD supplied very little in the way of it's source or accuracy ? For someone who prides himself with accuracy over others you would think he would lead by example.

 

[par4ken]

I have that conversion(?) myself. But for all we know it could be a discreet upmix that was encoded , OD supplied very little in the way of it's source or accuracy ? For someone who prides himself with accuracy over others you would think he would lead by example.

It didn't sound to me like an upmix!

 

[fredblue]

I have that conversion(?) myself. But for all we know it could be a discreet upmix that was encoded , OD supplied very little in the way of it's source or accuracy ? For someone who prides himself with accuracy over others you would think he would lead by example.

i think you're right to be cautious fizzy after all nobody's perfect, we all make mistakes. one of the most obvious examples i was made aware of was his 'release' of Weather Report's "Tale Spinnin'" which was patently the Stereo run through his SQ process.

 

[fizzywiggs41]

It didn't sound to me like an upmix!

Ken , it may be legit , but I think more source accuracy would be required. Especially considering what can be done with a good discreet upmix nowadays. Everyone on QQ knows this quad album was withheld by ABC Records.
I have lot's of his conversions , and they are very good , some excellent. But this one , well , I just find somewhat questionable.
Everyone makes mistakes , including me, but he would be the last one on QQ to admit his errors. My dealings with him on his former site confirm this.
FWIW It does sound pretty good .