Lou Dorren: A new CD-4 Demodulator!!! [ARCHIVE]

[Bonzodog]

Me too.

I'm no longer a subscriber either.

Used to subscribe - for many years, and Robert Harley would invite me to their annual "Wine and Cheese" party. Helped him out on their first CD. (OOPS - I take it back. That was Stereophile)

Anyway, he stopped inviting me, so I dropped my subscription. (Or was it the other way around.)

So, what's the letter say?

 

[vinylguy4]

short letter, most probably a QQ member.
Returned as subscriber after many years, listens only to quad or surround sound, please have more reviews of sacd/dvd-a/surround equipment and music. And by the way, vinyl freaks and quadraholics will want to know that Lou Dorren is making a new killer CD-4 demodulator and will have it for sale in the future.
That was the gist. And it got printed!

The sentence about the vinyl quadraphonic rebirth is a bit premature. Need to find some of that JVC supervinyl for making new CD-4 records. But a vinyl reissue of Dylan - Desire SQ would be a good idea.


vinylguy4

 

[Quadro-Klaus]

Lou has been crazy busy lately so I'll answer you about the power supply. It WILL be universal... I'll let him give the details when he's on the board.

@ wa6ubw, thank you, this will be fine

 

[wa6ubw]

The sentence about the vinyl quadraphonic rebirth is a bit premature. Need to find some of that JVC supervinyl for making new CD-4 records. But a vinyl reissue of Dylan - Desire SQ would be a good idea.

unless somebody finds a lathe sitting in a garage or basement, there's no hope of pressing new CD-4 vinyl. :yikes

 

[Quadro-Action]

Ar the moment it seems, that Lou is working with the fine adjustment for the prototype of the new demodulator. And then should later start the "mass production" or those by the orders from the fans (I hope many). With this can be true till the end ore even during 2008, I have hope, that he has in the background technical skilled helpers or has connection to a little firm for techncal productions. Some similar it was her in Germany in the 80's, as a technical skilled hifi-journalist has made the technical instructions and a few helpers built us 20 sets of a QSD-2. One can built alone not any or many items self. Back to the Demodulator: Gradually I am really curious, when I can inform our quadraphonic fans here about details and price - and of course, how many will make then an order. But also a new statement from Lou will satisfy our curiousity.

Dietrich

 

[surroundophile]

short letter, most probably a QQ member.
Returned as subscriber after many years, listens only to quad or surround sound, please have more reviews of sacd/dvd-a/surround equipment and music. And by the way, vinyl freaks and quadraholics will want to know that Lou Dorren is making a new killer CD-4 demodulator and will have it for sale in the future.
That was the gist. And it got printed!

The sentence about the vinyl quadraphonic rebirth is a bit premature. Need to find some of that JVC supervinyl for making new CD-4 records. But a vinyl reissue of Dylan - Desire SQ would be a good idea.


vinylguy4

I wrote that letter, thank you very much!:sun .I didn't know it got printed. The response I got didn't didn't make me think it would be printed.

Here is my original letter:
I am now a subscriber to TAS because you shut down TAV(ision). Wow have you guys changed (for the better) ! The last time I looked at you guys, you were a small magazine that hurt my eyes to read, only reviewed components that Trump could afford, and had absolutely NO interest in multi channel sound (which is the only way I listen), turning up you nose to Quadraphonics in the 70's.
Thank you for you SACD reviews, the new Multichannel column, and the guest editorial about "A Grand Multichannel Experiment"; what a great idea! Don't forget to do Multichannel equipment reviews, along with reviews of DVD-As, and rock, jazz and other types of SACDs & DVD-As. Also, your vinyl affeciandos might want to know, along with today's vinyl rebirth, there will soon be a vinyl quadraphonic rebirth too. One of the original promoters of the CD-4 (Quadradisc), Lou Dorren, is working on a new, up-to-date, modern CD-4 demodulator that he himself will be selling, that won't have any of the problems that the units of the 70's had. For further on this , or ANY info on {not just} quadraphonic and multichannel sound, please visit www.quadraphonicquad.com .
Thanks for the changes!! I will be renewing.

And here is the response I got :

Dear Mr. Thomas:

Thanks for the note. I'm thrilled that you like the direction TAS has taken. We'll be reviewing plenty of multichannel software and hardware, and will keep an eye on developments in CD-4.

Best regards,

Robert Harley
Editor-in-Chief
The Absolute Sound


As far as the quadraphonic vinyl rebirth, I was hoping we could still find a
CD-4 lathe that still worked when I wrote that letter. But now according to Lou's post above, it looks like it won't be

 

[ChristopherLees]

JVC super vinyl ended because it was carconogenic in the manufacturing process....at least that's what MFSL told me...
and the UHQR plant was replaced with cd manufacturing

 

[kfbkfb]

Regarding making CD-4 records in 2008:

In an earlier post I described a method of creating
a CD-4 "encoded" 2-channel master recording that
could be used with a 1/2 speed record cutting lathe
to create CD-4 master discs.

I still think my idea would work because the CD-4
"encoded" 2-channel recording is just an analog
signal with a great deal of continuous high frequency
content (the FM based carriers).

The 1/2 speed record cutting lathe wouldn't "know" it
was a CD-4 "encoded" 2-channel recording, the lathe
systems could be adjusted to deal with all of the high
frequency content (up to about 23kHz) and could cut
the master disc the same way any master recording
with a lot of high frequency content would be cut.

Kirk Bayne

 

[vinylguy4]

TAS did not print this sentence:
"For further on this , or ANY info on {not just} quadraphonic and multichannel sound, please visit www.quadraphonicquad.com ."
The wording was also changed a bit, but the rest of the letter was all there.

vinylguy4

 

[The Quadfather]

Don't you hate uppity editing. It would certainly have been a service to their readers whom are interested in CD-4 to include the weblink. I guess no one can be allowed to compete with them.

 

[loudorren]

Hello Quadrafiers,

I am posting the 2 dimensional drawing of the front and back panels of the new demodulator. A full 3 dimensional drawing will be shown shortly.

ChristopherLees, MFSL was misinformed. The actual compound is Q-540 developed by Monarch processing, RCA Record labs and QSI. It was never discontinued and is still being used to press stereo records.

Lou Dorren

 

[aludra]

Hey Lou,

Sure is good to see you here again....The front and back panels are beautiful. I am chomping at the bit to get my hands on your new design....I LOVE the seperate outputs (Wideband, RIAA)....perfect!!!!!
Is the Riaa+LPF connectors for re-inputing signal back to demodulator(I hope!!!!)
Already bought your QSI cleaner...cant wait to get that too...

Welcome Back!!

Mike

 

[jdmack]

Lou, a quick question, and I apologize if this has been discussed already.

What is the Wideband output? Is it just a straight phono output without any RIAA equalization? If so, that would be great to use for my turntable that I play 78s with (the antithesis of quad, I admit, but still a useful thing).

J. D.

 

[Quadro-Action]

Hello Lou, now we have another step forward with your printed and very much interested picture or illustration of the new Demodulator. That means - the expectation will further escalate. The quadraphonic world has never seen before such an expensive technic and modes for the adjustement. When you will mail the part 3, I will give this news about this CD-4 candy-piece as further information to our fans here.

Dietrich

 

[kfbkfb]

Regarding the Carrier Level meters:

Various reports say that, after 100 plays, the carriers
are down 3dB at times, what'll the display range for
the meters be?

Kirk Bayne

 

[loudorren]

Hello QQFans,

I corrected an omission on the 2 drawings. I had forgotten the line input.

Lou Dorren

 

[aludra]

Yipeeeeee!!!! Thanks Lou!!!!

 

[Quadro-Klaus]

@ Lou - Respect! That's great!

 

[Q-Eight]

So, there is no adjustment for carrier level? Does it automatically compensate as seperation is turned up to avoid distortion?

 

[The Quadfather]

Lou is not using the traditional method of carrier level regulation. He is instead using a method that is common in FM receivers. The carriers are separated from the audio and amplified. The tops and bottoms of the waveform peaks are cut off (as viewed on an oscilloscope) this creates what is essentially an FM/PM modulated square wave. Since the cutoff is rather drastic, minor variations in level do not survive the trimming and therefore cannot affect the output. what does survive is the FM/PM modulations that contain the original difference signal. This is fed to the traditional phase locked loop circuit at the optimum level. The oscillator frequency follows that of the truncated signal. The oscillator is controlled by a phase comparator that tracks the signal, and feeds a correction voltage to the oscillator. It is this correction voltage that is used as the output for it is an exact duplicate of the original modulating signal. It is because the signal level is kept constant by trimming it, that the phase lock loop circuit performs better than in the legacy demodulators. Did I get that right Lou?

The Quadfather