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

[loudorren]

CQ CD-4ers,

kfbkfb,
Kirk, Demodulators that did not have limited PLL detectors used a signal level detector after the 30KHz bandpass filter. This detector would pickup any energy in the passband (incidental AM) and would flash the CD-4 lamp and open the sub-channel audio switch momentarily letting burst noise through. Demodulators with limited PLL detectors ignore any incidental AM and will only lock to an FM-PM-SSBFM signal.

Quadfather, Don't you wish your 4dd5 had a limiter!

Quadzilla, The LPF was a band aid so the the pickup would work with 4dd5s etc.

To all: New Demodulator update. Things are working very well and you all should be hearing from Jon fairly soon. I will post a photo of the populated working circuit board shortly,

73's

Lou Dorren, WB6TXD

 

[aludra]

Yea!!!!!lou!!!!!!!

Thank you for all your hard work and brilliance...i cant wait!!!

Mike

 

[The Quadfather]

Hey Lou:
I had often thought that the limiting technique used in FM radio would be the way to go in demodulator design even before I read your writings. However, the 4DD5 does perform adequately without it. But you do have to throw the switch when listening to stereo material. Of course, when you finish that new demodulator, my new demod will have a limiter!

The Quadfather

 

[loudorren]

Quadraphonic Quad New CD-4 Demodulator NEWS:

Hello ALL CD-4ers,

I have just received the first new cartridges. They are to say Fantastic. Just some specs for you to review:

Frequency Response 5Hz to 62KHz
Channel Separation at 1KHz 38dB
Channel Separation at 60KHz 18dB
Load Impedance 50KOhm
Output Level at 1KHz 5CM/sec. 4.5mV
Recommended Tracking Force 1.5 grams
Stylus Type Shibata
Compliance 34.5 x 10-6cm/dyne


The CD-4 performance is superb and audio quality is great! More information about it's performance with the new demodulator will be published shortly.

Jon's evaluation will be soon.

Lou Dorren

 

[roundhousequad]

Quadraphonic Quad New CD-4 Demodulator NEWS:

Hello ALL CD-4ers,

I have just received the first new cartridges. They are to say Fantastic. Just some specs for you to review:

Frequency Response 5Hz to 62KHz
Channel Separation at 1KHz 38dB
Channel Separation at 60KHz 18dB
Load Impedance 50KOhm
Output Level at 1KHz 5CM/sec. 4.5mV
Recommended Tracking Force 1.5 grams
Stylus Type Shibata
Compliance 34.5 x 10-6cm/dyne


The CD-4 performance is superb and audio quality is great! More information about it's performance with the new demodulator will be published shortly.

Jon's evaluation will be soon.

Lou Dorren

Hello Lou just wondering the JVC specs have the Load Impedance at 100k is this taken into consideration in the the new box?
next will it have impedance switch to take advantage of our good carts that are 100k like the AT20?
Thank you for the update
Jim

 

[loudorren]

Hello QQ People,

roundhousequad,

Jim, Most phono pre-amps have a 50 (47) KOhm termination resistor on the input. A cartridge such as the AT20, being a generator type will drive the 50 (47) KOhm with no effect on frequency response, separation, or distortion. The output level will be 6 dB lower than one that has a 50 KOhm impedance. The new demodulator will have no problem with 6 db cartridge level difference.

Lou Dorren

 

[JonUrban]

OK Folks. I heard from Lou tonight. He wanted me to tell you all that he's not given up and that the project has actually advanced to a very late state, and that the performance of the beta unit far surpasses even the best CD-4 demodulators of the past. He has been bogged down by his real job, and is currently experiencing some family issues that are taking up most of his free time. He does plan to get the unit out for evaluation soon, and as he's indicated earlier, the cartridges are all set and in stock.

Since no one has put any money down on these units, and no one is obligated to actually buy one at this point, all I can ask is that you continue your patience and give the guy a chance to get the thing done right.

As soon as there are more developments, the info will be here at QQ first. Once it's time to actually have members start ordering the thing, we'll do it all over again. Remember, no one is obligated. Times change for folks, and some who wanted to buy when this first started may not be able to afford it now. No big deal.

Lou promises that once the units are out there, you'll all be "thrilled!" (or at least happy)

 

[Bonzodog]

Thank you.

Still looking forward the the unit.

 

[aludra]

Thanks for the update Jon!! I will crawl over broken glass to get one of these so I appreciate Lou's efforts!!! Keep us updated!!Thanks

 

[Tonedoev]

While we are waiting:
This is what the last announcement of an advanced CD-4 demodulator looked like.
The excerpt is taken from The Gramophone / May 1975, p. 149.

 

[bmoura]

I remember the X-1 CD-4 Cartridge. A very good one! And John Eargle - a great audio guy and very knowledgeable about all things CD-4.

 

[Quadro-Action]

I self own the JVC Cartidges X1 and X2. Well systems, but little soft by the dynamic. So I am working actual with the MC systems from Elac
EMC-1. But it would be very interesting to connect them (with the nice word) soon with a new demodulator.

Dietrich

 

[kap'n krunch]

Dude!
John Eargle; he's the author of the Handbook of Music Recording that I have!..great book!!!

 

[loudorren]

hello to all CD-4 Quad Fans,

First I would like to thank Jon for covering for me during the last period of time. I also appreciate the patience in all on this thread for the past few months. I have had a personal situation which unfortunately has taken all of my time from engineering, music, and CD-4.

I am now back and I hope to get the pre-production prototype to Jon this month. I have mentioned in the past TASS and UDAF. These are 2 very significant projects that me and my colleagues have been working on for the last 3 years and because of my problem the product roll out has been delayed. This also has affected my record company by delaying releases of several new CDs.

I will now put the pedal to metal to get everything back on track and I will keep everyone up to date with more frequent postings.

Again I thank every one for their patience and understanding during what was a pretty rough time for me.

onward and upward to the new CD-4 demodulator,

Lou Dorren

 

[The Quadfather]

Dear Lou:
Sorry to hear that you are having a rough time. It happens to us all. I hope that all goes better for you and yours. We all patiently await the release of the new demod.

Thne Quadfather

 

[Quadro-Action]

Hello Lou, really after a long time of waiting well news. When Jon has written his test report - may be in beginning May, I can also inform our pre-buyers to hold them togehter for the 18 wanted items and they may hold their money together for the coming payment. Together with my next informations I report also from a quadraphonic and of course CD-4 demonstration at 19 May by the firm BRAUN in the near of Frankfurt (Germany) in the technical exhibition of their hifi sets. But that is unfortunately too short for demonstration the new demodulator. That would have been an absolute highlight. But may be then by another quadraphonic demonstrations. By the way, I think, you must have a group of helpers by manufacturing the end product of the demodulators. But important also for you, that you can have now a real well and free feeling to finsih the development. It was really a hard work, but now we are really happy to know the near succes of your efforts. We have had some skeptics among our fans here, but I have always said: Lou Dorren will have the staying power to fulfill his big work.

Dietrich

 

[rolvkarsten]

Hello Lou. Been busy myself. And you too it seems. Have you had any time with the demodulator design recently? I hope to see a photograph of a real unit soon. I hope you will finish The Project and I wish you good luck.

 

[Quadro-Action]

Hello dear Lou, when Rhino begins with re-releases of quadraphonic productions (now the second) in mastetape quality, we CD-4 fans want of course expecially now also the best results by playing our CD-4 records. which are also near the mastertape quality. 2,5 years after your announcement for a new demodulator engineered by your technical abilities I think, that I am not too curious when I ask now again for the real actual situation of the project. The last message from you is from beginning april and now we habe beginning July. That ist the biggest periode of silence between your notifications. Jon should receive the prototype also during april for his tests. Are there meanwhile unforeseen problems with the varied modes additional to the standard modes of usual demodulators? I think that most of us would be satisfied with those stanard modes, when they give us mor channel separation and more fideltity. So most of us don't really the additional pre-amplifier outputs. That could make the developement easier. So it would for us helpful to know the actual situation. Or have you arranged meanwhile a hidden production of all 120 ordered demodulator items, which would need also monthes? My new ask ist not grumbling, but should show you again the real interess for a new demodulator from me and others - although I own the JVC. 1000.

Dietrich

 

[captqtrs]

Hello Mr. Lou from dick Collins 1-800-659-7111 please contact us PLEASE
We Hope & pray that things are improving for you Health, family & business
e-mail [email protected]

 

[ress4278]

Hello Mr. Lou from dick Collins 1-800-659-7111 please contact us PLEASE
We Hope & pray that things are improving for you Health, family & business
e-mail [email protected]

Is Lou OK? Is there anything we can do?