Lou Dorren: A new CD-4 Demodulator!!!

[callmez]

My piggy bank is going to meet an "unfortunate end"...

Mark Z

[proufo]

Lou, how would I play SQ records using the phono preamp of the demodulator?

[loudorren]

Hello proufo

Just play the record. It is after all a 2 channel stereo record. IF you want to connect your "SQ Decoder" you would connect the RIAA, or RIAA + LPF or the Left Front and Right Front outputs to the Left and Right inputs of the "Sq Decoder".

Lou Dorren

[zabble]

Wow, that looks sweet! I can't wait until they're ready to ship!

[RenoKen]

Lou, I too am impressed. As I get older and further away from the 70s when I was deployed in Southeast Asia during the first years of Sansui Quad, the memories and the music I started to collect there get more precious. Looking forward to having the opportunity to own your CD-4 package and experience a rebirth, as well as being able to experiment a little. I wish I was more technical, but I can follow much of the discussion Thanks for your effort; I am sure it is a labor of love for you.
Ken

[loudorren]

Hello CD-4ophiles,

zabble, RenoKen,
Thanks for the posts!!

Lou Dorren

[Justforthesoundofit]

Lou,
Pardon my ignorance in the matter, but as I understand from one of your earlier comments, the ceramic CD-4 cartridge was superior to the magnetic. Why then did everyone else go with the magnetic? I would have to believe the ceramic cartridge to be less expensive to manufacture and have less circuitry (no preamp or RIAA filter).
Rick

[loudorren]

Hello Quadies,

Justforthesoundofit,

Rick, The Technics 450c, 451C, and 460C were not ceramic. They were silicon semiconductor strain gage cartridges. During the Quad days, every pro audio engineer that I demonstrated these pickups to, converted to them. They did not suffer from velocity hysteresis, common with moving magnet and moving coil pickups, nor did magnetic field build up occur since there was no magnets involved in the construction.

The semiconductor pickup is not a generator type cartridge. It must be DC biased somewhat like an electret microphone. As it tracks the groove, it's resistance varies with the groove undulations. The generator type pickups must create an AC voltage on the output from groove undulations. Because there is some time (nano to micro seconds) for the magnetic lines of flux to build and collapse (hysteresis), some harmonic (THD) and inter modulation (IM) distortion can be created in the output.

Magnetic field build up happens over time. The result is a gradual reduction in output. Clever pickup design can minimize both of these effects, however it is a good idea to have a phono cartridge de-magnetizer (NOT TAPE HEAD)
and use it about every 6 months. One other point, the semiconductor cartridge left and right outputs are out of phase, so one output must be inverted by the preamplifier.

Lou Dorren

[ChristopherLees]

Hello Quadies,

One other point, the semiconductor cartridge left and right outputs are out of phase, so one output must be inverted by the preamplifier.

Lou Dorren

on the other hand,if you use it for stereo only ,(and don't care about recording stuff) you can get away with just reversing the phase on one channel of speaker terminals. (i.e. just wire your stereo speakers out of phase)

[aludra]

Hey Lou,

What type of cartridge will be included with your new demodulator??? Will replacement stylus be available??

Hows your testing coming along???.....any updates would sure be appreciated....I just cant wait!!!!
Thanks,
Mike

[kfbkfb]

Regarding CD-4 Quadraphonic playback
using a "stereo" phono cartridge:

Quoting from the 1973 consumer's guide to
FOUR-CHANNEL SOUND:
JVC answers leading questions on the CD-4 disc
For example, JVC has found that a $12.95 Shure
cartridge purchased at Radio Shack plays
satisfactorily as popular-class equipment.

I know that CD-4 approved cartridges were rated
A, B or C but I know of no rating system for
"stereo" cartridges that could be used for CD-4.

It might be informative to try some of the well
known brands of "stereo" cartridges with the
2008 CD-4 demodulator to see how poor channel
separation and (possibly severe) roll off in
the 20kHz to 45kHz range affect the CD-4
demodulation process.

Kirk Bayne

[Justforthesoundofit]

Lou,
Like I said, pardon my ignorance. I love to learn as much as I like to listen to the music. Are phono cartridge de-magnetizers still available?
Thanks,
Rick

[loudorren]

hello CD-4 Supporters,

ChristopherLees, That is one way, however don't forget that you need DC bias on both channels to make the semiconductor pickup operate. Also if you want to listen to FM radio or a CD player it might be easier to add a DPDT (Double Pole Double Throw) switch on one speaker to easily change phase. I have included a circuit diagram in this post.

aludra,

Mike, Pickup to be announced, replacement pickups and styli will be available. Circuit board artwork now in progress.

kfbkfb,

Kirk, More 1973 advertising hype. "Plays satisfactorily" generally means light the CD-4 indicator, less than 10% breakup distortion and not very good separation. In my opinion, why settle for less when you can get more!

Justforthesoundofit,

Rick, the Aesthetix MC Cartridge Demagnetizer! is available from:

http://www.musicdirect.com/product/49736

for $199.00. It is a good one that I recommend.

Lou Dorren

[wa6ubw]

I don't think anybody but Lou Dorren could make a single switch into a system.
(note the carefully chosen "song & dance" smiley)

[kfbkfb]

Regarding CD-4 Neutrex Predistortion:

(1963) RCA Dynagroove information:
http://www.stereophile.com/asweseeit/95/index3.html
The predistortion phase of Dynagroove--the adding
of complementary distortion to offset the effects
of stylus tracing distortion--appears now to be
based on sound engineering principles, even though
the amount of predistortion that is added is
predicted on the normal amount of tracing distortion
produced by a 0.7-mil stylus, a size that has been
generally abandoned by the high-fidelity industry.


Is CD-4 Neutrex predistortion set to provide the
minimum (sum signal) playback distortion with a real
Shibata stylus, Line Contact (type) stylus, Elliptical
stylus or a range of stylus shapes?

Kirk Bayne

[loudorren]

Hello QuadraCD-4 Fans,

kfbkfb,
Kirk, The original Dynagroove spec was modified several times. First was for diameter compensation. Then a slight modification was made to compromise tone arm vs. linear tracking turntables. Another mod was made for variable depth, variable pitch recording. One of the last mods was to accommodate short side radius (.1 to .4mm).

The CD-4 Neutrex pre-distortion system also covers the .1 to .4mm short side radius with more robust diameter signal conditioning control.

With this posting I have included a photomicrograph of the QSI5022 chip. In its time is was the most complex combination analog-digital chip that had ever been produced. Thanks to my good friend Gerry O'keefe who had a copy of this photo.

The stylus brushes have arrived and record cleaning kits will start to ship on Friday.

Lou Dorren

[ndiamone]

Lou.

Any hope/idea for future supplies for guys to be able to update their Tates etc once the chips die and/or become unavailable?
I would hope somewhere, somebody would have the inside schematics to these chips and could at least update their design
and/or recreate them on printed crt boards out of modern components to keep these gems working.

[krkier]

Any hope/idea for future supplies for guys to be able to update their Tates etc once the chips die and/or become unavailable?
I would hope somewhere, somebody would have the inside schematics to these chips and could at least update their design
and/or recreate them on printed crt boards out of modern components to keep these gems working.

Maybe this guy can help you?:

http://www.spaceandimagecomposer.com/

-Kristian

[aludra]

Hey Lou,

Just checking in with you...Hope all is going smoothly with your circuit board development...

Hope you and everyone else have a happy and safe 4th.

Mikehttp://www.quadraphonicquad.com/forums/images/smilies/SUNNY.gif

[etzeppy]

Hello Quad Fans,

I have arranged for a short run of the QSI record cleaner. This is a run of 50 kits. The kits will include a box of lab grade Kim Wipes, and 8 ounce bottle of QSI record cleaner and instruction sheets on how to clean CD-4 disks and how to restore badly abused conventional vinyl records, acetate dubs, and shellac 78s for archive recording purposes. The cost is $28.00 per kit which includes shipping. California residents add 8.25 % state tax. Delivery will be in 4 weeks.

To get into the queue, send the cost using a credit or debit card through PayPal to the following ID:

xytar@netscape.net

You do not need a PayPal account to do this. Just log on to www.paypal.com, click on the personal tab. From the menu bar click on send money selection and from the drop down menu click on "send money on line".

When the Send Money window opens enter xytar@netscape.net in the "To" area, your email address in the "From" area, 28.00 in the "Amount" area and check the Goods circle. Then click on the continue button and in the next window fill in all the requested information,your name, address, credit card info etc.. When you are finished click on "agree and continue" and the next window will let you verify all the information. If everything is OK then click on "send money" and wait (click only once). The next window will verify that the money has been sent.

Enjoy the QSI record cleaner,

Lou Dorren

Hi Lou,

Got any of the first run left? Is this cleaner also intended to serve as a preservative similar to the LAST Record Preservative? On that note, what is your experience/opinion on the LAST preservative product? Some seem to love it and others claim it ruins vinyl forever. I have not tried it myself.

Keith

[loudorren]

Hello Quadraphers All,

Aludra, Board art is proceeding and looking good I will say. Happy 4th to everyone and as some say have a 5th on the 4th!

etzeppy,

Keith, Oh how I like black magic and snake oil! Even better when described by technical drivel! You must watch out for those shock waves in front of your super sonic stylus because like an earth quake, no wait a minute, record quake, they will turn micro cracks into giant sink holes. Where is RECORD MAN and RECORD WOMAN when we need them.

Record wear is caused by over tracking force, worn styli, improper storage and high ambient temperature playback. The type of styli also can increase wear. Point contact styli such as conical or elliptical at a typical 1.5 gram tracking pressure can exert 15000 lbs. per square inch at the point contacts in the groove, creating accelerated wear. Line contact styli like Shibata or Microline at 1.5 grams tracking pressure only exert 150 lbs. per square inch at the line contacts in the groove, reducing wear.

Seriously, the people that sell this junk are another group selling snake oil to the consuming public just like Monster cable, CD sound rings and green marking laser filter pens, speaker wire lights etc. In fact, if I am not mistaken, they sell a $650.00 speaker cable with more technical jaronese baloney. I would no more put that stuff on my vinyl water hose, let alone my vinyl records.

You will always find some people that will believe that stuff, and unfortunately they stand to ruin a record collection.

Yes, there is 15 kits left.

Everybody who ordered the kits should have received them by this coming Friday the 11th. If not send me an email. I have USPS tracers on all of them.

Lou Dorren

[The Quadfather]

Hey Lou:
I've been saying all that junk is bunk for years. Nice to hear an expert say it. I use lamp cord for speaker wire. It comes in 500 foot rolls, and it has a marker for polarity, and is of sufficient guage. That's all you need, it sounds great.

The Quadfather

[Doug G.]

Unless, of course, it's like 88 gauge lamp cord.

Believe it or not though, there are audiophiles who claim that the thinner, the better!

Doug

[The Quadfather]

Yeah, well the point is, No need for extremes.

The Quadfather

[Bob Squires Jr]

Unless, of course, it's like 88 gauge lamp cord.

Believe it or not though, there are audiophiles who claim that the thinner, the better!

Doug

Hey, I like my 88 gauge lamp cord... it goes well with my 3 watt amp!