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

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

    Hello Everyone,

    First, Happy Holidays to everyone and may the New Year have good things for all. As a gift to all the CD-4 fans I would like to report that the new demodulator design is complete and now in prototype construction stage. Starting with this posting I will describe the design in detail so that technical and non-technical people should understand. The papers are in PDF format and look the best on screen at 125%. They print at 100%. You will find them by clicking on the link http://www.johana.com/~johana/dorren [NOTE: Link is now dead]
    Enjoy!

    Lou Dorren

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    Default Re: Lou Dorren on his CD-4 45rpm record, and FM Quadraplex

    Hello Lou, your newest message is very interesting and wellcome especially for those - like me - who have collected a lot or some hundreds CD-4 records. Till now I am working with a Technics SH-400 and a JVC 1000, but I am further interesting for a new Demodulator, which can make a further high level of CD-4 quality and reproduction. Of course, for many this new item should be not too expensive. If this new CD-4 demodulator is available, I will inform further(more) the known Q-fans in our Quadro-Action. Together with the fans in this forum I will have hope, that there will be a worthwhile demand for those high quality Demodulator, which will give a new and sparkling live for our CD-4 gems.

    Dietrich

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    Member Desmo888's Avatar
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    Default Re: Lou Dorren: A new CD-4 Demodulator!!!

    Lou,

    Looking forward to the new CD-4 Demodulator, please keep us informed.

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    1K Club - QQ Shooting Star Doug G.'s Avatar
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    Default Re: Lou Dorren: A new CD-4 Demodulator!!!

    Thanks Lou! Who would have ever thunk 30 years ago that we could read about a new CD-4 demodulator now?

    Of course, reading about quad has always held a particular fascination for me.

    Doug

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

    Quote Originally Posted by Doug G. View Post
    Who would have ever thunk 30 years ago that we could read about a new CD-4 demodulator now?
    ...and that we would be reading it on an internet forum and not in Popular Electronics.
    P.S. I may have to buy a Shibata cartridge since Lou never gave me the one he promised.
    --------------------
    order list keeper for new Dorren CD4 Demodulator

    Quad enthusiast since 1974 or so

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    The Real Thing Cai Campbell's Avatar
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    Default Re: Lou Dorren: A new CD-4 Demodulator!!!

    Man, in the electronics world nothing would make me wet my pants faster than a modern, fully realized CD-4 demodulator. I mean, how cool would that be!


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    300 Club - QQ All Star ress4278's Avatar
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    Default Re: Lou Dorren: A new CD-4 Demodulator!!!

    This was intriguing to begin with. Once I read your bio, it became even more so. I am very interested. Will this be manufactured at some point?

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

    Hello to Cai, Quadzilla, and ress4278,

    The answer to your question is in the first download from the link!

    Enjoy,

    Lou Dorren

    ps Second dowload to follow shortly.

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    The Real Thing Cai Campbell's Avatar
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    Default Re: Lou Dorren: A new CD-4 Demodulator!!!

    Well, if you're taking pre-orders or only "indications of interest", sign me up!

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

    I would be interested one also a kit would be fun.

    RoundhouseQuad

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

    I would buy one as well.

    Thank you Lou for all your work!
    Quadraphonic.info - Free Manuals, Articles and more.

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

    I, too, am also interested.
    Thank you for your innovations.

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

    I can't imagine how good will it sound....
    Ciao, Luca.

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    Senior Member soesbeout's Avatar
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    Default Re: Lou Dorren: A new CD-4 Demodulator!!!

    Is this were the line starts,thanks Lou for some great reading and keeping the hope alive.
    Soesbeout

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

    Definitely count me in as well! Any way you can make the new decoder box look like a vintage demodulator box with dials and buttons and various gee-gaws?? hehe
    The voices in my head come from Right Rear only!

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

    Lou, I am sure this is way too early for this question, any ideas of price point. I just need to ask. At least a range, are we talking over a grand? With all these LPs, i would be interested.
    “Humility is not thinking less of yourself, but thinking of yourself less.” – C.S. Lewis

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

    Hello Everyone,

    Thanks for all the nice words.
    Quadtrade, well below that number and it will include a CD-4 prime pickup cartridge!

    Lou Dorren

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    Board Operator JonUrban's Avatar
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    Default Re: Lou Dorren: A new CD-4 Demodulator!!!

    OMFG! Sign me up too!
    :-jon

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    1K Club - QQ Shooting Star zabble's Avatar
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    Default Re: Lou Dorren: A new CD-4 Demodulator!!!

    Please put me on the list. This is an exciting prospect!

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

    Yes, me too. Already making space. Thanks, Phil.

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

    Please add me to the list as well. Thanks!

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

    Please sign me up too!
    You'll have plenty of buyers here

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

    Hey Lou:
    I have always contended that it might be possible to build a demodulator with improved technology and that had CD-4 suceeded, the modern demodulators would be vastly improved over the old designs. However, I have to look at the reality that while this could improve our current CD-4 performance, it will not spark a return to record companies pressing CD-4 releases. Therefore the design will probably be a limited run. It would be a good thing for us if it is possible to do it with out any proprietary components which will be impossible to find in say 20 years. We currently face this problem with our Tate SQ decoders, Variomatrix QS decoders and our Technics SH400 demodulators. Once the chips die, it's over for that unit. But then, if that is not possible, I would still buy it, for I will always have my backup 4DD5 demods and my SH400.

    Incidently, if the transistors in the chips were bad back then, would a chip made to the same design but of modern manufacture improve the legacy demod it is installed in?

    The Quadfather

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

    Less than that - WITH a cartridge ! !

    I'm drooling.

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

    Hello Quadfather,

    I understand what you mean. The problem of course, is whether the chip manufacturers will continue building legacy components. In the case of the old CD-4 demodulators, some of the original chips that I used in the first modifications that I made are still being produced. Sadly, some custom chips (QSI5022 etc.) are not(this does not mean that they don't exist). In the new design I am using chips that should be around a long while. As far as transistor chip technology, your premise is a good one. Reality is, however, as circuit designers in the 1970's we knew how bad the PNP types were. We simply avoided using them unless it was absolutely required. Most circuits back then were NPN transistor only. To take advantage of the better transistors of today, the circuit designs would also have to change.

    Lou Dorren

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