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

[Quadwreck]

Wonderful news on all fronts, glad to have you still here for all the same reasons.

 

[maspadaro]

Welcome back Lou, and happy that you are doing better.
Even though I am new to the CD-4 world I have read most of the posts, and would like to be part of the process of acquiring a set (demod/cart and stylus) when they become available. I will add myself to the list on the other thread.
Again welcome back.
Regards,
maspadaro

 

[zabble]

Lou -

It sounds like you dodged a bullet. I'm glad you're better. Thanks for the update.

 

[loudorren]

Hello CD-4 Multichannel people,

Here is the schematic of the final revision 5.

Enjoy,
Lou Dorren

 

[JonUrban]

continued............






View attachment 8090

 

[JonUrban]

continued..............

 

[krkier]

Page 5 is missing.

-Kristian

 

[loudorren]

Everybody CD-4,
Here is the pdf of the whole schematic. Jon will fix missing page 5.


Lou Dorrren

 

[proufo]

A couple of audiophile tweaks that are sure to appear after the demodulator is out are beefed-up power supply capacitors and upgraded opamps.

Questions: are the capacitors in the PS as irrationally large and high-quality (say, low ESR) as possible to prevent any upgraditis?

Are the opamps as irrationally good as possible to prevent the above mentioned disease?

 

[krkier]

Thanks, Lou!

I have some questions regarding the OPAs: I see there are some operational amplifiers supplied with 40V. What type are they? I know the majority of operational amplifiers can only be supplied with 30V to 36V (+/-18V).

What type is the limiter? There are several NXP (FM IF Mixer) chips matching the pinout of U8/U34.

You used the ol' NE570/NE571 for ANRS (U16/U42). Please be aware that now these are obsolete from most known manufacturers. I found a Taiwanese company who are producing it under the name UTC571 (Unisonic Technologies), but have the fear this component won't be available from them outside Asia.

Any chance to see schematics of the filters?

-Kristian

 

[JonUrban]

Page 5 is missing.

-Kristian

FIX-ED

 

[Q8]

But does it come in wood grain?

 

[jefe1]

I'm more concerned about Kristians comment Lou is using an old obsolete component for ANRS. Will there be a problem getting these for production? Or future repair of these demodulators? I'm not technically proficient so my ignorance may be causing unwarranted concern and I leave it to further comment from the experts here.

But wood grain would be nice....or how about a custom built wood case???

 

[krkier]

I'm more concerned about Kristians comment Lou is using an old obsolete component for ANRS. Will there be a problem getting these for production? Or future repair of these demodulators? I'm not technically proficient so my ignorance may be causing unwarranted concern and I leave it to further comment from the experts here.

You may still be able to get it at electronic shops, but I don't think you will be able in a long term.

Those chips (compander and the FM demodulator Lou mentioned earlier) were developed somewhere in the seventies and eighties, but available up until the nineties (and maybe even early 2000). But now things change because less and less demand exist for this kind of analogue functionality.

Example here, and here.

But wood grain would be nice....or how about a custom built wood case???

If all elses fail: Put it in a cigar box!

-Kristian

 

[proufo]

I'm more concerned about Kristians comment Lou is using an old obsolete component for ANRS.

What would he use instead for old, obsolete technology such as CD-4?

 

[jrlinks]

What would he use instead for old, obsolete technology such as CD-4?

<grin></grin>

 

[bmoura]

What would he use instead for old, obsolete technology such as CD-4?

Good point.....

 

[roundhousequad]

I have a better ? are any of use going to be alive by the time these start having problems

 

[krkier]

I have a better ? are any of use going to be alive by the time these start having problems

Depends on how many teeth we have left...

-Kristian

 

[krkier]

I'm more concerned about Kristians comment Lou is using an old obsolete component for ANRS.

Not as obsolete as I first thought. ONSemi is still holding the flag high. - Phew!

-Kristian