demodulator troubles

[Kbunting]

Hi, i'm singing the demodulator blues. I had a harmon Kardon 44 that worked great but then it developed a humm.

Then i got a marantz cd-400b it worked and the radar light came on and then the radar light doesn't come on anymore.

has anyone made a modern demodulator? i feel like i saw something on here for 600 bucks that was new and people were raving about?

 

[gene_stl]

You are thinking about the Surround Master which does cost around $600 and people do rave about it. It is only a matrix decoder and does not do CD4.

I know of no modern CD 4 decoders. You could do a needle drop and digitize it at a high rate and use software to decode it.
https://www.pspatialaudio.com/

 

[Kbunting]

Damn it! LOL i guess i will keep buying demodulators until one works.

 

[furui_suterioo]

A modern demodulator was very close to being produced. Lou Dorren was a pioneer of discrete Quad who developed discrete 4 channel FM and CD-4 circuit designs. Its a bit sad but still interesting to read through since Lou passed and the demod didn't get produced. (except the very last post )
https://www.quadraphonicquad.com/forums/threads/lou-dorren-a-new-cd-4-demodulator-archive.9035/

 

[jefe1]

Hopefully our friends at Involve will come up with something after version 15 of the SM. I'm sure they got Lous new design to look over....

 

[Kbunting]

Fingers crossed!! Because when they work.. my mind is blown !

 

[jaybird100]

Hi, i'm singing the demodulator blues. I had a harmon Kardon 44 that worked great but then it developed a humm.

Then i got a marantz cd-400b it worked and the radar light came on and then the radar light doesn't come on anymore.

has anyone made a modern demodulator? i feel like i saw something on here for 600 bucks that was new and people were raving about?

There was one in the works from Lou Dorren, who created the system for discrete quad to be broadcast on FM. That system was approved by the FCC, but came too late to catch on. His demodulator was supposed to be able to overcome the limitations past modulators had, and he did create a prototype. Unfortunately, he died before the units could go into production.

 

[barfle]

IMNSHO, a hum isn’t a difficult fix. CD-4 decoders are pretty simple designs by today’s standards, and if you can get your hands on a circuit diagram, a decent tech should be able to track it down. Also, a fairly common issue with vintage electronics is dried-out aluminum electrolytic capacitors. Recapping is tedious, but often solves the problem.

 

[MidiMagic]

The one with the hum probably just needs new power supply capacitors.

 

[kfbkfb]

IIRC, the JVC 4DD-5 CD-4 demod was designed to be an OEM circuit:
https://www.sm5cbw.se/audio/jvc/4dd-5.htm

Kirk Bayne