CD-4 demodulator adjustment

[fredblue]

Thank you both, Doug and quadsearcher.

To be honest, I didn’t like the idea of placing a screwdriver in the back of a live unit, so I did what quadsearcher suggested...

I put a Quadradisc record on the turntable, disconnected the CD-4 RCA cables, then placed one of them in each of the four inputs. They all hummed, and played independently. I connected them all back, and I’m pleased to say that miraculously, it’s now all working, and I’m experiencing the glory of discrete quadraphonic sound! The Discrete 4 mode on my receiver is working fine.

Interestingly though, the CD-4 adjustment record still doesn’t separate front and rear; could it be that it was just a poor record?

Many thanks for all your help, everyone!

one of the JVC Adjustment 45s (4DE-202) had an issue, which one do you have?

 

[RockaMarka88]

one of the JVC Adjustment 45s (4DE-202) had an issue, which one do you have?

Hi, fredblue.

Yes, my one is 4DE-202.



So it had an issue? No wonder I couldn’t get any separation! In the end, I just used one of my Quadradisc records!

Many thanks!

 

[Doug G.]

*

 

[fredblue]

Hi, fredblue.

Yes, my one is 4DE-202.

View attachment 62194 View attachment 62195

So it had an issue? No wonder I couldn’t get any separation! In the end, I just used one of my Quadradisc records!

Many thanks!

yes 4DE-202 has the channels lumped together in one of the test tracks so you can chuck it!

tbh my favourite CD-4 setup disc is the Fisher Test & Performance Standard CD-4/SQ LP, i like having separate L&R adjustment tones and some of the demo tracks are hilarious with fun mixes!

Various - The Fisher Test & Performance Standard Quadradisc

View credits, reviews, tracks and shop for the 1974 Vinyl release of "The Fisher Test & Performance Standard Quadradisc" on Discogs.

www.discogs.com

 

[J. PUPSTER]

yes 4DE-202 has the channels lumped together in one of the test tracks so you can chuck it!

tbh my favourite CD-4 setup disc is the Fisher Test & Performance Standard CD-4/SQ LP, i like having separate L&R adjustment tones and some of the demo tracks are hilarious with fun mixes!

Various - The Fisher Test & Performance Standard Quadradisc

View credits, reviews, tracks and shop for the 1974 Vinyl release of "The Fisher Test & Performance Standard Quadradisc" on Discogs.

www.discogs.com

View attachment 62208

Thanks Freddie, just picked one up for a Jackson

 

[aludra]

Would this defect also be on the Pioneer PQX-1101? On the disc itself it is written in underneath (4DE-202)...Is this a JVC disc with a Pioneer stamp? Thanks for any info.

 

[surround.sound.enthusiast]

Glad to hear it all worked out for you RockaMarka88, welcome to the world of CD-4. I hadn't read about the botched JVC calibration disc before. I got lucky that my 4DD-5 came with a different iteration - because it set-up very easily.

 

[fredblue]

Glad to hear it all worked out for you RockaMarka88, welcome to the world of CD-4. I hadn't read about the botched JVC calibration disc before. I got lucky that my 4DD-5 came with a different iteration - because it set-up very easily.

4DE-205's the other JVC 4DD-5 pack-in adjustment disc that i have and afaik its fine, even if it doesn't have separate warble tones for Left & Right but only L&R simultaneously it seems to be ok for setting up.

there were quite a few of these 7-inch 45rpm CD-4 Setup discs bundled in with demodulators made by the numerous brands doing CD-4 Quad at that time, some appear to be clones of the JVC discs but some have unique material including a couple of examples for the Japanese market i found from manufacturers including Toshiba and Kenwood, which have narration and channel announcements in English by folk with Japanese accents and rather than duplicate Side A's setup tones they have demo music material in 4-channel on the B-Side.

 

[The Bushmaster]

Whew!! Just checked my adjustment 45s. I have the 4DE-205 and Panasonic's SPR 111-1 (MA-4006).

 

[Wathen1955]

Interesting discussion. I have a JVC 4dd-5 demodulator that I bought brand new in the box from Ebay last year. I'm using it with my Audio Technica AT12s cartridge and a brand new stylus that I bought from the 70's as a backup to my original one that broke. I pretty much had the same issue as RockaMarka88 but have ignored it so far. I guess I need to turn on this unit more frequently to exercise it.

 

[Doug G.]

Of course, the most likely components in a piece of solid state equipment to deteriorate are the electrolytic capacitors since they are chemically based and a reaction is going on even when the piece isn't being used. Hence the recapping craze present these days. Applying current to the piece may restore operation as the electrolytics "reform" and function again.

Other components like resistors and transistors are much less likely to go bad over time since they are "solid state" and are pretty inert without current flowing through them.

Also, I wanted to write this earlier but didn't, I like the Fisher record too and, in fact, it agrees with the Harman-Kardon one in setup results. I'm still trying to figure out exactly what the guy sings in those little snippets. It sounds like "...in time" at the end.

Doug

 

[Doug G.]

Oops, I was mistaken in my post above. It isn't on the Fisher record where the guy does the little snippets (along with other singers and music). It's on the Lou Dorren Quadradisc setup record.