CD-4 - The thin line between success and failure, but still in the fight!

QuadraphonicQuad

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Sonik Wiz

πŸ‘‚ 500 MPH EARS πŸ‘‚
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Two other demods have evident problems. Scratchy, faint, silent channels, etc.
The Lafayette seems to be ok. I have the separation knobs jacked all the way up!
Congrats on the new toy & all the adventures that will go along with it!

I must agree with @fredblue it is not usual to set the separations controls as you have. On a proper functioning unit it would tend to be a bit to one side or the other of mid-point. Just because the separation pots are set to max it does not mean you are getting maximum separation. How did you arrive at this setting?

Does this unit have a CD-4 carrier level adjustment as well? Or is it auto set like the Marantz 400 B?
 

fredblue

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What was that test method you described elsewhere?
Certain albums. Turn off the fronts. Do something with the knobs?
ooh yes! πŸ˜‹ if you turn the Front pair Off or right down low and listen out for Lead Vocals in each of the Rears (individually is best if possible) on The Spinners' S/T Track 1 or The Doobies' Toulouse Street Track 1 and then turn the Separation knobs down until you can barely hear those lead vocals, that should be helpful 🀞
 

fredblue

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Congrats on the new toy & all the adventures that will go along with it!

I must agree with @fredblue it is not usual to set the separations controls as you have. On a proper functioning unit it would tend to be a bit to one side or the other of mid-point. Just because the separation pots are set to max it does not mean you are getting maximum separation. How did you arrive at this setting?

Does this unit have a CD-4 carrier level adjustment as well? Or is it auto set like the Marantz 400 B?
the Lafayette has auto carrier lock iirc
 

fredblue

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Unable to test yet! Just thought it'd be a good starting point.
from reading around it seems some folks like to start with the separation knobs halfway, some all the way up and some all the way down.

personally i prefer the right down method.

that way you can check how distorted the difference signal is (that hollow kinda muffly sound you get when you turn those separation knobs right down). then when listening to that hollow sound, if it is distorted, you can fiddle with your turntable to get that sound with the separation knobs all the way down as distortion-free as possible -- unless its disortion-free already, in which case don't adjust anything on the turntable!

then slowly turn the separation knobs up, one by one, until you get just Rear channel content along with a faint whisper of Lead vocals... 🀞
 

edisonbaggins

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from reading around it seems some folks like to start with the separation knobs halfway, some all the way up and some all the way down.

personally i prefer the right down method.

that way you can check how distorted the difference signal is (that hollow kinda muffly sound you get when you turn those separation knobs right down). then when listening to that hollow sound, if it is distorted, you can fiddle with your turntable to get that sound with the separation knobs all the way down as distortion-free as possible -- unless its disortion-free already, in which case don't adjust anything on the turntable!

then slowly turn the separation knobs up, one by one, until you get just Rear channel content along with a faint whisper of Lead vocals... 🀞
The way you describe fiddling with knobs is simply titillating!
Honestly, this MF already sounds pretty bitchin'.
I followed the recommended TT set up. Hopefully when I test I'll hear an amazing difference signal!!! :SG
 

furui_suterioo

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Basically same as others have described here, I don't type as fast. Here's how I was setting it.
Unable to test yet! Just thought it'd be a good starting point.
Adjust the seperation so the tones on the test record are at minimum level in the rear channels to "get in the neighborhood".
Then put on headphones and a music CD-4. Very slightly reduce seperation until just past the point where distortion goes away.
I was using the Fisher/Enoch Light CD-4/SQ test record. The 45rpm CD-4 test records are difficult to work with and results not as good as full size 33 test records.
 

fredblue

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Basically same as others have described here, I don't type as fast. Here's how I was setting it.

Adjust the seperation so the tones on the test record are at minimum level in the rear channels to "get in the neighborhood".
Then put on headphones and a music CD-4. Very slightly reduce seperation until just past the point where distortion goes away.
I was using the Fisher/Enoch Light CD-4/SQ test record. The 45rpm CD-4 test records are difficult to work with and results not as good as full size 33 test records.
totally agree with everything you say, that Fisher/Enoch Light disc is superb and those 45rpm 7" adjustment discs are mostly problematic in some way and at least one i tried was completely useless!
 

fredblue

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I believe one of the JVC 7" is bad.
yes! i just checked, its the bottom one of these two (4DE-202)

FAC7A048-E201-4946-B21A-23E0E47ED7E3.jpeg
 
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