904C. Cloned ...working...but suspect..

[Rarecomponent1]

My 904 C combination seems to be working ....but I'm not sure about the setting when switched to Band Pass.
The audio signal on Band Reject comes thru more or less Ok however, on Band Pass I have to juggle with both the Bandwidth and Centre Frequency to actually get audio thru and it seems to be only on a narrow margin.

I'm wondering if I have a wiring mistake in the fiendishly complicated multi waifer switch ...or is this normal to the 904C...?

Both the 904 A and B work fine as stand alone units. The connections to the 904C have been doubly checked.
The settings of the 904 A B are set as recommended by the Dan Wyman manual.

I've found no videos demonstrating the working of the 904 abc which is the reason for this post.

[EMwhite]

I bought a MOS-LAB 904a, 904b, and 904c some time ago and when I first got the coupler hooked up I found myself frustrated beyond belief!

As it turned out, I didn't read the FM

Of course it didn't come with a manual but the original Moog specification came to the rescue, which prescribes:

904a fixed control voltage = +6
904a frequency range = 2
904b fixed control voltage = -1
904b frequency range = Low

Maybe you know this and maybe there is something wrong with your build; if you would like me to get you a good picture of the MOS-LAB 904c monster switch, I'll be happy to do so (it's said to be a 1:1 clone).

[Rarecomponent1]

Thanks EM

I pretty much have a good waifer switch replica as used by Moog and I've checked it over and over for connection and wiring ...all seems to be in order.
But like you say I find using the 904C pretty frustrating, particularly using EG control on the control inputs.
Which is why I suspected I had done something wrong, but if your getting this problem ...maybe not ?
we need to see a demonstration of one which is correctly set up.

[EMwhite]

Master of the obvious again, but one thing to realize is that with a small band and the wrong frequencies being played you'll hear next to nothing. Not sure how much calibration is available or how you go about tuning it, (on a scope with reference frequencies I would gather).

I'll rip my system apart for you : ) and take some pics and maybe a quick video. To reiterate what should be obvious... I don't have vintage Moog, but I did buy MOS-LAB a few years ago and added the 904b and 904c about a year ago so I have some experience.

FWIW, I still use envelope generators the usual way (on the Low past cutoff, despite the Moog instructions; likewise for hi pass). Voltage which run the typical range (from envelopes) will swing the bands on the coupler very fast and very far. Best to get it working right before getting tricky. But then again, I'm a mere amateur. Will have some more soon.

[Rarecomponent1]

Thanks EM...actually from what your saying it sounds as though my 904C may be working normally. The disappearing frequencies and very strong control input effect are what I'm getting..so maybe the faults I imagine are actually normal?

But it would great to see/hear any 904C video etc.