The Schematic is on CJ's site i think, thats where i'm linking it from, he has the other side as well.
not really thinking of it as a repair, but as part of a DIY i'm working on. It's a cool simple eq that doesn't require expensive multi ganged rotary switches. I'm just thinking of saving some board space and $$ and time by not using stepped gain, to me it's not really needed.
(unless of course, per the design, it's really needed)
The design is really similar to the API553 and the values around the Q8 gain switch total in around 10k, which is the value of the pot in the API.
On my "project", if it works out, i'd just put an "off", per band, on the freq. selector switch.
I'm not knowledgeable enough to figure this one out.....
the API still connects to the "swiper" from the cap/inductor as the Q8 does, and maybe i'm missing something, but the resistive value around the Q8 allows for essentially the same value of resistance when switching gain or cut.
(ok the final resistors in the Q8 vary, but not in the way a pot varies from one end to the other)
so i'm stumped, thought maybe someone here could help.
[quote author="franklinh"]I have some mm310 modules, I'm curious about where would you mount the pot that replaces the gain switch - not so much free real estate in those modules!
Part of the problem with this idea looks like the null position disconnects from the resistor network, so "center" even on a detented pot (in practice) wouldn't be the same as that switch at "0". The fact that you're involving either the inverting or non inverting side of the opamp as you turn the knob one way or the other makes a stepped switch look ideal for this design. Why not look into a stepped switch with more positions? There should be a link for a stepped attenuator calculator around here somewhere...
In using these modules (I gots 12 in a diy summing network) I find the frequency selection more limiting than the 2db steps in gain. When mixing from the computer I can always use a plug in to bridge the gaps, but even then the limited options remind me that less is often more.
Any chance of throwing up the rest of that schematic?[/quote]
