Pro Audio Design Forum

Roger - I'm happy with the board pic you posted yesterday which has the one DPDT. You may want to change the labeling and pad orientation but I'd keep that one soft-bypass relay. No one has to stuff it and I think we're going to find a lot of people will use it . The size was OK too. With that board...

Paul - Having a 2 pos switch in (addition to the pot) which has "fixed" (calibrated) and variable positions wouldn't require a center tap on the pot. (There would be one switch each for M and S.) The center position on the pot wouldn't have the 0.05 dB/0.005% accuracy. But that accuracy wo...

Thanks for the input everyone. Another option is, of course, a knob with a pushbutton to switch between "fixed" and variable. With only +/- 3dB range the knob would have fair repeatability (and less chunkiness compared to a switch) based on pointer position. The switch or relay would only ...

Let me expand on Roger's question: What gain trim amounts and number of steps would be required?

+/- 3 dB 6 dB?

6 steps, 12?

Roger - Nice tight simple layout. I like it! FWIW: The type of resistors that would be needed for external gain trimming that equal the matching accuracy of the balanced line receiver's internal ones would be something like these Vishays: http://www.vishay.com/docs/63001/s.pdf The 1240 line receiver...

This thread has been renamed since it picks up JR's original thread on an OTB mixer using VCAs and current summation. I happen to be the guilty party who mentioned that Pease's article contained info which could potentially solve a VCA bus capacitance issue. The first couple of posts discuss Pease ...

Oh yeah, do we need termination Rs on both drivers?

With THAT1646s they are not needed. If someone wanted to use SSM2142s or DRV134s they need to be pre-loaded in 600 ohms to be gain-accurate with active balanced (bridging) inputs. If there's not room for them don't worry about adding them.

Don't forget the french fries cooked in lard, the Jolt Cola (hard to find here) and unfiltered cigarettes. My Dad smoked Lucky Strikes.

When you finish the meal, they'll gladly have the nursing staff roll you out in a wheelchair.

Very nice layout! An early Christmas present.

Works for me. Then we can link them and when we come up with a trim method they can be inserted.