Pro Audio Design Forum

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.

Yes happy Thanksgiving everyone! Yesterday I had a chance to sketch a few things out with the 0 dB position being a wire to the previous stage. I'd like to find a simple way to provide this trim without the 0 dB gain error. I'm not there yet. Complete bypass of the stage is another option, one being...

Roger - There needs to be some means to bypass this stage to provide accurate gain in addition to the bypass we already have that goes competely around the insert. We need wire between the decoder's line receiver and the matrix. Without that, the 0 dB attenuation setting will not be exactly 0 dB (wi...