bjoneson
Well-known member
I'm continuing work on a summing amp project. The whole unit will consist of 24 inputs, with a gain pot, and 2 busses (L/R). I don't have a need or desire to have pan pots, but would like to be able to independently assign each channel to the L bus, R bus or both. This in and of itself is quite simple, but I'm trying to determine if there's away to apply 3dB of attenuation when both buses are assigned.
The concept I came up with is to use a DPDT push button for bus assignment (one for L, one for R), and using the spare pole / throw to introduce 3dB of attenuation on the opposite side when it's engaged. The only way I can think of to make that work is to switch a shunt resistor in a voltage divider in and out for attenuation.
The math is complex, and since this doesn't follow any of the "normal" cases for L-Pad or T-Pad attenuators, there doesn't seem to be any nice formulas to plug in to.
The truth is, I'm not even sure this is technically feasible, and achieving 3dB of attenuation could be made as simple as turning the channel gain pot counter clockwise a little bit when both busses are assigned. But alas... I'm a glutton for details.
The channel amp I'm planning to use is the gar2520 (from classic API) which can hypothetically drive loads down to 75 ohms. The busses will be virtual-earth type with 4.7K feedback.
Hoping someone can validate if this is even a feasible approach to solve the problem, and if so give some advice on calculating resistor values.
Thanks in advance for any help / input!
The concept I came up with is to use a DPDT push button for bus assignment (one for L, one for R), and using the spare pole / throw to introduce 3dB of attenuation on the opposite side when it's engaged. The only way I can think of to make that work is to switch a shunt resistor in a voltage divider in and out for attenuation.
The math is complex, and since this doesn't follow any of the "normal" cases for L-Pad or T-Pad attenuators, there doesn't seem to be any nice formulas to plug in to.
The truth is, I'm not even sure this is technically feasible, and achieving 3dB of attenuation could be made as simple as turning the channel gain pot counter clockwise a little bit when both busses are assigned. But alas... I'm a glutton for details.
The channel amp I'm planning to use is the gar2520 (from classic API) which can hypothetically drive loads down to 75 ohms. The busses will be virtual-earth type with 4.7K feedback.
Hoping someone can validate if this is even a feasible approach to solve the problem, and if so give some advice on calculating resistor values.
Thanks in advance for any help / input!