Panning Mixer Modification

[RishiRishiRishi]

Hi,

I'm planning on using the attached panning mixer to mix the signals of several mic pres and need to make a few changes to:

1. Keep the input gain fixed (as mic pres will have individual gain controls)
2. Introduce gain pots to the left, right and stereo headphone outputs.

Can I replace the 100K pots on the schematic to 100K resistors to fix the input gain?

To introduce output gain controls to the left, right and stereo headphone outputs, can I replace the 39K resistors between 1 & 2 and 6 & 7 of the TL084 for left and right gain control, with 50k/100k pots? Lin or log?

And do a similar thing for the headphones out, replacing the 100k resistors across pins 9 & 8, and 13 & 14 but use a dual pot?

Any help would be hugely appreciated!

 

[David Kulka]

Hi,

I'm planning on using the attached panning mixer to mix the signals of several mic pres and need to make a few changes to:

1. Keep the input gain fixed (as mic pres will have individual gain controls)
2. Introduce gain pots to the left, right and stereo headphone outputs.

Can I replace the 100K pots on the schematic to 100K resistors to fix the input gain?

To introduce output gain controls to the left, right and stereo headphone outputs, can I replace the 39K resistors between 1 & 2 and 6 & 7 of the TL084 for left and right gain control, with 50k/100k pots? Lin or log?

And do a similar thing for the headphones out, replacing the 100k resistors across pins 9 & 8, and 13 & 14 but use a dual pot?

Any help would be hugely appreciated!

On the input side you can just connect the .1 uf caps directly to the 20k panning input resistors. Or used a fixed resistor to reduce gain if you want. But probably smaller than 100k.

For the output side, not a good idea to use a pot in the feedback circuit. This can cause instability and other problems. Best to add a level pot with a second opamp stage as a buffer.