This design is based on the Alps "Blue Velvet" RK027 pot. I'm using OPA2134 opamps and Rod Elliot's P05B power supply board with an Antek 10VA transformer in a Hammond case. It has turn on/off muting via a shorting relay (driven by the AUX supply on the P05B). It is DC coupled, and intended to be used with AC coupled source and amplifier.
On the board? No, I used 2pin Molex connectors for the signals and a 4pin molex for power (+15V, -15V, GND, AUX for relay). I used milspec shielded wire for the signals with solder sleeves for the shield terminations.
What is the point of the input buffer on each channel? You have it set up for G=1, 47K input Z, but it is driving a 100K pot, so you could eliminate it and just go straight onto the top of the 100K pot.
Comes to that, why 100K? Seems more then a little on the high side.
What are the opamps? With a 100K pot you are asking for small DC level shifts as the pot is turned and worse, crackle once the pot ages if there is any significant input bias current present.
Comes to that, why 100K? Seems more then a little on the high side.
What are the opamps? With a 100K pot you are asking for small DC level shifts as the pot is turned and worse, crackle once the pot ages if there is any significant input bias current present.
The opamps are OPA2134.
I used the 100K Alps because that's what was available without resorting to possible fakes on ebay, and with the JFET input opamps there is no DC on the pot, or the output.
You could eliminate the input buffer with the 100K pot, but it doesn't hurt anything.
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