eikoow
New member
[quote author="Svart"]what was your estimated current draw increased by and how many opamps did you try this to?[/quote]
I don't have the schematics in front of me, but here's a rough count:
160 - OPA2604
40 - OPA604
24 - OPA627
16 - AD797
All of these have a 3k resistor from output to negative supply, except for 9 - OPA2604's which drive the VU meters.
Subsequent tests in my lab have convinced me that an OPA-627 sounds slightly better if the resistor goes to the positive supply. However, by the time I figured this out, Joshua had already installed all the resistors to the negative supply, and the improvement was slight enough that we weren't tempted to go back and change them.
Before re-chipping and class-A mod, current draw was about 1.5 amps at +/- 16.5 volts. After mods, current draw is close to 4 amps at +/- 17 volts. Fortunately, I had a spare Amek power supply rated at 15 amps, so we used that. It runs nice and cool at 4 amps.
The interior of the console does get noticeably warmer, but everything is still well within rating. If we wanted to use a lower resistor value, we'd have had to install some air vents in the console frame, and beef up the internal power supply distribution system, so we didn't do that.
I don't have the schematics in front of me, but here's a rough count:
160 - OPA2604
40 - OPA604
24 - OPA627
16 - AD797
All of these have a 3k resistor from output to negative supply, except for 9 - OPA2604's which drive the VU meters.
Subsequent tests in my lab have convinced me that an OPA-627 sounds slightly better if the resistor goes to the positive supply. However, by the time I figured this out, Joshua had already installed all the resistors to the negative supply, and the improvement was slight enough that we weren't tempted to go back and change them.
Before re-chipping and class-A mod, current draw was about 1.5 amps at +/- 16.5 volts. After mods, current draw is close to 4 amps at +/- 17 volts. Fortunately, I had a spare Amek power supply rated at 15 amps, so we used that. It runs nice and cool at 4 amps.
The interior of the console does get noticeably warmer, but everything is still well within rating. If we wanted to use a lower resistor value, we'd have had to install some air vents in the console frame, and beef up the internal power supply distribution system, so we didn't do that.