Hi
I'm modding my Soundcraft Venue II sum amps. After blind testing various opamps I decided to go OPA1612 for mix sum, fader post and balanced output opamps - see the attached schematic please. However I run into a problem in regard to mix sum position.
Mix sum opamps are running quiet hot (50-60°C), compared to post fader and balanced output opamps, which run at about 10-15°C less. Various other opamps in the sum mix position run much cooler, again about 10-15°C less. All opamps are decoupled with .1uF NPO ceramics from +/- 17VDC supply rails to GND. 0.1uF caps are very close to OPA1612 supply pins (~5mm).
Any ideas what could cause such a problem? Maybe I need a small cap across some of those feedback resistors (R4, R8, R10)? If so what value?
I checked 'Small signal audio design' book by D.Self but don't have a clear idea on where to start.
Thanks
I'm modding my Soundcraft Venue II sum amps. After blind testing various opamps I decided to go OPA1612 for mix sum, fader post and balanced output opamps - see the attached schematic please. However I run into a problem in regard to mix sum position.
Mix sum opamps are running quiet hot (50-60°C), compared to post fader and balanced output opamps, which run at about 10-15°C less. Various other opamps in the sum mix position run much cooler, again about 10-15°C less. All opamps are decoupled with .1uF NPO ceramics from +/- 17VDC supply rails to GND. 0.1uF caps are very close to OPA1612 supply pins (~5mm).
Any ideas what could cause such a problem? Maybe I need a small cap across some of those feedback resistors (R4, R8, R10)? If so what value?
I checked 'Small signal audio design' book by D.Self but don't have a clear idea on where to start.
Thanks
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