elpechos
New Head-Fier
- Joined
- Sep 3, 2009
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I've got my first cmoy up and running
The first problem I ran into was the virtual ground was many volts off
My virtual ground circuit is resistor divider into a OPA633.
I solved this issue by reducing the 220k resistor dividers to 22k and now the ground is accurate to about 0.1 or 0.2 volts under load.
Unfortunately one channel is quite noticeably louder than the other
--I think both sides are amplifying as placing a finger on the respective input channels will produce a nice humming noise.
I measured resistance from ground to L and ground to R to ground on the outputs and they are quiet similar
they are
10860 ohm one channel
10900 ohm other channel
This seems to suggest both channels have same feedback resistors etc
I am using gain 10, 10k and 1k resistors.
I double checked the feedback resistor values for both channels.
I tried listening to sound without the potentiometer and one channel is still louder than the other.
I have double checked the PCB visually with a torch and also
by checking resistances on each channel are roughly the same to ground.
When operating there is a small 0.004 volt DC offset on one channel
The only thing I can think of is maybe one of the channels in the amp is damaged?
Or is there any other possibilities?
The first problem I ran into was the virtual ground was many volts off
My virtual ground circuit is resistor divider into a OPA633.
I solved this issue by reducing the 220k resistor dividers to 22k and now the ground is accurate to about 0.1 or 0.2 volts under load.
Unfortunately one channel is quite noticeably louder than the other
--I think both sides are amplifying as placing a finger on the respective input channels will produce a nice humming noise.
I measured resistance from ground to L and ground to R to ground on the outputs and they are quiet similar
they are
10860 ohm one channel
10900 ohm other channel
This seems to suggest both channels have same feedback resistors etc
I am using gain 10, 10k and 1k resistors.
I double checked the feedback resistor values for both channels.
I tried listening to sound without the potentiometer and one channel is still louder than the other.
I have double checked the PCB visually with a torch and also
by checking resistances on each channel are roughly the same to ground.
When operating there is a small 0.004 volt DC offset on one channel
The only thing I can think of is maybe one of the channels in the amp is damaged?
Or is there any other possibilities?