I am designing a DAC using CP2114 + PCM1794A and the audio outputs will be balanced. I am now struggling with how to implement the volume control. I will mostly use the digital volume control on my Mac but I still want to have a control over it with a normal pot.
There are nice PGAs but the problem is they are all digitally controlled and I don't want to put an MCU there. A suitable voltage controlled gain amplifier would be the ideal solution I think.
The obvious solution is to use a potentiometer to attenuate the voltage after the DAC I/V stages and then buffer it and feed to output connectors. However, I have now four voltage lines to be controlled because the signalling is balanced. Options for this:
So what, how and why?
There are nice PGAs but the problem is they are all digitally controlled and I don't want to put an MCU there. A suitable voltage controlled gain amplifier would be the ideal solution I think.
The obvious solution is to use a potentiometer to attenuate the voltage after the DAC I/V stages and then buffer it and feed to output connectors. However, I have now four voltage lines to be controlled because the signalling is balanced. Options for this:
- Use a four gang potentiometer to attenuate each signal and feed this buffered to the output connector.
- Use a two gang potentiometer to attenuate single-ended signals (after conversion), convert back to differential and feed this buffered to the output connector.
- Use a two gang potentiometer to attenuate single-ended signals after I/V stage (use only Iout+ and connect Iout- to GND), convert these to differential and feed to the output connector.
So what, how and why?
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