I've just finished building this circuit (see attached) and have 2.3mV DC offset in the Left channel, but -17.5mV DC offset in the right channel. How would we locate the source of the discrepancy?
Is this worth worrying about? It doesn't appear to affect the sound, but I could always install a capacitor to remove the offset, if others would recommend doing so?
Is this worth worrying about? It doesn't appear to affect the sound, but I could always install a capacitor to remove the offset, if others would recommend doing so?
Attachments
Ok good to hear. Seemed like a significant difference between the two channels. What might cause it?
This is normal for some, I've had the same on some PCM1704K chips, Abraxalito made a nice circuit that you can null this out with, and works a treat, and it's simple, I used it from the PCM1704K to the AD844 i/v stage.
Cheers George
Cheers George
Attachments
PS Watch your negative power supply rail on the PCM1704 use something beefy, as it sucks the current.
Explained by the great, self made primadona and rightfully so, "Jocko Homo" here> DIYHiFi.org • View topic - PCM1704
Cheers George
Explained by the great, self made primadona and rightfully so, "Jocko Homo" here> DIYHiFi.org • View topic - PCM1704
Cheers George
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Very clever! Only issue is I'd need to cut a few traces on the PCB. Was yours done on a PCB or was it wired point to point?
Mind you, I do have DC blocking capacitors at the power amp input....so it may not be worth going to the effort? How high was your offset George?
Ultimately I want to use your ad844 idea...just built as per the datasheet for now.
Mind you, I do have DC blocking capacitors at the power amp input....so it may not be worth going to the effort? How high was your offset George?
Ultimately I want to use your ad844 idea...just built as per the datasheet for now.
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No need to cut traces, as the supply comes from -+5vdc of the dac and then the output of the 220K goes to the output of the dac and other side of the 220k to analogue ground.
And yes it can null out the dacs dc ofset to <1mv, and then you can get rid of that coupling cap on your poweramp (I hate caps in the signal path) they all sound different but have the same trait (softening)
And yes use the AD844 x 2 per channel, you won't look back, ever EVER again at feedback I/V stages
Cheers George
And yes it can null out the dacs dc ofset to <1mv, and then you can get rid of that coupling cap on your poweramp (I hate caps in the signal path) they all sound different but have the same trait (softening)
And yes use the AD844 x 2 per channel, you won't look back, ever EVER again at feedback I/V stages
Cheers George
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