PCM1704 Help needed with higher dc offset from one channel - Page 2 - diyAudio
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Old 9th October 2012, 08:28 AM   #11
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They are original and socketed, I swaped left for right but still had the 50mV on the same channel, it could be the layout of the right is making that side oscillate. Next time I have my scope out and hooked up I will check for oscillations.

PS thanks for the reminder of opamp stability

Cheers George
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Old 12th December 2012, 01:39 AM   #12
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Hi abraxalito, thank you very much for the dac dc offset nulling circuit it worked a treat, instead of 17mV left and 50mV right comming out of the OPA627 I/V's, now I have +- .1mV I don't know why but the sound has improved very much overhaul esspecially in the bass. Is this possible, that the OPA627 as an I/V does not like to see any dc comming into it from the dac/s???

Cheers George
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Old 13th December 2012, 10:08 AM   #13
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Hi George - since you asked for my input I can only say scrap the opamp I/V if you're really concerned about SQ. Its really a waste of a decent R2R DAC chip. Go for something with more immunity to glitches as a post amplifier like a discrete JFET design, or use passive I/V and fierce passive post-filtering to remove all the RF. I've posted up a suitable filter schematic on my thread called 'Digital, but not by the numbers' in Digital Line.
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