silvalis
Head-Fier
- Joined
- Feb 20, 2005
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I just recently bought an X-fi extreme music to replace my revo 7.1. I normally run a PPAv2 off the front L/R output but I've noticed that it's giving me a 30mV DC offset which my PPA amps up to something around the 120mV mark.
Has anyone else with an x-fi (of any sort) noticed something like this? The other channels don't have anywhere near as large a DC offset - more along the lines of 1mV!
I decided to pop out & jumper the opamps and remove the class A bias resistors and the offset fell to 50 or 60mV. Putting the ground channel opamp back in made it 80mV. I'm using the standard AD8610s and the offset without being connected to the source is something alonge the lines of 2mV.
I think I'm going to have to add in a DC blocking cap/highpass filter on the input stage, though I'd prefer not to. Are there any disadvantages of placing the filter on the input of the amp, before the volume pot? Would it be better to insert this between the pot and R1/R2? Are there any other methods for removing this dc offset? What about introducing a +ve DC bias into the ground channel?
Has anyone else with an x-fi (of any sort) noticed something like this? The other channels don't have anywhere near as large a DC offset - more along the lines of 1mV!
I decided to pop out & jumper the opamps and remove the class A bias resistors and the offset fell to 50 or 60mV. Putting the ground channel opamp back in made it 80mV. I'm using the standard AD8610s and the offset without being connected to the source is something alonge the lines of 2mV.
I think I'm going to have to add in a DC blocking cap/highpass filter on the input stage, though I'd prefer not to. Are there any disadvantages of placing the filter on the input of the amp, before the volume pot? Would it be better to insert this between the pot and R1/R2? Are there any other methods for removing this dc offset? What about introducing a +ve DC bias into the ground channel?