Akku
Head-Fier
- Joined
- Oct 14, 2003
- Posts
- 77
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From time to time these days I had a feeling my PPA had something strange. I wasn't able to realize what, so I though it was suggestion (returnig to 8610's after months with 627's).
Today I decided to check my PPA with RMAA to have a performance benchmark for the other headamp I want to mod.
The results were not very good and looking closer at graphs I realized that the left channel was performing really bad.
I mesured the left channel's offset and is huge: 150mv. I was puzzled because I mesured all the channels' offset some week ago (when I swapped 627's for 8610's) and it was everything OK.
I connected my V6 (that are more revealing than the hd580 I wear usually) and a clear hiss is audible on the left channel.
I swapped opamps and buffer all around the channels but I ever get the same problem from the left one.
Strange things: while G and R op-amps are running at +/- 13 volts, the L rails are at +/- 12.1. When I biased the op-am in class A I chose the resitors to get exactly 1.1 mA in each channel but now through R9L I read 0.95.
What have I to do?
Today I decided to check my PPA with RMAA to have a performance benchmark for the other headamp I want to mod.
The results were not very good and looking closer at graphs I realized that the left channel was performing really bad.
I mesured the left channel's offset and is huge: 150mv. I was puzzled because I mesured all the channels' offset some week ago (when I swapped 627's for 8610's) and it was everything OK.
I connected my V6 (that are more revealing than the hd580 I wear usually) and a clear hiss is audible on the left channel.
I swapped opamps and buffer all around the channels but I ever get the same problem from the left one.
Strange things: while G and R op-amps are running at +/- 13 volts, the L rails are at +/- 12.1. When I biased the op-am in class A I chose the resitors to get exactly 1.1 mA in each channel but now through R9L I read 0.95.
What have I to do?