civilmonkey
100+ Head-Fier
- Joined
- Feb 17, 2006
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I bought 3 new BUF634P and replaced the original stacks with single buffers. So the pimeta is running 3 buffers with 113 ohm bandwidth resistors. DC offset measured from IG to the outpin pins on the op amps is now 4-5 mV. Also, each buffer is drawing 9.4 to 9.8 mV, which is right inline with expected. The PIMETA now draws 40 mA when not playing music.
Thanks for everybodies help! Troubleshooting is tough for me, but with this forums help, it's been kinda fun!
As a side note, I de-stacked my buffer stacks, and put them in the amp. Some caused higher DC offset (20 - 30 mV), some worked as expected. I can attribute my problems to either me destorying the odd buffer when stacking them, or broken buffers from eBay.
I also tried a straight DIP8 ground channel (TL081) and a OPA2227 in the sockets. It didn't not affect the DC offset. So, it's nice to think I managed to solder the brown dog adaptors sucessfully.
I know the buffer distortion is supposed to go up now in my setup, but to be honest, although I can tell a difference, I'm not sure if it's because I'm running single buffers (i.e less current to my ER6i 16 ohms earbuds), or distortion. Either way, I'm happy and the amp sounds great.
My last question to wrap this thread up is something I asked previously. Measuring in ground or out ground to output pins on the opamp, I get DC offset. Measuring IG or OG to the output jack solder lugs L and R channels I get 0 - 1 millivolts. I'm confident in my measurments. Is it possible the buffers are blocking offset? What am I missing?
Thanks for everybodies help! Troubleshooting is tough for me, but with this forums help, it's been kinda fun!
As a side note, I de-stacked my buffer stacks, and put them in the amp. Some caused higher DC offset (20 - 30 mV), some worked as expected. I can attribute my problems to either me destorying the odd buffer when stacking them, or broken buffers from eBay.
I also tried a straight DIP8 ground channel (TL081) and a OPA2227 in the sockets. It didn't not affect the DC offset. So, it's nice to think I managed to solder the brown dog adaptors sucessfully.
I know the buffer distortion is supposed to go up now in my setup, but to be honest, although I can tell a difference, I'm not sure if it's because I'm running single buffers (i.e less current to my ER6i 16 ohms earbuds), or distortion. Either way, I'm happy and the amp sounds great.
My last question to wrap this thread up is something I asked previously. Measuring in ground or out ground to output pins on the opamp, I get DC offset. Measuring IG or OG to the output jack solder lugs L and R channels I get 0 - 1 millivolts. I'm confident in my measurments. Is it possible the buffers are blocking offset? What am I missing?
