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Build help and troubleshooting => MP512 Microphone preamplifier => Topic started by: hanssongt on August 17, 2026, 08:03:05 PM

Title: Clipping/distorting noise on High Z input
Post by: hanssongt on August 17, 2026, 08:03:05 PM

Hi!

Recently finished my latest build. Everything works except when connect the DI. I can hear the source (bass in this case), but it sounds like it's clipping/distorting even on low gain. Any idea what could cause this?

I should mention that when I first tried the DI I coulnd't hear anything, but that was because I had missed soldering a couple of the resistors on the DI board. After doing that I got sound but got the problem mentioned above. I hope I didn't mess anything up by testing it without all parts soldered first.

Thanks,
Tobias

Title: Re: Clipping/distorting noise on High Z input
Post by: JPK on August 18, 2026, 11:04:36 AM

Check that Q2 (2SK170) is in the correct position A.
Can you measure the DC voltage (against 0V) on both sides of R51: near connector (16V) and near C24 (15V) ?
Can you measure the DC voltage (against 0V) on both sides of R48: near C23 (8V) and near R41 (1V) ?