Ambika Main Output Distorted


Hopefully the ambika section of this forum is still active. I just finished a build. (Project was sitting on shelf for a few years)

Everything is working except the signal from the main output is very distorted and clippy. All 6 Individual outputs sound fine.

Any ideas what could be causing this?

I’m a noob to electronics.

btw it has 6 x smr-4 cards

Check all parts around IC1 (which mixes all 6 voices together). In particular:

  • Bad solder joints on the IC1 socket.
  • Wrong resistor values.
  • RN1 soldered backwards.

Wasn’t there a value change for one of the resistors (I think it was R13 from 10K to 4K7) to address a clipping issue on the summing output?

The problem you refer to was rather difficult to trigger with the SMR4 filter boards.

Since yfi mentions that the signal is “very distorted and clippy”, I believe it’s something else.

Yes it was a problem around IC1. I forgot the R13 resistor altogether. Oh boy.
I put in a 6.8k and everything works perfect now.
Thank you for your advice.