Why thump when reading TOC?

[toufu]

I just modified my Marantz SA-15 to use the Lampziator output. I stole the D+ and Dgnd signal for each channel. But now I have a loud thump or two each time a new disc is inserted and the TOC is being read. The onboard discrete output board doesn't have that, what's causing it and what can I do to fix it? Thanks.

 

[amc184]

It's because the old output stage included a muting circuit, and the one you installed doesn't. There are two ways to fix this:
- build a new muting circuit
- reverse the mod and reinstate the old output stage

 

[toufu]

Got it, thanks!