I really hear the e12 relays tripping. What could come and be an issue from the analog input of the SOHA II amp ?
It is possible to reduce the sensitivity of the E12. This is from AMB's website;
Hope this helps.
it may be working properly...did you check for DC on the output? The reason I say this is because I built a single 12AU7 tube amp and I run it on a 7Ah sealed lead acid 12v battery...like the kind on a scooter. When the battery starts to run down the DC measured at the output jumps around...like 13-3-8-16-23-1 mA very quickly...maybe the e12 is just doing its job.
Measure DC voltage from output ground to the amplfiers left and right outputs, most easily done at the headphone jack. I usually check this with no source plugged in. You will be looking at the mV scale. Wait at least a minute for the tube to warm up before measuring...
my bad...the only amp I've ever built with the E12 was the old Millett hybrid about 8 years ago...I timed how long it took for the tubes to settle down and set the E12 accordingly. It worked perfectly, so I never had to troubleshoot it. All of my DC offset problems have been with SS amps with no E12.
Searching this thread for "tripping" yields this: http://www.head-fi.org/t/374941/soha-ii-builders-thread/570#post_5392652
Read down a bit & it talks about how to make pre-e12 offset measurements. And other related things.
I finally checked this DC issue.
I measured the Voltage between ground and R8 (http://www.cavalliaudio.com/diy/soha%20ii/main.php?page=schematics/ampschematic). I use a DMM, as I don't have a scope.
It is usually within few mV. But when the e12 trips, I can catch figures above 100 mV (sometimes 200 mV). Thius is for short time... but it is really annoying when listening to music seriously.
So it seems that there is an issue in the amp stage. As I have only very basic knowledge in electronics, I have no idea what to look for in this amp stage.
I'm going to check if it is the same on the other chanel.