Bogner Uberschall schematic

[SIX el SIX]

Hi folks. I usually haunt the Hoffman forum. I'm SIX el SIX over there as well.

I've got a Bogner Uberschall on my bench with a very low volume clean channel. Gain channel is fine.

I've been looking for a schematic, but as appears to be common in the high gain amp world ( a subculture of amp culture?) it doesn't seem easy to find.

Anybody have one or have any tips on diagnosing one of these?

Thanks,
SIX

[John_P_WI]

Does it have a LDR or vactrol separating the clean and the gain channels? What happens if you jumper across the ldr? Is there a relay after the individual tone stack volumes bringing the signal back to the effects loop? My guess would be the ldr or relay, or obviously somewhere in between on the clean channel. Not trying to be a smart ass, just a guess....

[Gaz]

Check the Sloclone forum.

[tubefix]

I have that amp on my bench now and as far as I can see there's a lot of signal waisted on the clean channel. With having just two 12AX7 stages and a strange kind of tone shaping, this channel can't be louder as it is. I added a 3rd stage, wiring tube 4a for a fender like boost stage after the channel, works.

[mmmoser]

The clean channel on the SLO is much lower in volume than the OD channels. Its the nature of the beast if built stock.