DSL40CR Ultra Gain flabby pulse - any ideas?

[tonymaull]

Hi all

Today I had delivery of a 2nd hand DSL40CR. I seem to be getting a 'flabby pulse' on the ultra gain channel when playing the lower strings. I've got a sound file but cannot post as a new user, happy to send it through to anyone.

So far I've looked at the power tubes which seem to be fine (normal glow and clink), tried the built in speaker and my old 1936 with same issue, different guitars (les paul and strat). Therefore I am ruling out a unbroken speaker, issue with values, or issues with guitars.

Everything else appears to be working fine, and the amp is practically new. I will admit I hit the string hard but it can still be heard when strumming. It does sound like a weird compressor perhaps?

What I have not tried is anything to do with adjusting bias, or fully cranking the amp.

Anyone got any ideas or suggestions?

Thanking you in advance

 

[mickeydg5]

Does the TONE SHIFT make any difference?

 

[GregM]

Welcome to the forum .
Have you tried a different guitar cable ? Tried it with the loop engaged and disengaged ? Tried your guitar going straight into return of the loop ? Tried rolling the preamp tubes , or swapping them around if you have no spares ?

 

[Jethro Rocker]

Settings as well. Gain n volume amd OD1 or OD2?
Valves can look fine and be defective too.