Dt25 Effects Loop Pop On Channel Change

[ghostrider25]

I have a delay pedal running through the effects loop of my DT25 amp and when I switch channels on the amp, there is a very nasty and loud pop followed by repeats of the pop as it is picked up by the delay. Now, without the loop, I realize there is some clicking as the analog circuits are switching, but I would think that the effects loop would (should?) be bypassed during the switching process and automatically re-enabled once the switch is completed. Am I missing something?

[sparkyERTW]

The pop - as Line 6 makes mention of somewhere in the documentation and I think has also been brought up in the forums - is the result of the amp re-configuring between Class AB and Class A (someone correct me if I'm wrong on that); the suggestion is not to set up your patches so you do a lot of that on the fly.  Effects bypass during that process would probably be a good idea, but there may be some other complications that come with doing that.

[spaceatl]

+1

Most of the time an AB<->A switch can cause a little pop. What I have found is that it is most prevalent when running the master low. With the little bit I know about power class it makes sense to me when going from AB to A. In a nutshell, class A means that the power section is running at full tilt all the time regardless of the master volume setting. Classic class A designs have no master volume as this is the nature of the operating class. Class B is a very efficient operating class where the power section ramps up and down based on the signal. This makes a lot more use of the discharge caps. Class AB is a mixed mode. How much B component there is basically depends on how loud you are running the amplifier. So when I think about the power section going from AB to A, in my mind's eye I see this caps discharging when the class switches...

 

Anyhoo, I am not trying make any excuses here, just that the power swing from AB to A is huge and the variance based on the master volume level could make it very hard to predict. But I have had better luck reducing it when the master is running a little higher...basically where the AB mode is running a bit more A than B if that makes any sense...