TH100 - Low volume Q

[Samskeyti]

I just upgraded from a TH30 to a TH100 (both were off the used market) and I noticed something strange. I have the amp running in full 100w mode, dirty volume max, gain at 9 o' clock and there's hardly any volume. Output doesn't seem to develop until 11 o' clock. Is this normal? Seems weird that 1/4 of the gain knob is non-functional. I seem to remember being able to run low gain on my TH30 without this issue, maybe my memory is failing me.

[Hubaxe]

I have not access to my TH100 (in the rehearsal room), but as I go there I'll give it a try. But don't remind such issue.
Full volume you say.. that's interesting. Mine at 11 can beat any bodybuilder drummer (and the one I play with pulverize drumsticks).
I'd suggest a full retubing first, especially if you just bought a used head.

[Samskeyti]

I forgot to include that the clean channel operates well and the amp becomes extremely loud once the gain hits 12 or later.

[thinspirits77]

I could be mistaken here, but it sounds like maybe the first preamp tube for the dirty channel. If the clean is fine it doesn't sound like a power tube problem. Plus you said that you start getting output around 11 o clock which must be when you are about to get into the next gain stage. Maybe see about replacing one or both of the dirty channel's preamp tubes before a full tube change to make sure that was the problem? That said, a full replacement is not a bad thing if you don't know the history of the amp (just more expensive).