I can dig that, just hoping for some advice with a starting point. I bought by Bluesmaster used, so I'm not really sure that the trimmers were set anywhere in the ballpark of a usable tone in the first place. It doesn't sound very good right now. It's pretty harsh and constricted, with out the normal controlled feedback I'd expect from a D-style amp.

Can you share your trimmer settings and how you decided on them? I'm really struggling with the OD channel on my Bluesmaster. Thanks!

Thanks Gregg,

I had my BM modded to have a 100k pot to adjust the PAB volume, so in theory if I crank it up at about 80%, that should get enough signal and produce the same sort of result? The boost in volume I'd imagine would be quite big.

I'll be tweaking the HRM trimmers this weekend a little more and I've made note to bump the mids and turn the treble down as silly me, I did all my sound checks only on the jazz setting. Sounds a little too trebly on rock.

The tonestack bypass mod I have on the amp too, but from the sounds of it, you're partially lifting the tonestack, where as I'm completely bypassing it. I might try put in either a 250k pot or 100k pot where the existing switch is, to try get it to partially lift and get it to middle grounds.

I've played both a real 150w Dumble Steel String Singer, and a clone of one (Bludotone High plains), both amps had different circuits but with 150w 6550 equiped pwr sections. The volume was fine, the huge power section just gives the amp more girth, volume is never an issue. You won't have to push the amp to get the goods. With that said, a 100w amp should be just as fine, just not as girthy sounding because of the 6L6's

Ok, Gregg got here while I was typing. 

Yeah, what he said. 

Okay, another update... Trying to keep my tone chasing progress in this single thread as I started wondering into other people's threads

In addition to the change of tubes, speakers as previously mentioned, know now done the following;

- adjusted the internal HRM trim pots
- placed a mxr 6 band EQ in the FX loop
- tested the LNFB switch which I actually forgot about!

Of all of the above, I must say that the HRM tonestack adjustment was the most affective. The change was rather big as I tested it with the PAB and OD channel on from time to time to listen for the changes. The EQ in the loop and in the front obviously changed the amps tone, but I found myself preferring the OD channel without it. Just sounded more "fat" as opposed to the EQ, it sounded either thin or too muddy because of the boost in mids. Just didn't sound natural to me, and it also messed around with them amazing cleans on the BM.

Played with the LNFB switch a little today, but the change was very subtle. Not sure if i need to retweak everything again to get the most out of it, but I might have more time this weekend to do so. As mentioned in another thread, I've found that tweaking this amp requires very small adjustments and some controls are very subtle. A good example is the presence and pull bright switch on the volume control. Winding the presence from nil to max doesn't immediately sound different on the clean, but you notice a certain brightness on the OD which can make it sound harsh.....

Not quite sure where to go from here in search of those dumble OD tones...

the countdown is on until mine ships...  right nik??    now someone buy my ots

What's funny is that I found the Weber clips of your Alnico 12-65 toally awesome. Dumbelish if ever....?? 

THanks Gregg, great insight. I agree totally on the quality of clean+boosted tone of the BM, it's addictive. I'm leaning towards using the amp like that as well with an overdrive pedal. The EQ-in-the-loop also opened the door wide-open for the OD tones.