My OTS sounds great with the master volume down below 9 o'clock but when i start to crank it up it seems to get a little more of an edge that i don't like.  What is it that causes this and how can I fix it?

what is it that causes this?

Just to repeat, but in a different way what the others I think are saying. It will be necesarry to adjust the tone and pre-master gain levels somewhat as the the master volume is increased.

Also, are these observations when you are playing in a small room (bedroom) by yourself or live with other instruments? Because, I feel my HRM "seems" a little harsh when all by myself and cranked, but when I listen to it recorded live with other insturments (drums, guitars, bass) it's incredible how it just cuts through everything yet sounds so full and smooth compared to other guitars and amps.

I say this only because I tend to play more by myself in a small room than anything else and have been realizing more lately, the huge difference between live and this and the misconceptions I may have about what sounds good in a given situation and what doesn't.

Indeed. The heart of the D-Style design is a cascading gain setup. this especially evident in the non hrm models, as there is only one master and the ratio is used to dial more or less of the OD sound into the final mix. Very different than the standard preamp/ master setup. The OTS will remain fairly clean when pushed hard, in other words, if setup properly, the output section should remain fairly neutral. The BM is a lil different due to the PI setup,  and two master volumes, however that is another story.

My lil BF princeton had a crude switchable cascade gain feature which worked very similarly to the D Style OD.

Gregg

the clean channel on the BM can get pretty aggressive when pushed. It really takes on the tweed side of its personality in a big way, especially if it is biased hot. You may wanna check the bias.  Also, turn the bass down a bit, and turn the presence up, which will help tighten it up. also, mine sounds better with the deep switch on when pushed like that. sounds counter intuitive, but it seems to work

Gregg

what are you guys biasing the amps at?  I am around 41ma right now I believe.  I'm running the sovtek power tubes that were in there when I got the amp.  I switched out to TAD 6L6's briefly but didn't quite like them so I switched back to the sovteks.  Maybe I had the TAD's biased to hot?  I think I had them up around 44 if I remember correctly.