-I thought I could handle 2 of the same amp for a stereo pair, but I'm gonna still need more clean headroom, for clean tones and effects.
The reason I suggested KT-88's (on page 1) is that I thought they were the best SE approach to sufficient clean headroom. Which raises the musical question: where is the dirt in the power amp coming from -- the small bottles, the big bottles or both? If it's the small bottles, you might get more clean headroom from a higher mu tube, despite your affection for the 12au7.
Also, if you add a second identical amp & speaker, you will get a 6dB boost, which may be good enough: 3dB for double amp power + 3dB for double the speaker cone area.
Some of my thought comes from the idea that I won't need this much KT character and drive X 2
I got
this amp to a point where I love it and the drive is incredible and I now I cant turn around,,,so that's enough of that for the DRY side.
The character of the KT88 is there and it
stings like a bee.So now I'm thinking I want the other side to be a cleaner reproduction (or my vision of "more headroom") so that the cleans don't drive so hard and there will be enough "headroom" to reproduce the effects well....this side should
float like a butterfly. And I'm thinking of a p-p setup for that so it will be a lot like running 2 completely different amps (through different speakers) at the same time where they fill each other out. I just don't think it would be
the best idea to duplicate the 88 amp and wind up with too much of this good thing.
As far as the 12AU7s go....it's time for me to learn something because I thought I was using this tube to provide the biggest swing without clipping.
The KT88 output appears to square before the input signal does AFAICT,,,but that character is worth keeping, and it cleans up just enough as I turn the volume down on the geetar so that it is useable (and desireable).
Going forward I will need to figure out how to drive the p-p side
cleaner, so if a higher mu tube will do it 'better', I'm all ears.
It is counter-intuitive to my thoughts about 'gain' to use a higher mu tube for 'less gain'(?)
One last thing, while I'm typing...
Even though I like the EM-12 speaker better than the Greenback, it just opened my eyes to the possibility of the speaker's effect.
I'm not sold on the EM-12 as THE speaker for the KT88 (dry) side, but at least now I won't just settle for the Greenback because I thought it was the 'right' choice.
I will probably wind up using the EM-12 as more of a full-range speaker for the p-p (wet) side, and keep experimenting with different single 12"s until I find one that matches the character of the 88 output. The Greenback sounded congested. The speaker in the pic below is the G12H-30 70th anniv. and it has way too much 'sizzle' to pair well with the 88.
I'm gonna look at some frequency curve charts and see if something stands out that will counteract the extended response of the EM-12
Here's the other cab I'm building for the 88 to push...it will be fully open back, and angled up like this to act as a monitor.