So is the UA really that much more friendly to the lower frequency spectrum compared to a PA? I’m not really looking for tube breakup since I’ve got my dirt needs covered, just a good alembic fender tone stack with rich, warm cleans and good lows.
When you want something that closely resembles the Alembic F2-B, the PA is that.
If I remember the chronicles of Sushi Box FX correctly, there were two pedals.
The Particle Accelerator, which was the Sushi take on the F2-B and the London Underground, which is based on a 200W tube amp of a company that is in the middle between red and yellow.
The PA had the tonestack going for it and it was a great choice if you wanted super clean tube sounds.
The LU had such a sweet breakup. You can ride it completely clean - just back off on the gain, but there is this range where breakup just starts with a few added rich, singing harmonics - and that range is wide.
Mr. Sushi decided that those pedals were to have a worthy successor, one that holds the advantages of both.
The Underground Accelerator was born. You can pretty much make it sound like a PA, but it has a little bit more low end if you're into that. It sounds a bit warmer, I want to say more refined. And then, there is breakup.
On my version with my bass, I have clean tones with the gain below 10 o'clock. That sweet spot where we're in the no man's land between clean and fully saturated, which on other pedals can often only be set with using a long pair of pliers because it's not there at noon and you're past it at 12:01, is from 10 o'clock to about 2 o'clock.
It's huge.
I have mine set so the lows are warm, rich and clean, but when I pluck a chord beyond fret 12, the notes saturate. Just a bit, though. Like a musical singing saturation that does not feel dirty yet.