it would only need one knob too. I would make sure that the head is designed to sound like how I want it to sound.
Tom B and to Roger Sadowsky....I'm in a respectful total disagreement, which I'm entitled to be, that I think the Sadowsky Preamp both on board his basses and as an outboard box are really off base frequency wise. It's totally unrealistic in the real world of gigging to have a single sound with nothing more than a couple of frequency boosts and cuts at the very bottom and top of the cabinet's useable range.
Now maybe in the sterile and real world of recording, having a preamp +- at 40hz and whatever Roger's high frequency boost / cut is right on when added to the adjusting by your sound/studio engineer, but I only play live. Based on my needs, both the Sadowsky (and many others...for example....Aguilar is just the same) preamp and the new tube amp, as is, would not be able to get me the adjustability I need.
I don't know where, if, or how often you play Tom, but outta my current pace of 50-60 gigs per year, we may repeat a club, party center, or hotel 30% of the gigs, leaving essentially 30+ gigs at 30 different venues year. Sorry but 40, 800 Hz and 3000 or 8000 hz are not the frequencies that I usually need to be boosted or cut in these venues to make my sound happen or to cut through the mix....they're too low and too high. There's absolutely nothing musical in my mind about a 600 to 800 hz boost or cut on an amp. And again, IMHO, there's nothing that 40 or 3000 hz can add to my tone with an on board the bass preamp.
Take a quick look at GK's amps.....lows 80, mids 250, hi mids, whatever, treble, whatever. It needs a 125 knob...that's the "punch" control on my rig, and the 250 on my bass is the icing on the cake.
So, respectfully yours, I prefer adjustability in the 60 100, 125, 200, and 250 ranges, partially on board the bass and overlapping with much more on the amp or outboard EQ.
Try to remember something ladies and gentlemen of the jury.....the utmost vast majority of bass players do not play high end basses or use boutiquish heads or cabinets. What one high end, and a great one at that, feels is the right frequencies to offer boost/cut on his active basses or his outboard or addon on board preamp are his opinion, not the majority of bass players. It wasn't proxied by the rest of the bass players, many of which have never read talkbass, Bass Player, bassgear.com, or even heard of 1/2 the stuff that you and I have owned and played through Tom.
The skinny is that what matters is what matters to me and my ears, not your's or Mr. Sadowsky's. If I love or hate his basses or not, or have never heard his tube head or not is not a problem nor issue with me. What is are the obvious holes in the frequency spectrum that my experience has shown me to have to be adjustable when playing multiple venues. A combination 40, 800, and 3000 don't cut it. Make the preamp a two or three dial, 40-800 adjustable boost, cut with volume control and a DI and 1/4 inch out, and I might be the first in line to buy it.
LKaye