Nice! I agree with Isaac that both sound fine and the differences are pretty subtle, but it sounds to me like the Sunn has a wider response curve, more low-low and certainly more high mid-high. Sounds a little scooped by comparison to the Ampeg. The B15R certainly has that classic B15 warm middy thing going on. I have a 70's B15N but I've never had the opportunity to play the reissue. I like the switchable 50/100 watts part, like the modern features and the switchable OT taps (the vintage B15 is 8; period) not wild about the 110+ lbs, and am completely baffled as to why Ampeg decided to include a piezo tweeter in a freekin'
Portaflex of all things.
I didn't hear the hiss in your recording; maybe you had the piezo turned off?
Anyway, it's no secret I'm a "little" Sunn biased, and straight up and side by side I prefer the bigger dynamic and more "musical" character of a Sunn/JBL rig over the vintage Portaflex.
But... That said, in a recorded mix I think the vintage B15 is absolute King, and from your limited solo clips it seems to me that the B15R carrys on in that tradition.
They can sound a little boring, even a little midrange "honky" solo, but when you add the rest of the band they just sit
right where they need to be, and sound phenomenal.
All IMO of course!
No, not flat. Like most amps, 200S tone controls are boost only. The flattest setting is usually with the tone controls all the way down at zero.
Years ago I used a RTA in a fairly dead studio iso room on a bunch of rigs and tube amps to see what "flat" was relative to control settings, but I can't find the results. I know I have them somewhere...
Anyway, going from memory all of the amps were "whacked"; the tone controls were all over the place in my attempts to flatline the RTA, and none of them actually got
real flat. I was using appropriate speaker cabs, which of course presented another obstacle to the search for "flat". I didn't have the appropriate equipment to test just the amps themselves at power. Another observation (which I expected) was that at different volume levels the rigs changed character and needed to be adjusted as the volume increased to stay "flat".
I post back if I can find my notes and charts, but from memory at 100dB pink noise the 200S rig needed both boost switches on , the bass control at zero and the treble jacked pretty good to get the closest approximation of "flat".
As I said, "whacked".
On a side note, I am also sure that the differences between individual amps, even of identical vintage, make and model can be pretty significant also. So take my observations with a grain of salt;
your results may vary...
Here's something I remember for sure though; ALL of the rigs sounded like ass "flat" when I played through them. Lifeless and truthfully pretty annoying, disgustingly mid heavy and IMO useless for any live or recording application.
My overall suggestion would be to "season to taste" with your gear and not worry about "flat", or for that matter what anyone else thinks of your tone.
I'd love to hear your B15/200S comparo with both amps adjusted to what you think sounds
best rather than trying to get a level playing field, funky!