Chiming in; I agree 98% with your comments, and also what the others guys are saying here about the need for a sub IF you have a heavy left hand gig with a loud guitarist and a heavy handed drummer...I'd say "play it safe", bring a sub.
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That said, and not trying to be argumentative..BUT..I take issue with just 2% of that comment; the SS v.3 IS a "ported cab", it's CX2008 8" driver has a very big 2" voice coil, and we did computer modeling it to it's environment to maximize it's LF...so "for it's size", it can really crank out some LF. And by no means does it "die" at 100 Hz, it just starts to roll off at respectable 3dB per octave.
Thanks Aspen, and sorry, did not realize looking at the amp that the 8" is ported, but hope you realize too that the post was not intended in any way to knock the 8" (in fact, I noted it will "clearly produce notes at volume in low ranges") but to just honestly answer a fellow forum member (whom I recognized from many other posts, particularly about venue house pianos, as someone who has played some terrific acoustic piano powerhouses) about achieving that low end grand AP tone and resonance - a tall order indeed - but one I believe is filled by the SSv3 coupled with a small bass amp (and as I am about to further respond to timwat, the GK MB210 amp I'm using is probably overkill).
I don't see that as a negative, but rather as high praise indeed for the small unit on top that's doing the magic other amps are unable to emulate.
And as I mentioned in the post as a caveat to my comments, I use IEMs and rehearsal speaker systems that have a lot of bass handling and headroom that frame my tone mindset; I probably should have also added that part of my lower register AP thinking stems from owning and playing an '86 Kawai KG2D over the past decades - and further from possessing a left-hand piano-playing touch that quite often might best be described as "having the touch of a blacksmith."
As I also wrote, I do believe a well-positioned SS3 alone will be all that's needed for many players in many circumstances. I really like what the 8" does, so much so that I don't have any desire to use a crossover to cut the lower end freqs flowing into the SS3 (the roll-off you designed into the amp prevents any undesirable low-end results); I like the partnership the 8" makes with a small bass amp, with each having some excursion into the range of the other; I think the result is a thick rich tone that is still clearly defined, with high notes from the SS3 seeming to dance somehow.
After just three full days of ownership, I wouldn't want to be without this amp. Thanks for a truly game-changing product. I mentioned in an earlier post seeing several well-seasoned musicians (over 140 years of playing collectively) acting like children over the sounds coming from this thing in rehearsal - they're musically hard to surprise, and they were truly enchanted with it. I'm just going to be one of the smaller percentage of happy users who want to use it in conjunction with a bass amp, but still achieving previously unthought of results in stage floorspace of less than two square feet with no poles or negotiation of space for second "spread" stereo speaker to worry with.