I have a K1800FX (180W keyboard combo) - took it to a rehearsal, plugged into PA, sounded great

. Took it to another band's rehearsal, not plugged into their PA this time, sounded... not great
Back home I investigated, tests showed, the internal mixer has 66kHz+ bandwidth and was flat all the way!!
Then I did a check on the power amp, which is indeed 180W into 4ohm, that came up a good 20kHz

wow!!
The 12" speaker is the Beh 600W type so that seems good, the tweeter is their compression driver that looks good also, so what's the problem?
I notice there is no pad in the tweeter driver, I'm sure Beh. will talk about sensitivities already being matched, anyway I added a 2.5dB L-pad to the tweeter and it seems much better now. I also removed the foam plug from the second bass port, that lifts the very low bass response a little.
I also tested the graphic EQ, the frequences were spot on!
The K1800FX is very well built, thick heavy wood, lots of glue, great design, even that "shape" button adds perfect tone. What a product.
Behringer, if you are reading this, consider a pad in the tweeter and add a block diagram in the manual as now I know the Sub out doesn't have a steep LP filter, I can use this as a mono mix to feed rehearsal PAs. And also where the EQ is placed in the chain (only to the internal power amp).
The amp is "flat" with the "shape" button disengaged which is the basis from which to set the amp up, the little graphic EQ is then perfect to adjust tone for its small enclosure and knowing it is not added to the line out is good also. The "shape" button is good at low vol, think "loudness" button on Hi-Fi.
A totally superb unit - needs the L-pad.