Well, I got me my haflers (9180's), and think they are engineered incredibly well, except for one single stupid cheap part... the variable pots for the bias setting.
A - I'd like to replace them at some point with precision pots somehow, but doubt the solder holes will match anything.
B - Any tips on setting the bias? The manual says 200ma is the recommended setting. The value seems about right since there are 2 FETs per rail. The cheapo pots actively float between 180-210 when I've reset them (hate that stupid paint the put over them so makes it a pain to change them).
Not sure if it's related, but being an amp, there is a tiny microscopic buzz in one of the channels. Might just be my brain, but felt when I adjusted the bias to the 190ma level, it was reduced somewhat... Am I going crazy? I think I'm just spoiled from using the old yamaha M-series amps with 127db S/N... Not a single peep at full. Annoying.... but you have to put your ear directly to the tweeter to notice it. Maybe add some kind of capacitor somewhere for extra filtering?
Anyway, great amps, may even bypass the (crunchy) input gain pots for a much shorter signal path. Way too easy to mod. I use an external box for balance/levels anyway. DIYaudio seemes to have disappeared today...
Any ideas welcome.