Loading caps on 604Es

[Earl K]

@quaramon

I don't believe that for regular home HiFi the pressure ( within a box ) is an issue ( perhaps it might be at H.T. levels ).

FWIW, the 900 series ( 902, 908, 909 ) drivers have a rubber boot that surrounds the ferrite magnet, which then terminates ( wraps over ) the first few mm of the top plate.
- The back cap is then bolted down on top of this rubber ( which then acts as a gasket, of course ).

Its clear to me that Altec was addressing the pressure issue ( for SR/PA work ) with this design.