Modifications to my M1200s

I’ve had mine since May; they’ve been driving, most often, very sensitive Serenity Super-7s… (I had in that combination only about 1150 WPC in excess of what I ‘needed’.) They’re now driving the 89dB-insensitive Vienna Acoustics Mahlers… These I’ve improved by removing the MR-drivers’ (2) hi-pass-filter caps and replacing the tweeter caps with better ones… Also have separated the input wires driving the bass-crossover board from the single pair of input binding posts and added a separate, large-gage cable running directly from the board to the amps. They sound quite good, overall, with the treble sounding a little hard at times(1).

The poweramps apparently sound as good driving the Mahlers as driving the Super-7s, but the cable switching reminded me how BAD the bindingposts are… Why on earth PSA used binding posts with harshly serrated edges is beyond me; not only do they hurt my fingers a bunch but they require pliers–I use 7" Channel Lock ‘waterpump’ pliers–to tighten and loosen the nuts. Frustrated with these, I replaced the ‘main’ pair of posts with Cardas CCRR (copper post, copper nut, rhodium-plated post, rhodium-plated nut) and the ‘auxiliary’ pair with less-expensive Cardas HCBP Long posts… Used the original post-locator antispin plastic washers and metal flatwashers and the Cardas thick-plastic washers. All this hardware works well altho two of the eight posts will rotate if torqued hard; I do not twist them that hard.

While the amps were open, I again thought about replacing the very good REL 'propylene-film-and-tin-foil coupling caps with something better… I already had MultiCap RTX (‘sytrene-film-and-tin-foil) 1/100 caps plus a quad of well-used SoniCap Platinum (Teflon-alloy-film-and-tin-foil 0.047) caps to use to bypass (parallel) the RTXs. My goodbuddy said he’d be happy to do it, and he did, and quickly, too… The installation doesn’t look very good because of the well-used Platinums’ leads, but it works just finely. I’m confident that when both sets of caps are thoroughly broken-in, the amps will sound more transparent (and spacious) and a tad less edgy.

If anyone has questions, I’ll try to answer them.

(1) But how would I know? My hi-frequency hearing is so bad I wear hearingaids.
(2) The drivers themselves are bass/MR drivers, so they’re not being overdriven.

1 Like