Thursday, August 26, 2010

Upgrading the B&K ST-140 amplifier

This was an easy upgrade - on both boards, replace the 100uF/100V and 47uF power supply electrolytics. The 47uF electrolytic input capacitor was replaced by a 10uF film unit. You can use anything from 10uF to 47uF here. Due to the size of the film capacitors, I bypassed the circuit board capacitors with wire and installed the new units inline on the leads from the RCA jacks.

The end result was an amplifier that sounded much more detailed and immediate. Gone was the treble roll off and plummy bass. The big 47uf electrolytic input definitely added some major coloration to the sound as now it sound much more neutral. Though not in league with my big Threshold S/500, the B&K is now one heck of an amp for the money.