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B&K ST 125.2 Modification Project
B&K ST 125.2 Modification Project
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Old 30th December 2004, 02:07 PM   #1
spence is offline spence  United States
diyAudio Member
Join Date: Jan 2004
Location: New Jersey
Default B&K ST 125.2 Modification Project

Hello All,

I have modified a B&K ST 125.2 power amp with the following:

1. 10 uF electrolytic input caps changed to Solen Fast Caps

2. Power supply capatance upgraded from 30,000 to 60,000 uF

3. Power supply caps bypassed with 10 uF and 10 nF caps as an RF filter in the PSU (to allow for the fact that really big caps may not have the HF response of smaller caps)

Anyway, my question is this:

On each channel PCB there are two N- and two P- MOSFETs for the output stage. However, on the PCB there are empty spaces which are labeled and have traces for additional MOSFETs (and sharing resistors). The heatsink that the MOSFETs are on are even pre-drilled for the open spaces in the board.

If would populate these empty spaces with the additional MOSFETS, this would double the number of output devices (which is why I would like to try this). My guess is that the next model up from my amp (the Reference 200.2 uses the same PCBs with a larger transformer and PSU).

Can anybody guess if this will work? Does anybody know if trying this could severly damage the amp?

Sorry that I have no schematics... B&K is not very forthcomming, and a web search found nothing.

I apreciate any comments.

Thanks in advance,

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