Has any of you ever bothered to check why the stock B&W Filter sucks? Guess not or else these comments wouldn't be posted.
Look at the puny power-supplies that barely can do 50-100mA. Open that filters hood & take a deep look at the crap parts sitting inside (thanks to a 3rd party assembler that B&W entrusted the job to - so called Manby Electronics & probably at a contracted rate).
In short, the circuit is great but the assembling dudes did a shoddy job, hence it sucks.
After almost a decade, I took that Filter & worked on it. Fully reg PSU with 2.5+ amperes juice using encapsulated transformers in today's age of common SMPS. Heavyduty AWG 16 screened wiring to kick RF goodbye, all internal parts scrapped & substituted using Vishay Bulk-foil resistors that are very, very expensive, again expensive Teflon Multicaps & fully buffered active input stage with output impedance of 10 Ohms!
BTW - I've the Krell filter too. The fully modded B&W filter now walked over D'agostino's Filter like it had it for yesterday's breakfast.
My motivation was spruced up after 2+ decades; having vaguely remembered that I came across an article in 1988 written by a Matrix 801 S2 owner (an EE tech guy) in a magazine 'AUDIO' (that mag is years' history) towards the correct way to use the Filter with the implementation of a top-notch active buffer BUF03AJ/883 MIL spec to lower the impedance.
Tip: Filter MUST be placed either before the audio signal entering your Pre (between analog OUT from source to Pre) OR in the Tape-loop of the Pre (if it has one). Never between Pre & Power.
Now, enjoy your Matrix 800 series! They rock big time.
