anyone here use BK MXF amp range?

[sergiox]

Hi guys, just asking if somebody can report his own experience about these pro mosfet amp made in uk, somebody says they're are slow and without verve and rythim some others praise them... what do you think about them? If you can compare these range with "hi-fi" amps (like exposure, audiolab, inca tech, magnum, creek, onix etc etc )what would you say? What are their sonic charateristics and signature?
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http://www.bkelec.com/Pro/Rack_Amps.htm

Tnx in adv

cheers

s

[Ali Tait]

I have had some of the amp modules which were used for a sub. They did sound as criticised until they had been on overnight, when they sounded a lot better.

[Ali Tait]

Of course this is only valid if the amps use the same circuits as the modules.

[sergiox]

up...

[Reid Malenfant]

Hi Sergio, while I haven't heard them myself I can tell you a little bit about them :)

They use lateral mosfets on the output, which means they are pretty easy to design as the output Mosfets don't suffer from thermal runaway like other mosfet types or transistors for that matter.

I suggest you might like to look up reviews of the early Hitachi mosfet amps, as these are based on the same design. While it's not exactly the best amp design, they do have certain redeeming features, they are damn near bomb proof if designed correctly :eyebrows:

I think you'll find most are under biased on the output stage, you see the thing is they work in the opposite way to most conventional output stages. As they get hotter the bias current lowers due to increased on resistance of the lateral mosfets. So they need setting at a much higher bias or quiescent current than any normal class AB amp.

Unfortunately the Mosfets have low transconductance, so the amps need a hell of a lot of feedback to make the output linear, not the best for hifi, but fine for a disco :lol: