This site http://nikkoe.com/xcart/product.php?productid=122846 suggest the IRF540, but no justification is given
Can you give us any clues like supply voltage, output power?
Can you give us any clues like supply voltage, output power?
is IFR540 the ONLY replacement part.
Deceesed Arcam Alpha 5+ Amp [Archive] - pink fish media
.. suggests the sound quality is poor(er?)
Any suggestion on an upgrade part? 37v 40w similar pin width etc
Deceesed Arcam Alpha 5+ Amp [Archive] - pink fish media
.. suggests the sound quality is poor(er?)
Any suggestion on an upgrade part? 37v 40w similar pin width etc
Hi
I wouldn't be concerned about "upgrading" output Mosfets. The matter of VMosfet sound quality rests with bias - specifically, having enough of it. The service manual details bias as 4mV but the circuit's provision seems a weird place to adjust it, as far as I can see. This is one area to address, if substitutes are needed.
The reference in your post to someone who repaired their Alpha 5 and measured bias at only 2mV (presumably across the designated 0R22+0R22 parallel drain resistors) indicates it will be way too low at only ~20mA. Provided there is the safety of a large enough heatsink to cope with the constant extra heat, up to 100 mA bias or 11 mV across the resistors would be more suitable for hi-fi. Obviously, this won't be a simple part swap if you have the same small part in mind as that repairer.
You might then be pleasantly surprised with great sound quality using suitable bias with any similar type Mosfets in that application.
I wouldn't be concerned about "upgrading" output Mosfets. The matter of VMosfet sound quality rests with bias - specifically, having enough of it. The service manual details bias as 4mV but the circuit's provision seems a weird place to adjust it, as far as I can see. This is one area to address, if substitutes are needed.
The reference in your post to someone who repaired their Alpha 5 and measured bias at only 2mV (presumably across the designated 0R22+0R22 parallel drain resistors) indicates it will be way too low at only ~20mA. Provided there is the safety of a large enough heatsink to cope with the constant extra heat, up to 100 mA bias or 11 mV across the resistors would be more suitable for hi-fi. Obviously, this won't be a simple part swap if you have the same small part in mind as that repairer.
You might then be pleasantly surprised with great sound quality using suitable bias with any similar type Mosfets in that application.
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