Matching Mosfet already in Amp

toufu · 15th January 2013, 08:34 PM

Hi guys, I built a new Aleph 30 without matching the MOSFET's, can just I measure Vgs with the amp on and see how closely they are matched?

Loudthud · 15th January 2013, 09:01 PM

That would give you a pretty good idea how close they are matched, but you would be assuming they are all conducting the same current. That also depends on how close the source resistors are matched. Not the best way, but you can tell if there is a gross mismatch causing one to conduct perhaps 5-10% more than the others.

toufu · 15th January 2013, 10:41 PM

What about the differential pair? Would it tell me anything if I measured their vgs?

wayne · 15th January 2013, 11:15 PM

Measure across the source resistors.

15th January 2013, 08:34 PM	#1
toufu diyAudio Member Join Date: Jun 2008 Location: San Francisco	Matching Mosfet already in Amp Hi guys, I built a new Aleph 30 without matching the MOSFET's, can just I measure Vgs with the amp on and see how closely they are matched?

15th January 2013, 11:15 PM	#4
wayne In the hills diyAudio Member Join Date: Jan 2002 Location: Northern California	Measure across the source resistors. __________________ wizards assistant

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15th January 2013, 09:01 PM	#2
Loudthud diyAudio Member Join Date: Nov 2007 Location: Near Dallas Texas USA	That would give you a pretty good idea how close they are matched, but you would be assuming they are all conducting the same current. That also depends on how close the source resistors are matched. Not the best way, but you can tell if there is a gross mismatch causing one to conduct perhaps 5-10% more than the others.

15th January 2013, 10:41 PM	#3
toufu diyAudio Member Join Date: Jun 2008 Location: San Francisco	What about the differential pair? Would it tell me anything if I measured their vgs?