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MOSFET sub. for ESP proj. 101
MOSFET sub. for ESP proj. 101
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Old 4th September 2008, 11:17 PM   #1
lawbadman is offline lawbadman  Jamaica
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Default MOSFET sub. for ESP proj. 101


I have a number of BUZ901/906 MOSFETs that have been sitting down for years doing nothing.
I have acquired a few high power transformers and heatsinks so I figure its time to build some amps
I was thinking of ESPs project 101 ( http://sound.westhost.com/project101.htm ) but the MOSFETs are very expensive. But I was wondering if I could substitute 2Sxxxxx for the BUZ901/906 that I have. I have been looking at the datasheet for both and I have noticed that the BUZs have about 33% more capacitance than the 2Sxxxxxs.
I was hoping that I could do a direct replacement but I really am not sure. Can some of you experts advise me as to whether I can make the substitution or not?

Also if you know of any other amps that I can use the BUZs in let me know.
I have the itch to build something In any case I need a pair of amps for the woofers on my new OB speakers.


Thanks all,

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Old 5th September 2008, 02:37 AM   #2
jaycee is offline jaycee  United Kingdom
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They should work. If in doubt, ask Rod himself
The capacitance might affect distortion a bit as the MJE350 in the circuit will have a harder job, but it shouldn't explode or anything like that.
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Old 5th September 2008, 09:19 AM   #3
AndrewT is offline AndrewT  Scotland
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as far as I have seen all the Lateral FETs are expensive cf. BJT and VFETs.
regards Andrew T.
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Old 5th September 2008, 09:42 AM   #4
burbeck is offline burbeck  United Kingdom
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Location: Ratae Coritanorum
hi there,
have you got the the 16 Amp, DP suffix devices?
these are "dual die" two fets in one can, so they will have twice the gate capacitance.

some tweaking of c11/c12 may be needed
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Old 5th September 2008, 10:59 AM   #5
homemodder is offline homemodder  Portugal
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Join Date: May 2006
Nelson Pass has recently done some measurements about mosfet capacitances. I think you guys are going to be pleasantly surprised. The BUZ will perform just fine, maybe even better than the 2s.
Head over to Pass Labs and read how capacitances are affected when mosfets are used in linear operation.
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