In a monoblock aleph two there are a total of 12 IRFP240, six per side. When matching do all 12 have to match or just 2 sets of 6?
You just have to match two sets of six.
/Freddie
A recent article by Mr. Pass titled, "Practical Mosfet Testing for Audio" is a must read. It's in PDF format at the www.passdiy.com site.
Regards,
Dan
Regards,
Dan
Only devices that actually work in pararell have to be matched.But I always wondered if devices that work at the same place in each channels should be matched to each other or not ,and how does it apply to gain of circuit and stereo balance.
Bartek
Just to sure ,I always match both channels ,so for Aleph 2 I would go for two banks of 12 devices.
Bartek
Just to sure ,I always match both channels ,so for Aleph 2 I would go for two banks of 12 devices.
Interesting that you should mention it. with an "X" type ampzygibajt said:Only devices that actually work in pararell have to be matched.But I always wondered if devices that work at the same place in each channels should be matched to each other or not ,and how does it apply to gain of circuit and stereo balance.
I prefer to match all of the negative side output transistors, and
with a slightly lessor priority all the positive side output devices
(this in the case of the XA).
Since the two opposite "channels" of the balance output cancel
distortions in common, you get a little more of that cancellation
that a diff pair input enjoys.
I don't regard this as a big item, though because once Vbe
matching has occured in a parallel bank, they statistically show a
lot of AC performance matching, particularly if they are from the
same lot code.
It still distorts, but a little less.
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