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Old 14th August 2002, 09:05 PM   #1
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Default P-channel mosfets for Aleph

Can Aleph be built with P-channel devices? I was thinking about IRFP 9130, since I might have some extras from modding A75 into Aleph. Any drawbacks, advantages when using those for Aleph?
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Old 14th August 2002, 11:47 PM   #2
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Yes, an ALEPH can be build using P Channel mosfets. At least
I do not see to much problems.
To illustrate this I made an example schematic of an ALEPH 3
with P Channel IRFP9140. As you can see you need to change
the input stage a little. (i.e. use n-channel IRF610).
I simulated this circuit, and it behaves very similar to the
original ALEPH 3.

I hope this helps you a little.
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File Type: zip aleph1_pmos.zip (25.6 KB, 144 views)
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Old 14th August 2002, 11:57 PM   #3
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Thumbs down P Channel

More capacitance less transconductance... Not a good choice.
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Old 15th August 2002, 12:12 AM   #4
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Just some examples...

Looking at the datasheets

For IRFP240
Ciss 1300 pF
Gfs 6,9 S min. pulse

For IRFP9140
Ciss 1400 pF
Gfs 6,2 S min. pulse

Please check the curves!

So, N-channel are only slightly better, but P-channel will not
make a terrible amplifier.

I remember their use in the original ZEN.
I think they are used in the X series as well.
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Old 15th August 2002, 01:54 AM   #5
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Default remember their use in the original ZEN.

Yes..... as a fixed current source. The lastest variation of the Zen uses two N channels in the output stage. I wonder why that is?
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Old 15th August 2002, 03:26 PM   #6
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Yes, I wonder too.
Thanks for schematic rtirion.
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Old 15th August 2002, 08:52 PM   #7
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I made an Aleph with 9240's just for the hell of it about
8 years ago. I didn't hear or measure much difference,
but the lower price and better availability of the N channels
made it a moot point.
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Old 15th August 2002, 09:33 PM   #8
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Aleph amps and X series amps are using devices with TO3 cases. What is the major advantage of that package?
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Old 15th August 2002, 09:52 PM   #9
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They look great. Now that they have been discontinued
and cost a lot more, they look even better!
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Old 15th August 2002, 10:00 PM   #10
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Quote:
Originally posted by Nelson Pass
I made an Aleph with 9240's just for the hell of it about
8 years ago. I didn't hear or measure much difference,
but the lower price and better availability of the N channels
made it a moot point.
I know the Pchannel Hitachis have a failure mechanism (precisely what I don't know) that the Nchannels lack....Seems maybe the IR Pchannels are 1rst to blow also ?????????????????
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