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Old 19th November 2001, 09:34 PM   #11
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Certainly, but I wouldn't lose any sleep over it.
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Old 20th November 2001, 02:10 PM   #12
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Join Date: Oct 2001
Location: Taipei TW
I build Aleph3 and found the Matching MOSFET is some kind of difficult. And few kinds of method for VGS measurements.
1. Use a power resistor to measurement it individual with same current & temp.
2. Use an Aleph3 circuit with only one Pair of IRFP240. Also individually.
3. Measurements it on real Aleph3 circuit. Check VGS on site.

Actually I do it step by step. Then, I can get closest VGS & Voltage over Source Resistor.

I got 16 of IRFP240 & Use 12 of them for my stereo Aleph3. I set 0.4V over 0.49ohm resistor (2W, 2%). All of the effort returns by Music. I am very enjoying it now. I think in such simple circuitry, have to control the performance by components quality & lots of matching works. Also more current is better.
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Old 20th November 2001, 08:24 PM   #13
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Join Date: Nov 2000

One channel running with 0.5V over each resistor and 0.6V in the other channel is fine by me.
Yes, I suspect this is partialy a consequence of using the BC550C in one channel and a ZTX450 in the other. Their is a noticable difference in gain for both transistors, so it is very likely to have an effect on the DC setting of the current source circuit. I don't think this is a negative effect. Actually a little more quiescent current in the ALEPH is probably a benefit. I know this small diffence will not have significant sonic effect.
So go ahead, and enjoy your ALEPH

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