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Old 25th November 2010, 03:07 PM   #81
chip_mk is offline chip_mk  Macedonia
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Quote:
Originally Posted by Zen Mod View Post
gate current - pretty much predictable - counting on Jfet input/transfer capacitances ; small bjt is already small ..... why choking him also with smaller voltage
Actually I was talking about DC current. Looking into datasheet it seems the gate absorbs probably couple of mA with no AC signal present. Generg can check this by measuring voltage drop across gate resistor R52. What is more peculiar, it seems input impedance of the SS device is negative at low Vgs which could affect stability.
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Old 25th November 2010, 03:22 PM   #82
Zen Mod is offline Zen Mod  Serbia
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Originally Posted by generg View Post
......

when I try the "EF xsistor" flg suggested.... can I measure anything to proof the success?

only hearing is very difficult.......
well - I think that just hearing is absolutely adequate in your case

you can only check voltage across gate resistor - as chip_mk wrote , from different reasons
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Old 25th November 2010, 07:59 PM   #83
generg is offline generg  Germany
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Thanks to all that contributed to my growing knowledge .......

so many suggestions I have to buy a second soldering iron.....


the next days I will try some ideas and btw: does anybody know why the aleph ccs makes distortion lower but only at smaller levels of signal...?
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Old 25th November 2010, 08:28 PM   #84
Zen Mod is offline Zen Mod  Serbia
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if you need kinin ...... hope that Captain Nemo is around .......

Aleph Current Source Modifications, A W Newby
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File Type: pdf Aleph CCS modification.pdf (52.2 KB, 105 views)
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Old 25th November 2010, 08:34 PM   #85
Zen Mod is offline Zen Mod  Serbia
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Generg - look at picture No.12 on this page : Long Tailed Pair Zen, A W Newby, Jan 2007

Click the image to open in full size.
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Old 25th November 2010, 09:54 PM   #86
generg is offline generg  Germany
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Very good material for greedy generg ......
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Old 25th November 2010, 10:07 PM   #87
Zen Mod is offline Zen Mod  Serbia
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NB that arrangement of source/drain resistors in post #85 is different in another important/tricky/interesting way - with usual Aleph arrangement of output sense resistors, loudspeaker's back EMF is included in modulation of Aleph CCS

at least as I see it

which way you'll prefer ..... dunno
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Old 26th November 2010, 10:32 AM   #88
generg is offline generg  Germany
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this version sounded best ......
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Old 26th November 2010, 10:48 AM   #89
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Quote:
Originally Posted by Zen Mod View Post
Generg - look at picture No.12 on this page : Long Tailed Pair Zen, A W Newby, Jan 2007
There have been an update.
Aleph Current Source Mod

See also Wensan thread
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Old 26th November 2010, 11:02 AM   #90
Zen Mod is offline Zen Mod  Serbia
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tnx to pointing to that thread ...... seems that I already forgot more than I know now

in any case - it looks that picture in post #85 is latest iteration/result of Allen's work
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