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.
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
😀😀😀 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...?
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...?
if you need kinin ...... hope that Captain Nemo is around ....... 
Aleph Current Source Modifications, A W Newby
Aleph Current Source Modifications, A W Newby
Attachments
Generg - look at picture No.12 on this page : Long Tailed Pair Zen, A W Newby, Jan 2007
An externally hosted image should be here but it was not working when we last tested it.
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
at least as I see it
which way you'll prefer ..... dunno
There have been an update.
http://www.diyaudio.com/forums/pass-labs/161716-aleph-current-source-mod.html
See also Wensan thread
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
in any case - it looks that picture in post #85 is latest iteration/result of Allen's work
so - hybrid SS/IRF ......
power on 8 and 4 ?
what's AC gain of A CCS ?
and sound , comparing to two crown shark ?
The results are embarrassing,
With the J-fet inputstage the SemiS sound better than the IRF in the signalpath and the aleph current sound mix with the IRF is not so pleasant to my ears, so better no aleph feedback.
But with the original IRF9610 input stage and the IRF output stage it's another world of sound, more earthbound, more dynamic, sharper, a little bit more dirty in sound.
Of course not the resolution, the airiness of the J-FETs ..... It seems difficult to get both.
Is it possible the j-fet input stage I used has no good point to work, because I loose 17V over the 1k resistor leading to the SK170, from the positiv 24V ?
I did not hear Babel two crowns for over a week, because I have only one set of power supply, but for the sure it was the best sound I heard up to now.
But only 13 W at 4 ohm is not much and wanted to see what the alephs can do.
And I do not want to stop to make experiments. I think I need another set of heatsinks and so on that I can hear with the best set I have and at the same time experiment with another set.
With the J-fet inputstage the SemiS sound better than the IRF in the signalpath and the aleph current sound mix with the IRF is not so pleasant to my ears, so better no aleph feedback.
But with the original IRF9610 input stage and the IRF output stage it's another world of sound, more earthbound, more dynamic, sharper, a little bit more dirty in sound.
Of course not the resolution, the airiness of the J-FETs ..... It seems difficult to get both.
Is it possible the j-fet input stage I used has no good point to work, because I loose 17V over the 1k resistor leading to the SK170, from the positiv 24V ?
I did not hear Babel two crowns for over a week, because I have only one set of power supply, but for the sure it was the best sound I heard up to now.
But only 13 W at 4 ohm is not much and wanted to see what the alephs can do.
And I do not want to stop to make experiments. I think I need another set of heatsinks and so on that I can hear with the best set I have and at the same time experiment with another set.
that's irrelevant
that 1K resistor is just saving your CCS from excessive dissipation ;
there is no embarrassing result ... when one is learning from results
try Babelfish Two Crowns with 2 pairs in output
It is one of the new Semisouth J-FETs Nelson Pass uses.....🙂
http://www.semisouth.com/products/uploads/DS_SJEP120R100_rev1 2.pdf
Tea-bag sells them matched!😀
http://www.semisouth.com/products/uploads/DS_SJEP120R100_rev1 2.pdf
Tea-bag sells them matched!😀
You want to adjust it for best measurement and/or best
sound. Ideally the Aleph IRF240's will not contribute
much to the sound on their own, but of course no situation
is ideal. I can tell you that they measure a little
differently than other FETs in the same spot.
😎
thank you Mr. Pass for your comment!🙂
Unfortunately I do not understand the meaning of the quotation above....
The IRF240 measure a bit differently than.....? Semisouth?
🙂🙂
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