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Old 24th November 2010, 01:42 PM   #51
generg is offline generg  Germany
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Hi Bill, Hi Zen Mod,

the new news... yesterday I was very convinced I would measure the AC current delivered by the Semisouth and by the CCS like Nelson suggested.

this morning bevor I took out the soldering iron, I heard some music and because I had yesterday implemented three resistors for R21, the one that feeds back the signal to CCS, I switched only the three values 750 Ohm, 500 Ohm and 310 Ohm.
Result: less Ohm, louder sound, CCS contributes power
More result: sound got more and more darker, not unpleasant.
more more result: definition got worse
difficulty: changing the volume to get the same level between the steps
surprise:without any resistor (Nelson mentions this possibility) - best definition, most airy sound, nearly too soft, but impressive - a must hear

conclusions:

- because Nelson shows the decrease of distortion by using aleph ccs it must be the blend in of the IRF240, that takes away definition. I will not speak per se against the IRF, may be the mix does not work well or there is no way back the SemiSouth is simply better.

- would be interesting to replace the IRF by a Semi, I know it is not recommended, but i am interested to hear the blend with two SemiS

- small signal j-fets and SSouth are unbeatable for resolution, airiness and more or less analogue softness. (the same experience I made with ZMs Babelfish J2, being more precise, less soft)

next steps: I will try three models CCS for the differential pair, original A5 with IRF9610, two or three SK170 (see frontstage BA-2) and the solution of aleph J

and look for the sound and hum..

happy generg
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Old 24th November 2010, 01:57 PM   #52
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Hi generg, removing the resistor turns the aleph circuitry off, making it a CCS. If you want to experiment more, increase the resistor to 1.2K or higher, that gives less AC current gain.
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Old 24th November 2010, 02:03 PM   #53
generg is offline generg  Germany
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yes Bill, I know and I did not want to do it because I wanted by the aleph CCS the more of power I needed for my four Ohm speaker but


as described the sound without is simply better....
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Old 24th November 2010, 02:20 PM   #54
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I understand. If your heatsinks are large enough you can increase the bias for a little more power capability.
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Old 24th November 2010, 02:22 PM   #55
generg is offline generg  Germany
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yes I will do this!

but first the little research about aleph with two identical semiconductors...
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Old 24th November 2010, 02:35 PM   #56
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally Posted by generg View Post
........

- would be interesting to replace the IRF by a Semi, I know it is not recommended, but i am interested to hear the blend with two SemiS


.....
I believe that small BJT will be starving at such low E-C voltage ;

anyway - be sure to set AC gain to desired level ...... because it is in function of Aleph CCS active output device

Quote:
Originally Posted by generg View Post
........

.....

next steps: I will try three models CCS for the differential pair, original A5 with IRF9610, two or three SK170 (see frontstage BA-2) and the solution of aleph J

and look for the sound and hum..

.....
I know what's my fave , if nothing else than from engineering reasons

be aware that I'm not an engineer
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Old 24th November 2010, 04:04 PM   #57
generg is offline generg  Germany
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o.k. I heard the aleph current source with two SemiS in the lower and upper half.

I tried all three values again and the change in sound to the darker and less resolution is not remarkable. BTW this are only small changes, nothing to get grey hairs....

means, with aleph current source its better to have to similar......

and two IRF will behave well also....
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Old 24th November 2010, 04:14 PM   #58
generg is offline generg  Germany
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and Zen Mod
is there any danger by the low E-C voltage for the small BJT or my amplifier, is their function not o.k. or what will happen...?
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Old 24th November 2010, 04:33 PM   #59
flg is online now flg  United States
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Exactly, except I'm not the "ZenMod". Look at the data sheet and the saturation charactersics.
I suggest an EF xistor from Colector of the the CSS "regulator" to the Gate of the CSS FET. Then the ZTX (BC whatever) has just enought EC voltage to operate well.

Choose.
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Old 24th November 2010, 04:57 PM   #60
generg is offline generg  Germany
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Hi flg,

Quote:
Exactly
should I not switch on the amplifier?

Quote:
suggest an EF xistor
I did not know the expression, I found "xistor" means "transistor" but what is "EF"? three legs? four legs are good, two legs are bad....

sorry.....
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