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Old 10th November 2012, 06:49 PM   #721
generg is offline generg  Germany
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of course.....

success has mostly many important fathers......

and one is called gmant123...
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Old 10th November 2012, 08:09 PM   #722
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greedy boyz ...........

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Old 10th November 2012, 10:36 PM   #723
dsdjoy is offline dsdjoy  Germany
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Quote:
Originally Posted by generg View Post
Congratulations.... I know you worked hard!
Thanks Generg ! It was you, who got me started, guided and motivated me during this longish J2 expedition.....thanks !!!
(....and we both know how many times we were close to giving up...)

So, it's all your fault
As a compensation, I expect to hear a report of working and nice-sounding Generg-J2 soon.

Last edited by dsdjoy; 10th November 2012 at 11:02 PM.
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Old 11th November 2012, 03:15 AM   #724
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Default Pictures found

Just found heat sink CAD database layout in my HDD but there're no any link to factory
I can't remember it maybe I need to send this picture to everyone whom in my email list (over 1000)

Ha Ha.......................
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Old 11th November 2012, 01:41 PM   #725
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I thinks that we must live the Pass/FirstWatt design to Mr Pass !!!
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Old 11th November 2012, 02:37 PM   #726
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That's definitely mine.

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Old 14th December 2012, 10:48 PM   #727
dsdjoy is offline dsdjoy  Germany
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I compared 6 Semisouth in 30 different combiations. One SS in upper, the other one in lower position. Measuring THD and 2nd, 3rd harmonics.

The result was really surprising: Regardless of matched or unmatched pairs being measured, the transistors showed very different behaviour in terms of 2nd, 3rd, 4th and 5th harmonics.

It occurs to me, that different Semisouth transistors show different distortion behaviour, and that it is worthwile to select them for the distortion pattern each one of them (or each push-pull pair) generates.

I also would like to emphasize regarding clones (some indicated in this thread):
Semisouth are nowadays almost unobtainable. One element of perfection of FirstWatt amps, is the meticulous selection of transistors from a stock of thousands, so the selected pairs create the desired sound, the designer aims for. In my opinion the selection does not happen only on Idss, Vgs, but also on gate leakage and harmonic distortion spectrum. So, individual diy guys with a large stock of semisouth and a LOT of time might be able to get close. Cloners with the intend to release many amps - forget it - without extreme effort and knowledge it is not possible to reach the same level of perfection.

Last edited by dsdjoy; 14th December 2012 at 11:02 PM.
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Old 14th December 2012, 11:40 PM   #728
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Another revelation of just how hard he works at bringin gthese amps to market. I am hoping to start my F6 clone soon an dhope i am as successful as you in my efforts.
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Old 15th December 2012, 12:25 AM   #729
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Quote:
Originally Posted by dsdjoy View Post
I compared 6 Semisouth in 30 different combiations. One SS in upper, the other one in lower position. Measuring THD and 2nd, 3rd harmonics.

The result was really surprising: Regardless of matched or unmatched pairs being measured, the transistors showed very different behaviour in terms of 2nd, 3rd, 4th and 5th harmonics.

It occurs to me, that different Semisouth transistors show different distortion behaviour, and that it is worthwile to select them for the distortion pattern each one of them (or each push-pull pair) generates.

I also would like to emphasize regarding clones (some indicated in this thread):
Semisouth are nowadays almost unobtainable. One element of perfection of FirstWatt amps, is the meticulous selection of transistors from a stock of thousands, so the selected pairs create the desired sound, the designer aims for. In my opinion the selection does not happen only on Idss, Vgs, but also on gate leakage and harmonic distortion spectrum. So, individual diy guys with a large stock of semisouth and a LOT of time might be able to get close. Cloners with the intend to release many amps - forget it - without extreme effort and knowledge it is not possible to reach the same level of perfection.

Hi dsdjoy:

I remember reading a while in the Ba1/3 thread (from Gerd) that did not vary much the sound putting R100 or IRFP240 in the upper position, can you comment something about that?
Thanks ..
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Old 15th December 2012, 12:39 AM   #730
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Its yfs level will certainly affect balance and distortion spread.
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