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Old 30th March 2012, 02:09 AM   #561
TB is offline TB  United States
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gaborbela,
Thank you very much for the schematic. This is very kind of you. I should have both On Semi transistor types. Since I saw it on ...stigerik.. site few years ago.
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Old 30th March 2012, 04:21 AM   #562
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Hello
Your welcome!
Here is these good quality PC board, if you interested or if you want to produce yours I will look it up.
Stereo amplifer PCB Hiraga super 30W class A !!! | eBay
Someone from the forum purchased these PC board and great quality.
Schematic is same minor change.
You still can use the schematic I posted even with these PC boards.
Greetings Gabor
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Old 30th March 2012, 05:16 AM   #563
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Hello
I tried to answer to your PM but it didn't went on so I lost the answer.
Please do not change under any circumstances the 2SA782 &2SC1775 BJT-s.
Please try to look up the lay out and the rest of the info, I posted several time on the forum. Probably I deleted because I do not find them.
Greetings Gabor
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Old 30th March 2012, 06:48 AM   #564
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Quote:
Originally Posted by megaymir View Post
Perhaps this one? (Fig. 2.)

What kind of output devices would you use?
Yes indeed: Fig. 2: Modified version, class A, 60 Watts, using V-Fet transistors at the output
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Old 30th March 2012, 07:06 AM   #565
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Quote:
Originally Posted by gaborbela View Post
Hello
I tried to answer to your PM but it didn't went on so I lost the answer.
Please do not change under any circumstances the 2SA782 &2SC1775 BJT-s.
Please try to look up the lay out and the rest of the info, I posted several time on the forum. Probably I deleted because I do not find them.
Greetings Gabor
Gabor,
though you are pertinent (DON'T ), but .. . . is 2SA940/2SC2240 an option? I have seen this pair as a replacement in Le Classe A - but I can't find the Rbb. I bought two lots of both, match well. Intend to use these.

The commonly seen BC549/BC559 etc has a higher Rbb, in the order of 20 ohms. But they do have a flat Hfe, which is important too.

Just searching on the net, I found 2SA1316 with an Rbb of 2 ohm, and a Cob of 6 pF. I bought some, measure well, but I can't find the complement 2SC3329.
[I find the prices for 2SA782/2SC1775 just too steep]

The circuit boards of Jims audio are good: plated through holes. Thick copper. Military grade. You need a good soldering iron!
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Old 30th March 2012, 01:59 PM   #566
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Hello
Look I know after my experience what I advise. You can take it or you can try to replace those BJT-s and after start all the endless research.
If we would talk here BC550C & 560C right away I would say replace it wit 2SK170BL & 2SJ74BL. Great improvement.
Since I tried several other type BJT and after I went back to use my short cut leads over soldered orig BJT I know it worth to buy them if you have source and you have no more headache.
I have a circuit I want to test someone mod it lot of LED, other type BJT etc I still I test it with the orig 2SA782/2SC1775.
It is possible to replace those BJT? Yes I don't say not. I built several Hiraga.
The problem these amp very sensitive every parts U use plus the PS is very important to.
If you want have a peace of mind at least test one side with the orig another side replace it ans com pare them again and again. Let us know if you find something close (sound wise) to the orig please.

Greetings Gabor
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Old 30th March 2012, 02:07 PM   #567
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Quote:
Originally Posted by triode_al View Post
Yes indeed: Fig. 2: Modified version, class A, 60 Watts, using V-Fet transistors at the output
Hello
I wanted to try that V-Fet type. Forget it. Even if you get the orig V-Fet for horrible price the measurement no longer much with the data.
Someone get those I think (I'm not sure but not Ebay product) from Mouser , he did some measurement , after returned to the seller (company). I read that and I'm not willing to pay for those ancient parts $60/each or so.
Greetings Gabor
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Old 30th March 2012, 02:25 PM   #568
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gaborbela,
Thank you very much for your response. Let me search for them.
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Old 30th March 2012, 03:14 PM   #569
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Quote:
Originally Posted by gaborbela View Post
Hello
I wanted to try that V-Fet type. Forget it. Even if you get the orig V-Fet for horrible price the measurement no longer much with the data.
Someone get those I think (I'm not sure but not Ebay product) from Mouser , he did some measurement , after returned to the seller (company). I read that and I'm not willing to pay for those ancient parts $60/each or so.
Greetings Gabor
I will use 2SK175, 2SJ55 as I have a bunch of them and they work very well in my F5. The schema remains the same this way. The gate voltage will be around 1,6 V plus the voltage across the emitter resistance of 1 ohm at 1 ampere (1 ohm in this diagram; in the common BJT output there is o,47 ohm or lower).
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Old 30th March 2012, 05:40 PM   #570
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Suggested 2SA940/2SC2240 transistors by triode_al are available from MCM.
2SA940 - $1.65
2SC2240 - $0.40
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