Any class A amp with 2SK1058/2SJ162 ??

nina · 24th December 2005, 04:56 PM

I am looking for a low power ( 10-25W) class A amp using with 2SK1058/2SJ162 MOSFET but cannot find it yet? Any guide? Thanks

lineup · 24th December 2005, 08:11 PM

I searched for 2SK1058 here.
I found several schematics.
Not for full Class A, but would be something to start working with.

2SK1058 / SJ162 is a very good choice.
They have been popular in amplifier outputs.

I am almost sure you will find some others interested in making such a project.

mlloyd1 · 24th December 2005, 09:08 PM

The Audio Express has had a couple of class A designs in this power range using similar Hitachi MOSFETs. Maybe someone has the issue numbers. I can't get to mine.

mlloyd1

AndrewT · 25th December 2005, 09:10 AM

Hi,
push pull presumably?

+-22Vdc rails will give about 17W into 8ohm at 60 phase angle. The output bias current needs to be about 1100mA (24W/FET) for full classA into 8r.
It will go to 25W into 4r at 55 degree phase angle but most of this is classAB, unless you increase the bias to 1800mA (40W/FET, very hot!).

Try a simple ClassAB design modified to high bias. If you like the sound you will only have to change the voltage amp PCB for another and the cost will be quite low. The big cost is in the PSU, sink and case.

At these very high temps it might be worth thermally coupling the bias control to the output sinks. Even using radiation coupling might be enough to start cutting back on the bias as the temps come up. I have 400mA on a resistive bias control and it appears OK.

joensd · 25th December 2005, 09:19 AM

Search for "zenquito" here in the forums.
I´m pretty sure somebody built a HT amp with it.
You can adjust power output and bias by choosing your voltage rails.
See here:
http://perso.wanadoo.fr/jm.plantefeve/sche.html

nina · 25th December 2005, 05:12 PM

Thanks for all suggestion. "zenquito" looks interesting but just wonder if the 2SK170 still available. I will try get the page interpreted.

Thanks again.

widowmaker · 25th December 2005, 05:34 PM

Possible (better) substitution:
2SK389 (BL or V)

WALTER BURKHARD · 25th December 2005, 05:59 PM

Look for Boberly-Audio.
regards Walter

AndrewT · 26th December 2005, 07:40 AM

Hi,
for all your transistor needs in the UK, start your enquiry with http://www.dalbani.co.uk Excellent pricing, enormous range and good service.

ashok · 26th December 2005, 09:03 AM

Quote:

just wonder if the 2SK170 still available

Linear Systems of the US is now making these
LSK170 and LSK389
Check their web site.
http://www.linearsystems.com/

24th December 2005, 04:56 PM	#1
nina diyAudio Member Join Date: Apr 2005 Location: Earth	Any class A amp with 2SK1058/2SJ162 ?? I am looking for a low power ( 10-25W) class A amp using with 2SK1058/2SJ162 MOSFET but cannot find it yet? Any guide? Thanks

24th December 2005, 08:11 PM	#2
lineup diyAudio Member Join Date: Dec 2005 Location: the north	I searched for 2SK1058 here. I found several schematics. Not for full Class A, but would be something to start working with. 2SK1058 / SJ162 is a very good choice. They have been popular in amplifier outputs. I am almost sure you will find some others interested in making such a project. __________________ lineup

25th December 2005, 09:10 AM	#4
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, push pull presumably? +-22Vdc rails will give about 17W into 8ohm at 60 phase angle. The output bias current needs to be about 1100mA (24W/FET) for full classA into 8r. It will go to 25W into 4r at 55 degree phase angle but most of this is classAB, unless you increase the bias to 1800mA (40W/FET, very hot!). Try a simple ClassAB design modified to high bias. If you like the sound you will only have to change the voltage amp PCB for another and the cost will be quite low. The big cost is in the PSU, sink and case. At these very high temps it might be worth thermally coupling the bias control to the output sinks. Even using radiation coupling might be enough to start cutting back on the bias as the temps come up. I have 400mA on a resistive bias control and it appears OK. __________________ regards Andrew T.

25th December 2005, 09:19 AM	#5
joensd diyAudio Member Join Date: Dec 2001 Location: Germany	Search for "zenquito" here in the forums. I´m pretty sure somebody built a HT amp with it. You can adjust power output and bias by choosing your voltage rails. See here: http://perso.wanadoo.fr/jm.plantefeve/sche.html __________________ jens

25th December 2005, 05:34 PM	#7
widowmaker diyAudio Member Join Date: Nov 2004 Location: Sofia, Bulgaria	Possible (better) substitution: 2SK389 (BL or V) __________________ Audio Researcher Daniel Petrov also known as widowmaker


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24th December 2005, 09:08 PM	#3
mlloyd1 diyAudio Member Join Date: Feb 2001 Location: illinois	The Audio Express has had a couple of class A designs in this power range using similar Hitachi MOSFETs. Maybe someone has the issue numbers. I can't get to mine. mlloyd1

25th December 2005, 05:12 PM	#6
nina diyAudio Member Join Date: Apr 2005 Location: Earth	Thanks for all suggestion. "zenquito" looks interesting but just wonder if the 2SK170 still available. I will try get the page interpreted. Thanks again.

25th December 2005, 05:59 PM	#8
WALTER BURKHARD diyAudio Member Join Date: Dec 2002 Location: Helsinki	Look for Boberly-Audio. regards Walter

26th December 2005, 07:40 AM	#9
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, for all your transistor needs in the UK, start your enquiry with http://www.dalbani.co.uk Excellent pricing, enormous range and good service. __________________ regards Andrew T.

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