Self Class G. Transistor matching?

subculture · 29th May 2005, 05:12 PM

Hello,

I am building a system based on the following-

Douglas Self Preamp. PCB by Signal Transfer Company
8 channels of Doug self design Class G amp using PCB's by Signal transfer Company.
Linkwitz Orion speakers with active crossovers.

I have hit a snag, and am hoping someone can advise me.

Do I need to match the transistors on this design. If so, does anyone offer a transistor matching service.

Regards

Andrew

MGR · 30th May 2005, 02:04 AM

I have built the class G amp that Douglas Self designed and as far as my working prototype there was no need to match the transistors.My amp has been working for about 2 years with no problem.I used +- 60 volts dc for the low and +- 120 on the high side.I used toshiba 2SA1943 and 2SC5200 for the outputs.

K-amps · 30th May 2005, 04:06 PM

Man how many watts do you get out of that... I am guesssing the trafo's are not tightly regulated otherwise the Toshiba's will not like those rails....

MGR · 31st May 2005, 02:12 AM

I am getting 500 watts at 8ohms ,because of the series connection the output transistor never sees more than 60 volts,the 120 volts dc is without load with load it will drop to 110 volts.It uses 6 NPN and 6 PNP toshiba per channel.

K-amps · 31st May 2005, 02:55 AM

Ah, the old totem pole... gotcha... The issue I have with Totem poles is lack of damping factor, at higher volumes, the woofer's cones are out of control... it might be ok in your amp but thats my experience with series OP stages.

29th May 2005, 05:12 PM	#1
subculture diyAudio Member Join Date: May 2005 Location: London	Self Class G. Transistor matching? Hello, I am building a system based on the following- Douglas Self Preamp. PCB by Signal Transfer Company 8 channels of Doug self design Class G amp using PCB's by Signal transfer Company. Linkwitz Orion speakers with active crossovers. I have hit a snag, and am hoping someone can advise me. Do I need to match the transistors on this design. If so, does anyone offer a transistor matching service. Regards Andrew

30th May 2005, 02:04 AM	#2
MGR diyAudio Member Join Date: Oct 2002 Location: Philippines	Class G amp I have built the class G amp that Douglas Self designed and as far as my working prototype there was no need to match the transistors.My amp has been working for about 2 years with no problem.I used +- 60 volts dc for the low and +- 120 on the high side.I used toshiba 2SA1943 and 2SC5200 for the outputs.

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30th May 2005, 04:06 PM	#3
K-amps diyAudio Member Join Date: Nov 2003 Location: Indiana	Man how many watts do you get out of that... I am guesssing the trafo's are not tightly regulated otherwise the Toshiba's will not like those rails....

31st May 2005, 02:12 AM	#4
MGR diyAudio Member Join Date: Oct 2002 Location: Philippines	I am getting 500 watts at 8ohms ,because of the series connection the output transistor never sees more than 60 volts,the 120 volts dc is without load with load it will drop to 110 volts.It uses 6 NPN and 6 PNP toshiba per channel.

31st May 2005, 02:55 AM	#5
K-amps diyAudio Member Join Date: Nov 2003 Location: Indiana	Ah, the old totem pole... gotcha... The issue I have with Totem poles is lack of damping factor, at higher volumes, the woofer's cones are out of control... it might be ok in your amp but thats my experience with series OP stages.

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