Blameless Amp layout - Page 9

AndrewT · 19th February 2010, 12:54 PM

do not use driver type transistors (2sb649/d669) for VAS duty.

maouna · 11th March 2010, 06:10 PM

Why not to use 2SB649 -2SD669 for VAS?
What about 2sc4793-2sa1837 for VAS stage?

homemodder · 11th March 2010, 07:35 PM

Not a good idea, the bd139 will be better, the cob of the transistor is very important here, the cob of the 2sb649 or 2sc4793 is in the order of 20 - 30pf at 10v vcb while the bd is maybe around 4 to 5, if you want to improve the circuit change your output transistors, 2n3055 are really not so good for audio.

maouna · 11th March 2010, 08:13 PM

2sc4793-2sa1837 for VAS stage??

19th February 2010, 12:54 PM	#81
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	do not use driver type transistors (2sb649/d669) for VAS duty. __________________ regards Andrew T.

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11th March 2010, 06:10 PM	#82
maouna diyAudio Member Join Date: Oct 2008	Why not to use 2SB649 -2SD669 for VAS? What about 2sc4793-2sa1837 for VAS stage?

11th March 2010, 07:35 PM	#83
homemodder diyAudio Member Join Date: May 2006	Not a good idea, the bd139 will be better, the cob of the transistor is very important here, the cob of the 2sb649 or 2sc4793 is in the order of 20 - 30pf at 10v vcb while the bd is maybe around 4 to 5, if you want to improve the circuit change your output transistors, 2n3055 are really not so good for audio.

11th March 2010, 08:13 PM	#84
maouna diyAudio Member Join Date: Oct 2008	2sc4793-2sa1837 for VAS stage??

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