a wonderfull sziklai - Page 10

Marc Vi. · 31st December 2008, 12:45 PM

Thank you Stefano fot publishing "The Ultimate Suplifier" in your website (see post 83).

Who will take the challenge to use my output configuration (see figure 1 in the explanation of the Ultimate Suplifier) in the V3 circuit (see post 75)?? The only thing you have to change for a higher supply voltage, is to raise R39/R40 to 56 ohm. Because 2 transistors are added (Q13 and Q14) the Vbias must be higher which can be achieved by lowering R29 in the V3 circuit to 0 ohm. Of course the output "from the neg. amplifier" must be connected to the ground.

A sziklai pair sometimes tends to oscillate. Therefor the output resistors may not be wired but must be of carbon. 5 resistors of 1,2 ohm and 1 resistor of 2,7 ohm parallel gives 0,22 ohm.

If, by the reason of the overall neg. feedback, there is still some oscillation, try capacitors parallel to R39 and R40 with a - 3 dB point above lets say 200 kHz. This will be (for R39/49 = 56 ohm) 15 nF each.

Andrew, which schematic dou you refer to? If you mean the attached file, then I agree this is a potentionally thermal instabel output. The emittor of Q111 should be connected to the emittor of Q114 and the emittor of Q112 to the emittor of Q113. Then you have to match Q114 with Q116 and Q113 with Q115 otherwise there is a change of thermal runaway of Q116 and Q115.

Marc.

catalin · 31st December 2008, 12:54 PM

v1 tend to oscilate (1mhz) on different pcb.
By lowering the module of the function transfer (pole and zero,470p+330ohms),the v3 is more more stable and i couldn't make to oscilate.The pulse signal,amp reserve phase is better on v3.Dinamics also with the beta helper.

Stee · 31st December 2008, 01:08 PM

http://www.esafono.it/AudioPowerAmplifier.pdf

AndrewT · 31st December 2008, 01:18 PM

Stee,
note that tr6 & 8 are connected to the outputs and that the outputs are singletons.
Your's is completely different.

Stee · 31st December 2008, 05:18 PM

I have generate some confusing...
try again to convert in CFP output a "normal " amp:

http://www.mcmelectronics.com/conten...ts/50-6272.pdf

need just two resistors 120R

m2003br · 31st December 2008, 08:02 PM

nakamichi PA-7 is a Nelson Pass project. Threshold "Stasis" is the about the same.
Sakis: naka PA-7 service manual states 40mA idle for each transistor, 200mA total. It is not a class AB?

Stee · 1st January 2009, 02:20 PM

Hybrid CFP with mosfet driver 1A
exactly the same of the original BJT

Stee · 4th January 2009, 06:20 PM

hCFP
next days i have time to test

homemodder · 4th January 2009, 06:49 PM

Stee you might find reversing the mosfet and bipolar to be of greater benefit.

Stee · 5th January 2009, 04:30 AM

http://www.ampslab.com/bi70mk2.htm
as FET on input
now
is time to lighten the load on VAS
with Mos Drivers

31st December 2008, 12:45 PM	#91
Marc Vi. diyAudio Member Join Date: Feb 2004 Location: The Netherlands	a wonderfull sziklai Thank you Stefano fot publishing "The Ultimate Suplifier" in your website (see post 83). Who will take the challenge to use my output configuration (see figure 1 in the explanation of the Ultimate Suplifier) in the V3 circuit (see post 75)?? The only thing you have to change for a higher supply voltage, is to raise R39/R40 to 56 ohm. Because 2 transistors are added (Q13 and Q14) the Vbias must be higher which can be achieved by lowering R29 in the V3 circuit to 0 ohm. Of course the output "from the neg. amplifier" must be connected to the ground. A sziklai pair sometimes tends to oscillate. Therefor the output resistors may not be wired but must be of carbon. 5 resistors of 1,2 ohm and 1 resistor of 2,7 ohm parallel gives 0,22 ohm. If, by the reason of the overall neg. feedback, there is still some oscillation, try capacitors parallel to R39 and R40 with a - 3 dB point above lets say 200 kHz. This will be (for R39/49 = 56 ohm) 15 nF each. Andrew, which schematic dou you refer to? If you mean the attached file, then I agree this is a potentionally thermal instabel output. The emittor of Q111 should be connected to the emittor of Q114 and the emittor of Q112 to the emittor of Q113. Then you have to match Q114 with Q116 and Q113 with Q115 otherwise there is a change of thermal runaway of Q116 and Q115. Marc.

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31st December 2008, 12:54 PM	#92
catalin diyAudio Member Join Date: Jun 2007	v1 tend to oscilate (1mhz) on different pcb. By lowering the module of the function transfer (pole and zero,470p+330ohms),the v3 is more more stable and i couldn't make to oscilate.The pulse signal,amp reserve phase is better on v3.Dinamics also with the beta helper.

31st December 2008, 01:18 PM	#94
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Stee, note that tr6 & 8 are connected to the outputs and that the outputs are singletons. Your's is completely different.

31st December 2008, 08:02 PM	#96
m2003br diyAudio Member Join Date: Dec 2004 Location: Sao Paulo	nakamichi PA-7 is a Nelson Pass project. Threshold "Stasis" is the about the same. Sakis: naka PA-7 service manual states 40mA idle for each transistor, 200mA total. It is not a class AB?

4th January 2009, 06:49 PM	#99
homemodder Account disabled at member's request Join Date: May 2006	Stee you might find reversing the mosfet and bipolar to be of greater benefit.