Compensation capacitor Cdom - Page 6

sandyK · 16th August 2007, 10:31 PM

The attached image should help to understand the differential circuit modifications for improving soundstage, as described in my previous post.Different amplifiers may require different methods.

If anybody wants a larger copy, please email me.
Sandyk

lumanauw · 17th August 2007, 01:27 AM

Hi, SandyK,

Between those 3 methods, all using the same indicator (adjust for 0.0mV)?

sandyK · 17th August 2007, 01:50 AM

Lumanauw
Yes, assuming that the differential pair is closely matched for HFE and VBE, try to adjust to <5mV difference between their collectors when warm.Only use minor adjustment of the VAS emitter resistor so as to not affect it's correct operation. If unable to achieve with only a small variation of the VAS emitter resistor . try the diode and resistor method instead. Using the 2 series diode method, you may be able to get closer by selecting a suitable 1N4148, as their forward voltage does vary a little between diodes.
BTW, it is adviseable to use matched 1% resistors in the emitters of the differential pair and current mirror. The actual measured value of these 1% resistors isn't as important as them being close in value.
SandyK

Bonsai · 17th August 2007, 03:49 AM

SandyK,

any possibility you could email me the orogonal Silicon chip article, or point to where I could find it?

sandyK · 17th August 2007, 04:02 AM

Bonsai
Silicon Chip now has a brand new 20W Class A which does not need an external PSU. If you like to email me, I will give you further information.
SandyK

17th August 2007, 01:50 AM	#53
sandyK diyAudio Member Join Date: Apr 2007 Location: Sydney	Compensation Capacitor Cdom Lumanauw Yes, assuming that the differential pair is closely matched for HFE and VBE, try to adjust to <5mV difference between their collectors when warm.Only use minor adjustment of the VAS emitter resistor so as to not affect it's correct operation. If unable to achieve with only a small variation of the VAS emitter resistor . try the diode and resistor method instead. Using the 2 series diode method, you may be able to get closer by selecting a suitable 1N4148, as their forward voltage does vary a little between diodes. BTW, it is adviseable to use matched 1% resistors in the emitters of the differential pair and current mirror. The actual measured value of these 1% resistors isn't as important as them being close in value. SandyK

17th August 2007, 03:49 AM	#54
Bonsai diyAudio Member Join Date: Aug 2006 Location: Taipei, Taiwan	SandyK, any possibility you could email me the orogonal Silicon chip article, or point to where I could find it? __________________ bonsai Amplifier Design and Construction for MUSIC! http://hifisonix.com/

17th August 2007, 04:02 AM	#55
sandyK diyAudio Member Join Date: Apr 2007 Location: Sydney	Compensation capacitor cdom Bonsai Silicon Chip now has a brand new 20W Class A which does not need an external PSU. If you like to email me, I will give you further information. SandyK

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17th August 2007, 01:27 AM	#52
lumanauw diyAudio Moderator Emeritus Join Date: Oct 2002 Location: Bandung	Hi, SandyK, Between those 3 methods, all using the same indicator (adjust for 0.0mV)?

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