bypass output capacitor

wicked1 · 21st August 2009, 01:43 AM

Im building an F2 amp. I read a few posts in the F3 build thread about the output cap. Some say to use a good one, and don't bother w/ the bypass cap. I'm willing to try soldering 10-15 Silmic II's together, and the cost would be about the same as getting a decent bypass cap.

Any thoughts?

VladimirK · 21st August 2009, 04:01 AM

Quote:

Originally Posted by wicked1

Im building an F2 amp. I read a few posts in the F3 build thread about the output cap. Some say to use a good one, and don't bother w/ the bypass cap. I'm willing to try soldering 10-15 Silmic II's together, and the cost would be about the same as getting a decent bypass cap.
Any thoughts?

Sure with 10-15 small Silmic sound will be more dynamic than with 1-2 big ones, but no warranty that you can escape of using bypass polypropylene cap. Since special polypropylenes for audio are very expensive and do not have big values, you might want to test 30uF polypropylene starting cap. After burning in period this can be very satisfactory.

Nelson Pass · 21st August 2009, 04:15 AM

Remember that current source amplifiers tend to ignore the
artifacts added by capacitors - those artifacts show up as voltage
and do not tend to alter the current.

VladimirK · 21st August 2009, 04:50 AM

The artifacts of capacitors could be understood that they cause some small parasitic voltage, but almost no current, i.e. can not provide wattage. This makes more safe using them at an output than at input. But for listenable effects even tiny artifacts may play a role, something similar to effects of cables.

Magura · 21st August 2009, 09:57 AM

Quote:

Originally Posted by VladimirK

similar to effects of cables.

Not really happening in a current source setup.

Magura

fff0 · 21st August 2009, 01:46 PM

how about voltage output amp like F3, 4, 5?
Is the output shown in the schematics AC values? Like 21v in F3?

wicked1 · 02:09 PM

Hmm... to be honest, I already ordered the 30 silmics before I posted this

...
Maybe I'll save them for a possible future f3 build, if it doesn't make as much difference in the f2.
(ignorance isn't bliss.. it costs money!)

VladimirK · 21st August 2009, 02:26 PM

Difficult, but most valuable thing is when one try variants, compare and report his impressions.

wicked1 · 22nd August 2009, 09:49 PM

I'm thinking about capacitors again today...
For this amp (F2), the input cap is still important, right? But not the output as much, as it's current that matters at that point.
And so if the output cap doesn't matter much, why is the bypass needed at all? Because it matters a little, even though not as much as it would in a standard voltage amp?

thanks again.

21st August 2009, 01:43 AM	#1
wicked1 diyAudio Member Join Date: Jan 2008	bypass output capacitor Im building an F2 amp. I read a few posts in the F3 build thread about the output cap. Some say to use a good one, and don't bother w/ the bypass cap. I'm willing to try soldering 10-15 Silmic II's together, and the cost would be about the same as getting a decent bypass cap. Any thoughts?

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21st August 2009, 04:15 AM	#3
Nelson Pass The one and only Join Date: Mar 2001	Remember that current source amplifiers tend to ignore the artifacts added by capacitors - those artifacts show up as voltage and do not tend to alter the current.

21st August 2009, 04:50 AM	#4
VladimirK diyAudio Member Join Date: Feb 2007 Location: Tashkent	The artifacts of capacitors could be understood that they cause some small parasitic voltage, but almost no current, i.e. can not provide wattage. This makes more safe using them at an output than at input. But for listenable effects even tiny artifacts may play a role, something similar to effects of cables.

21st August 2009, 01:46 PM	#6
fff0 diyAudio Member Join Date: Jul 2008	how about voltage output amp like F3, 4, 5? Is the output shown in the schematics AC values? Like 21v in F3?

21st August 2009, 02:26 PM	#8
VladimirK diyAudio Member Join Date: Feb 2007 Location: Tashkent	Difficult, but most valuable thing is when one try variants, compare and report his impressions.

22nd August 2009, 09:49 PM	#9
wicked1 diyAudio Member Join Date: Jan 2008	I'm thinking about capacitors again today... For this amp (F2), the input cap is still important, right? But not the output as much, as it's current that matters at that point. And so if the output cap doesn't matter much, why is the bypass needed at all? Because it matters a little, even though not as much as it would in a standard voltage amp? thanks again.

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