Aleph 2 - 100k mfd enough?

TwangBar · 11th November 2006, 03:34 PM

I have an Aleph 2 with 100k mfd capacitance in the power supply (in a CLC configuration). I have noticed that many people use much larger capacitance.

Am I missing out on something with having less capacitance?

If I am over biasing, does this demand more capacitance as well?

Thanks for any help you can provide.

GRollins · 11th November 2006, 08:23 PM

Is that 100 thousand per amp (both rails), per rail, or for both channels? The amount of capacitance by itself doesn't supply enoungh information.
How much is enough depends on your point of view and on external factors like how noisy your power lines are.
That said, 100,000 uF per channel sounds like a good number.

Grey

EDIT: Yes, more capacitance is appropriate for higher bias.

TwangBar · 12th November 2006, 03:02 AM

Yes, 100k per amp (both rails). The service manual states 4 x 22K. I am using a 1000 VA tranny.

I guess I was just wondering why so many people are using much more capacitance.

Babowana · 12th November 2006, 10:37 AM

Quote:

Originally posted by TwangBar

I was just wondering why so many people are using much more capacitance.

I think that they want the ripple voltage as low as possible.
So, they try more capacitane than "good enough."
I can hardly say that something wrong there . . .

Holger Barske · 12th November 2006, 11:03 AM

Just ask Duncan's PSUD what's wrong with it.
Just paralleling capacitors at the rectifier's output makes things worse - charge current rises and generates nasty spikes you will hardly ever get rid of. Increasing capacitance behind the choke is another story.
Do yourself a favor and play with PSUD, there's a lot to learn about such a (not so) simple thing like a power amplifier supply.

TwangBar · 12th November 2006, 05:08 PM

Thanks - I will do that. I have much to learn...

GRollins · 13th November 2006, 09:38 PM

Caps across the diodes will do quite nicely in taming spikes. You can also use soft recovery diodes. It's not that big a problem.

Grey

TwangBar · 14th November 2006, 01:17 AM

I am using the IXYS FRED br. Would these benefit from the coupling caps?

11th November 2006, 03:34 PM	#1
TwangBar diyAudio Member Join Date: Jan 2003 Location: Ottawa, Canada	Aleph 2 - 100k mfd enough? I have an Aleph 2 with 100k mfd capacitance in the power supply (in a CLC configuration). I have noticed that many people use much larger capacitance. Am I missing out on something with having less capacitance? If I am over biasing, does this demand more capacitance as well? Thanks for any help you can provide.

12th November 2006, 11:03 AM	#5
Holger Barske diyAudio Member Join Date: Jan 2001 Location: Ruhrgebiet	Just ask Duncan's PSUD what's wrong with it. Just paralleling capacitors at the rectifier's output makes things worse - charge current rises and generates nasty spikes you will hardly ever get rid of. Increasing capacitance behind the choke is another story. Do yourself a favor and play with PSUD, there's a lot to learn about such a (not so) simple thing like a power amplifier supply. __________________ Best regards: Holger www.holgerbarske.com

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11th November 2006, 08:23 PM	#2
GRollins diyAudio Member Join Date: Feb 2001 Location: Columbia, SC	Is that 100 thousand per amp (both rails), per rail, or for both channels? The amount of capacitance by itself doesn't supply enoungh information. How much is enough depends on your point of view and on external factors like how noisy your power lines are. That said, 100,000 uF per channel sounds like a good number. Grey EDIT: Yes, more capacitance is appropriate for higher bias.

12th November 2006, 03:02 AM	#3
TwangBar diyAudio Member Join Date: Jan 2003 Location: Ottawa, Canada	Yes, 100k per amp (both rails). The service manual states 4 x 22K. I am using a 1000 VA tranny. I guess I was just wondering why so many people are using much more capacitance.

12th November 2006, 05:08 PM	#6
TwangBar diyAudio Member Join Date: Jan 2003 Location: Ottawa, Canada	Thanks - I will do that. I have much to learn...

13th November 2006, 09:38 PM	#7
GRollins diyAudio Member Join Date: Feb 2001 Location: Columbia, SC	Caps across the diodes will do quite nicely in taming spikes. You can also use soft recovery diodes. It's not that big a problem. Grey

14th November 2006, 01:17 AM	#8
TwangBar diyAudio Member Join Date: Jan 2003 Location: Ottawa, Canada	I am using the IXYS FRED br. Would these benefit from the coupling caps?

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