Aleph30 Turn-off Thump

hifimaker · 2nd October 2006, 07:44 PM

Hello everyone,

I built and absolutely love my Aleph30 based on BrianGT's boards. The amp runs and sounds great, however I'm concerned about a turn-off thump I'm getting on my speakers.

Schematic: http://www.diyamps.com/aleph/docs/miniAleph-sch.pdf

I'm using 6 IRFP144's per channel with standard Aleph 30 biasing.

Question: Where's a good place to start looking for a fix? Has anyone else experienced this issue and has been able to resolve it?

Thank you!

-David

eapavant · 2nd October 2006, 09:04 PM

I don't think I can help, but I can add that my Aleph 30 with brians boards does the same thing. I have not had a chance to look at the output with a scope. I am tied up with the AX and the 30 just sounds so good.

Dennis Hui · 3rd October 2006, 12:13 AM

Mr. Pass once mentioned this in passing about the turn off thump:

http://www.diyaudio.com/forums/showt...301#post402301

hifimaker · 3rd October 2006, 03:27 PM

Thanks Dennis for the post refrence!

I believe my off-set between + and - supplies are very low, like less than .1VDC. I'll measure again and also measure the offset during power down.

-David

2nd October 2006, 07:44 PM	#1
hifimaker diyAudio Member Join Date: Oct 2003 Location: San Jose	Aleph30 Turn-off Thump Hello everyone, I built and absolutely love my Aleph30 based on BrianGT's boards. The amp runs and sounds great, however I'm concerned about a turn-off thump I'm getting on my speakers. Schematic: http://www.diyamps.com/aleph/docs/miniAleph-sch.pdf I'm using 6 IRFP144's per channel with standard Aleph 30 biasing. Question: Where's a good place to start looking for a fix? Has anyone else experienced this issue and has been able to resolve it? Thank you! -David

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2nd October 2006, 09:04 PM	#2
eapavant diyAudio Member Join Date: Aug 2005	I don't think I can help, but I can add that my Aleph 30 with brians boards does the same thing. I have not had a chance to look at the output with a scope. I am tied up with the AX and the 30 just sounds so good.

3rd October 2006, 12:13 AM	#3
Dennis Hui diyAudio Member Join Date: Aug 2002 Location: Toronto, Canada	Mr. Pass once mentioned this in passing about the turn off thump: http://www.diyaudio.com/forums/showt...301#post402301

3rd October 2006, 03:27 PM	#4
hifimaker diyAudio Member Join Date: Oct 2003 Location: San Jose	Thanks Dennis for the post refrence! I believe my off-set between + and - supplies are very low, like less than .1VDC. I'll measure again and also measure the offset during power down. -David