Loud Buzzing on Start? [Orginal T-amp]

kenny12 · 12th July 2006, 11:13 AM

I have done the stealth mod with a 8.2uF Bennic Capacitor

i get a very loud buzzing sound on startup that lasts for less than half a sec then everything is fine.

what can i do to fix it?

thanks

spadulata · 12th July 2006, 01:09 PM

The noise on power up is related to the capacitor size. Most people use 2.2uf which eliminates the original bass roll-off and only introduces a very slight turn on noise. I don't think there is anything to gain going to higher values.

kenny12 · 12th July 2006, 01:10 PM

it was the only high quality cap i had, is there anyway i can reduce this noise?

Alastair E · 12th July 2006, 01:42 PM

This is a known issue with some of the Tripath chips. Its due to the voltage at the input pin, charging up the cap, but in doing so, causes the gain-op/amp to ocillate while the voltage stabalises at the input ....
Designers of amps with tripath chips tend not to go much above 4 mic for this reason....

I have successfully used a 3.3 mic cap with no start-up issues with the 1st gen TA2020-020 chips....
I think the chip's input impedance is around 100K, so theres no need to go higher than 3 mic really....

12th July 2006, 11:13 AM	#1
kenny12 diyAudio Member Join Date: Apr 2004 Location: Aust	Loud Buzzing on Start? [Orginal T-amp] I have done the stealth mod with a 8.2uF Bennic Capacitor i get a very loud buzzing sound on startup that lasts for less than half a sec then everything is fine. what can i do to fix it? thanks

12th July 2006, 01:42 PM	#4
Alastair E diyAudio Member Join Date: Feb 2004 Location: South Wales	Start-up oscillation... This is a known issue with some of the Tripath chips. Its due to the voltage at the input pin, charging up the cap, but in doing so, causes the gain-op/amp to ocillate while the voltage stabalises at the input .... Designers of amps with tripath chips tend not to go much above 4 mic for this reason.... I have successfully used a 3.3 mic cap with no start-up issues with the 1st gen TA2020-020 chips.... I think the chip's input impedance is around 100K, so theres no need to go higher than 3 mic really.... __________________ Das Beste Oder Nichts

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12th July 2006, 01:09 PM	#2
spadulata diyAudio Member Join Date: Feb 2006 Location: Surrey	The noise on power up is related to the capacitor size. Most people use 2.2uf which eliminates the original bass roll-off and only introduces a very slight turn on noise. I don't think there is anything to gain going to higher values.

12th July 2006, 01:10 PM	#3
kenny12 diyAudio Member Join Date: Apr 2004 Location: Aust	it was the only high quality cap i had, is there anyway i can reduce this noise?

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