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Old 1st January 2009, 11:45 AM   #1
veckans is offline veckans  Sweden
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Question Reduce "pop" noise when power on/off

I have a Tripath TA2024 amplifier that I really like the sound, and quality of. There is one problem with it however, it produces a "pop" sound when I turn it on/off. It isn't very loud but it ruins the quality feeling. And I'm also told this "pop" can demagnetize speakers after a while, is this true?
I have also heard that this "pop" noise is caused by the input capacitors charging up, and one way to fix it would be to change to max 2uF capacitors instead of the 470uF that are currently there.
I have measured the DC Offset of this "pop" and it was at most 125mV for one channel, and 90mV on the other.

So I wonder how I can fix it cheap. I saw on the charlize (tripath amplifier) info page that you can put the amplifier in "sleep-mode" instead of turning it off by just adding a 260ohm resistor on the input power line (12V). I tried this but the power LED was still on even if dim. The "pop" didn't disappear either, it was just slightly reduced.

Thanks for any help!
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Old 2nd January 2009, 07:01 AM   #2
hoka is offline hoka  Netherlands
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wich one do you have?

can you post a picture?

the 470uF caps are most likely not the input caps
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Old 2nd January 2009, 10:46 AM   #3
veckans is offline veckans  Sweden
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This is how the PCB looks:
Click the image to open in full size.

But, now I tried "sleep-mode" with a higher ohm resistor (330ohm this time) and for some reason the "pop" is very faint now, and non-existant on turn off, something I can live with
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Old 2nd January 2009, 03:22 PM   #4
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It is hard to know for sure without a schematic, but this board has two multi-turn pots that appear to be for adjusting the output offset (by adjusting the input DC offset). If you measure the DC output and adjust the pots to get the output DC level near zero I will bet that the pops can be, if not eliminated, at least reduced to acceptable small 'ticks'. It is worth a try.
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Old 2nd January 2009, 06:25 PM   #5
veckans is offline veckans  Sweden
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Quote:
Originally posted by audiosteve
It is hard to know for sure without a schematic, but this board has two multi-turn pots that appear to be for adjusting the output offset (by adjusting the input DC offset). If you measure the DC output and adjust the pots to get the output DC level near zero I will bet that the pops can be, if not eliminated, at least reduced to acceptable small 'ticks'. It is worth a try.
Adjusting the DC offset to +/- 1mV was one of the first things I did when I got this amplifier, I chose it because it had the ability to do that among other things.
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Old 2nd January 2009, 07:31 PM   #6
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Default Re: Reduce "pop" noise when power on/off

Quote:
Originally posted by veckans
I have also heard that this "pop" noise is caused by the input capacitors charging up, and one way to fix it would be to change to max 2uF capacitors instead of the 470uF that are currently there.

Hi, your input caps are the green 3.6uF items unless you have changed them to 470uF?
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Old 2nd January 2009, 08:21 PM   #7
veckans is offline veckans  Sweden
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Default Re: Re: Reduce "pop" noise when power on/off

Quote:
Originally posted by audio1st



Hi, your input caps are the green 3.6uF items unless you have changed them to 470uF?

I'm sorry, maybe I used the wrong word for them, but by input I mean the DC power input (the 2 smaller electrolytic caps).
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Old 8th January 2009, 08:02 PM   #8
v-bro is offline v-bro  Netherlands
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I've been told this circuit can be used on ANY Tripath amp to reduce on/off pops to zero.

Click the image to open in full size.

With credits to Aleka from http://www.41hz.com/forums
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Old 13th January 2009, 03:57 AM   #9
EdT is offline EdT  Canada
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That looks similar to the PCB on the Pop Pulse Tsunami T-Amp !
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Old 13th January 2009, 06:25 AM   #10
v-bro is offline v-bro  Netherlands
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Ah ok, I didn't know that thanks! I do know that Aleka had this circuit up and running a long way back, maybe two years?
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