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Old 3rd April 2009, 02:25 PM   #1
kanifee is offline kanifee  United Kingdom
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Default Getting rid of turn on pop?

Hi all, been a while since i posted but im commencing work on a enclosure for my chip amd, dac and pre.
what id like to know is a way to delay the power on of my power amp, when my dac is plugged up i get loud turn on pop if the dac is switched on at the same time or after the power amp, if the dac is already powerd when the amp powers up then there is no pop.
What are my options, a power delay circuit? or is the problem solvable without an extra circuit?
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Old 3rd April 2009, 03:20 PM   #2
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post what you are using and corresponding schematics if possible. From wha tyou posted sounds like your DAC has a dc offset on initial first power up. you could use a relay on the DAC output with a small time delay circuit to avoid this but the you would have to use a RELAY. If you can use the relay to short the output to ground through a resistor maybe that would be much better in my opinion then allowing the relay to be in series with the output signal (I'm not a big fan of relay's in audio path!).

there is also a mute pin on the LM3386 3875 chipamps that you could keep the amp muted until everything has settled and turned on... you would need some sort of control circuitry.

Dave
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Old 3rd April 2009, 05:12 PM   #3
Nuuk is offline Nuuk  United Kingdom
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I would go with a mute delay on the pre amp.
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Old 3rd April 2009, 08:29 PM   #4
KT is offline KT  United States
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Quote:
Originally posted by drummer_Dave


...there is also a mute pin on the LM3386 3875 chipamps...
I thought the LM3886 has the mute pin and the LM3875 does not. Isn't this the case?

KT
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Old 3rd April 2009, 08:33 PM   #5
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sorry, i know the 3886 does, i guess i was just assuming, always best to check the datasheet...

Dave
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Old 4th April 2009, 08:04 AM   #6
Nuuk is offline Nuuk  United Kingdom
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The LM3875 does not have a mute pin.
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Old 4th April 2009, 12:45 PM   #7
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Quote:
i get loud turn on pop if the dac is switched on at the same time or after the power amp, if the dac is already powerd when the amp powers up then there is no pop.
Hi kanifee

Looks like your dac power switch is arcing.

Solder a Suppression Capacitor (4.7nF/250VAC; CLASS X or X2 type) across the dac power switch contacts. It will snub the sparking.

Please note that you can only use CLASS X or X2 types. These are the only ones that are approved for use on Mains voltages.

Cheers
Mike
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Old 5th April 2009, 02:06 PM   #8
kanifee is offline kanifee  United Kingdom
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Sorry for the late reply, i think it best i say that this also occurs at power down aswell. I dont currently have a power switch fitted, there is only a fuse and if i wan to use it i just plug the mains plug in to the wall.
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Old 7th April 2009, 03:54 AM   #9
sasmit is offline sasmit  India
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use a speaker protection circuit with a turn on delay, you can find some schematics on Rod elliot's pages. This will prevent any pops clicks and also protect your speakers. Pop's clicks do damage speakers
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Old 7th April 2009, 04:51 AM   #10
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Quote:
Originally posted by kanifee
I dont currently have a power switch fitted, there is only a fuse and if i wan to use it i just plug the mains plug in to the wall.
If you get a loud bang when you plug/unplug the mains of your dac with the power amp on, the cause is arcing at the mains plug.

Plug your dac to one of those power strip junction boxes and use the switch on the power strip to ON/OFF your dac instead.
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