simple question: is midpoint voltage setting for adjusting the DC Offset? - diyAudio
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Old 28th April 2012, 07:40 AM   #1
Arnie75 is offline Arnie75  Germany
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Default simple question: is midpoint voltage setting for adjusting the DC Offset?

Hello,

I am no expert at all in electronics and just bought a small and finished TA2022 amp. Regarding this device I have a small question: According to the seller the two trimmers inside are for setting the "midpoint voltage". So is this also for adjusting the DC offset, or is this something different?

Thanks a lot,
Alex

Last edited by Arnie75; 28th April 2012 at 10:10 PM.
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Old 28th April 2012, 10:04 PM   #2
Arnie75 is offline Arnie75  Germany
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Buy Enthusiast TA2022 T class, digital amplifier, audio amplifier, 2 digital amplifier DIY Enthusiast TA2022 T class 90W at Aliexpress.com

This is the device I'm talking about. Can anyone help?
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Old 28th April 2012, 10:48 PM   #3
Pano is offline Pano  United States
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Yes, it's for setting the DC offset. Connect your speakers or an 8 ohm load. With your voltmeter in DC mode, and NO input to the amp, measure between the positive and negative speakers terminals one channel at a time. Tweak the trimmers until you have no more than a few millivolts DC offset.

Just a note: Some old VOMs don't do well on this adjustment as the HF carrier of the class-d amp fools them. Newer meters seem to be OK.
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Old 29th April 2012, 06:11 AM   #4
Arnie75 is offline Arnie75  Germany
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Thanks. I cannot do this without speakers, just between the terminals at the amp?
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Old 29th April 2012, 01:50 PM   #5
wwenze is offline wwenze  Singapore
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The speaker load is often part of the low pass filter to remove the switching noise that will make your meter's voltage jump around.

Short answer: no.
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Old 29th April 2012, 01:59 PM   #6
Pano is offline Pano  United States
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Long answer, Maybe.
But Wenze is right, it's much better to do this with a load attached. Any 4-8 ohm speaker will do, as will a resistor of the same value.
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Old 29th April 2012, 07:47 PM   #7
Arnie75 is offline Arnie75  Germany
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OK, thank you very much.
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Old 29th April 2012, 10:54 PM   #8
wwenze is offline wwenze  Singapore
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By the way what's the impedance of a speaker at switching frequency?
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