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Old 8th January 2012, 07:35 PM   #1
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Default Max allowable DC offset for power amplifier

What is the Max allowable DC offset for a Power amplifier- 100W or so.
I know it's not an exact science, but there should be a limit!? I'm feeding a 4ohm speaker. With the speaker connected I measure 40mV. Don't see any speaker excursions.
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Old 8th January 2012, 07:48 PM   #2
Zen Mod is offline Zen Mod  Serbia
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100mV as absolute limit , after temp equilibrium
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Old 8th January 2012, 07:52 PM   #3
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You are right about the 'not an exact science' bit. Some would have you believe any DC offset is unacceptable, others ate more liberal. IMHO, I would suggest there is no hard fault if it is 100mV or less, but pursuing a lower DC offset than that is good practice. I like to see offsets less than 25mV in general practice.
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Old 8th January 2012, 07:54 PM   #4
Bigun is offline Bigun  Canada
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Originally Posted by Zen Mod View Post
100mV as absolute limit , after temp equilibrium
Why ?
"The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.
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Old 8th January 2012, 08:14 PM   #5
wahab is offline wahab  Algeria
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The right question would be rather about Max allowable DC offset for...speakers.
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Old 8th January 2012, 09:48 PM   #6
AndrewT is online now AndrewT  Scotland
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If the range of DC offset when measured by the specified method is +-XYmVdc from cold to fully warmed up for Ta between 0degC to 40degC and you measure a random sample at >XYmVdc then you know that either you have measured it incorrectly, or the amplifier is faulty. Get it fixed, if it is outside specification.
Knowing that it is 40mVdc is only half the story. What are the specification limits?
regards Andrew T.
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