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Chip Amps Amplifiers based on integrated circuits

LM3886 - Hiss
LM3886 - Hiss
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Old 23rd October 2009, 04:36 PM   #1
Wizardmaxx is offline Wizardmaxx  United Kingdom
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Default LM3886 - Hiss

Tried to search for this and I am sure the answer is a simple one.

Got hiss coming through on mids and tweeters and once input is shorted out it disappears. The input is coming from the PC if that makes a difference.

What is the fix for this

Also idle temp is around 40 degrees. Is this normal. The heatsinks are Dynatron CPU sinks and appear more substantial than some projects I have seen.

Cheers

Wizard
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Old 23rd October 2009, 05:01 PM   #2
cliffforrest is offline cliffforrest  United Kingdom
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LM3886 - Hiss
Quote:
Originally Posted by Wizardmaxx View Post
Tried to search for this and I am sure the answer is a simple one.

Got hiss coming through on mids and tweeters and once input is shorted out it disappears. The input is coming from the PC if that makes a difference.

What is the fix for this

Also idle temp is around 40 degrees. Is this normal. The heatsinks are Dynatron CPU sinks and appear more substantial than some projects I have seen.

Cheers

Wizard


Err.. if the hiss goes when input is shorted, but is there when PC is connected, it seems to me it is coming from the PC! No?

Or, if it is running hot at idle, it is oscillating.
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Old 23rd October 2009, 07:40 PM   #3
star882 is offline star882  United States
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Turn the volume control on the PC to maximum and install a fixed attenuator to still allow you to get a useful volume range from the control. That helps to increase the SNR.
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Old 24th October 2009, 07:04 AM   #4
Wizardmaxx is offline Wizardmaxx  United Kingdom
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Many thanks Star

47k low noise audio pot sorted it out
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