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Chip Amps Amplifiers based on integrated circuits

lm3886 parallel
lm3886 parallel
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Old 20th March 2019, 09:58 PM   #1
rookiesparks is offline rookiesparks  Guernsey
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Default lm3886 parallel

need help or a finger in the right direction ! bought 4 lm3886 modules that look quite good (see pics) sound prety good singular, and unfortunately cant find a diagram ,replaced all resistors with hand matched ! replaced chips ! removed zobel networks and replaced it with 0.1r matched resistors !joined up as in diagram with 2 x 24v smps, replaced zobel on + binding post ,,,,,the problem is just a bad popping sound from test speakers and have lost a couple of chips so far,,,,, ps does seem ok without input signal as no popping,,, any help welcome
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Old 20th March 2019, 10:55 PM   #2
JonSnell Electronic is offline JonSnell Electronic  United Kingdom
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Do not wire the outputs together, it may cause unwanted issues.
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Old 20th March 2019, 11:00 PM   #3
rookiesparks is offline rookiesparks  Guernsey
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Originally Posted by JonSnell Electronic View Post
Do not wire the outputs together, it may cause unwanted issues.

hi can you explain ? thanks
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Old 20th March 2019, 11:05 PM   #4
scottjoplin is offline scottjoplin  Wales
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How well matched are the gain setting resistors?
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Old 21st March 2019, 03:33 AM   #5
asuslover is offline asuslover  Romania
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lm3886 parallel
Are you trying to parallel 2 separate lm3886 amplifiers/boards ? I tried that once long time ago, I remember it did not work. To many issues, ground loops/problems, gain will never be identical .
Good luck.
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Old 21st March 2019, 04:35 AM   #6
kokoriantz is offline kokoriantz  Lebanon
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You must add 0.1 ohm on each output before paralleling . Check first if you have very low difference ,offset voltage & ac voltage at highest output level .
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Old 21st March 2019, 05:48 AM   #7
rookiesparks is offline rookiesparks  Guernsey
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Originally Posted by scottjoplin View Post
How well matched are the gain setting resistors?

basically identical,,all matched on home made jig consisting of a low voltage through different resistors and taking mill / volt reading with dmm
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Old 21st March 2019, 05:51 AM   #8
rookiesparks is offline rookiesparks  Guernsey
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Originally Posted by asuslover View Post
Are you trying to parallel 2 separate lm3886 amplifiers/boards ? I tried that once long time ago, I remember it did not work. To many issues, ground loops/problems, gain will never be identical .
Good luck.

yes ! i have suceeded before with the simpler xy boards with no problems
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Old 21st March 2019, 05:53 AM   #9
asuslover is offline asuslover  Romania
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lm3886 parallel
You could easily bridge them, add drv134 and adjust the power supply voltage so it could go with your speaker impedance. Will give you 100w in 4 ohms and 120w in 8ohms.
Again , I don’t think that paralleling 2 boards will work, the idea is to parallel the chips and not the boards.
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Old 21st March 2019, 05:53 AM   #10
rookiesparks is offline rookiesparks  Guernsey
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Originally Posted by kokoriantz View Post
You must add 0.1 ohm on each output before paralleling . Check first if you have very low difference ,offset voltage & ac voltage at highest output level .

yes ! i have replaced the zobel network on each module with the 0.1r and reattached the zobel directly on positive binding post
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