Problems with OPA549/LM833 and static

soundNERD · 19th May 2005, 02:58 AM

I'm having problems with my subwoofer built with a bridged OPA549 and a LM833 for crosoover.

It's part of a 2.1 system rebuilt using a broken set of z-680 speakers. Ever since adding the LM3886 chips for the satellite speakers, I've been noticing the output from it a constant static sound that sounds like the input but with static in the sub, but it is only audible at lower volumes.

Is this just a sign my 100W transformers are crapping out with the load (like the other problem I have where the thing runs out of power and the 3886s start making some odd popping sound that goes away once the amp starts clipping), but I don't see how the power of a transformer would cause this odd static.

Thanks!

soundNERD · 21st May 2005, 02:35 AM

Nobody has any ideas?

I can make a recording of the sound with my microphone tomorrow if it will help

Leolabs · 23rd May 2005, 08:26 AM

Possibly layout problem or even passive component

soundNERD · 26th May 2005, 02:25 AM

Thanks!

You were right, it was a component problem. One of the 0.1uf caps on the crossover PCB had lost a solid connection, so it would barely make contact and cause the sound, or not make contact at all and cause even more static.

It's 9:30 here

soundNERD · 26th May 2005, 02:27 AM

Thanks!

You were right, it was a component problem. One of the 0.1uf caps on the crossover PCB had lost a solid connection, so it would barely make contact and cause the sound, or not make contact at all and cause even more static.

It's 9:30 here now, so I will try re-soldering that part tomorrow. Hopefully it will work!

Thanks again,
Mike

soundNERD · 30th May 2005, 01:17 AM

That was it! thanks! Now it works perfectly,and, somehow, even the problem with the popping sound in the 3886s are gone.

19th May 2005, 02:58 AM	#1
soundNERD diyAudio Member Join Date: Sep 2003 Location: Illinois	Problems with OPA549/LM833 and static I'm having problems with my subwoofer built with a bridged OPA549 and a LM833 for crosoover. It's part of a 2.1 system rebuilt using a broken set of z-680 speakers. Ever since adding the LM3886 chips for the satellite speakers, I've been noticing the output from it a constant static sound that sounds like the input but with static in the sub, but it is only audible at lower volumes. Is this just a sign my 100W transformers are crapping out with the load (like the other problem I have where the thing runs out of power and the 3886s start making some odd popping sound that goes away once the amp starts clipping), but I don't see how the power of a transformer would cause this odd static. Thanks!

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21st May 2005, 02:35 AM	#2
soundNERD diyAudio Member Join Date: Sep 2003 Location: Illinois	Nobody has any ideas? I can make a recording of the sound with my microphone tomorrow if it will help

23rd May 2005, 08:26 AM	#3
Leolabs diyAudio Member Join Date: Dec 2004 Location: Bukit Mertajam	Possibly layout problem or even passive component

26th May 2005, 02:25 AM	#4
soundNERD diyAudio Member Join Date: Sep 2003 Location: Illinois	Thanks! You were right, it was a component problem. One of the 0.1uf caps on the crossover PCB had lost a solid connection, so it would barely make contact and cause the sound, or not make contact at all and cause even more static. It's 9:30 here

26th May 2005, 02:27 AM	#5
soundNERD diyAudio Member Join Date: Sep 2003 Location: Illinois	Thanks! You were right, it was a component problem. One of the 0.1uf caps on the crossover PCB had lost a solid connection, so it would barely make contact and cause the sound, or not make contact at all and cause even more static. It's 9:30 here now, so I will try re-soldering that part tomorrow. Hopefully it will work! Thanks again, Mike

30th May 2005, 01:17 AM	#6
soundNERD diyAudio Member Join Date: Sep 2003 Location: Illinois	That was it! thanks! Now it works perfectly,and, somehow, even the problem with the popping sound in the 3886s are gone.

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