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Author Topic: Monitor Noise hard to track down  (Read 1939 times)

Jax.

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Monitor Noise hard to track down
« on: April 28, 2004, 01:03:46 pm »

Hello Mr. Klett,

I was referred to you at this site by Brad Blackwood after asking him the following question:

What could be causing intermittent, high mid, phasey buzzing in my monitors, even when no music is playing?  When music is playing, it sounds like a weird LP filter twists the tone around for a moment.  Too bad I can't control it and patch in!

Have you heard of something like this before?

If it helps, they are JBL LSR28P's, active monitors.

I know the culprit could possibly be a 20' bundle of extension cord connected to the AD/DA, but I have my doubts that this is the cause.  The noise occurred many months after I left the bundle of cord on the floor - which I'm planning to shorten (lazy musician type).
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Ethan Winer

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Re: Monitor Noise hard to track down
« Reply #1 on: April 29, 2004, 12:38:34 pm »

Jax,

> What could be causing intermittent ... <

If it's intermittent and no music is playing, it's most likely a bad component in the built-in power amp. That is, it's time to take it in for service.

What happens if you unplug the audio cord going into the speaker?

--Ethan

barefoot

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Re: Monitor Noise hard to track down
« Reply #2 on: April 29, 2004, 12:48:00 pm »

I know other LSR28P owners who have the same issue.  I think it's just inherent in the electronics.  Sad

Thomas
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Thomas Barefoot
 Barefoot Recording Monitors

Jax.

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Re: Monitor Noise hard to track down
« Reply #3 on: April 29, 2004, 01:47:30 pm »

Ethan Winer wrote on Thu, 29 April 2004 09:38

Jax,
What happens if you unplug the audio cord going into the speaker?

--Ethan


I haven't had a chance to check yet, but will next time I'm at the studio.
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Jax.

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Re: Monitor Noise hard to track down
« Reply #4 on: April 29, 2004, 01:51:40 pm »

barefoot wrote on Thu, 29 April 2004 09:48

I know other LSR28P owners who have the same issue.  I think it's just inherent in the electronics.  Sad

Thomas


That would truly suck.  I've had the JBL's for only about 3.5 years... pretty short time to have a problem with the electronics.

I'll have to listen more closely to see if it happens in both speakers or just one.  It seems unlikely that they would be develop the same problem at the same time, but you never know.
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bblackwood

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Re: Monitor Noise hard to track down
« Reply #5 on: April 29, 2004, 02:15:28 pm »

If it's just one, swap the input cables and see if the noise follows. If it does, it's a problem before the speaker, if it stays in the same monitor, you likely have a speaker problem...

If it's both, disconnect the inputs and see if it goes away. If it's still there, you have an amp problem, if it goes away, work your way backward until you find the problem...
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Brad Blackwood
euphonic masters

kifaru

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Re: Monitor Noise hard to track down
« Reply #6 on: May 03, 2004, 04:49:26 pm »

Sorry to hear that someone else is suffering what I suffer through. I can tell you now that JBL is going to give you the run around. In my case they sent me to all these rinky dink "authorized" JBL techs here in NC and they didn't do jack but scratch up the bottom of my monitors. Did you buy yours from B&H? That's where I got mine. Not that I blame B&H. If you figure out a way to get JBL to come clean and fix these bad boys let me know. I'm kicking myself everytime mine buzz thinking, " I should have bought the ADAMS." I am fortunate that the Buzz is intermittent or that would be 1.75G's down the toilet.
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Jakob Erland

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Re: Monitor Noise hard to track down
« Reply #7 on: May 04, 2004, 07:53:46 am »

Intermittent phasing-like sound could very well be caused by RF inteference. Make sure that your line-level cables are well shielded and terminated...

Jakob E.
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..note to self: don't let harman run your company..

R. Foote

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Re: Monitor Noise hard to track down
« Reply #8 on: May 04, 2004, 11:45:29 am »

Be sure to try breaking the shield on one end of both balanced cables going from the mixer/ audio interface to the monitors. Only takes a minute to try and just might clear up the noise.

Hope it helps

rf
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R. Foote

erikj

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Re: Monitor Noise hard to track down
« Reply #9 on: May 07, 2004, 12:15:00 pm »

There's always been a minor issue with the noise floor in mine, but Jax's issue reads like an RF problem.

Have you tried re-arranging the cables so that the AC and audio to the monitors only cross at right angles?  Do you have a computer store nearby that could sell you a ferrite donut filter?

I suspect the PSRR (and CMRR?) goes to shit after a while on these, what with the heat from the power amp degrading the caps and all....

-erikj
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