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Author Topic: Bellowing noise when amp is powered up  (Read 4023 times)

Steve Crump

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Bellowing noise when amp is powered up
« on: October 11, 2020, 12:37:16 PM »

I was bored and pulled some gear out to mess around the other day. Connected a monitor that I had modified and tested a few months back, powered up a rack with a MR18, no input device (music or mic) connected at this point, then I turned on a QSC GXD8 amp, the speaker let out a bellowing sound that dissipated quickly. I thought crap it probably got my HF driver, but it didn’t.

What could it have been? It sounded like a build up of energy, like capacitance. Is the issue with the amp? I have only used these GXD8 amps a couple times. I periodically would get a failure message from one, carried it to a service center and they said they could not get it to recreate the failure.

A few years ago I had a similar event at the venue, QRX 115s and Crown XLi amp, but this was a the end of the night and it happened a couple times, muted mixer, walk up to rack to power down, when I powered off the amp I would get this HF kind of bellow that dissipated quickly from the QRXs. This amp did eventually fail.

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Dave Pluke

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Re: Bellowing noise when amp is powered up
« Reply #1 on: October 12, 2020, 10:13:16 AM »

Might humidity/condensation be the culprit?

Dave
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Mike Caldwell

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Re: Bellowing noise when amp is powered up
« Reply #2 on: October 12, 2020, 12:28:14 PM »

Was the amp connected to the mixer?

Steve Crump

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Re: Bellowing noise when amp is powered up
« Reply #3 on: October 12, 2020, 01:03:14 PM »

Might humidity/condensation be the culprit?

Dave

At the venue moisture is definitely an issue. Where the GXD is stored it’s for the most part conditioned.
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Steve Crump

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Re: Bellowing noise when amp is powered up
« Reply #4 on: October 12, 2020, 01:15:48 PM »

Was the amp connected to the mixer?

Yes. What are your thoughts? I am just trying to figure out if I need to avoid using the GXD.
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Tim McCulloch

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Re: Bellowing noise when amp is powered up
« Reply #5 on: October 12, 2020, 01:39:16 PM »

I think you need to call QSC.  Just 1 channel or both?
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Steve Crump

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Re: Bellowing noise when amp is powered up
« Reply #6 on: October 12, 2020, 02:09:44 PM »

I think you need to call QSC.  Just 1 channel or both?

Yelp, I agree. I had only one channel connected when this happened.
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Mike Caldwell

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Re: Bellowing noise when amp is powered up
« Reply #7 on: October 12, 2020, 05:00:18 PM »

Yes. What are your thoughts? I am just trying to figure out if I need to avoid using the GXD.

Just trying to eliminate any outside sources for the noise.

Don T. Williams

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Re: Bellowing noise when amp is powered up
« Reply #8 on: October 12, 2020, 06:40:56 PM »

You're not trying to Buffalo us are you?  LOL
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Steve Crump

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Re: Bellowing noise when amp is powered up
« Reply #9 on: October 12, 2020, 07:47:22 PM »

You're not trying to Buffalo us are you?  LOL


Don,

I wish I were. The thing that stinks is that I think it is out of warranty now. I bought two of the amps on sale, when I received them one had an excessive amount of hours on it for a new amp, so the vendor replaced it. I did test both and then set them to the side and when I went back to play around with the amps months later, one of them had a failure message at start up, cycled a couple times and it went away, cycled again the message came back.
Contacted QSC they told me to carry it to a service center because it was still under warranty. The service center could not find anything wrong with the unit. I brought it back home, I might have used the amp twice in the field and haven’t touched it in close to a year now, plug it up and then this happened. I am going to play around with it a little more when I get back home.

This amp has left me questioning it’s reliability. Of course, I’m not stressing over this, it’s not like I have a use for them at the moment.

Plus I just wanted a chance to talk gear...LOL

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Re: Bellowing noise when amp is powered up
« Reply #9 on: October 12, 2020, 07:47:22 PM »


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