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Author Topic: VT 4880 odd cone movement and crakling  (Read 458 times)

Pat Fahey

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VT 4880 odd cone movement and crakling
« on: March 26, 2019, 12:29:35 pm »

Hello, I was hoping some of you could give me some insight on an issue I'm having. Recently I have upgraded from a JBL SR4719x to a VT 4880 (great deal). My main reason for upgrading from the SR-X was when driven hard it would start to crackle and make these little popping sounds, I did some troubleshooting and researching and came to the conclusion that they just didn't have the xmax for the output I was looking for. It was being powered by an Ashly MFA-8000 bridged into 4 ohms (I know people have mixed opinions on this) good for about 3000 watts, this being fed by a Driverack PA 2.

Fast forward and I have the VT-4880 being powered by the same Ashly MFA-8000 bridged with the Driverack. The sub has a high pass at 31.5Hz and a low pass at 90Hz. I've been using it for a little while and just got the chance to crank my whole system up, it sounded great but a few minutes in I started hearing the same crakling/popping noises. I took the grille off to see if it was hitting anything or if something go in there, I was in denial that the same thing was happening. Nothing was there, so I left the grille off and got it back to the same level so I could watch it.

I noticed 2 things, there was no way it was anywhere near xmax for the 2258h driver and also on certain frequencies one of the drivers would pull way in while the other one had normal movement. I'm starting to think the amp is at fault, everything sounds great up to a certain level but then those noises start happening and things get weird. If anyone has any input it would be great appreciated. Thanks!
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Taylor Hall

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Re: VT 4880 odd cone movement and crakling
« Reply #1 on: March 26, 2019, 01:51:09 pm »

How do you have the amp connected to the cabinet? As I recall these allowed you to power each driver individually or as a pair, so be sure you've properly wired everything.

Assuming all is well there, your amp could very well be the weak link. Do you have any other subs that you can hook up and push similarly hard? Does the amp ever show that it's going into clip/limiting when the noises occur? Do you have other amps that you can test with the same subs?

What other testing did you do when the SRX started making noise?
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Rob Spence

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Re: VT 4880 odd cone movement and crakling
« Reply #2 on: March 26, 2019, 01:59:23 pm »

You might simply be asking too much from a single sub?
What is your application? Rooms or crowd sizes?



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Pat Fahey

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Re: VT 4880 odd cone movement and crakling
« Reply #3 on: March 26, 2019, 02:30:16 pm »

How do you have the amp connected to the cabinet? As I recall these allowed you to power each driver individually or as a pair, so be sure you've properly wired everything.

Assuming all is well there, your amp could very well be the weak link. Do you have any other subs that you can hook up and push similarly hard? Does the amp ever show that it's going into clip/limiting when the noises occur? Do you have other amps that you can test with the same subs?

What other testing did you do when the SRX started making noise?

My understanding was that each driver had to be ran individually so I have a cable from each driver going to the same terminals for the bridge mono operation at 4 ohms , because the drivers are 8 ohms each.

Unfortunately I donít have any other amps to try on the sub, and the only other sub that can be pushed similarly is the srx which has the same noise. The amp is not clipping or limiting. The vt4880 wants about 4000 watts so I doubt Iím overpowing it.

I ran the srx off of one channel on the amp, so thatís 4 ohms at 1200 watts and I was able to get pretty close if not there in terms of output from the one channel the noise was pretty much gone. 
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Pat Fahey

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Re: VT 4880 odd cone movement and crakling
« Reply #4 on: March 26, 2019, 02:39:01 pm »

You might simply be asking too much from a single sub?
What is your application? Rooms or crowd sizes?



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Currently just sound reinforcement for a dj, I havenít brought the VT to a show yet (just that new to me). I was testing in a room that was probably 30x20 with about 12 foot ceiling.

There was plenty of output, itís just that in the middle of a song the noise will start happening.
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David Sturzenbecher

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Re: VT 4880 odd cone movement and crakling
« Reply #5 on: March 26, 2019, 02:50:28 pm »

Try a different amp. Let us know what you find.


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Re: VT 4880 odd cone movement and crakling
¬ę Reply #5 on: March 26, 2019, 02:50:28 pm ¬Ľ


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