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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB Subwoofer Forum => Topic started by: Jack Murry on February 12, 2018, 07:19:46 pm

Title: JBL SRX800 series 828sp-835p Weird "sucking" feeling on Eardrums
Post by: Jack Murry on February 12, 2018, 07:19:46 pm
So I recently purchased  the JBL SRX 828sp's with matching 835p's (powered) speakers for my bands new P.A. and I am having a hell of a time dialing them in.... The last two gigs as I walked around the club on my wireless at volume for mid sized club, I have been noticing a weird sucking sensation on my eardrums?  ...We dont have a soundman so we run the board (Presonus 24.4.2 StudioAI) on the stage...  Also (its hard to articulate) but its like our instruments arent cutting through like I want them to and I know this system is capable of the sound I am looking for.... I know this is limited info but If anyone has any advice? I know the "sucking" sensation is a big part of it. Sub DSP set to SRX top, Tops set to SRX sub  ...crossed 80hz. Sensitivity presets are on "line" ...pretty much out of the box settings

As I side thought: It seems that this sucking sensation only happens when our band is playing, not so much during the break music.
 If you need more information to offer a suggestion I can try to answer specific questions

Thanx you guys
Title: Re: JBL SRX800 series 828sp-835p Weird "sucking" feeling on Eardrums
Post by: Gordon Brinton on February 12, 2018, 07:51:08 pm
Gee, that really sucks.
Maybe the "Suck" knob is turned up too high.  ;D

But seriously...
I have no idea what you are talking about, but I'll make a rough assumption that maybe there is a phase issue somewhere in the system. That can sometimes make things sound weird.
Title: Re: JBL SRX800 series 828sp-835p Weird "sucking" feeling on Eardrums
Post by: Mac Kerr on February 12, 2018, 08:46:11 pm
The last two gigs as I walked around the club on my wireless at volume for mid sized club, I have been noticing a weird sucking sensation on my eardrums? 

In my experience, if you are experiencing weird pressure sensations you have speakers out of polarity. I would go through your whole setup 1 speaker at a time and determine the absolute polarity of each speaker. Any speakers of the same type should have the same polarity.

Mac
Title: Re: JBL SRX800 series 828sp-835p Weird "sucking" feeling on Eardrums
Post by: William Schnake on February 12, 2018, 09:25:05 pm
In my experience, if you are experiencing weird pressure sensations you have speakers out of polarity. I would go through your whole setup 1 speaker at a time and determine the absolute polarity of each speaker. Any speakers of the same type should have the same polarity.

Mac

Best advice you will ever get.  +100
Title: Re: JBL SRX800 series 828sp-835p Weird "sucking" feeling on Eardrums
Post by: Jack Murry on February 12, 2018, 10:16:19 pm
I thought about that. Ive had the speakers for less than 6 months with maybe 50 hours on them. They are literally right out of the box ....How do I test the polarity of the speakers?  Do I have to open up the cabinets?  Do you know if the subs are out of phase with the tops would create a similar symptom?
In my experience, if you are experiencing weird pressure sensations you have speakers out of polarity. I would go through your whole setup 1 speaker at a time and determine the absolute polarity of each speaker. Any speakers of the same type should have the same polarity.

Mac
Title: Re: JBL SRX800 series 828sp-835p Weird "sucking" feeling on Eardrums
Post by: Mac Kerr on February 12, 2018, 10:29:20 pm
I thought about that. Ive had the speakers for less than 6 months with maybe 50 hours on them. They are literally right out of the box ....How do I test the polarity of the speakers?  Do I have to open up the cabinets?  Do you know if the subs are out of phase with the tops would create a similar symptom?

It could be a cable, either a speaker cable or a signal cable in any part of the signal path. It could be a polarity switch in the console. It could be an amp switched to bridged mode. It could be in the cabinet. You really have to test every part of your system.

I would not expect that result from a sub to mains out of polarity since the 2 speakers don't cover the same spectrum. I would suspect the subs, or the low section of the mains, but if the problem was with the subs that does not mean the speaker is the problem. The whole system needs to be tested.

Mac
Title: Re: JBL SRX800 series 828sp-835p Weird "sucking" feeling on Eardrums
Post by: Tim McCulloch on February 13, 2018, 12:13:36 am
It could be a cable, either a speaker cable or a signal cable in any part of the signal path. It could be a polarity switch in the console. It could be an amp switched to bridged mode. It could be in the cabinet. You really have to test every part of your system.

I would not expect that result from a sub to mains out of polarity since the 2 speakers don't cover the same spectrum. I would suspect the subs, or the low section of the mains, but if the problem was with the subs that does not mean the speaker is the problem. The whole system needs to be tested.

Mac

The speaker system is self-powered.  I'm putting my bet on an XLR cable with pins 2/3 swapped at one end.

We need more details about how Jack hooks up the rig.
Title: Re: JBL SRX800 series 828sp-835p Weird "sucking" feeling on Eardrums
Post by: Chris Grimshaw on February 13, 2018, 03:38:55 am
The speaker system is self-powered.  I'm putting my bet on an XLR cable with pins 2/3 swapped at one end.

We need more details about how Jack hooks up the rig.

+1.

Disconnect one of the subs, see if that improves matters. Sounds to me like the subs aren't working together.

Chris
Title: Re: JBL SRX800 series 828sp-835p Weird "sucking" feeling on Eardrums
Post by: Jack Murry on February 13, 2018, 03:54:42 am
Thanx for the replies

Yes they are powered .... XLR from the board. You said pins swapped? Is that something that can happen from the factory the cable was manufactured at? I can give you more info on how I have it all set up but its pretty straight forward. Board outputs (Presonus Studiolive 24.4.2 AI) to bottom subs Ch. 1  ...then short jumper XLR's to Ch. 1 on the tops... But if you want more info I can provide if I know what you need

The speaker system is self-powered.  I'm putting my bet on an XLR cable with pins 2/3 swapped at one end.

We need more details about how Jack hooks up the rig.
Title: JBL SRX800 series 828sp-835p Weird "sucking" feeling on Eardrums
Post by: John Ferreira on February 13, 2018, 01:11:54 pm
If you output a single sine wave at 60Hz from any device (iPhone app) and then disconnect 1 sub (they should be side by side), if it gets louder your polarity is reversed in one of them.
Title: Re: JBL SRX800 series 828sp-835p Weird "sucking" feeling on Eardrums
Post by: Chris Grimshaw on February 13, 2018, 01:39:47 pm
If you output a single sine wave at 60Hz from any device (iPhone app) and then disconnect 1 sub (they should be side by side), if it gets louder your polarity is reversed in one of them.

Also try around 150Hz. Could be the tops.

Chris
Title: Re: JBL SRX800 series 828sp-835p Weird "sucking" feeling on Eardrums
Post by: Rob Spence on February 13, 2018, 02:08:57 pm
Thanx for the replies

Yes they are powered .... XLR from the board. You said pins swapped? Is that something that can happen from the factory the cable was manufactured at? I can give you more info on how I have it all set up but its pretty straight forward. Board outputs (Presonus Studiolive 24.4.2 AI) to bottom subs Ch. 1  ...then short jumper XLR's to Ch. 1 on the tops... But if you want more info I can provide if I know what you need

Yes, factories make mistakes too.

If you have cables, you need to be able to test them.
A multimeter (if you do sound, you should have one) will do but a cable tester is faster.



Sent from my iPad using Tapatalk Pro
Title: Re: JBL SRX800 series 828sp-835p Weird "sucking" feeling on Eardrums
Post by: Don T. Williams on February 13, 2018, 03:43:02 pm
Even rooms can do odd things to phase relationships.  With the system in its usual place invert the polarity of one of the subs (or even the input of the whole stack) and listen to what happens.  Does the problem get better or worse?  This may or not solve the problem, but it might give you a clue.  If you can't just invert the polarity at the console or at the speakers themselves, get a A3M to A3F coupler and wire it for reverse polarity.
Title: Re: JBL SRX800 series 828sp-835p Weird "sucking" feeling on Eardrums
Post by: Art Welter on February 13, 2018, 09:50:27 pm
Yes they are powered .... XLR from the board. You said pins swapped?
Jack,

There certainly could be XLRs wired wrong.
You mentioned:
"The last two gigs as I walked around the club on my wireless at volume for mid sized club, I have been noticing a weird sucking sensation on my eardrums? It seems that this sucking sensation only happens when our band is playing, not so much during the break music."
You likely don't also play your break music through your monitors and stage gear- when you hear the combination of both while walking off stage the difference can be rather stark, and room changes interacting with monitors and mains as you walk around can be huge, regardless of individual speaker polarities.
If by "my wireless" you mean in ear monitors, forget about them being "in phase" (or polarity) with the mains as you walk around.

Title: Re: JBL SRX800 series 828sp-835p Weird "sucking" feeling on Eardrums
Post by: David Allred on February 14, 2018, 09:31:26 am
Do you know anyone with a Cricket tester?  Post where you are and maybe someone here has one and would work out a loan-a-tool with you.