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Author Topic: JBL SRX815P  (Read 3871 times)

Jim Babo

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JBL SRX815P
« on: March 16, 2018, 09:59:20 pm »

Hello everyone, new here and being DJing for a couple of years. I used a brand new pair of JBL SRX815Ps for a gig last Saturday and I ran them pretty good for 8 hours. About five hours into it I was getting LIMIT flash on the LCD and I smelled a funny smell, electronic. As I brought the volume down, limit would go off and no more smell. Speakers are working fine but I am a little worried about the smell and limit light. I also set the speaker main volume to 0, didn't want to touch it. Should lit be set higher than that? I used a Behringer 18 in powered sub but left the SRX setting to preset main. The manuals are not much help with these questions and hope to get some input from the pros. Thank you

Jim
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Chris Grimshaw

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Re: JBL SRX815P
« Reply #1 on: March 17, 2018, 05:33:20 am »

Hi Jim,

New speakers do smell sometimes as the glue around the voice coils gets warm. Not something I have a lot of experience with, but others around here might. The smell might also have been something in the amplifier itself, in which case that's cause for concern.
A flashing limit light means you're not going to get any more volume out of these boxes. Limiters are there to make sure nothing breaks, so the indicator is telling you it's doing it's job. Occasionally touching the limiters is fine, but if the light's on more than that, you need a bigger system.

If you set the SRX815P for use with a subwoofer, you'll get considerably more headroom as the 15" driver won't be flapping around trying to do bass. Hope the Behringer sub can keep up...

Chris
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Johannes Halvorsen

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Re: JBL SRX815P
« Reply #2 on: March 17, 2018, 05:57:13 am »



Hope the Behringer sub can keep up...


I have never used any of those speakers myself, but I'd guess you could turn the Behringer sub on or off and not notice much difference when the JBL is running full tilt boogie in full range mode.

Seems like a quite odd combination of speakers...

But to adress the OP: Have you tested the speakers afterward? Any strange sounds etc? In my experience it is easier to check if a speaker sounds ok when using a recording of a single instrument. Some old audio test CDs (e.g. Parson/Court) have nice clean recordings of uncompressed guitar, piano, human voice, etc.
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Mike Pyle

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Re: JBL SRX815P
« Reply #3 on: March 17, 2018, 12:41:49 pm »

... I used a Behringer 18 in powered sub but left the SRX setting to preset main.

If you are running the tops full range over subs it is possible that they cancel each other out at some bass frequencies. That can lead to burnt voice coils from DJs driving the system into limiting trying to get higher bass levels.
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Don T. Williams

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Re: JBL SRX815P
« Reply #4 on: March 17, 2018, 05:30:31 pm »

+1 for the suggestions about running the SRX in a mode set for use with a subwoofer.  In the "main" full range mode it is possible that the JBL and Behringer products are out of phase at most frequencies, and you will get less bass. 

The easy way to tell is to set them each where they are about the same level on bass program material. Better yet, use a bass test CD (or a frequency generator if you have one) sending 40Hz - 80 Hz material to both units independently.  Then run them together with the JBL's (set for main) and turn off the sub.  If the bass is stronger, they are substantially in phase, if weaker they are substantially out of phase.  If you have a way to invert the polarity of the signal to the subs, try it again and listen for the results.  If there is no difference, then the phase relationships are somewhere in between.  It's still best to set the JBL for use as a top cabinet only.   
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boburtz

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Re: JBL SRX815P
« Reply #5 on: March 18, 2018, 04:29:02 am »

Hello everyone, new here and being DJing for a couple of years. I used a brand new pair of JBL SRX815Ps for a gig last Saturday and I ran them pretty good for 8 hours. About five hours into it I was getting LIMIT flash on the LCD and I smelled a funny smell, electronic. As I brought the volume down, limit would go off and no more smell. Speakers are working fine but I am a little worried about the smell and limit light. I also set the speaker main volume to 0, didn't want to touch it. Should lit be set higher than that? I used a Behringer 18 in powered sub but left the SRX setting to preset main. The manuals are not much help with these questions and hope to get some input from the pros. Thank you

Jim
We took a pair of SRX812p out for a maiden voyage with a small outdoor festival stage where we weren't expecting a lot of people to be in front of the stage. We also had four JBL single 18" subs lined up in front of the stage (MP418s). It actually was a good balance, those srx800's are pretty stinkin' loud! We ran the system for about 8 hours and after the seventh hour I started occasionally hearing a very audible, crunchy distortion that was becoming more and more frequent. I walked up to one of the 812s and noticed a burning plasticky smell and saw the limit light was on, not steady but it was mostly in limit. The limiters on these are very transparent, so you would never know it was limiting unless you were turning it up and not getting more volume, or you were looking at the limiter light. I suspect I was probably in the limiters all day. Anyhow, I turned it down and the distortion went away, I have never heard it since, and we use these things all the time.  I opened it up when I got it back to the shop and I didn't notice anything visually obvious in any of the electronics to indicate permanent damage. These were being run at line level, 0db on the input and the output.
I'm sure you're fine, just keep an eye on the limiters and try to run them within their linear limits. They are great speakers.
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Jim Babo

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Re: JBL SRX815P
« Reply #6 on: March 19, 2018, 08:09:33 pm »

Thank you everyone, great forum with lots of knowledge and experience. I am definitely looking at getting two JBL subs very soon ;)
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Tim McCulloch

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Re: JBL SRX815P
« Reply #7 on: March 20, 2018, 02:28:59 pm »

Hello everyone, new here and being DJing for a couple of years. I used a brand new pair of JBL SRX815Ps for a gig last Saturday and I ran them pretty good for 8 hours. About five hours into it I was getting LIMIT flash on the LCD and I smelled a funny smell, electronic. As I brought the volume down, limit would go off and no more smell. Speakers are working fine but I am a little worried about the smell and limit light. I also set the speaker main volume to 0, didn't want to touch it. Should lit be set higher than that? I used a Behringer 18 in powered sub but left the SRX setting to preset main. The manuals are not much help with these questions and hope to get some input from the pros. Thank you

Jim

Addressing the text in boldface first-

Hell no.  You're already in limit to the point of burning smells and likely audible distortion.  What do you expect to happen if you turn it up?  Ponder that for a moment and apply some logical tests...  The gain knob on the back doesn't limit the output, it determines the input level needed to drive the speaker's amplifier.  If you turn it up, it takes less input signal to reach Full Tilt Boogie.  You're already there (into consistent limit) so you get nothing but more limiting and burning smells unless you turn DOWN the mixer to compensate (yeah, like the level will stay there... uh huh, sure thing, pal ;) ).  Hint:  if the level you like to run your mixer at keeps the speakers in limit, turn the speakers down from 0.  You want the smell to stay away.  8) There are other reasons to adjust the input levels at the speakers - and they're beyond this current discussion - but for now consider 0 to be your friend unless you need to change it.

Next, I suspect the comments about the sub are correct - either it's out of polarity with the JBL tops (and running the 815 in full range "main" mode would make that worse, not better) *or* the sub has radically different phase (not polarity) response than the tops (and again having the tops in "main" mode would accentuate the problem) *or* the 815s simply outrun the sub (likely) and you couldn't tell it was on... or "D, all the above."

FWIW it takes a lot of sub to keep up with the new JBL SRX/STX top boxes.  If you're doing gigs that need the LF to be physical and keep up with your 815 tops you'll need more subs than you are probably estimating.  Trust me when I say that 2 SRX828sp per 815sp is not too much subwoofer.

Have fun, good luck.

Tim Mc
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Don T. Williams

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Re: JBL SRX815P
« Reply #8 on: March 20, 2018, 06:02:05 pm »

+1 for Tim.  The SRX/STX is just in another league from the Behringer Sub.  I have SRX835P's which might be just a little louder than the 815's, and dual 828's are really needed to truly keep up with the 835's in most situations.  It is fairly normal to need two to four times as much sub as full range speaker.  The subs are typically run 6 to 10db hotter, especially for outdoor events.
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Geert Friedhof

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Re: JBL SRX815P
« Reply #9 on: March 21, 2018, 08:10:01 pm »

blabla  ... The subs are typically run 6 to 10db hotter, especially for outdoor events.

The subs should typically be able to run 6 to 10db hotter, especially for outdoor events.

Fixed that for ya.
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Chris Grimshaw

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Re: JBL SRX815P
« Reply #10 on: March 23, 2018, 09:22:18 am »

The subs should typically be able to run 6 to 10db hotter, especially for outdoor events.

Fixed that for ya.

+1. There's a difference between headroom and an uneven frequency response.

Chris
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Jim Babo

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Re: JBL SRX815P
« Reply #11 on: March 30, 2018, 11:02:46 am »

Great information guys. I was thinking of selling my 18 Behringer Sub and buying the JBL SRX 828SP. Should be a good combination for the power.
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