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burning smell coming from speakers


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#1 313DJ

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Posted 26 August 2012 - 10:24 PM

if anyone can help with this problem i would greatly appreciate it,i have blown about about 2 of my subwoofers in my old jbl sr4719a's and i found out it was because i didn't have enough power on them,i know have a crown i-tech8000 and hooked it up to my jbl srx728's and my ev qrx 218s's and have been getting a burning smell but have not blown them,the speakers were used,but i'm wondering is this is because they have never seen this kind of power and they're getting broke in or is it something i'm doing wrong,i have the average and peak settings correct

#2 dakos

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Posted 26 August 2012 - 10:50 PM

Am I correct to assume the smell is comming from the speakers? Which one? Speakers get ruined because of over excursion or overheat, nothing else, not too little power. If you have a smell comming out of them then you probably pushed them too hard, did you clip the signal anywhere on the signal chain?. What settings do you have for them on the itech or some other processor?

You need to keep in mind it's not recommended to mix different boxes because the difference in frequency response will cause comb filter effect between the two. That is true unless you have very expensive gear.

#3 313DJ

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Posted 27 August 2012 - 12:25 AM

ok dakos no speakers are being mixed not using the sr4719a's anymore,i have a djm-600 and i do let the levels go into red which i assume is clipping,but i have limiters on my amps and they don't clip at all,maybe it's the amp or could it be my crossover setting would that make the speakers work to hard if i don't have it set right,i use the bbe sonic maximizer with the subwoofer output and it's not digital

#4 dakos

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Posted 27 August 2012 - 02:03 AM

Got that about the 4719 but I thought you were using the JBL SRX728s and your EV QRX 218s at the same time.

Yes, that's clipping... clipping the signal at any point in the signal chain is still clipping even if the amp is not the cause of it :(
Note, due to the way clip sensing on the amp works, if you clip the signal before the amp, the clip LED on the amp might not light on most of the amps.
Limiters only limit the amplifiers maximum peak or average voltage, but it's not a magic cure for all clipping.

You avoid the over excurtion and overheat damage by:
1. limiting the amp to the specified speaker long term power specs and many times allot less then the spec (to avoid power compression).
2. Use a HPF to filter out the unreproducable frequencies that create huge cone movement, usually a 24dB/octave (IIRC Butterworth) at the -3dB point of the speaker.
3. Never clip anything on the signal chain!!!
4. Keep your ears open for destortion and back off a bit when it happends.

I suggest you read this article for more detailed knowledge about the whys and hows:
http://www.bennettpr...undamentals.pdf

#5 Deromax

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Posted 27 August 2012 - 08:52 AM

A limiter will protect against overexcursion, but if pushed, it will actually increase the average power delivered.  Peaks are kept under control but what is between the peaks will increase.  That's the average power that is producing actual heat in the drivers.  Too much heat will produce smell, then failure.

#6 313DJ

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Posted 30 August 2012 - 08:39 PM

thanks dakos and deromax,i cut down the levels on my mixer so i should no longer be clipping,the subwoofers still sounded good at the end of the night,just had the burning smell do u think i damaged them?

#7 dakos

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Posted 30 August 2012 - 11:15 PM

Yes, I believe you did :(

Did you set both limiters on the itech? Continuous and peak? If so then to what level?

#8 Deromax

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Posted 31 August 2012 - 09:04 AM

I think if there was a single incident, it may be somewhat OK.

I've once had an old EV sub driver smelling with the slightest overload and decided, the h*ll with it, I'll replace the thing when it fail.  It lasted for nearly two years before seizure!  But I had redundancy in the kit and could allow to lose it mid show.  If your drivers are mission critical, use more restrain!  :)

On the use of limiter, I see them as a protection for *exceptionnal* overload in the program material.  I think if you are constantly bumping against the limiter in normal use, then the system as a whole is underpowered for the application.  What's good about an expensive and powerfull amp like the itech, if you're gonna waste half its power by using a -3 dB limiter?

#9 313DJ

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Posted 31 August 2012 - 03:12 PM

yes i set both limiters,on the ev qrx218s's the continuous is 1200 and the peak is 4800,so i  set the average to 1200 and the peak to 138,

#10 dakos

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Posted 31 August 2012 - 05:02 PM

What other settings? Attack, Release? Any HPF? At what frequency are you crossing it?

#11 313DJ

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Posted 02 September 2012 - 07:36 PM

crown gave me attack and release setting but i couldn't find out how to get to them,never hooked it up to the pc scared i'm gonna mess something up

#12 dakos

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Posted 03 September 2012 - 11:25 PM

I would suggest you watch the tutorials on YouTube and then install and start configuring, you will see it's pretty much self explanatory. If you mess things up beyond ability to repair, though not recomended for this usage, you can always do a firmware update and it deletes all the changes you made.

#13 313DJ

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Posted 06 September 2012 - 06:23 PM

ok thanks dakos

#14 313DJ

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Posted 28 September 2012 - 09:59 PM

hey thanks dakos and deromax i have did a few gigs lately and no more burning smells coming from the speakers,i think the biggest  problem was me clipping my mixer i'm watching that very closely know,but since i wasn't clipping my amps i thought i was ok but i guess i was wrong