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Author Topic: Changing the compression drivers in the JBL MRX525 cabs  (Read 31697 times)

Alan Sledzieski

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Re: Changing the compression drivers in the JBL MRX525 cabs
« Reply #20 on: January 15, 2011, 10:11:08 am »

Richard Stringer wrote on Sat, 15 January 2011 09:59

Ivan Beaver wrote on Sat, 15 January 2011 07:44

Richard Stringer wrote on Sat, 15 January 2011 07:06

What do you think my mate should do then Ivan? Would be a better idea to get a JBL 2426 instead :

   http://www.music.mcgill.ca/caml/lib/exe/fetch.php?media=equi pment:jbl2426.pdf

Hopefully because it's made by JBL it'd be better.

I think he should replace the driver with the correct one, and TURN IT DOWN!

Or buy a new system or just keep spending more money on replacements.

It is NOT a matter of what is a better HF driver-but what is better in the exisiting cabinet.

Now if he wants to replace the current driver with a better one-and then pay somebody WHO IS KNOWLEDGABLE to redesign the crossover so the new driver will work with exisitng horn and woofer then that would be an option.

But chances are-he will spend more on that redesign than new cabinets would cost-if done correctly.  If done "halfway", then you will get "halfway" performance and that may be good enough for your friend.

There are limits to what any system can do-and he is wanting too much out of his system-so he needs a different system.


I like the way you say "buy a new system" like everyone can afford it, I know for a fact he can't afford to buy a new system so that's not even an option. You say turn it down, but thye fact is, the problem isn't that the MRX525 cabs aren't loud enough, the problem is the little 25 watt compression driver outputting enough high frequency to keep up with the dual 15" drivers in the MRX525 and also the 4 18" drivers in his subs.



25 watts, thats all that thing handles?
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Ivan Beaver

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Re: Changing the compression drivers in the JBL MRX525 cabs
« Reply #21 on: January 15, 2011, 11:26:28 am »

[quote title=Richard Stringer wrote on Sat, 15 January 2011 09:59
I like the way you say "buy a new system" like everyone can afford it, I know for a fact he can't afford to buy a new system so that's not even an option. You say turn it down, but thye fact is, the problem isn't that the MRX525 cabs aren't loud enough, the problem is the little 25 watt compression driver outputting enough high frequency to keep up with the dual 15" drivers in the MRX525 and also the 4 18" drivers in his subs.
[/quote]
Well him to have fun.  Or take the system back to who he bought it from and get a refund because it does not get loud enough for his needs.-yeah-like that's gonna happen.

What you are asking for is a simple solution to a problem that is rather complicated with a lot of variables.

Good luck.

Take this as an example.  You break the axle on your truck.  It is rated for 1000 lbs.  But you put 2000 in it.  You take it to the dealer and they tell you to either get a new truck or don't put as much in it.

Same thing as I told you.  But what if the front axle does not break?  Does that mean that something is wrong with the ratings?  No.  It just means that the rear axle will fail first.

In the loudspeaker is the loudspeaker at fault if the horn fails before the woofer?  What if the woofer failed first?

Do you expect them both to fail at the same time?  And what music source would you be using and how would the system be ran to get that failure mode.  Maybe somebody who runs the system different would get a different failure point.  So now what is the problem?  

Somepeople like the high freq to be screaming because they have hearing loss up high. Those people will put more strain on theHF driver.  Some people like to have the HF reduced because they are more sensitive up high-so they put less strain on the HF.

Different uses will have different results.
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For every complicated question-there is a simple- easy to understand WRONG answer.

Can I have some more talent in the monitors--PLEASE?

Ivan Beaver
dB Audio & Video Inc.
Danley Sound Labs

Richard Stringer

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Re: Changing the compression drivers in the JBL MRX525 cabs
« Reply #22 on: January 15, 2011, 11:46:25 am »

What are you on about if it's not loud enough, have you actually been listening to a word i've said Ivan? I've already said twice that the problem isn't that the MRX525 isn't loud enough, it's definately nice and loud, it's just that the compression driver can't output enough. When you play bass heavy music like hip hop of drum & bass the high frequency kind of gets overwhelmed by the 15" low frequency drivers in the MRX525 cab, my mate doesn't need the sound any louder overall, he just needs a compression driver that can keep up with the 15" drivers in the MRX525 cab. It really is that simple, there's nothing more he wants.
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Ivan Beaver

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Re: Loudness vs time
« Reply #23 on: January 15, 2011, 01:00:01 pm »

Richard Stringer wrote on Sat, 15 January 2011 11:46

What are you on about if it's not loud enough, have you actually been listening to a word i've said Ivan? I've already said twice that the problem isn't that the MRX525 isn't loud enough, it's definately nice and loud, it's just that the compression driver can't output enough. When you play bass heavy music like hip hop of drum & bass the high frequency kind of gets overwhelmed by the 15" low frequency drivers in the MRX525 cab, my mate doesn't need the sound any louder overall, he just needs a compression driver that can keep up with the 15" drivers in the MRX525 cab. It really is that simple, there's nothing more he wants.

No-it is you that don't understand.

It is OBVIOUS that it can'T get loud enough-AND STAY that way without breaking.

Sure your car might can do 40mph in 1st gear.  But how long before it breaks?  OK no stupid high performance cars opinions here-you know what I am talking about.  You know-cars along the caliber of the loudspeakers in question.  We aren't talking aobut high performance loudsepeakers-so no high performance car either.

I have no opinion or experience on whether or not the particular cabinet can produce the rated specs.

THAT is what I mean by getting loud enough.  Most loudspeakers can get quite loud-but some can STAY that way-and others will break.

So the ones that break CANNOT maintain that loudness.

Loudspeakers fail with a combination of time vs heat.  Reduce either one and the other can go up.

I don't know how to explain it any better than that.

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For every complicated question-there is a simple- easy to understand WRONG answer.

Can I have some more talent in the monitors--PLEASE?

Ivan Beaver
dB Audio & Video Inc.
Danley Sound Labs

Ivan Beaver

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Re: More than just "watts".
« Reply #24 on: January 15, 2011, 01:04:02 pm »

Alan Sledzieski wrote on Sat, 15 January 2011 10:11

25 watts, thats all that thing handles?


That may not be so bad.  That is the rating of the HF driver.  But the cabinet will handle much more.

Consider these ideas.  The HF has a much higher sensitivity-so it will need to be padded down 10dB or more to match the woofers.

So that already adds an effective zero to the power-so now we are at 250watts (kinda).

Also add in the fact that the HF durations and heating is not as much as the lower freq (look at a time vs freq energy curve of normal music) and you can add some more to that.

There is A LOT more to ratings than just watts.

A simple number does not accurately describe the performance.
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For every complicated question-there is a simple- easy to understand WRONG answer.

Can I have some more talent in the monitors--PLEASE?

Ivan Beaver
dB Audio & Video Inc.
Danley Sound Labs

Richard Stringer

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Re: Loudness vs time
« Reply #25 on: January 15, 2011, 01:08:49 pm »

Yeah ok Ivan, I understand what you meant now, it's just you said it in a way that made me think you meant something else. Well my mate uses my JBL MPX1200 to power the MRX525 cabs, we live together in my flat, and seeing as I was a member of here I thought i'd ask you guys. I got him to register on another forum to ask there but he seems to be getting abuse from one member there lol, he's not happy at all, lol, at least you guys don't come straight out with it and call people an idiot.

Anyway, back on topic, i've told him to try and save up for an XTA DP224 seeing as they've got RMS limiting built in and from what little I know, peak and RMS limiting together should provide a bit more protection for his 2408 drivers hopefully. I'll have a word with him and advise him to get new drivers. Oh I just thought, a place near us has a DP226 for hire, we could hire it out for a few gigs, see if it helps to stop the 2408 drivers blowing. Sying that, this is the first time they've blown.
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Dave Dermont

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Re: Changing the compression drivers in the JBL MRX525 cabs
« Reply #26 on: January 15, 2011, 01:20:20 pm »

Richard Stringer wrote on Sat, 15 January 2011 11:46

What are you on about if it's not loud enough, have you actually been listening to a word i've said Ivan? I've already said twice that the problem isn't that the MRX525 isn't loud enough, it's definately nice and loud, it's just that the compression driver can't output enough. When you play bass heavy music like hip hop of drum & bass the high frequency kind of gets overwhelmed by the 15" low frequency drivers in the MRX525 cab, my mate doesn't need the sound any louder overall, he just needs a compression driver that can keep up with the 15" drivers in the MRX525 cab. It really is that simple, there's nothing more he wants.


You know, sometimes it's really hard to accept the reality of a situation.

First of all, it's either loud enough or it's not. If you are blowing up drivers, my guess is that it's not.

Ivan is not trying to bust your balls, he's just telling you how it is. If you can't handle the truth, that's your problem, not Ivan's.

You are trying to drink champagne on a beer budget.

It's really really difficult for someone with Ivan's experience to explain everything he knows about speaker design in a couple forum posts.

Indiscriminate replacement of horn drivers with something "better" is inviting to a train wreak. Please trust us on this.

 
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Dave Dermont - Chief Lizard, LAB Lounge

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Dave Dermont

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Re: Loudness vs time
« Reply #27 on: January 15, 2011, 01:28:55 pm »

Richard Stringer wrote on Sat, 15 January 2011 13:08

Yeah ok Ivan, I understand what you meant now, it's just you said it in a way that made me think you meant something else. Well my mate uses my JBL MPX1200 to power the MRX525 cabs, we live together in my flat, and seeing as I was a member of here I thought i'd ask you guys. I got him to register on another forum to ask there but he seems to be getting abuse from one member there lol, he's not happy at all, lol, at least you guys don't come straight out with it and call people an idiot.

Anyway, back on topic, i've told him to try and save up for an XTA DP224 seeing as they've got RMS limiting built in and from what little I know, peak and RMS limiting together should provide a bit more protection for his 2408 drivers hopefully. I'll have a word with him and advise him to get new drivers. Oh I just thought, a place near us has a DP226 for hire, we could hire it out for a few gigs, see if it helps to stop the 2408 drivers blowing. Sying that, this is the first time they've blown.


Richard,

I was writing my response while you posted what's quoted above.

You seem to get it now. I was wondering what amps you were using, and if they might be part of the problem. The JBL MPX1200 seems like they'd be a good fit with your speakers.

Good luck.

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Russel Murton

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Re: Loudness vs time
« Reply #28 on: January 15, 2011, 01:45:22 pm »

I've had this happen before. You keep pushing your cabs too much, you are hitting a limiter somewhere, amps, DSP, crossover, comp/limiter. Anywhere int he chain. Sure, you hit the limiter and don't peak your amps, you think you are safe.

What you don't realize is that probably low frequencies are hitting that limiter, you keep turning it up without getting louder, you just keep slamming your limiter. Then the frequency responce starts to look more like that of your speaker and your program material starts to look increibly flat.

Then you have huge amounts of sustained HF content going to the HF driver.

Your amps are probably peaking at low frequencies as we are more sensitive to HF then LF, so you naturally compensate by having a kind of slope to your program material from LF to HF.

The more you limit and compress your program material, you are feeding more RMS power to your HF driver and it will blow, even though you aren't peaking your amps.

Solution: Get a multiband compressor or a DSP unit and set some RMS and peak limiters before your amps which prevents that amount of sustained RMS HF signal to your HF drivers. Operate with more dynamic range in general aswell, the more dynamic peaks music has, the louder we perceive it. Limited music brings up the overall level, dynamic but equally as loud in terms of peaks sounds louder as our ear relaxes after the peak making the next peak sound louder.

Therefore: operate within the speakers limits and you will be fine. I use the MRX dual 15 quite often and haven't had any problems with the amount of HF content. If anything, the dual 15"s get way too muddy, my KW153's 6.5" midrange and 1.75" HF make a much better, clearer combination than two 15's and a 1" HF.
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Alan Sledzieski

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Re: More than just "watts".
« Reply #29 on: January 15, 2011, 02:43:32 pm »

Ivan Beaver wrote on Sat, 15 January 2011 13:04

Alan Sledzieski wrote on Sat, 15 January 2011 10:11

25 watts, thats all that thing handles?


That may not be so bad.  That is the rating of the HF driver.  But the cabinet will handle much more.

Consider these ideas.  The HF has a much higher sensitivity-so it will need to be padded down 10dB or more to match the woofers.

So that already adds an effective zero to the power-so now we are at 250watts (kinda).

Also add in the fact that the HF durations and heating is not as much as the lower freq (look at a time vs freq energy curve of normal music) and you can add some more to that.

There is A LOT more to ratings than just watts.

A simple number does not accurately describe the performance.


I don't know, 25 watts seams low.  the cab. will handle 800 on the low end and 25 on top.

I'm used to the jbl 1'' and 2'' horns, drivers that take 100, 150 watts.  the srx double 15 take 1200 on low and 150 on the highs, seems like a better balance.

Thats why I think getting a set of 1'' or 1.4 or 2'' jbl horns , drivers would be perfect.  Is there enough room to put a 1'' jbl horn in the box, with a 100 watt driver, or stack above it?

Even if he use the crossover in the box as is at 1.8 khz it would be better then what he has now I would think.  Probably need to be lower like 1200hz on the 1''

I just recently put a pair of 2426 and 2370 together for a single 15 box that I use for small shows.  I paid $200 for the pair of horns and drivers, when all said and done.

I think it would be a great option right now?
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