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Author Topic: 4 JBL MRX528s VS 2 JBL SRX728S  (Read 21335 times)

g'bye, Dick Rees

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Re: 4 JBL MRX528s VS 2 JBL SRX728S
« Reply #20 on: October 24, 2012, 05:39:26 pm »

I have the mains dropping around 60-70 as their frequency response is down to 57 if I remember correctly. I think I have my subs around 120 on the top end and 35-40 on the low end though I don't remember the amount of decibel drop at each frequency.

I believe this to be non-standard practice.  I don't want to say "wrong", but having your subs and your tops both operating in the same octave can't be doing your sound much good.  Is there a particular reason to have both boxes overlap in their output?  Just because your tops are rated down to 57 doesn't mean you have to run them that low.  With that kind of reasoning you'd think that you should run your subs up as high as they're rated as well.

I don't think so.
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Bob Leonard

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Re: 4 JBL MRX528s VS 2 JBL SRX728S
« Reply #21 on: October 24, 2012, 06:14:26 pm »

I believe this to be non-standard practice.  I don't want to say "wrong", but having your subs and your tops both operating in the same octave can't be doing your sound much good.  Is there a particular reason to have both boxes overlap in their output?  Just because your tops are rated down to 57 doesn't mean you have to run them that low.  With that kind of reasoning you'd think that you should run your subs up as high as they're rated as well.

I don't think so.

The upper cabinets may well be good down to 47hz, but at how many db down from higher freqencies, say about 1K. Dick is correct in that you are following a non standard practice. The center frequency for the subs you're using is somewhere in the neighborhood of 80-90hz.
 
Generally that would indicate a high pass filter about 85hz for the subs and a low pass filter for the tops about 5hz higher, or 90hz. This would eliminate overlap at the center frequency eliminating a possible 6db hump at that frequency (depending on filter type and DSP).
 
The second mistake you're probably making is not setting the low pass filter for the sub at an appropriate frequency. set the low pass too low and your speakers will attempt to handle sounds that are of no benefit to the music being played. Low order harmonics, etc. do not make for good sound. Try setting the filters to 90hz and 45hz and see where that gets you. Also note that you may have to drop the input to the upper cabinets 6db or more in order to balance the transition from top to bottom. Start with the sub and mute the upper cabinets while you work with the crossover and keep in mind that you shouldn't hear the snare in the sub, but you should hear the kick in the upper cabinets AND the sub.  ;D
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Scott Bolt

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Re: 4 JBL MRX528s VS 2 JBL SRX728S
« Reply #22 on: October 27, 2012, 09:51:26 am »

The SRX728 is a much better sounding sub.  By better, I mean articulate, punchy, not woofey.

You can't couple any number of MRX's together and get the sound you will get from an SRX sub.

Volume wise, the SRX series seem to thrive on ample power (properly limited) while the MRX series seems to go into compression much earlier (ie adding more power doesn't give you more output).

What are you using for tops?   What amps are you using?
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Andrew Brubaker

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Re: 4 JBL MRX528s VS 2 JBL SRX728S
« Reply #23 on: October 28, 2012, 08:43:54 am »

I believe this to be non-standard practice.  I don't want to say "wrong", but having your subs and your tops both operating in the same octave can't be doing your sound much good.  Is there a particular reason to have both boxes overlap in their output?  Just because your tops are rated down to 57 doesn't mean you have to run them that low.  With that kind of reasoning you'd think that you should run your subs up as high as they're rated as well.

I don't think so.

I do not run a bi-amped system. I run my mains full range and use the subs just for the low frequency extension of certain instruments (ie. bass, kick, etc). I typically do a line check with the mains alone and add in the subs after I already have a good sound of the instrument. This way I have more control on what is going through the subs and how much. I have also found that I get a tighter bass response this way because of the help of the mains in some of the lower register.

How would you propose doing things "the standard way"? Running the mains and subs as one system and not running the subs on an aux?
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Andrew Brubaker

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Re: 4 JBL MRX528s VS 2 JBL SRX728S
« Reply #24 on: October 28, 2012, 08:56:49 am »

The SRX728 is a much better sounding sub.  By better, I mean articulate, punchy, not woofey.

You can't couple any number of MRX's together and get the sound you will get from an SRX sub.

Volume wise, the SRX series seem to thrive on ample power (properly limited) while the MRX series seems to go into compression much earlier (ie adding more power doesn't give you more output).

What are you using for tops?   What amps are you using?

Thanks for the info on the SRX728s!

I am using four MRX525 (two a side) and am using 4 XTi6000s. One amp per pair of mains and one amp per pair of subs. (I have 2 pairs of mains and 2 pairs of subs)
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g'bye, Dick Rees

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Re: 4 JBL MRX528s VS 2 JBL SRX728S
« Reply #25 on: October 28, 2012, 09:38:49 am »



How would you propose doing things "the standard way"? Running the mains and subs as one system and not running the subs on an aux?

Get a decent cross-over and re-read Bob Leonard's post.

You are apparently satisfied with your setup and convinced that it is giving you what you need, so I'm not going to try and convince you to do otherwise.  I'll just say that it's likely not the best way. 

Have fun......
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John Chiara

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Re: 4 JBL MRX528s VS 2 JBL SRX728S
« Reply #26 on: October 28, 2012, 03:56:06 pm »

"rig for the gig" comes from something I started saying about gear a long time ago.  "Enough Rig for the Gig"  means that you have both the coverage and output necessary to meet the demands of the act, audience, promoter and Band Engineer.

Seems to be lost on many in my area.
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g'bye, Dick Rees

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Re: 4 JBL MRX528s VS 2 JBL SRX728S
« Reply #27 on: October 28, 2012, 03:59:42 pm »

Seems to be lost on many in my area.

Not enough "smarts in your parts"?
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Andrew Brubaker

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Re: 4 JBL MRX528s VS 2 JBL SRX728S
« Reply #28 on: October 28, 2012, 11:40:05 pm »

Generally that would indicate a high pass filter about 85hz for the subs and a low pass filter for the tops about 5hz higher, or 90hz. This would eliminate overlap at the center frequency eliminating a possible 6db hump at that frequency (depending on filter type and DSP).

Thank you for the input, Bob! I will definitely try these crossover settings the next chance I get. Unfortunately, I do not have my own space to tweak settings regularly anymore but will keep you posted once I have been able to do so!
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Andrew Brubaker

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Re: 4 JBL MRX528s VS 2 JBL SRX728S
« Reply #29 on: October 28, 2012, 11:43:09 pm »

Get a decent cross-over and re-read Bob Leonard's post.

You are apparently satisfied with your setup and convinced that it is giving you what you need, so I'm not going to try and convince you to do otherwise.  I'll just say that it's likely not the best way.

Re-read.

Any particular crossover that you'd recommend? Also, I am more than willing to try different approaches and learn better ways to do things so if you have a better method please enlighten me!  :D
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Re: 4 JBL MRX528s VS 2 JBL SRX728S
« Reply #29 on: October 28, 2012, 11:43:09 pm »


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