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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: Will Knight on July 21, 2013, 09:55:49 pm

Title: gx vs rmx series for srx718s subs
Post by: Will Knight on July 21, 2013, 09:55:49 pm
Need some advice on powering SRX subs
Just picked up a pair of practically new srx718s subs and was curious whether my xti2k vs qsc g7 amps would be good enough to push them.
50% of the time they're used for band and other half for background music. DJ is occasional and limited to r+b top40 jazz classical.
Venues are small /medium club type for 50-200 people.  Again on rare occasion may be up to 400 people in large hall

Suggestions?
Title: Re: gx vs rmx series for srx718s subs
Post by: Corey Scogin on July 21, 2013, 10:15:25 pm
Need some advice on powering SRX subs
Just picked up a pair of practically new srx718s subs and was curious whether my xti2k vs qsc g7 amps would be good enough to push them.
50% of the time they're used for band and other half for background music. DJ is occasional and limited to r+b top40 jazz classical.
Venues are small /medium club type for 50-200 people.  Again on rare occasion may be up to 400 people in large hall

Suggestions?

Either amp will work.  The difference in output between those two amps running 1 sub per side will be less than 3db. 

My suggestion would be to try them at a show with the equipment you have and see how it works.  If you need more, then I'd suggest more subs and more powerful amp(s).
Title: Re: gx vs rmx series for srx718s subs
Post by: Will Knight on July 22, 2013, 10:24:51 am
Either amp will work.  The difference in output between those two amps running 1 sub per side will be less than 3db. 

My suggestion would be to try them at a show with the equipment you have and see how it works.  If you need more, then I'd suggest more subs and more powerful amp(s).

Thanks Corey.  I've done a lot of reading in this forum and other places that the SRX718s require a lot of power to function properly.  Although I've been playing music for +40 years, only recently made decision to turn sound reinforcement from a hobby to an active (secondary) business.  I've heard the xti2K is best operating bridged mono which would mean 1 per sub.  I only have 1 xti but 2 GX7's and was wondering - keeping investment to an absolute minimum at this point, if the GX7 would be suficient...or scrap one (or both) and get a more robust unit like an RMX 1850HD or a PLX3602 to run 1 sub per channel.
The GX7's currently do duty to what's become my "B" rig....MRX515 tops and MRX518s bottoms.

Title: Re: gx vs rmx series for srx718s subs
Post by: Corey Scogin on July 22, 2013, 01:27:56 pm
Thanks Corey.  I've done a lot of reading in this forum and other places that the SRX718s require a lot of power to function properly.  Although I've been playing music for +40 years, only recently made decision to turn sound reinforcement from a hobby to an active (secondary) business.  I've heard the xti2K is best operating bridged mono which would mean 1 per sub.  I only have 1 xti but 2 GX7's and was wondering - keeping investment to an absolute minimum at this point, if the GX7 would be suficient...or scrap one (or both) and get a more robust unit like an RMX 1850HD or a PLX3602 to run 1 sub per channel.
The GX7's currently do duty to what's become my "B" rig....MRX515 tops and MRX518s bottoms.

I was under the impression that you were considering purchasing GX7's, not that you had them on hand.

You're right that a bridged XTI2000 would be "just right" for one sub since the common recommendation to match an amp to a speaker is to get one that is capable of the "program" power rating of the speaker.  In this case the XTI2000 is rated at 1600W/8ohms bridged and the sub is 1600W "program"/8ohms. 

Without purchasing any equipment, you have a few options:
1. GX7 with one sub per side
2. XTI2000 with one sub per side
3. XTI2000 bridged with subs in parallel.

I would experiment with each of these configurations and pick which one you prefer.  Option 3 should deliver the most power to the subs but bridging an amp can have adverse effects on the damping factor which may make the sound less "punchy".

It usually makes more sense financially to use what you have until it's not enough then purchase more or rent more if possible.

As with almost all questions here, there isn't one answer.

Title: Re: gx vs rmx series for srx718s subs
Post by: Paul G. OBrien on August 08, 2013, 10:28:46 am
I've done a lot of reading in this forum and other places that the SRX718s require a lot of power to function properly. 

No.. you have completely misunderstood what you have read. Speakers do not require any particular input power to "function properly" they will work just fine with any input signal from milliwatts to thousands of watts. So you only need to supply enough power to get the SPL you want/need from the particular speakers you have without pushing the amplifiers into clipping.
Title: Re: gx vs rmx series for srx718s subs
Post by: duane massey on August 09, 2013, 12:44:10 am
+1 on Paul's post. You only need enough power to achieve the levels that your application(s) require. If the GX 7 does that, you're good. If not, go bigger.
Title: Re: gx vs rmx series for srx718s subs
Post by: Dustin Campbell on October 14, 2013, 11:53:51 am
I know this post is a little older - I just wanted to see which way the OP went with the subs? And how it worked out?  I too have a pair of srx718's just curious of how people are deploying them - I use 1 rmx2450 per sub personally seem to work ok - I would like some I-techs or qsc PL series
Title: Re: gx vs rmx series for srx718s subs
Post by: Will Knight on November 10, 2013, 09:29:56 am
I know this post is a little older - I just wanted to see which way the OP went with the subs? And how it worked out?  I too have a pair of srx718's just curious of how people are deploying them - I use 1 rmx2450 per sub personally seem to work ok - I would like some I-techs or qsc PL series

Dustin,

I stayed with the current XTI2K and GX7 sets.  I acquired SRX712M's for tops and now run the XTI2K's, one per sub Bridged Mono 1600W@8ohms for the 718s and the GX7's for the tops @ 8ohms Stereo pair.  So far, sound is ok but not earth shattering.  And as Corey pointed out, I plan to try different combos (switch the XTI and GX7's around for top/bottom result, etc) over the coming weeks to keep any additional $ investment to a minimum until it pays for itself.

I was considering ridding the XTI's and replacing with RMX2450's.  You mentioned "OK"...is that a "just ok" impression. .or does the 2450 really perform better.  I've continued to read on the forum various common options that the XTI series is basically not recommended for sub duty, particularly the SRX.

look forward to you observations on the RMX..

Bill

 
Title: Re: gx vs rmx series for srx718s subs
Post by: Tim Padrick on November 10, 2013, 11:34:13 am
Many have opined that the XTI are not very good on subs.
Title: Re: gx vs rmx series for srx718s subs
Post by: Dustin Campbell on November 11, 2013, 04:27:34 pm
Thanks, Bill
The rmx2450 do seem decent(1500@8ohm) - just not sure if is the rmx2450's fault - I have the feeling I may need 2 more srx718's or a single srx728- I have heard the newer generation of XTI's do a better job on the subs-Also the internal DSP on the XTI's should be able to match the srx718's as well- I am running my system with a beringer dsx2496 speaker management- and am seriously jonesing for the DBX DR260- so I can have the proper settings on my srx's. 

on paper the rmx2450's do the job for 1 per cab 718 - I am not a power amp expert but I have heard something about voltage swings on the rmx, 4050, 5050, Crest style amps (heavy iron) are better suited for sub duty.  I still want to test my system with some I-tech's and the DR260 ( one can dream) 

PS - score on the srx712's- those are hard to find- i've been wanting some of those for monitors - I may have to bite the bullet and get the stx812's - and then have to buy another power amp- Zoichs
Title: Re: gx vs rmx series for srx718s subs
Post by: Tim McCulloch on November 13, 2013, 12:12:14 pm
Thanks, Bill
The rmx2450 do seem decent(1500@8ohm) - just not sure if is the rmx2450's fault - I have the feeling I may need 2 more srx718's or a single srx728- I have heard the newer generation of XTI's do a better job on the subs-Also the internal DSP on the XTI's should be able to match the srx718's as well- I am running my system with a beringer dsx2496 speaker management- and am seriously jonesing for the DBX DR260- so I can have the proper settings on my srx's. 

on paper the rmx2450's do the job for 1 per cab 718 - I am not a power amp expert but I have heard something about voltage swings on the rmx, 4050, 5050, Crest style amps (heavy iron) are better suited for sub duty.  I still want to test my system with some I-tech's and the DR260 ( one can dream) 

PS - score on the srx712's- those are hard to find- i've been wanting some of those for monitors - I may have to bite the bullet and get the stx812's - and then have to buy another power amp- Zoichs

There is a rumour going around that JBL is planning another run of SRX712m.  Not sure how big the run is supposed to be...

Kind of like the SRX728... they are out of the catalog for over a year and show as a legacy product on jblpro.com, but I just unpacked 4 brand new units last week.  I suspect either that JBL has consolidated unsold dealer inventory or that the majik elves "found" more in the factory corners...  I'm betting on the latter as the shipping cartons only had 1 address label. ;)