An amp to power a JBL SRX728 sub

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J

Jack the ripper

New DJ
Nov 6, 2009
59
1
London
Hi ya guys, i've just bought a JBL SRX728 sub and i'll be getting another in febuary, but anyway, some people say stick 3,200 watts through it, some say stick 1,600 watts through it. These 2 music styles are the main 2 styles i'll be playing through it :

http://www.youtube.com/watch?v=D80L...k"]http://www.youtube.com/watch?v=D80LzbMVVV8


If you fast forward the 1st style to 1:13 you'll see the kind of awesome sub bass thats in this style of music.

And lastly this style :

http://www.youtube.com/watch?v=VQik...FB94E1BA&playnext=1&playnext_from=PL&index=46


The 2nd style is not that bass heavy but is heavily compressed. So I was thinking about powering the SRX728 sub with a Crown K2 bridged. What amps do you guys reccomend, taking into account the music styles i'll be playing through the sub? I know with more energetic music, like these 2 styles you have lay off on the wattage more than you would playing country music which doesn't punish speakers the way these 2 styles do.
 
Are you sure that wouldnt be too much power considering the frankly hyped and awesome amount of bass in the 1st style of music I play? My events go on from 9pm-4am continuous. JBL say that the program power rating and amplifier reccomendations are just a guide.
 
You'll be fine with the 3602. I use two of them in bridged mono to power 4 Cerwin Vega AB-36B Afterburners and have had no problems. The SRX728 is very power hungry so you need to feed it accordingly.
 
3,600 watts from a PLX3602 even with the bass heavy music I play? I thought with music with more low frequency energy you couldnt put as much wattage through a speaker, and with music like say, country, seeing it doesn't punish speakers like dance music, with country you can put more wattage through it. What kind of music styles do you guys all play through your system?
 
Number 1. the PLX3600 in bridged mode will just barley get you to the program rating of the JBL728 your power level needs to fall somewhere between the program and peak level for that speaker just for a tiny bit of headroom!

Number 2. 5 or 6 thousand watts certainly isn't out of the question when considering these boxes!

I don't know how the JBL SRX728 hooks up but my old Peavey DTH 218s could use two amps hooked to the box one for each driver. Check into that and you may be able to hold the cost down some by using two smaller amps one bridged for each driver in the sub.

Wattage is what is reqiured to reproduce the lower frequencies!
 
In my case the AB-36B's are rated at 1500 watts peak and each one is getting 1800 watts from the QSC's, no problem amazing bass and have never had a problem. As Thunder mentioned for bass you need watts. The 1800 watts are not constant but peak numbers and having the headroom available you'll never need to run the amps to full clip to get the most out of them.
 
Running (2) SRX 728's with sub sonic bass??

I'd be running a QSC Powerlight 6.0 on then.

Big boy subs require a big boy amp.


When dealing with very low frequencie bass (50hz and below) More power is
Much better than not enough!!!! Clip your amp at those freq's and Poof!!!!

Buy a dedicated sub amp....
 
DJ SVO, the QSC PLX-3002 figures are continuous, it even says it in the specs, so the PLX-3002 will give the sub 3,000 watts continuous into 4 ohms bridged. The QSC RMX-2450 is rated at 2450 watts continuous bridged into 4 ohms, but obviously its a 1khz rating so you can safely take off 200 watts off that to give you a more accurate full bandwidth figure, which means that in the REAL world, it'll probably give 2,000 watts bridged into 4 ohms. The Electrovoice P-3000 also has a continuous rated power spec, but it too is full bandwidth (20hz-20khz) and is rated at 3,000 watts bridged into 4 ohms. The continuous full bandwidth ratings are more accurate than the silly 1khz power ratings which never apply to a subwoofer seeing as you dont use subwoofers at 1khz.
 
Yes it's continuous, but you're not giving 3600 watts every single second the music has it's ups and downs. For bass only you need a lot of power and underpowering the speakers will give you a headache and you will not get the sound you're expecting. Let me put it this way, some cars can run perfectly at 50 MPH but there are others that don't come to life up until 140 MPH that's where they start shining and justify their price. The SRX is the same thing look around the boards and see how many persons are feeding them with amps putting out the peak numbers for the SRX, yes they are using i-Tech's, Macro Tech's, QSC PL's, etc.
 
crown xti6000 would be my choice.i run the JBL single 18's with the xti4000 and it drives them like a champion sound.
 
http://qscaudio.com/products/amps/plx2/plx3602_specifications.htm

Take a look at the bottom of the page and look at the power consumption at full power (This will be full clip). You won0t be able to coax that amount of power out of the outlet of your average venue. Going with big amps with lot's of headroom means you'll be able to get the most power from your amp while making the clip lights flicker. This means you're feeding it a clean signal. When clip lights start barely flickering you're at 1/8 power, when the clip lights remain on and flicker less then you've reached 1/3 power. Here's where the extra watts from the big amps make the speaker shine since you'll get the right amount of power to the cabinet without distorting the signal.

Remember when you run the amps hard that's when you really start sucking in power from the outlet. You'll pop the circuit breaker for the outlet before you get anywhere near full power.
 
Are you telling me to clip the amplifiers to get full power out of them? I hope thats not what your saying, cos if you are, that is the most stupid piece of advice i've ever heard in my life. You NEVER clip an amplifier. Headroom is all about having too much power so you dont have to run the amp into clipping to get the spl out the subs. Clipping will seriously damage speakers and will blow your speakers pretty quickly. I just hope that you said that wrong, and dind't mean actually clip the amplifier.
 
DJ SVO: I'm wondering if you ment the Signal lite and not the Clip indicator.... because as far as I know Jack is right you don't want to send your amp into clipping as an indicator of the power being sent....

Clipping means the amp has reached power saturation and is now chopping off the peaks of the signal which is what clipping means.... and therefore distorting the sound and yes potentially harming the speakers especially those without protection circuitry....not to mention what you'd be doing to the amp itself.

Honestly I think he ment the Signal indicators.... and that would make sense what he was saying.
 
Surely he didnt mean the signal indicators. He must have meant the clip lights, because then you'd at least know there was a hell of a lot of voltage ( a speaker killing clipped signal) coming to the speakers, wheras the signal lights just indicate that there's a signal coming into the amplifier. The only way you could get an idea of what kind of voltage is coming to the speakers is to use a multimeter with the red and black wires touching the corresponding amplifer out terminals. Obviously you'd have to disconnect the speakers 1st.
 
No I Rob I meant the clip lights, that's why you run so much amp to the subs to get clean power them. Once you're clipping you're sending square waves in there and it sends everything out the window. My Cerwin Vegas have been powered by QSC RMX2450's in bridged mono, When I was running into clip with them I knew I was missing something so I also plugged them into a bridge mono Yamaha P7000 and still felt there was more to it so I bought the PLX's you get the clean power to it. I have no need to go further than having the clip lights flicker once in a while to get the walls shaking.
Rob hook your old amp to your old Yamaha's and then plug it in to an ammeter and you'll see what I'm talking about power wise as you start raising the volume and you get to clip. The whole reason of getting such a big amp is to keep the signal clean and not worry about running out of power and damage your speakers doing so.

Now Jack if you think it's stupid advice that's up to you. Power them with a small amp and see what you kind of sound you get out of them.
 
There it is then, you've admitted to running the amps into clipping, why? I'd never clip an amp. NEVER. You shouldn't run an amp into clipping just to see if you have enough power. Running an amplifier into clipping it a stupid idea ANY time, and under ANY circumstances. If you want to see if you have enough power, and what your speakers can handle, the best way is to hire an amp out then run it as hard as you can WITHOUT clipping it. If you still feel your speakers can handle more power, hire a more powerfulk amplifier out, and run that amp as hard as you can WITHOUT clipping that amp either. I'm not trying to offend you, but if you care about your speakers you should never run the amplifier into clipping. Its a stupid idea. You don't have to show me those links to the pictures, or tell me about square waves. I never have clipped an amplifier and I never will. If an amp is running full steam (without clipping) and I feel the speakers can take a bit more power, and/or I need a little more spl, i'll either use a more powerful amplifier or save for another pair of speakers.

In my opinion, even having the clip lights flicker once in a while means you're being silly with you equipment and should use a more powerful amplifier or get another set of speakers. I dont ever want to se a clip light on my system. EVER.
 
When the clip lights barely flicker (That's once in a while not constant flicker) that's 1/3 power that's where the volume stays. I've been running my speakers for years that way and I've never blown a speaker or melted anything. Ever swince I started unning things. I have speakers that are 30 years old and still work perfectly. Compressors and limiters have always been used so mo problem there.

If you want to run the SRX728 with a PLX 3102 you're going to be dissapointed as you'll run out of amp nowhere near where the speakers have been designed to run.
 
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