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Author Topic: JBL SRX-728 or EV QRX-218? Which best for my music style?  (Read 35953 times)

Scott Smith

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Re: JBL SRX-728 or EV QRX-218? Which best for my music style?
« Reply #20 on: October 06, 2009, 05:34:33 pm »

Don't forget, there is "old iron" 3kw, then there is switching "burst" power 3kw.  I don't assume that both amps will do the same job or sound the same.  It is however, better to have more either way, than not enough.
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Matt Vivlamore

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Re: JBL SRX-728 or EV QRX-218? Which best for my music style?
« Reply #21 on: October 06, 2009, 05:37:35 pm »

I posted my main response on DJ chat...

I went SRX718s (x4) instead of SRX728s (x2). I started out with an XTi6000 on the subs, very good amp for the price.  I was offered an IT8000 at a killer price that I couldn't pass up.

I test drove both the QRX218 & SRX728s.  Both are excellent choices.
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I'm using: EV QRx212 over JBL SRX718s(2) with Crown IT's and MRX512m & MRX525 on monitors with XTi's; all controlled by Yamaha LS9-32.  I have a bunch of other stuff too.

Adam Schaible

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Re: JBL SRX-728 or EV QRX-218? Which best for my music style?
« Reply #22 on: October 06, 2009, 05:49:40 pm »

That's not the same as saying "they really come alive at 3kw".

I'd be very surprised if they ever see more than 100v without clipping.
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Tom Reid

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Re: JBL SRX-728 or EV QRX-218? Which best for my music style?
« Reply #23 on: October 06, 2009, 05:55:37 pm »

jack smith wrote on Tue, 06 October 2009 15:22

To Tom Reid,

What do you mean 2k is asking for heat? I've been told by people on this very forum (cant remember who) that 2k each sub is about right. Any more than that and its too much power for the seriously bass heavy music i'll be playing through them. I always set system gain structure by using a pink noise test tone and making sure all equipment clips at the same level, then back off on the 1st piece of equipment to 0db on the mixer, and then not exceed that level all night. Surely 3k into an SRX-728 while playing the kind of music i'll be playing is way too much power.

If I set the gain structure, then keep the level at or below  all night, but...I put 3000k through each sub, it'll blow them to bits wouldnt it?


SRX728 are rated 1600/3200/6400.
I've ran some synth heavy bands getting into clip lights occasionally without woofer damage.
ymmv.
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tom

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Tom Reid

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Re: JBL SRX-728 or EV QRX-218? Which best for my music style?
« Reply #24 on: October 06, 2009, 06:10:37 pm »

Adam Schaible wrote on Tue, 06 October 2009 16:49

That's not the same as saying "they really come alive at 3kw".

I'd be very surprised if they ever see more than 100v without clipping.


I think you need to put away the slide rule and do some listening test.

At first you say the LG will blow away the bridged xti.
The LG puts out 2000w vs. 3200w on the xti.
Yes 1.5db difference is difference.

Then you ask RMS, or peak.
If ya knew the parameters of the amps (which obviously you did) you wouldn't even need to ask.

Then you talk about 800w on a driver.  Were talking about a 2 driver cabinet so it's 1600w per cab unless you discrete the loudspeaker.

Now we're measuring heater voltage before clips.

How many different amp/728 configs have you ran in the past year?

I spend minimum three days a week in front of these cabs with all types of input.  They work best when an amplifier can give them at least 3000w of power.  Like all JBL they work the best when the amplifier rating is within the middle power rating.

My stuff sounds good.  I was offering advice to jack to make sure his stuff sounded good.  
I have no issue with you, but you seem to be stuck on a paper trail and not real life experience.

I've beaten this horse enough.

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tom

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Adam Schaible

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Re: JBL SRX-728 or EV QRX-218? Which best for my music style?
« Reply #25 on: October 06, 2009, 06:46:01 pm »

No paper trail.

I have a pair of 728's.

I have had a pair of XTi 4000's bridged 1 per sub.

I have I-Tech HD's.

The I-Tech's are rated at less power than the XTi's, but sound a ton better at -6db than the XTi's did at clip.

I do agree, the 728 needs a few hundred watts to get loud, but if you were to measure how much voltage your speakers are getting when it sounds good, I think you'd be surprised.  There's an insignificant difference between 2000w and 3000w especially when you think about how much additional heating (and thus power compression) that extra power adds.

I've really never seen a driver that benefits much from over 250w RMS.  The power demands of increasing volume force the cab to dissipate more heat, etc.

My observations/measurements lend me to believe that huge power handling numbers are insulators for the companies warranty as well as letting them pad their spec sheet peak numbers.

Just out of curiosity - have you ever used yours with any high quality 2kw amps?  Lab Gruppen, ITech, etc.
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Caleb Dick

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Re: JBL SRX-728 or EV QRX-218? Which best for my music style?
« Reply #26 on: October 06, 2009, 09:08:35 pm »

The difference between small and large amps, as well as cheaper vs higher quality, isn't the extra dB or two.  It's for reproducing the transients accurately, and likely other good things.  

Headroom is your friend, especially with subs.

Caleb
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Caleb Dick
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Experience is something you get just after you need it

Tom Reid

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Re: JBL SRX-728 or EV QRX-218? Which best for my music style?
« Reply #27 on: October 06, 2009, 10:21:14 pm »

Differential drive was made for guys who thermalled too much stuff in the 80's.  

A single loudspeaker that can take a 3200w peak is built pretty rugged.  Rugged things don't respond as well as fragile bits and need a little more encourgement to get moving.

I like an Itech 8k on the woofers.
A bridged xs1200 will clip a breaker if it clips too many times.
I have A/B Lab Grup with other amps.
I have not run the on 728s.

I know what the hear and feel when a loudspeaker gets into power compression and there ain't no more and before it starts to smell ...  I don't get to that point.  
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tom

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Bob Leonard

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Re: JBL SRX-728 or EV QRX-218? Which best for my music style?
« Reply #28 on: October 06, 2009, 10:26:48 pm »

Caleb Dick wrote on Tue, 06 October 2009 21:08

The difference between small and large amps, as well as cheaper vs higher quality, isn't the extra dB or two.  It's for reproducing the transients accurately, and likely other good things.  

Headroom is your friend, especially with subs.

Caleb


I agree to the above statement. The OP asked what would be the best sub for his type music. My answer would be the sub you LISTEN to that's powered properly and sounds the best. Powered properly is 2x long term power rating, or for the SRX 728 that would be the 3000 watts already mentioned in this thread. Will the OP ever use all of that power? Probably not continuously, but he'll need the HEAD ROOM.
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Jim Smith

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Re: JBL SRX-728 or EV QRX-218? Which best for my music style?
« Reply #29 on: October 06, 2009, 10:44:18 pm »

Tom Reid wrote on Tue, 06 October 2009 21:21


I have A/B Lab Grup with other amps.
I have not run the on 728s.

I know what the hear and feel when a loudspeaker gets into power compression and there ain't no more and before it starts to smell ...  I don't get to that point.  


Wow......Matt Viv couldn't have said that any better.  Laughing
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