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Author Topic: EV EKX18sp and QSC KW181 vs EV ELX118p  (Read 23717 times)

Richard Penrose

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Re: EV EKX18sp and QSC KW181 vs EV ELX118p
« Reply #20 on: January 04, 2016, 02:55:30 AM »

Thanks Luke. Yes I agree the SRX818sp would be he one I'd get if I could afford it but unfortunately it cost a lot more than I can afford!
Whilst the EV ELX specs say it puts out 134dB and can get as loud as the PRX718xlf, everyone I've spoken to says the JBL goes quite a lot louder. Most say the QSC goes a little louder than the PRX.
The DXS18 is too big and heavy for me so I've ruled that one out.
The QSC is a strong contender for me at the moment and I'm wondering if it will go as deep as the ELX118p's in real world performance?
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Andrew Zannetos

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Re: EV EKX18sp and QSC KW181 vs EV ELX118p
« Reply #21 on: January 04, 2016, 02:12:29 PM »

I've heard that while the ELX118p does sound nice, it limits very early relative to the mid-tier subs like the KW181 and PRX718xlf (hence the large price difference).

While the QSC doesn't reach extremely low, I will admit it has a very nice knock to it.  I will share a story of their performance in the real world. It might've been the room, but I was at an event where the DJ used 2 PRX712s or 15s over a QSC KW181, and I didn't realize they were using a subwoofer until about halfway through the event when there was an 808 that sounded way too loud for them not to be using a subwoofer.

I know you said the SRX is a bit too costly--however, if you're looking at current SRX800 series below MAP prices, they're about $100 higher than they were initially--if you're willing to do some haggling, the SRX818 can be had for under $1300.
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Luke Geis

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Re: EV EKX18sp and QSC KW181 vs EV ELX118p
« Reply #22 on: January 04, 2016, 05:37:57 PM »

I still think you are throwing money away. They may get louder at one frequency or another, but will they get so much louder that you never have to worry? If you are getting what you need with what you have, then why change it up? If you actually need more output you may want to consider changing your whole approach?

The SRX-818SP is rated for 135db peak while the dual 18" 828SP is rated for 141db peak!. This is a 6db difference. Now it does not matter if they will actually reach their stated peak values, but it is highly likely that the 828SP will be about 6db louder than the 818Sp in real world use. It would take 4 818SP's to match the output of 1 828SP....... Now I'm no mathematician, but 1 speaker that costs only $2k vs 4 that would cost $5k seems like an obvious choice.

You're reaching the point of diminishing returns. If you want more for the sake of more, then have at it. If you actually need more, then you will have to sell off what you have and reconsider your true goals. To me this is not getting rid of one perfectly fine speaker and spending more for another one that is only marginally better in spec. The ROI is important. Two speakers in the same class rent for the same amount, so spending more to get a little more isn't going to earn you more. You simply decreased your ROI. Now adding more of the same to your inventory does cost more as well, but gives you options and allows you to charge even more if the client wants the added performance gains. This can increase your ROI if you can move the inventory. If your always going to go out with 4 subs you can factor that into your cost and increase your return.

The single 18" market is just so close in performance that if you need more than a pair will provide your either going to have to spend real money to get a true performer, or simply stock more of what you have. What you have is not bad and should perform quite well. If not look more into what you can do to improve the performance. There is a couple ways to get some free SPl. One is clustering the subs together, another is putting them on their own AUX feed ( it saves headroom for the instruments you really want to hit hard ) and you can also work with limiting to decrease the dynamic range and reduce the crest factor. Mixing technique is another way. Eliminating low end content from instruments that don't need to extend that low can free up more headroom and make it easier to hear things that do rely on that sonic space. I think in most instances the equipment is not the under performing part of the whole system; it's the user a lot of times.......

We are asking mid tier systems these days to do more than was even possible for top end pro level stuff 20 years ago of similar design to do, and we keep demanding more. A single 18" sub that produced 135db and only cost $1k was unheard of 20 yeas ago. Somehow the PA's of that day managed? The technology of bands has not changed at all. We had 100 watt Marshall amps just as much then as we do now. So why do we need a pa now that could best a pro level PA from back when by an easy 20db? Be realistic in your goals and seriously consider what you need and what your being paid to do.

There is a reason the saying not enough rig for the gig came to be. It's because people are using systems that are under spec'd and taking gigs they truly couldn't support. If your finding that your system is under powered for the majority of the gigs you take, then you are undercutting someone else who has the right stuff to do the job better. You at that point should really consider stepping up your game and or being more realistic with what you can do. Don't take a job that you can't properly support. If you do then spread the love by renting equipment that will properly do the job. If you want to continue taking those jobs then seriously upgrade your system so your not always on the edge and charge appropriately. I think trading equipment around is foolish from a goal oriented standpoint. So the KW is a little bit louder, big whoop, does it sound better? Perhaps so to you? Your going to replace a $600 speaker with a $1k one and only be able to charge roughly the same rate for it. You gain a little bit of headroom and still can't take any bigger a job with it. Seems like a loss to me. You could get another pair of the same subs you have for roughly the same cost of one of the KW's and get the same results and have more options with it and charge more for it.
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Andrew Zannetos

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Re: EV EKX18sp and QSC KW181 vs EV ELX118p
« Reply #23 on: January 04, 2016, 06:22:14 PM »


The SRX-818SP is rated for 135db peak while the dual 18" 828SP is rated for 141db peak!. This is a 6db difference. Now it does not matter if they will actually reach their stated peak values, but it is highly likely that the 828SP will be about 6db louder than the 818Sp in real world use. It would take 4 818SP's to match the output of 1 828SP....... Now I'm no mathematician, but 1 speaker that costs only $2k vs 4 that would cost $5k seems like an obvious choice.

It will only take 2 SRX818sps coupled next to each other to reach the SPL of an 828sp (that's why the the 828sp is rated 6dB higher-- +3dB with double power and +3dB from coupling.)
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Luke Geis

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Re: EV EKX18sp and QSC KW181 vs EV ELX118p
« Reply #24 on: January 05, 2016, 12:43:18 AM »

It will only take 2 SRX818sps coupled next to each other to reach the SPL of an 828sp (that's why the the 828sp is rated 6dB higher-- +3dB with double power and +3dB from coupling.)

That is incorrect. You only get a 3db boost for every doubling of power. So 1 x 818 = 135db , 2 X 818 = 138db and to get another 3db requires double the power again so 4 x 818 = 141db. coupling and doubling the power are basically interchangeable. Keep in mind we are already considering these to be rated for half space loading, so you can't count that gain anymore. You don't get +6db by simply taking 2 subs of equal power and putting them next to each other, you get +3db. Now even when the subs are spread apart you will get spots where they couple and create a +3db addition ( again from double the power ) but with comb filtering elswhere. This is what creates the power alley in a stereo deployed sub setup.  Up the middle ( the power alley ) the two subs are equidistant and the output from them couples and increases SPL. Placing the two subs together nets the exact same thing with reduced comb filtering. This is why center clustered subs is desirable in many situations.

However we should define the difference between coupling and doubling of power. Having two subs that sit together that are not equal in output or frequency response are what is known as " NON LINEAR " ( the output between the two doesn't match ). Where the output and response does match you will get coupling or addition and where the response between them doesn't match, you will have either a little bit of subtraction or addition that is disruptive to the performance of that system. The amount of course depends on how close in output and response the two subs really are or not. Now with doubling of power you follow the same rules as simply adding twice the wattage to the same speaker. If you have 1 speaker powered by 100 watts and it produces 100db, then you provide 200 watts to that speaker, its output will increase by +3db. Now if you take two identical speakers with identical power you will have the exact same scenario as with twice the wattage. One speaker alone would be 100db and adding the second will net you the other +3db.

Now half space loading is a whole different story. It is a form of coupling. The speaker, if placed in a whole space ( imagine it sitting 100' in the air ), would radiate energy in pretty much a 360 degree radius or whatever directional control the box can provide. Now if you place the speaker on the ground, half the " area " around it has been converted into an infinite baffle. The ground becomes a directional baffle for the speaker. This means that you have the same amount of energy in half the space, or the same as doubling the power. This is why you add +3db to a speakers output when you place it on the floor. Now regular speakers don't follow this rule as well because the horn and box design helps direct sound in a direction already, so only coupling in the lower frequencies occur. This is why you roll off the low end in monitors. A sub on the other hand is pretty much omni-directional. It will radiate energy in all directions pretty much the same, so when placed on the floor it couples with it really well, and the full +3db can be noticed at pretty much all frequencies it produces.

So while it would seem to make sense that placing two 818 subs together should equal one 828 it isn't always that easy. The design of the box has a large part to do with it. The frequency response between the two speakers is the same in this case. It is possible that JBL tuned the 828 to get the high SPL instead of utilizing its entire possible frequency range? Giving up bandwidth for power is a good way to gain some SPL. There is also this little tidbit. JBL uses differential drive woofers. The driver in the 818 and 828 use a dual voice coil and each voice coil is rated at 2ohms. It is possible that in the 818 they ran the voice coil as a 2 ohm load and in the 828 it could be possible to run the amp down to a 1ohm load? Don't think it to be funny, they are running a lot of their other differential drive speakers at 1ohm!!!! Not knowing exactly how they managed it, I am only speculating. What we do know is that one amp is 1000 watts and the other 2000 watts and that one speaker has a single 2 ohm driver in it, and another that can either have a 1 ohm or 4 ohm load in it. Now if you double the power at half the load, you can nearly quadruple the efficiency; couple that with two drivers in a single box, you may be able to coax out the other 3db to get the +6db advantage the 828 claims to have over its little brother? That's what I would try and do anyway......
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Lyle Williams

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Re: EV EKX18sp and QSC KW181 vs EV ELX118p
« Reply #25 on: January 05, 2016, 01:13:48 AM »

If a cure for gear aquisition syndrome is sought, design and buy a "final" coordinated/matched system.  Then just use it.  Incremental upgrades towards an undefined goal system just result in future incremental upgrades.
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Andrew Zannetos

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Re: EV EKX18sp and QSC KW181 vs EV ELX118p
« Reply #26 on: January 05, 2016, 02:19:16 AM »

You don't get +6db by simply taking 2 subs of equal power and putting them next to each other, you get +3db.

Granted coupling yields varied SPL changes depending on a multitude of factors, taking two identical subwoofers and putting them right next to each other will in theory provide an extra +3dB as opposed to spread apart.

From an EV MTL-1 subwoofer manual: "When two speaker systems are placed side by side, the woofer cones mutually couple, causing the two systems to act as one system with twice the effective cone area at very low frequencies, giving an additional 3-dB increase in maximum acoustic output. Mutual coupling will occur when the frequency is such that the center-to-center distance between the two woofer manifolds is less than about one-half wavelength."

The SRX818sp and 828sp are tuned exactly the same--the JBL SRX828sp has nearly the same dimensions and the same frequency response as two SRX818sps placed together (I assume that two 818sps are slightly bigger because each cabinet needs its own DSP, whereas the 828 drivers can share some of the same computers.) The 828sp is just a cabinet with two equally-powered 818 drivers (+3dB) that are mutually coupled (an extra +3dB). That's where the extra SPL of the 828 comes from on the spec sheet.
« Last Edit: January 05, 2016, 02:34:31 AM by Andrew Zannetos »
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Tim McCulloch

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Re: EV EKX18sp and QSC KW181 vs EV ELX118p
« Reply #27 on: January 05, 2016, 06:04:40 PM »

Granted coupling yields varied SPL changes depending on a multitude of factors, taking two identical subwoofers and putting them right next to each other will in theory provide an extra +3dB as opposed to spread apart.

From an EV MTL-1 subwoofer manual: "When two speaker systems are placed side by side, the woofer cones mutually couple, causing the two systems to act as one system with twice the effective cone area at very low frequencies, giving an additional 3-dB increase in maximum acoustic output. Mutual coupling will occur when the frequency is such that the center-to-center distance between the two woofer manifolds is less than about one-half wavelength."

The SRX818sp and 828sp are tuned exactly the same--the JBL SRX828sp has nearly the same dimensions and the same frequency response as two SRX818sps placed together (I assume that two 818sps are slightly bigger because each cabinet needs its own DSP, whereas the 828 drivers can share some of the same computers.) The 828sp is just a cabinet with two equally-powered 818 drivers (+3dB) that are mutually coupled (an extra +3dB). That's where the extra SPL of the 828 comes from on the spec sheet.

Acoustic coupling happens when the 2 source's acoustic centers are within 1/4 wave length.  Note the operative words "acoustic centers".
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Richard Penrose

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Re: EV EKX18sp and QSC KW181 vs EV ELX118p
« Reply #28 on: January 05, 2016, 06:24:05 PM »

Thanks guys. I need to point out I'm not a sound company. I work in various bands and provide pa for small local community events. The reason why I want to change my subs is because during some of the gigs I do the ELX118p's limiter light comes on a lot (not just flickering) and I end up turning the sub down till the limiter oonly comes on with the kick. This ends up with the FOH sounding bass lite. The venues that this happens in are reasonably big plush marquees that sound quite dead acoustically. If I could use the EV's at their full output without the limiter light coming on this would be enough for me. I would like the subs to match the output of my DXR15's and don't need anymore than that. For any gigs bigger than this we hire a company to provide sound.

The EV ELX118p sounds pretty musical to me and not a one note wonder like some subs I've heard other people use. I'm a little worried the QSC KW181 may fall into this category so not sure if this would be the right sub for me.
There are quite a few user reports of people comparing the new EV EKX18sp with the QSC KW181's and they all prefer the sound of the EKX18sp and say it pretty much matches it regarding output. They also say that the EKX18sp goes noticeably louder and deeper than the ELX118p. There's also been a few user reports that the RCF718as goes louder and deeper than the QSC KW181!
I'm hoping to arrange being able to hear these in the next month or so
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Steve Anderson

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Re: EV EKX18sp and QSC KW181 vs EV ELX118p
« Reply #29 on: January 05, 2016, 08:14:58 PM »

That is incorrect.

Actually Luke, Andrew is quite correct.

The term you are looking for is COHERENCY, not LINEARITY. Coherent being equal in both freq response and phase response (as Tim mentioned, within 1/4 wavelength). Being that both subwoofers have the same signal put into them, and are the same model (thus the same phase response across their passband) you will get close to 6dB more by putting two sub side by side (within 1/4 wavelength). So 1 x 818 = 135db , 2 X 818 = 141db

The 1/4 wavelength (90 degrees) mentioned by Tim is the rule of thumb to get some noticeable addition. Destructive "addition" (i.e. the start of cancellation) starts at 1/3 wavelength or 120 degrees. At 120 degrees of time (or space) separation you get neither addition or subtraction.

Dave Gunness' white paper here discusses coherent summation in detail.
« Last Edit: January 05, 2016, 08:19:24 PM by Steve Anderson »
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ProSoundWeb Community

Re: EV EKX18sp and QSC KW181 vs EV ELX118p
« Reply #29 on: January 05, 2016, 08:14:58 PM »


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