EV QRX 218 Subs

[agedhorse]

No problem.

[Mogwix]

I've been finding the scheme of overpowering speakers rather common in my experience with other sound companies, and even or especially with the big guys. I'd say 9 out of 10 rigs I've worked with (on crew) have their woofers grossly overpowered, such as an FP6400 bridged into each SB28 . When I mention this to the system tech they generally always tell me that subs don't open up until you give them a lot of power, with the side comment of "set your limiters".

 

Then later in the discussion we're talking about the subwoofers themselves, and system tech comments that "yeah they sound great, but they're kinda unreliable. I mean, once you get pushing 'em into a good groove they just crap out on ya."

"Maybe it's cause you're throwing 6400 watts into a 1225 watt speaker?"

"Nah man, they're supposed to be able to take that kinda punishment"

 

Then a month down the road I get a call asking if I want to buy a pile of blown SB28's for dirt cheap. They've decided to buy a different subwoofer because "the SB28's just keep blowing on us".

[Unalaska]

You'd think that in the current econimic conditions that most people would want thier equipment to last. I can't say I'm not guilty of blowing drivers, it just happens to be the carvin PS12's and a few older 22xts in some monitor cabs. To be far 1ea PS12 and 22xt had the magnet shift, the others I did overpower and I'm sorry. OK, I admit it, I blew them up myself. I can't wait til EWI has the APX2206 in stock again. As for the actual JBL boxes, they're all on original cones.

 

another side note: When I used to sell EV in the late 90's, they would rate their cabs from low to high...

200w Continous Program

400w RMS

800w Peak

 

And it kinda makes sense. Under heavy compressed music 200w would be about right, more dynamic would be 400w. 800w would be to make sure the amp driving it couldn't send that much to it. EV would recommend most end users to power around 1.5 times the cont. prog. rating, or around 300w. Seems like a good compromise...

[agedhorse]

Multiply the cost of repair by a dozen cabinets and now you are talking about real money too.

 

I have maybe 150 drivers in my inventory. If I had to recone them every 5 years (reasonably common in the pro world), that's almost $15k or $3k per year in real operating cost. I typically get 20+ years before needing to recone, so over 20 years, that's a savings of $60k.. well worth being conservative IMO. Heck, the savings is more than many of you guys will make (as profit) in this business over your lifetime. That's how significant this is.

[Unalaska]

In the case of the EVX driver, 2x 600w, EV would recommend around 1800w per box or 900w per driver. (close to the 1000w rating they also give the same driver depending on what lit you're reading)

[agedhorse]

 

You'd think that in the current econimic conditions that most people would want thier equipment to last. another side note: When I used to sell EV in the late 90's, they would rate their cabs from low to high... 200w Continous Program 400w RMS 800w Peak And it kinda makes sense. Under heavy compressed music 200w would be about right, more dynamic would be 400w. 800w would be to make sure the amp driving it couldn't send that much to it. EV would recommend most end users to power around 1.5 times the cont. prog. rating, or around 300w. Seems like a good compromise...

 

 

Yup, those were the days where real performance sold product, not marketing numbers and glossy ads. Conservative was the nature of real pro audio.

[Unalaska]

In can remember really trying to justify the expense of the (very new at the time) RMX1450 over the EV7300a for FOH full range boxes (EV S15's). The difference was 260w @ 8 vs 200w @ 8. When I got an EV 7600 I didn't know what to do with all the power. But math quickly makes 600 @ 4 turn in to 300w @ 8 x 2. oh well.

[kennyp]

 

You'd think that in the current econimic conditions that most people would want thier equipment to last. I can't say I'm not guilty of blowing drivers, it just happens to be the carvin PS12's and a few older 22xts in some monitor cabs. To be far 1ea PS12 and 22xt had the magnet shift, the others I did overpower and I'm sorry. OK, I admit it, I blew them up myself. I can't wait til EWI has the APX2206 in stock again. As for the actual JBL boxes, they're all on original cones. another side note: When I used to sell EV in the late 90's, they would rate their cabs from low to high... 200w Continous Program 400w RMS 800w Peak And it kinda makes sense. Under heavy compressed music 200w would be about right, more dynamic would be 400w. 800w would be to make sure the amp driving it couldn't send that much to it. EV would recommend most end users to power around 1.5 times the cont. prog. rating, or around 300w. Seems like a good compromise...

 

 

So would you guys say that the QSC RMX5050 rated at 1800 watts per side @ 4 ohms, and throttled back some, is ok on the QRX 2-18" subs then since the continuous is 1200 watts. I am going to also look at the limiter settings as Agedhorse suggested on the Driverack.

 

Is there such a thing as damage from "underpowering"......if an amp clips does it cause damage? Or does the listener just hear bad sound reproduction?

[allexcosta]

 

if an amp clips does it cause damage?

 

 

It could.

[agedhorse]

If you have limiters engaged and run normal (ie. proper) gain structure, clipping is not going to be an issue.

[Unalaska]

With proper limiters and HPF set 1800w should be fine. For specs you can always check the actual archetectual specs on EV's (crappy) website. They used to be fairly detailed on how to set HPF and slopes though many times when I read then 10years ago EV recommended a 12dB slope. 12 and 18dB/oct slopes were much more common on crossovers back then and many amps had plug in cans to set those points.

[witesol]

are we all assuming in these discussions that everyone has a Driverack or similar product? I still see a lot(own a couple too) analog Xovers

[B. Adams]

 

So would you guys say that the QSC RMX5050 rated at 1800 watts per side @ 4 ohms, and throttled back some, is ok on the QRX 2-18" subs then since the continuous is 1200 watts.

 

 

I worked for a company a few years ago that used RMX4050's on their QRX218's, one sub per channel. It seemed like a good match for those boxes. A 5050 might be too much.

[Unalaska]

The difference between 1600w at 1800w isn't much at all. The 4050 is nice though since it could drive a 2nd pair...

 

Driveracks are nice but a decent analog crossover works just as well. Only problem s many analog xovers have fixed or no HPF on the LF band at all so it limits choices. Also no limiters either. Still I find many DRPA users in the area that really don't know what they're doing at all and would be better off with the analog alternative.

[agedhorse]

If you size the amps reasonably, and the amps have HPF's and limiters, you are most ofthe way there. Add to that an analog x-over that's 24dB/octave LR alignment (most common these days) and you have the basis of a pretty reliable system. The key is reasonably sized amps.