Need SUB help...

V

Vinny D'Agostino

Junior
Jan 12, 2011
268
0
0
56
Warwick, Rhode Island, United States
I can't decide what to do, and why I am getting the results that I am. (so this all could be me!)
I have (2) different subs that I use:
EV QRX218s - powered by a QSC RMX4050HD (1-per channel, 1300w @ 4ohms)
Yorkville LS801P - Active sub with a 1500w Program powered amplifier (which I assume is really just 750w?)

I use two different systems because people hire me alot of times with there eyes (weekend warrior type gigs).
Large system is (2) EV QRX218s & (2) Peavey QW3f
Small system is (1) Yorkie LS801P & (2) RCF ART325i

People pay me more for the *larger* system because it looks more "Rock & Roll" to there eyes, even though I tell them that my smaller system is just as good if not better.....but they don't believe me.

What I need help with is I just don't know what to do with the EV QRX218s!?
On a 1 to 1 comparison the LS801P destroys the QRX218, this in my mind should not be happening.
The EV QRX should be a much better sub in terms of output and sound quality, at least that is what my bank account has told me.
Side by side in my basement I switch back and fourth between the two, bringing the RMX4050 too just flicker the clip lights on the amplifier, I do the same with the powered LS801P just getting the yellow limit light to flicker.
The QRX218 should be moving more air as there is more cone surface area, but the LS801P is clearly the winner.
Both in output and bottom end.
I am using in my test the QW3f high packs with both subs, I have both subs crossed at 90hz by an Ashly XR1001.
My EQ on the QRX218 is completely flat from 100hz down, when I switch to the LS801P I actually cut 6db @ 80hz to get rid of the annoying boom sound the sub has.

WTF am I doing wrong??!!
I am looking at larger amps for the QRX subs thinking they are not getting enough power, but even at that, I don't know if it will make them any better then the LS801P seems to be.

Am I missing some EQ or more power solution that will help the QRX? or is the LS801P just a better sub?

Please help!
Thanks,
Vinny
 
Re: Need SUB help...

Vinny,

You are assuming that limit lights mean the same thing and indicate it usefully. I have no experience with the EV sub, but the Yorkville sure has a lot of HF output. It could be that dissimilar equalization curves are telling you something that doesn't exist.

It could also be that the Yorkville is louder. Do they sound as good at max output?
 
Re: Need SUB help...

Couple things Vinny... you are comparing front loaded subs to horn loaded subs! In my experience, horns typically produce very efficient forward spl's, compared to omni-directional front loaded boxes. Secondly, horns can have a "different" kind of sound... I find them more "punchy". They are often more efficient at the higher sub frequencies.

I am a HUGE fan of horn loaded subs! They are much more directional, putting more sound forward, than rear-ward, or to the sides. They usually work even better paired (or in groups)... and there is additional spl gains to be had when horns are coupled. Center clustering is usually best when it is an option.

Ironically, the LS801P design looks to me like an old-school "scoop". The old scoops I have will blow away my JBL718's above 50hz. While your ears are probably telling you the truth, you should consider doing metered SPL comparisons at different sine-wave frequencies. Just be aware of proper testing proceedures to get accurate results. Flickering LED's really don't mean much, especially from different amps and brands. Getting voltage readings from a powered box may not be a practical option either. Of course, you can always just go for max output readings.

Cheers!
 
Re: Need SUB help...

A few things,
First I have NO DSP, so setting a delay for the tops is not possible.
I don't have any fancy metering things, I just have my ears.

But, I did go play with the QRX subs a little bit with what I have.
I took just (1) QRX218 and I ran the RMX4050HD in bridge mode for power, this on paper should be 4000w @ 4ohms.
I know this is way to much power for this sub so I depended on what is left of my hearing to listen for signs of stress from the sub.
It made a big improvement on the performance from what my ears tell me.
The sub certainly had more output and hit harder, as it should seeing how it was beeing powered with 2500w more then it was used to.
Here is the thing,
I don't really want to sell what I have, it's all paid for and makes me some nice money.
I do want better performance from the QRX subs, and I want the best way to achieve this.
I have been looking at replacing the amplifiers with something more effecient and higher output.
Should I look for (too me) big dollar amps like the QSC PL380 & Crown MA-I series, this way I would not have to bridge any amplifiers into my cabs....or, is it worth while to go with something like the new Crown Drive core series or Peavey IPR series running them bridged and finaly getting a DSP.
I am thinking an amplifier in the 2500w @ 4ohm range would be about right for the subs, as that is there program rating.
And, I probably should move out of the stone age and get a DSP either in the amps or a seperate unit.
 
Re: Need SUB help...

Vinny,
Your crossover point is too high on the QRx subs. Move it down to 70-80hz and I bet you'll like the way they sound a lot better.

Also, there's no replacement for displacement. You're only hitting those QRX's with their RMS power rating. Something that puts out around 2200w @ 4ohms will be a much better match for those subs. It's that extra voltage on the peaks that will give you the extra punch you're craving.


Evan
 
Re: Need SUB help...

Evan Kirkendall said:
Vinny,
Your crossover point is too high on the QRx subs. Move it down to 70-80hz and I bet you'll like the way they sound a lot better.

Also, there's no replacement for displacement. You're only hitting those QRX's with their RMS power rating. Something that puts out around 2200w @ 4ohms will be a much better match for those subs. It's that extra voltage on the peaks that will give you the extra punch you're craving.


Evan
Click to expand...
I was playing around with the crossover point, it's just hard to tell where it really is on the XR1001.
I am considering the Crown MAi5k for the subs, that would power them right at there program rating.
They certainly did wake up with the wattage I threw at them from the 4050hd!
 
Re: Need SUB help...

Vinny D'Agostino said:
I was playing around with the crossover point, it's just hard to tell where it really is on the XR1001.
I am considering the Crown MAi5k for the subs, that would power them right at there program rating.
They certainly did wake up with the wattage I threw at them from the 4050hd!
Click to expand...

whooooooa Throwing 2200w at those would be asking for a close relationship with your local recone shop. At least without a limiting scheme. I think your main issue is the quality of amp you are using... You could throw a Crest CA12 on them and they will sing... Because of the quality of the transformer and its ability to react to transients. The LS800P has a high quality amp in it with a processor which is why it performs so well. The QRX subs are not my 1st choice because i feel the drivers are a bit weak for what they cost. But you should still be able to do some damage with them if you choose the right amp.
 
Re: Need SUB help...

Audioeast said:
whooooooa Throwing 2200w at those would be asking for a close relationship with your local recone shop. At least without a limiting scheme. I think your main issue is the quality of amp you are using... You could throw a Crest CA12 on them and they will sing... Because of the quality of the transformer and its ability to react to transients. The LS800P has a high quality amp in it with a processor which is why it performs so well. The QRX subs are not my 1st choice because i feel the drivers are a bit weak for what they cost. But you should still be able to do some damage with them if you choose the right amp.
Click to expand...

Mr Audio East

You need to change your name.

It appears you missed the entire point of what Vinny is trying to do. He's looking for lighter amps, not bigger, heavier ones than he has. :lol:

There is absolutely nothing wrong with having a giant amp, even on the tiniest driver, it is all a matter of limiting. Obviously, the MacroTech i series has excellent 2-stage limiting built-in, and would be a great match for any driver from 2 watts to 2000. In fact, the extra peak power would help him to get more "punch" out of his subs (without blowing them or exceeding RMS power), as a kick drum doesn't have much heating potential for the voice coil, but bass guitar and synths do.

Your experience seems to be limited to the old "heavy iron" amps and analog crossovers, in which case, limiting doesn't exist, and matching amp wattage to load power capacity is far more critical.

Vinny, I'd be happy to stop by and assist you with Smaart and your subs. Due to room modes, testing subs in your basement is nearly impossible, as moving 2 feet could change the perception of sub loudness. You need to do your comparison outside.
 
Re: Need SUB help...

Silas,

Please just use the post reporting system (triangle with exclamation mark at post bottom left) when you encounter a user who hasn't yet changed to their real name. Dan is no schmuck, he's a long time community member, your rudeness is uncalled for.
 
Re: Need SUB help...

Here is the reply I received from EV about my amplifier/sub issue:
I am not too familiar with the QSC RMX series but I think those are entry level
amps. So with that said it may very well be that the amp is just running out of
gas, because at 50' you should be able to achieve an SPL of approximately 105dB
with the 1300w of power and still have about 3db of head room. Our CP4000s,
which is a mid level amplifier that delivers 1200w of power, does a good job of
powering the QRX218. If you want even better performance you could upgrade to an
even higher end amplifier like a P3000 or a TG series. Or you could stick with
QSC if you feel more comfortable with there amps but make sure you get a higher
end amplifier. You can call up QSC and see what they tell you about the RMX
series and ask them how well it handles sub frequencies. I really think the
amplifier is just running out of juice. So to answer your question an amplifier
with 1300-1400watts should be enough power to drive the speaker to full output.
Click to expand...

They seem to feel it is the amplifier I am using (which I never doubted that it could be).
So if I upgrade the amp I could go higher power with DSP limiting, or, power them like I have been but just with a better amplifier.
 
Re: Need SUB help...

Bennett Prescott said:
Silas,

Please just use the post reporting system (triangle with exclamation mark at post bottom left) when you encounter a user who hasn't yet changed to their real name. Dan is no schmuck, he's a long time community member, your rudeness is uncalled for.
Click to expand...

Hey Bennett! I wasn't trying to be rude, I even used the laughing smiley face thing to show how lighthearted I was being. I certainly wouldn't have phrased it "Mr. Audio East" if I were trying to be rude, becuase I do know who Dan is, too!

Hope he didn't take it the wrong way, I was just kidding around.

Sorry guys-
 
Re: Need SUB help...

Evan Kirkendall said:
Vinny,
Your crossover point is too high on the QRx subs. Move it down to 70-80hz and I bet you'll like the way they sound a lot better.

Also, there's no replacement for displacement. You're only hitting those QRX's with their RMS power rating. Something that puts out around 2200w @ 4ohms will be a much better match for those subs. It's that extra voltage on the peaks that will give you the extra punch you're craving.
Click to expand...

Evan,

Wasting money for 2dB more output would be silly. If the subs don't get it done with the 4050, they ain't gonna get it done with a bigger amp either.

Has anyone mentioned a polarity problem? That's my guess for the QRX system... that or some severe room issues.
 
Re: Need SUB help...

Ryan Lantzy said:
Evan,

Wasting money for 2dB more output would be silly. If the subs don't get it done with the 4050, they ain't gonna get it done with a bigger amp either.

Has anyone mentioned a polarity problem? That's my guess for the QRX system... that or some severe room issues.
Click to expand...

The difference between a bridged (or even stereo) low-quality amp and a pro-quality, class D or I amp of the same power, is nothing short of huge in my experience. The overall power may not be much more, but the vastly better sound quality and cone control is beyond worth it in my opinion. Not to mention the limiters allow one to hit the subs much harder without fear of blowing them up, getting every last ounce of output from them.
 
Re: Need SUB help...

Ryan Lantzy said:
What about within the box?
Click to expand...

That I will have to check, I still don't think it's a polarity problem because the sub comes to life with the 4050hd in bridge mode.
I just can't run it that way as it is way too much power.
I will open the sub up and take a peek when I get home, but I am thinking the answer is just to get a better quality sub amp as the EV rep mentioned and others here as well.
But, it's still a big decision on which make/model/price!
 
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