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[Grayson Rech]

If someone ask me to research subs and didn't like what I had to say or found out then I would wash my hands of matter if I wasn't the one in first step with whoever is placing the money down.  If this guy knows so much then he should have no trouble tackling this issue.  If he just happens to be in a higher position than you and isn't qualified enough to perform his job then in this instance I would speak with whoever is next up the ladder to address concerns.  The key reason is because it sounds like he's already figured out a plan regardless of your findings and with what would work best and when things go sour after money has been spent watch your back for I wouldn't want to be the one he points to as a fall guy . . . perks of the job of being a manager.  Best of luck to you, you have quite a "sound superior" to deal with.  As for subs and what not, perhaps a demo from another rig (rent, borrow, convince a local store for a test before you buy) will shed some light on what is "needed" and what is the "myth".  

. . . and I say unto thee shazbot!
Hoob

[Bill Horn]

 OK I'm reading between the lines a bit here...

It sounds like the church is replacing all FOH boxes? The decision to get rid of the Crate tops ( I hope) has been made? If so, I would hold off on a sub decision for now. Get used to the sound of your new tops...whatever they are they're going to sound better than what you have, and since sonic information that defines kick and bass as such comes from frequencies above 100 Hz your new tops may actually clean up the apparent mud from your subs somewhat.

Now...area you offering to donate your time in constructing the subs, or are you in business...essentially in competition with commercially built products? If the latter is true, you need to drop the matter of homemade cabs and abide by the decision of the church. If it's the former, build a couple and donate them, or keep ownership and let the praise band use them for free and consider it as part of your tithe.

I've built all the cabs my club band uses myself...four 18's, four tops, all the monitors...but I didn't charge the band for them (they're mine of course). I get asked to build cabs for people all the time, but politely decline because once I figure in my time the cost will be pretty close to a commercial product, and their resale value would be almost nothing. But I've let my church borrow whatever I can help them with when they need it.

[Chip Prendergast]

I am currently constructing dual 18" using the Peavey Low Rider.  I never even gave Peavey any thoughts but after seeing how many people on this board rave about the QW18 I checked into the drivers and found them for $179 ea at www.8thstreet.com.  That's pretty cheap.  When I ran the design through software I come up with no overexcursion at 1700 watts and 133 dB at 45 Hz.  Should have this finished in a week or so.

People on here are quick to say build a LAB sub and I looked into it.  For me cutting all the pieces with the many different angles and such is way beyond my woodworking experience or tools.

Speaking of Selenium (I checked them out and the Peaveys blow them away in software design)but they had some interesting horn loaded 12" mid/hi box plans (but same problem cutting all the pieces).

[[x]]

Money's always tight, and we've decided that we need to go ahead and replace our FOH boxes because we think that will do us more good than the sub upgrade at this time.

What do people here think about the JBL MPRO MP412 cabs? Or would we be wasting our time with those as compared to JBL SR4722X tops? Again, the primary consideration here is how much bang for the buck we can get.

[bo putnam]

BHFProfessional wrote on Mon, 30 August 2004 09:21

Transportation is a big concern. Right now, we have a pickup bed to work with. I think they need a covered trailer, but we have a very limited budget. Our current subwoofers are Peavey dual-15" in bandpass enclosures. They are very boomy and indistinct, which led our sound guy to the conclusion that the room was being "overpowered" by them, which is why he wants to step backwards to single 18s when we buy new subs. I think that idea is dumb, dumb, dumb, but as I said before, our sound guy doesn't really place that much stock in what I have to say. The reason why the room seems to sound so bad is because the mains we were using are Crate brand, with cheap 15" woofers and made from 1/2" particleboard material with no inner bracing, thus boomy, indistinct midbass, further exacerbated by the subwoofers' poor transient decay and majorly not-flat frequency response.

You might look into the EV Eliminator subs.  They are a single transverse mounted 18-in that many have real good luck with.  Paired with either EV's Eliminator Mains (15-in 2-way) or even better the EV QRx 115/75 main (better 15-in 2-way) are superb combos on a budget and space-restricted.  I would strongly suggest you go to the Ashly XR-1001 stereo 2-way crossover - it's flexibility really brings out the optimum crossover point and character to the response curve.  Check them out: http://www.ashly.com/product/xr-series.htm  Your audience will be very, very appreciative.  I concur with the potential boomy-ness of dual-subs - they can easily overpower / outweigh small rigs.  

BHFProfessional wrote on Mon, 30 August 2004 09:21

I have advised him that our new mains need to use 12s instead of 15s for better midrange clarity, and that they need to have better build quality. He said that made sense.

I do not agree with that - just MO.  You can get excellent voicing with the right transducer / cabinet combo.  Staying with EV here, their Ring Mode Decoupling (RMD) cabinet design minimizes standing waves (feedback) and has great voicing / clarity.  I think overall your frustration is a combination of transducer and  poor cabinet design.  

[yam4000vca Jim Gould]

I am trying to sort this thread out in my head as it has covered a lot of ground.
First good call as to replacing the Crate mains boxes with something else. Subs are nice but the main boxes here are more important.
You say the word bang for the buck. That is good but then you mention JBL. I think JBL is a good product but for you I think there are several other brands that would give you more bang for the buck. Peavey,Yorkville Community come into my mind as being better than JBL in the leauge you are in. At least the lower lines of JBL. It is not fair to compare the lower lines to the SRX which in my mind is where JBL starts but still a bit pricey for many.
You also state that you have built many hifi projects. That has given you SOME background but the things that matter in a box for live or pretty different in several ways. You also mention the word extension. I am not sure what exact frequency you are tryng to obtain live but it is probably lower than what really matters in this case.
In general I prefer a 12 above an 18 in a 3way system. That is my preference and not meant to mean that 15s can not work too.
I think one of the main things that you can do to sort all this out is to forget about the real time part of the DriveRack and bring in someone that really knows to optimize the whole system for you.
There are many ways to do this but I do think with the proper set up you may be suprised what your current subs can do.

[[x]]

Well, as far as tops go, which do you think would mate the best with our dual-15" Peavey subs? I am looking for something that will do great in the midrange and not suck away all our budget for music stuff. I think that a two-way 12" cabinet would be the best balance with the dual-15's down below handling bass duty. I'm looking for something that can go loud without being fatiguing, since a large part of what the PA is amplifying is voice. The room is a large lecture hall with a balcony that sometimes gets filled, and about 400 seats.

Suppose I'm considering the MPro MP412 cabinet. What other models from other manufacturers would you suggest that I look at as a better alternative, while staying under $650 per box? (The MPros are $579 from Sweetwater.) Again, there will be acoustic and electrified instruments, drums, vocals, and voice being carried by these, and a Peavey Dual-15" subwoofer enclosure will be handling bass below 250 Hz, so that's how they fit into the system.

[bo putnam]

BHFProfessional wrote on Tue, 31 August 2004 17:44

I think that a two-way 12" cabinet would be the best balance with the dual-15's down below handling bass duty.

I don't find size-comparisons (i.e., 12's vs 15's mains), per se, particularly compelling.  What matters is frequency response, efficiency and remaining "linear", or flat as possible.  I see no issue with paring 15-in 2-ways with dual 15-subs.  What matters more is how / where you are crossing over to the "mains", what control you have over the bi-amped configuration, and the linearity of the "mains".  

What is your crossover?  What is your crossover point?  What are the slopes?  

If you use the subs to merely do sub work, i.e., below say 70-90Hz, you will want more support from the mains.  I have used dual 18-in subs crossed at ~150Hz, paired with 15-in 2-ways and have VERY good results.  It's all in the control provided by the crossover.  

Most of your applications don't seem to need dual subs, IMO, but go your own way.  I think a single 18 might be sufficient, based upon the locations I've used same-same.  But I don't use the cabinet brands you are using - their response and your experience will be quite different.  

[bo putnam]

BHFProfessional wrote on Tue, 31 August 2004 17:44

a Peavey Dual-15" subwoofer enclosure will be handling bass below 250 Hz, so that's how they fit into the system.

Oh, wait a minute.  I re-read your post.  I think that high a crossover might be problematic.  It might contribute to "boomyness".  I would be interested in the impressions you get from a lower xover point, -24dB/octave slopes, and handing more off to the mains.  250Hz is well within the Second Decade, right in the vocal range, and any notch/peak at the crossover point will suck.

[[x]]

I have spun off a new topic, "Choosing Main Speakers", because the topic of this discussion os no longer about subwoofers, but main speakers.