Dual 18 incher???

[DrWho]

That system drops like a rock below 50Hz. You can see the freq response on page 5 of the pdf:

http://www.electrovoice.com/Electrovoice3/files.nsf/Pages/MTL-1X/$file/mtl1x-eds.pdf. That cabinet is already at 17 cubic feet as well...I can't imagine wanting to go much bigger, lol.

It sounds like you need to build yourself an IB design if you really really want to use an 18" driver.

I've personally heard and used the MTL-1X (6 of them actually) for an outdoor rig and I must say I was rather unimpressed with them. Ya they went loud, but you gotta have output down to at least 40Hz to get that nice rich deep kick drum sound (and powerful bass guitar). In the room though they probably benefit a bit from room gain. In fact, I was even more impressed with the short demo I got with the dual industrial lascala bass bins that I heard at colter's place.

If you really can support cabinets this big, then perhaps you should be looking into the EAW BH822e:

http://www.eaw.com/products/BH822e.html (-3dB @ 24Hz)

With room gain it should go strong below 20Hz and you're looking at well over 140dB of max SPL.

The best part though is you only need 1 watt to get 109dB! Talk about fast powerful bass.

[masterngc]

That's all great, but I only wanted to use a modified version of the cabinet, the drivers suck unless you've got 8 stacks of the things...

these are the drivers in the ev cabinet:

www.cameronproaudio.com/pdf/evx180b.pdf

but if i put like an ascendant avalanche 18 in them and modified the tuning frequency to be lower.... welll then i'd better reinforce my foundation.. heheh

If rather use this:

http://www.eaw.com/products/KF940.html

with this warning:

A word of warning: high levels of low frequency information can and do cause intestinal distress. Please use these devices with caution.

but those kinds of subs have to be used in groups of 4 or more to be effective...

[rockbobmel]

try this. http://www.billfitzmaurice.com

[DrWho]

The KF940 and BH822e are the exact same speakers.

As far as using them in groups of 4 or more, that's only when using them in PA applications and under such situations where they are sitting in half space or whole space (flown). Putting them in your room in 1/8th space is going to drastically improve the LF response of the system...flush mounting into the wall will even further improve the LF response (so much so that an EQ will be needed to lower the output as the frequency decreases to restore a flat response).

[masterngc]

Ouch... OWNED!! ok, u win..

but i want to build it myself... so buying a cab would take the fun out of it...

but thanks for the suggestions, you know your way around pro audio, we should talk sometime...

[formica]

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On 7/6/2005 12:07:26 PM DrWho wrote:

Mike Hurd and I talk about all sorts of different possible combinations and we always come to the conclusion that it's a huge system of compromises and you just gotta choose what best fits your situation. ... From there it's just a matter of matching a woofer to your situation ...

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Very true... it is all about compromises... no system is perfect. When you decide to DIY, you gain a little more control on adapting the subwoofer to your needs, but you are still restricted to the same physics speaker manufactures are.

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On 7/6/2005 12:56:11 PM DrWho wrote:

well that's cuz the ascendent 15" drivers aren't that good (but what do you expect for $300).

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I'd disagree. You need to reread your other quote... as it depends what you are trying to do with it.

It's a question of compromises and the Ascendant18 does very well considering it was optimized for providing lots of displacement in LARGE enclosures (good efficiency/extension but large enclosure). The Tumult, although it was using the same motor tech, was optimized for small enclosures (good enclosure/extension but POOR efficiency).

Your graphs do not take this into account... as you fixed the enclosure size to 10ft3 and tuning to 15Hz but provide unlimited power. This won't be optimal for all the drivers compared (esp Tumult vs Ascendant).

Also note that optimizing for large enclosures... not only optimizes bass extension and efficiency, but will also result in a less expensive driver and amplification.

Unfortunately not everyone can live with a huge sub, so back to the compromises...

Rob

PS: Note that those EAW subs recommend a very LOW "Recommended High-Pass Frequency 25 Hz, 12 dB / octave Butterworth". Basically it's a trick to flatten the responce of a horn whose responce is falling at 12db/octave. Not sure if efficiency / max SPL is measured with that x-over activated.

[DrWho]

Well I was thinking 10 cubic feet would be as large as anyone sane would want to go

Both of the 18" drivers mentioned will give the same slope as a single 15" Tumult in a 20 cubic foot enclosure and give about 3dB more output...though in that size cabinet, you could drop in two 15" Tumults and now the 18" drivers put out 3dB less.

I guess the way I approach the situation, the enclosure is the limiting factor and that's why I posted the graphs comparing the drivers in the same enclosure with the same tuning (I had already noticed that the optimum for the 18's was 20 cubic feet).

So ya, if you could house a 20 cubic foot cabinet for those 18's then it would be cheaper to go that route instead of getting two 15's and needing twice the amp power.

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I'm not sure what you mean about the high-pass filter on the EAW...A high-pass limits the low end delivered to the driver so it will further decrease the output below 25Hz (aka, making the horn less flat, and not boosting a decreasing slope). I did notice the 146dB peak was a rating for 4 systems playing at the same time, so subtract 12dB and your real peak for a single unit is 134dB @ 28Hz with the same power-handling. That puts you at a max of 124dB @ 20Hz (without the filter). At least I'm pretty sure those specs aren't with the filter installed, but not like you would be using the filter in your home because will never come close to those levels. The -10dB @ 20Hz though would get nicely flattened out by room gain...even moreso if you could fit the unit in a corner.

Unless something better comes out before I get my own place, I plan on using at least 4 of these suckers up front in my HT. That would basically be 2 units that are each 3 feet tall and 6 feet wide which would fit nicely around let's say a lascala center and inbetween two lascala mains...that's like a 24 foot wide front wall with room to spare. It also leaves 2 feet behind the scalas to fit bass traps in the rear corners because those subs are a bit longer that 4 feet (If I line the front faces up).

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If you're going to be making your own subwoofer enclosure and all that, then I would suggest getting this program (which is free):

http://www.linearteam.dk/default.aspx?pageid=winisdpro

Hunting down specs for your driver can be a little tedious at times, but the models turn out to be very close to how it works in real life so it's worth it. Just make sure you don't get carried away with the frequency response of the driver and ignore all the other graphs (especially cone-excursion and the air-velocity in your ports).

[formica]

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On 7/7/2005 5:58:08 PM DrWho wrote:

Well I was thinking 10 cubic feet would be as large as anyone sane would want to go

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The Ascendant18 are / were very popular with the IB crowd... where enclosures of 200ft3/driver are common but the selection of high excursion 18" is not. An array of 15" Tumults in an IB would be to expensive and require massive amplification to be practical.

Both are good drivers, but I think one has to choose a driver which best suites the intended design. I wanted to keep my ported box sub to about 6 to 7ft3... and chose the driver I found worked best in that size. If you are willing to live with 10ft3 (yes, that is pretty large in my book) you have to find a driver which performs well in THAT volume.

With the DIY drivers available today as well as the new Adire releases, there is a driver for most needs...

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I'm not sure what you mean about the high-pass filter on the EAW...A high-pass limits the low end delivered to the driver so it will further decrease the output below 25Hz (aka, making the horn less flat, and not boosting a decreasing slope).

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opps... I read "low pass" ...

EAW are a pretty respectable company, but I just don't see the 25Hz output from a horn with that size of mouth. I'm sure there is something I'm not seeing, but I'm not a horn guru....

Rob

[DrWho]

EAW are a pretty respectable company, but I just don't see the 25Hz output from a horn with that size of mouth. I'm sure there is something I'm not seeing, but I'm not a horn guru....

Rob

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I totally agree that it seems improbable as well, but there's only so far one can stretch specs so it should still be impressive either way. I've sometimes wondered if the horn doesn't start to behave like a 4th order bandpass at the bottom end of its response or something fancy like that. A 13 foot throat has a quarter wavelength of 22Hz (http://www.quarter-wave.com). I've only started reading about quarter-wave designs, but perhaps there is some sort of correlation. The only other thing I can think of is that 4 units start to look like an infinite sized source at 1m...so there might be a 12dB boost due to "flush mounting."

[Jay481985]

DrWho

Sorry to be a thorn in the foot but did you factor other things in winisd other then volume size?

I mean the vented box will need to be much much bigger due to the loss of volume from the port. And I am positive that the tumult in a vented enclosure will need more length (since you put 15 hertz tuning frequency) then most boxes give. So in theory the vented box wins but since you gave only a 10 cubic foot size without subtracting the port, the vented box will need to be much much bigger. Modeling on the tumult 15d4 given full rms power of 1000 watts. I gave the port size the biggest they make of 2, 6 inch flared both sides. It comes to about 62.34 inches for both ports so 5 feet long for both ports which is hard to fit into a 10 cubic foot chamber which should be about 2.1544 feet on all sides if you made a square if the box were 10 cubic feet including port volume. Plus did you add in the port velocity keeping under 17 m/s you run out of port at around 16 hertz. So you would need to limit the bass extention to 16 hertz. Also the volume of the port will be ~ 2 cubic feet.

[DrWho]

Well there's nothing stopping you from using a passive radiator instead that corresponds to the same tuning and then you don't have to worry about it

Also, there's no rule stating that the ports need to reside completely inside the cabinet either. So if you wanted you could build smokestack ports. To be more realistic, I could totally see somebody building a large slot port that extends out the bottom of the cabinet or perhaps out the side following the wall or something like that...especially if they have the sub on a riser of some sort (either a front stage or in the back with raised seating).

To be honest, I didn't really spend too much time modelling the different drivers as I don't plan on building any of them. In fact, I didn't even look at the ports and try to find something that worked because that really needs to be left up to the builder to pick a compromise that fits his situation best. The point I was trying to make is that you can get better performance out of a 15" driver PER CABINET VOLUME than you can with an 18" driver. To get the same slope, the 18" drivers need to be inside a cabinet twice that of the 15...but if you're going to go with that size cabinet, then you can go with two 15's and get even better performance per cabinet volume than an 18.

If cabinet volume isn't the limiting factor (ie, you have a huge attic that you want to use for an IB), then by all means go with the 18's as they will have better performance PER DOLLAR. But for the majority of us, the volume of the cabinet is the biggest limiting factor.

[Jay481985]

yes, kinda like wheels on a car, at some point they are for show. I believe the mclaren uses only 17 inch wheels as that is the best size at that time. Anything over 20 inches without a motor actually makes the car accelerate slower... Kinda like subs, big looks cooler but also the fact that two 15 inchers have more surface area then a 18.

Also yes you can make a smoke stack but then again WAF or hell my acceptance factor. I don't like a smoke stack. Also I was trying to make a point about the vented versus a sealed. With the graph that you showed it made it look like the tumult sealed was the "chump" of subwoofers. But because the sealed box loses no volume to the ports it actually is more closer in power to the vented that has a smaller internal and the fact that you cannot put two 63 inch tubes in such a box. So when I went crazy trying to make a suitable box for a dual tumult designed I factored all of that in. Also the fact that I wanted to move it from room to room hence no wider then 32 inches. But the sealed actually had a better lower end response then the vented sub since I wanted the tuning frequency of the sub to be 20 hertz but the fact that 80 inches for a 18 x 3 inch slot vent didn't make anything easier. So the tuning frequency hit a high 40 hertz where for the people in the know after the tuning frequency of the vent is met it drops a fast 12 db per octave. So sealed was a better choice for me. It just the fact that the tumult was designed for either passive radiator or seal. Vented is out since the amount of air the tumult moves is too much. But I had to dropp passive radiator since I would need 4 stryke 18 inch pr at 150 dollars a pr so no way is 600 of pr worth it for a ~ 8 db inprovement.

[Marvel]

I think perhaps you should take a look at this thread:

Patent thread / Sub enclosure

It uses two LAB 12 speakers, does 31.5Hz at 92db 1 watt input. Size might be an issue, but this box is 41"x41"x18" They could be made to look nice. It is a Tom Danley design.

If you want to go an octave lower, this won't be what you want.

[djk]

Outdoors in a corner the B-DEAP32 is 100dB/W at 32hz.

Indoors with room gain it is useable to 15hz, some have used it for home theater.

"Originally, I asked about the formideable Contrabass, but it was too wide for my set up and the DEAP-32 was recommended instead - a professional grade subwoofer.

The company is very excited about this new sub and are readying it for the HT market. They also make the ContraBass. They offered to drive up and install two in my theater. They wanted to run some tests in a sealed, dedicated design theater to test out this sub and put it through the paces.

Of course, I agreed.

Mark Seaton and Jeff Parmanian drove up a pair of these from Chicago (5 hours) to Detroit. We had lunch and after pulling down the screen, removing the 4 Citation subs from behind the screen wall and installing these two new subs, we were ready to test (2 hours later).

We used a Professional grade amp and then my bridged Citation amps and EQ'd with my PE-17.

Between all of the testing on Servodrive's TEF device and Chris's room evaluation software, we mic'd the room and ended up with a flat response from 18 - 70 hz +/- 2 db. with useable bass under 14 hz.

Chris has pix and a better explanation as to the details of the set up and the proprietary design but the bottom line is I've never heard a tighter, louder, deeper sub ever. MY LCRs bailed before the sub did when we reached 120 bd peaks. The subs were amazing. Very powerful and authorative and fast.

The depth charges from U-571 and scenes from Titan AE (both DTS) were no match for these subs at full reference and beyond. Scenes from the Matrix, various test discs, and Saving Private Ryan couldn't strain tthese subs and performance to below 20 hz was loud, controlled and powerful. Really amazing and available for home use."

[Marvel]

This WOULD be what you want!

And they are so simple, too.