The XXX 18 subwoofer system

[TheEAR]

Ricci,

You will like the sealed,that is a given. I experimented with various 18's in EBS(LLT's) and sealed. EBS like your huge sub is the ideal choice to get the max output down to tune( and a low tune at this) when you have space for a HUGE box. As you can tune close to 10hz and get spectacular output slightly to ..below tune with room gain.

Me ..since space is at a premium...I ditched the EBS idea.Imagine 20 drivers 15's and 18's each in its optimal EBS config with proper porting and...HUGE.

So multiple sealed does it ...and BIG TIME.

With educated PEQ EQ use you can have astounding extension with a sealed,just triple the amount of drivers for a desired output(compared to output with one driver at..tune). With two RE XXX 18's...ha... 54mm one way Xmax...I would not worry too much.

[Ricci]

Yes. I agree of course. When you plan on playing with many different drivers you cannot have 14cu ft boxes everywhere. It's not worth it and besides once you've got like 8 solid drivers and the power for them you don't need to port them. I didn't plan on picking up these other XXX's at first. This was originally some kind of giant experiment to see "What if" that got way out of hand. I really liked how it turned out, so whe I saw the 2nd and the 3rd driver for very reasonable prices I snagged them. If I'd have known I would end up with 3 and soon the 4th before it was over I would've done sealed from the beginning. Oh well, it's not like I'm disappointed with this King Kong bubinga half wall!

That's what I was thinking. 2 XXX's each with a dedicated amp should be plenty for determining the value of the <10hz stuff. If it ain't then surely 4 will be enough[].

Have you done any testing on that wall yet? Have you run everything at once yet? With everything doing 35% of what it can, it's got to be absolutely crushing.

[TheEAR]

Ricci,

Yes I did run ALL these and nine commercial AT ONCE ! It is beyond mere,little and tiny words. Just the front wall has LIMITLESS extension and output,to anyone who says sealed is limited I dare to sit in a room where the sub(s) are up to the task and say that again.

Just the side towers I call them the TC Towers because all drivers are made by TC Sounds are crushing in output.Add the 18's and center SDX's and you have the Fedor of subs.

Now I am troubled..I cannot push this system. I cannot,the windows would break,and this is no joke. HUGE output,extension ...

You will be happy with four RE XXX's no doubt,I will buy two RE XXX 18's. As well as add any high end sub. I have to have'em. It is like a drug. []

[Ricci]

Here's a family photo. [] In the middle is a Klipsch K31E 12" woofer out of a KLF-30.

Here is the frequency response of the XXX sub system at the main 2 listening positions. This was taken with REW, a Turtle beach SRM, an ECM8000, and Xenyx 1202 mixer. Sine wave sweep from 0-200hz at a 75db target level. Raw response with no smoothing and no EQ applied. 80hz 24db octave X-over.

[jwc]

So multiple sealed does it ...and BIG TIME.

With educated PEQ EQ use you can have astounding extension with a sealed,just triple the amount of drivers for a desired output(compared to output with one driver at..tune). With two RE XXX 18's...ha... 54mm one way Xmax...I would not worry too much.

I don't come to this part of the forum much. However, I was gonna build a sub this late fall. I have the room for a pair 20 cu ft cabinets.

I was thinking of porting 4 Eminence Lab 12 per 20 cu ft box. This would be for music. Not HT. Wired in series paired then in parallel for 4 ohms per box. But I can wire other ways.

You guys are picking the 18" subs....what is the attraction?

EAR....for a DIY sealed enclosure, what do you suggest knowing I'm going to use it for music and can fit a 20 cu ft cabinet (2 of them).

Thanks

jc

[Ricci]

The reason that it is usually better to use 15" or 18" driver/s is because high output bass with low distortion is all about displacement and headroom. you can accomplish the same thing with 10's or 12's but you need more of them and that usually costs more in the long run. As an example the Lab 12 is a high quality medium throw 12" driver that does great in the right box, but I would not use them for the really low bass 25hz and below. The XXX 18 is capable of moving a volume of air greater than 10 Lab 12's according to the xmax and cone area's listed. Usually driver manufacturer's have a pricing structure where the next size driver up in the line is not much more expensive than the smaller ones. If the 12" is $200, the 15" is $240 and the 18" is $280 it makes the most sense to get the 18 since it will move more air than 2 of the 12" drivers which cost $400.

Now I'm not saying that 8 Lab 12's is a bad idea. Heck no! That would have absolutely insane output ported. I do think that you can do better though. What's your budget? I'm assuming it's decent since 8 Lab 12's is what, $1200?

This would be a killer set-up... 8 MJ18-M 18" drivers from Mach5 Audio. $148 each when you order 4 or more and shipping is included. $1200 for 8. Each 1 is capable of moving more air than 2 Lab12's. Put them in 4.5ft sealed each. You could run each set of 4 off of 1 Behringer EP2500 ($300ea) giving about 425 watts each. This would have more headroom than you would probably ever use and have useable output as low as you could want. Like 105db at 7hz before room gain, for a total cost of about $2500 after adding for building materials. This is just one option.

[TheEAR]

jc,

Knowing you can fit two 20cu ft cabinets,I would go with EBS(LLT). You can use LARGE diameter,HIGH displacement drivers in optimal EBS(LLT) configuration. You tune them Close to 10Hz and call it a day.

Or if you prefer you can run them sealed,and use several mid-large diameter drivers. Here they will in the end do as much down deep and best the EBS(LLT) in the audible range output wise. But with sealed added drivers and amp demands = higher cost.

Ricci,

the Klipsch KLF woofer looks like a squaker compared with these monster sub RE drivers ! Most impressive sight, I wil get a pair of these RE XXX's soon. [] Then my collection will be complete,RE XXX, Acoupower 18 and LMS-Ultra 18's...he he. HA HA HA HA...insanity

[Jay481985]

~ 1, 18 inch driver = 2, 15 inch drivers

~ 1 15 inch driver = 2 12 inch drivers

~ 1 18 inch driver = 4 12 inch drivers

Thats why we use 18 inch drivers.

[jwc]

OK. I hear ya.

Is this the driver:

http://www.mach5audio.com/zen/index.php?main_page=product_info&cPath=66&products_id=182

Quoted: EBS - 283 litres (10 cu. ft.) 18Hz tuning. Please explain this to me. I understand sealed and ported. But this sounds interesting.

Yes I can budget $2500 (excluding amp and processor). I don't want each cabinet to be over 20 cu ft though.

The reason I was toying with the Lab 12's is the amount of positive feedback I have run across on pro forums. Good horn loaded too and one day I may build a bunch.

I forgot to mention that I need this sub to make it out to about 80-100Hz. I'm in the process of making some big midbass horns (dual K31's each) to go with my K402/TADS. The midbass will poop out somewhere ~80-100Hz. I want my subs to keep up and I want tight low bass for funk and metal. No HT.

I have the EVDx 38 and will mess with an amp later.

jc

[jwc]

Ricci,

Where are are getting the info about the 4.5 cu ft enclosure for the Mach 18"? I'm at work and will someone tell me if these woofers are in WinISD?

jc

[TheEAR]

One 18" does not equal two 15's not even close. The 15" has ~70% of the area of a 18", not 50%. This taking both have the same Xmax and Xmech.

Two 15'" are almost worth one and a half times an 18".

One thing is sure,the 18" is preffered to a 15" as less units need to be used to move X amount of air.

[Jay481985]

thats why i said ~

[TheEAR]

The world famous ~ is too vague, the average Klipscher needs a more accurate ~. []

[Jay481985]

One 18" does not equal two 15's not even close. The 15" has ~70% of the area of a 18", not 50%. This taking both have the same Xmax and Xmech.

Two 15'" are almost worth one and a half times an 18".

One thing is sure,the 18" is preffered to a 15" as less units need to be used to move X amount of air.

[TNRabbit]

Does running the tube through the center as in this diagram do something I'm not aware of? I mean, aren't you basically reducing the effective diameter of that huge port by doing so?? Please explain to a layman why this design is better than a smaller, open port?

[Ricci]

Ricci,

Where are are getting the info about the 4.5 cu ft enclosure for the Mach 18"? I'm at work and will someone tell me if these woofers are in WinISD?

jc

Yes that's the driver. I'm just modeling them in Win ISD. Here is the information. You have to input these into the program. Now keep in mind that these are budget drivers and if you are going to build a big ported system you'll be better off with different higher quality drivers because you'll want to use only 2 or 4 drivers for that with your enclosure sizes. The MJ-18m is great once you start using multiples sealed, or you are on a strict budget though.

http://www.mach5audio.com/zen/index.php?main_page=product_info&cPath=66&products_id=182

147.25 ea shipped for orders of 4 or more. 8 = $1178 plus 2 Behringer EP 2500 amplifiers for $600 = $1778. Use the rest for the enclosures, EQ, cables, etc.

This system models to a clean 120db's from 18hz on up. 125db's from 25hz on up and 130db's from 39hz up. That should be enough headroom for anybody really.

[Ricci]

TNRabbit,

The port system is a design that was patented by Polk Audio back in the 90's. There was an article about it in Audio magazine(RIP) in 96 that had a request form that you could send in and they would send you a copy of their excel calculator sheet for it. I have wanted to try to use it in a design since I read that article. This was a perfect application for it because the XXX driver is capable of overloading conventional 8" or dual 6" ports with ease and a 10" port would have to be 62" long to get the correct tune in this size cabinet. Enter the power port.

The claims for it are... reduced port compression, chuffing, wind noise, reduced port resonance, better laminar air flow at higher velocities(lower turbulence), a lower tune for a shorter port. This is accomplished by the port having no straight line path from the inside of the cab to the outside air. The air is channeled by the flowguides and heavy flaring on both ends. The air entering the port is compressed and then slowed again at the exit due to the constantly expanding area at the port exit that couples it to a bigger mass of air and slows the air velocity down. The port in this design is said to be equivalent in area to a 14.87" diameter regular port at the entrance and exit. This is due to the area of the port not being the diameter of the port. The area becomes the distance between the baffles multiplied by the perimeter distance. This is highlighted below. The first screen shot would be a normal port's area highlighted in green.

This would be the area of the mouths of the power port design. Highlighted in green and red. You can see how this is a greatly increased area over the nominal pipe diameter.

The port design that I used is getting an 11.5hz tune (modeled as 11hz so it's close) with a straight pipe length of 36" and then the flow guides are spaced at 3.25" on each end matching the 1.5" flare on both ends of the port. With the flow guide disk diameter being 17" and the inner pillar guide being 3.5" diameter. This does reduce the effective diameter of the 10" tube down to the area of a 9.4" diameter vent, but even still you'd need a 50" regular 9.4" vent to get the tune achieved here. Honestly I'm not quite sure how it gets a lower tune.

For the real skinny please read the patent papers. They are interesting.

5,517,573

5,809,154

7,162,049

[Ricci]

I did some power response testing the other night to check for power compression and port compression effects. These were taken at the listening position with the 80hz crossover engaged. I used REW, a Turtle beach SRM sound card, ECM8000 mic and a Xenyx 1202 mixer for the tests. The sweeps were the largest and slowest that REW has to get maximum stress on the system. 7-200hz, 22sec duration and 1M size. I started at 95db target level and increased the level by 5db on my Outlaw pre-amp for each sweep up until 115db level where I had to stop due to running out of headroom in the input stage of REW. I would've had to recalibrate for a higher level and started all over so I stopped. I'm going to try again and start at 100db or 105db so I can attempt even higher levels. The sweeps were taken back to back, so I'm sure that things were well heated when the 115db sweeps were taken. Keep in mind that these are full on 22sec long sine sweeps too and are really taxing on the amp and driver at the higher levels. I'm not sure the CE4000 can handle a 22sec long 120db sweep level.

[TNRabbit]

Great GoogaMooga!

[Ricci]

And on the 8th day... God was enjoying a heavenly tasting brown ale, when he looked down from heaven... and saw the XXX subwoofer... and he decided it was good...[]