The 'XXX' sub

[ShinObiWAN]

After cancelling my last project:

http://www.avforums.com/forums/showthread.php?s=&threadid=121802

I thought it would be best to get back on the ball so its time to unveil my new project.

Its one goal in life is to be *the* ultimate HT subwoofer, it hopes to laugh in the face of a couple of servo15's and kick the DD18 around the room then sit on it. Actually thats what I hope it does but when you use a driver such as the Resonant Engineering XXX 15v3, its entirely possible.

The XXX 15v3 is based on technology licensed from the 15" Adire "Tumult" driver and is essentially identical in all but name, it even features the XBL^2 motor. One big difference however is the XXX 15v3 costs £400 as opposed to £570 for the Tumult.

For now I'll just say that its going into a 110ltr sealed enclosure and that construction has started

More to come soon.

 

[Mat-Moo]

110lt! Holy crap, that's a BIG box I only read the other day on the other project, then saw it got cancelled So any clues as to the shape of this one?

 

[ShinObiWAN]

 

[eviljohn2]

Have you considered an isobaric version?

Also, in order to laugh in the face of the DD18 presumably you'll have some form of room equalisation DSP? What amp/s are you going to use.

I can't wait to see this one take shape.

 

[micb3rd]

The RE XXX 15 is a very nice driver, I have heard quite a few in car audio installs, while it is cheaper it has a higher FS value.

The Tumult has a much lower FS and will perform far better in the size of enclosure you have sugessted.

Both drivers require massivly powerfull amplifiers, you want at least a solid 1 kw if possible.

If it was me, the Tumult would be the No. 1 choice.

On software/paper models it will drop lower then the RE XXX 15.

Also make sure you don't forget that these driver displace load of air space, make sure you have at least 110 after displacement.

I would shoot for 130-160 liters before displacement, If it was me I would go for the Lowest Q/Qtc enclosure I could fit in my room.

 

[ShinObiWAN]

Thanks for all the questions so far, I've attemted to answer them all:

So any clues as to the shape of this one?

Its a downward firing sealed design and the cabinet shape is a rip of the Stentor III style, think large coffee table, veneering, beveled edges and glass top.

Very close to finishing the basic MDF work.

Will get some pictures taken and posted soon.

Also, in order to laugh in the face of the DD18 presumably you'll have some form of room equalisation DSP?

Yes, FBD and PEQ will be custom tailored to the listening room via a Behringher DSP1124.
The EQ will be tailored for a response flat to 15hz and then roll off.

What amp/s are you going to use?

Two choices at the moment:

2 x BK OMP MF450 (450w 4ohm) basically one for each voice coil on the XXX.

OR

1 x BK OMP MF1000 (1050w 2ohm) powering both voice coils in parallel, then add another OMP MF1000 if and when needed.

I'm waiting on some information from BK regarding the MF450 driving a 2 ohm load before making a choice. Should it be able to do this without problem then I will be going with the first option, if not then it will be the MF1000 with option to add a second if needed.

If it was me, the Tumult would be the No. 1 choice.

Too late, already ordered the XXX15

Granted the Tumult is very slightly better but after PEQ the XXX will be good.

Both are really the cutting edge of what a subwoofer is all about - displacement, excursion and linearity. With nearly 3" peak to peak and the XLB^2 motor providing the best linearity in the industry along the length of this excursion, you can be sure that it is among the lowest distorting subwoofers out there.

Independant measuring shows that a single 15" XXX in a sealed cabinet hits 127dB at 20hz and a peak of 130db at 30hz. Ported sound pressure levels are obviously higher but I'm not taking that route so its not applicable. Mine won't go this loud because of PEQ but it will certainly go very, very deep. After modelling quite a few scenarios I'm looking at a peak SPL of 110-115dB @ 15hz and 12.5hz @ F3(-3dB) with 1200w, I should add that this is after PEQ.

Also make sure you don't forget that these driver displace load of air space, make sure you have at least 110 after displacement.

Cheers, its somewhere between 110 and 115ltr after bracing and driver displacement.

 

[micb3rd]

It should a great absolutly amazing subwoofer when done.

XBL^2 tech is excelent, it gives very flat BL curve and also seems to reduce IMD distortion.

1000 WRMS should be good for it, although I know for a fact an extra 500 to 1000 WRMS for future expantion is easly possible and the driver would sing along with the extra power.

May I ask where you got your sealed cabinet RE XXX 15 numbers from, did you model them youself?

 

[ShinObiWAN]

Originally posted by micb3rd
1000 WRMS should be good for it, although I know for a fact an extra 500 to 1000 WRMS for future expantion is easly possible and the driver would sing along with the extra power.

Not heard back from BK about the OMP MF450 driving a 2ohm load so I'm probably going with a single OMP MF1000 then add a second if the performance is lacking.

May I ask where you got your sealed cabinet RE XXX 15 numbers from, did you model them youself?

I first did a preliminary model in ISDpro, then modelled my room dimension in lspCAD and calculated room gain.

After this I simply added the room gain values to the SPL values of the ISD model.

 

[ShinObiWAN]

Evening all

Finished the basic MDF cabinet, next on the list is finishing and to that end I have a couple more bits to show you:

Spiked Feet
Quite proud of these. Very professional looking.

I cheated here because after looking around the web there was a lack of real heavy duty feet available.

So I talked with a good friend who works at the Vesuvius Machine shop - famous for manufacturing engine components for Cosworth no less.

He insisted on working a design for me. The brief I gave him was just 'heavy duty'

Anyway he's done good, real good and here's the finished products after spraying in matt black and adding generic 'black anodised' floor spikes:

Here's a possible choice on the veneer finish, looks a little rough here but thats because it needs waxing, afterwards it will have the same sort of deep gloss look of a piano for example. For those interested its 'Brazalian Mahogany Curl'.

 

[GJC]

Are these guys relatives of yours ShinObiWAN?


XXX Subs

Very Cool project by the way - Its not good reading these threads - I want to start a DIY sub now!

 

[ShinObiWAN]

Originally posted by GJC
Are these guys relatives of yours ShinObiWAN?


XXX Subs

Very Cool project by the way - Its not good reading these threads - I want to start a DIY sub now!

Them is some mad skillz that have gone into that enclosure.

The SPL guys really are crazy, I mean 3 x XXX15's in a car that size!

Binned the idea of veneering the box and instead, picked up some very thin sheets of polished marble, so am going to work on that over the weekend and then pictures!

 

[stuthemong]

nice thread this. best of luck mate, good to see some XXX behaviour @ home

(I am running an atomic thunder mouse in home- if that means anything to you )

could you let me know where you picked the marble from? sounds interesting!

Stu

 

[ReTrO]

Looking good mate!

Very nice feet.

 

[ShinObiWAN]

could you let me know where you picked the marble from? sounds interesting!

Sure no problem, Spittal Tiles in Chesterfield are your boys.

Personally I wish to god that I never bought this marble stuff now, absolute nightmare to work with - you need a definitely need a brand new and good quality diamond cutting blade otherwise the surface *will* chip or worse, crack!

I'm getting the hang of it now and have now managed to cut all the required panels, some smoothing of the edges is required but I'm impatient and have started to fix them to the basic MDF box already, I'll then sand them smooth in situ

Close up of the marble, the style/type is 'Jetstone':

One panel in place and fixed down to the MDF cabinet using strong contact adhesive, I'm hoping it doesn't fall off when the serious bass notes from the XXX start pounding the cabinet!

Also I'm not going with the spiked feet now as this thing will be just far, far too heavy once the driver and other panels are added. Instead I'll be using heavy duty metal type castors for ease of movement.

 

[stuthemong]

I like the marble, looks like a HELL of a lot of work though!!!!!

Just in case you are interested,

my sub here

its quite simple - large sealed box with a downfiring 15" atomic tunder mouse powered off a NAD 216 THX amp (getting 250WRMS a voice coil, so 500 WRMS total). Makes my trousers shake during saving private ryan, which is a start

The veneer is fablon - cost me £1.99 to cover the entire box, and lots of people seriously ask "did you build that yourself" - great stuff for those on a budget.

Look forward to seeing your completed sub.

Stu

 

[ShinObiWAN]

Like the sub Stu.

The finish in the photo looks particularly impressive for the outlay.

I did consider fablon but I was always disappointed with my skills applying it and was never satisfied with the finished results. Most of the time I normally just stick a 3mm plyboard veneer over the MDF and stain then varnish but this time I wanted something a little more different, hence the marble.

 

[stuthemong]

oh no, totally different league between fablon and proper veneer ill give you that. I kinda put that in there as a cheap and easy option in case others were reading.

as long as you aren't within a meter of it its all quite convincing

my next project will be a coffee table sub, with glass flush to the top of the box.

you marble idea has given me a slate/granite finish idea, though i think ill just be sensible and stick a black ash effect

Stu

 

[rob_w]

Originally posted by ShinObiWAN


Both are really the cutting edge of what a subwoofer is all about - displacement, excursion and linearity. With nearly 3" peak to peak and the XLB^2 motor providing the best linearity in the industry along the length of this excursion, you can be sure that it is among the lowest distorting subwoofers out there.

Independant measuring shows that a single 15" XXX in a sealed cabinet hits 127dB at 20hz and a peak of 130db at 30hz. Ported sound pressure levels are obviously higher but I'm not taking that route so its not applicable. Mine won't go this loud because of PEQ but it will certainly go very, very deep. After modelling quite a few scenarios I'm looking at a peak SPL of 110-115dB @ 15hz and 12.5hz @ F3(-3dB) with 1200w, I should add that this is after PEQ.



Cheers, its somewhere between 110 and 115ltr after bracing and driver displacement.

Interesting project - a few q's..

You've stated the xmax as nearly 3", the tumult has 34mm ( 1.34") xmax..

I've calculated the Tumult will do approx 105/108Db at 20Hz at xmax without room gain. Where do your figures come from ? If from car stereo stuff, then you'll lose all the cabin gain from being in such a small environment.

Cheers

Rob

 

[ShinObiWAN]

Hi Rob,

No problem answering a couple of questions if it helps you out.

You've stated the xmax as nearly 3", the tumult has 34mm ( 1.34") xmax..

34mm is one-way excursion, or travel in one direction if you like but as cones travel in both directions you can just double this figure to give a peak to peak of 68mm or 2.72". Some manufacturers list it as peak to peak in there specs and most others as one-way.

I've calculated the Tumult will do approx 105/108Db at 20Hz at xmax without room gain. Where do your figures come from ? If from car stereo stuff, then you'll lose all the cabin gain from being in such a small environment.

Those figures are including room gain which was calculated from my room model in lspCAD. The 110dB @ 15hz is the estimated output including room gain. The XXX is also more sensitive at a given wattage than the Tumult so ultimately has a higher SPL, in otherword you can't compare the SPL of each, especially after PEQ.

I did mention this somewhere back in the thread... ah here we go:

I first did a preliminary model in ISDpro, then modelled my room dimension in lspCAD and calculated room gain.

After this I simply added the room gain values to the SPL values of the ISD model.

 

[rob_w]

Cheers Shinobiwan- I think my brain was a bit frazzled last night

I'm using 3 tempests which I am hoping to reach 110Db @ 15Hz in room, so the figures you were quoting looked a bit high to me. All depends on the real room gain figures I guess.

I've read of figures from 10 - 15Db at 20's through to 1-2 Db's if at all.

Cheers

Rob

 

[stuthemong]

robwells

hee hee, you guys are nutters. its funny to think people pay£800+ for a SQ 10" sub, when we all know 15Hz it what they are really after

good luck on the amp / amp cooling !!! side

 

[ShinObiWAN]

A couple more pictures of the progress so far.

Part of the internal bracing, now ready to fit:

Nearly completed bracing, just four 2 x 2" vertical supports to fit and its finished.

Here's a shot of the two fitted marble panels, still another 2 more to go on the other sides, the top will have tempered glass inlaid but that's a way down the list of priorities. Incase you were wondering the open end is the bottom of the sub, so right now its on its side.

 

[Mr THX]

ShinObiWAN

What are you finishing the cabinet off with at the corners ??

 

[ShinObiWAN]

Originally posted by Mr THX
ShinObiWAN

What are you finishing the cabinet off with at the corners ??

Quarter round molding will be used on every edge of the enclosure.

 

[Mr THX]

Nice one

Where did you source the 'holed' bracing from, was it pre cut or did you make it yourself ???

Any chance of a 'to scale' picture of your cabinet ....... next photo stick a DVD case near/on it.

Top project mate, following it with much interest.