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Quijibo's XMASS 18 build.

14704 Views 69 Replies 13 Participants Last post by  ALMFamily
Just wanted to start a thread for my subwoofer build project.

It is heavily influenced by a build I saw from another forum from 2005.

I purchased a couple of the XMASS 18 drivers by mach 5 audio ($75 each with local pickup).
LINK for more info
Here's the Particulars of the drivers:

My project is to integate them into two separate boxes in a stage to go under the screen of my HT.
I want the stage to be stand-on-able for kids, and don't want it too high. I have done some work in sketchup tonight and did some modeling in WinISD to see what I can expect.
Here's the box(es).
I've only finished half... well, because the other side will simply be a mirror of the finished side. I will be raising it up about 4 inches off the floor as it is downfiring.

and here's the graphs

Although I have room to make the boxes bigger on the sides, I don't think I want to go much bigger just because of how unwieldy they'll get to be. I do plan on making speaker stands to raise my towers up more to be in line with the middle of the screen.

If anyone has suggestions, I'm all ears, this is my first sub build, and am getting pretty excited.

I do have one questions as to port location for the ported version. would it affect performance if the port 'empties' to the floor also, or does it need to vent to the front?


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Re: Quijibo's Dual XMASS 18 build.

How big is your HT room and what are you powering the drivers with?
Re: Quijibo's Dual XMASS 18 build.

the Room is 12'6" wide by 25' long with 7'6" ft ceilings.
Power will be from a pro-audio amp (juice 800 if I remember correctly) doing ~400w/ channel, but will have to double check the stats on it.

I'll post a sketchup of the room later today (currently at work).
Re: Quijibo's Dual XMASS 18 build.

Ported would give you the most low end output. Tuned to 20 hz you would need two 4" flared ports used full length. The Juice 800 is 800 watts 4 ohms bridged which would be ideal for a pair of these subs wired in series although you'll need a hi-pass filter at 16 hz.
Re: Quijibo's Dual XMASS 18 build.

High pass filter eh?
Time for more research.
Re: Quijibo's Dual XMASS 18 build.

Also, when you say "a 4" flared port used full length", what does that mean?
sorry for my noobness on this.
Re: Quijibo's Dual XMASS 18 build.

A hi-pass filter is a sub sonic filter, in your case you need to block the frequencies lower than 16 hz from causing the drivers to bottom out.

A 4" flared port used full length is this:


Both ends plus the center section total 17" , two of these ports will tune your 230 liter cabinet to 20 hz.
Re: Quijibo's Dual XMASS 18 build.

thanks mike.
Looks like the unit I'll be looking for in order to solve both my amp/receiver/driver problems is going to be a behringer MIC2200. it has an adjustable high pass filter down to 10 hz, and does the signal converting from the -10 dbv to +4 dbu.
Re: Quijibo's Dual XMASS 18 build.

Here's the drivers

Sitting politely beside my current ~7 year old 8" 80w "subwoofer" (and I use the term loosely)
I think a tad more air will be moving from these two. :hsd:

But.... anyone have tips on fixing a dented woofer bubble thingy?
Just took the plastic off the second one and saw this....

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Re: Quijibo's Dual XMASS 18 build.

That's a dented dust cap .Better ask the manufacturer what he suggests.
If they don't do anything about it. Sometimes a shop vac or of your really crafty and its a Poly cap you could use a little hot glue and a pencil. Glob of hot glue on the dent. Embed the pencil in the hot glue while it soft and wait for it to dry.(disclaimer) some materials hold on to the hot glue. I you are really risky and it is a poly cap. Sometimes a heat gun and holding the woofer upside down. Then dent will fall out. All tasks at your own risk.
Re: Quijibo's Dual XMASS 18 build.

Hi Ryan, swing back with that unit and I will be happy to replace the dust cap for you. That looks like the job of one of my cats...:sneeky:
Re: Quijibo's Dual XMASS 18 build.

I just noticed Ryan is from Winnipeg. Now that's an easy fix!
Re: Quijibo's Dual XMASS 18 build.

Well hows that for service.
I'll send you a pm to try to set up a time.
Re: Quijibo's Dual XMASS 18 build.

I was just doing some tinkering in WinISD (I really don't know that much about what I'm doing with that though). What if I made one 8 ft wide (length of a sheet of plywood/mdf) and maybe a bit deeper about 450 liters. with only 1 driver in it.

Win ISD is showing it would be pretty flat (-3db) to just below 18hz, where before, it was tapering off at about 25hz.

My goal with the build is to have smooth bass at various volume levels, not necessarily ultra loud, house shaking bass that would set off a tsunami in the bath tub.

Also, that would free up the other driver for a neat-o looking sealed build I've been thinking of.
Re: Quijibo's Dual XMASS 18 build.

I modeled it and 450 liters tuned to 20 hz looks good. Power would be 500 watts with a HPF at 18 hz.
Re: Quijibo's Dual XMASS 18 build.

mind posting the graph and/or the file so I can take a look at it?

Also, when I try to enter the watts of the amp into Win ISD, it says I need an SPL Value, happen to know what that would be for the Xmass?
Re: Quijibo's Dual XMASS 18 build.

The SPL value is 90 db. Here's the project file, this design will need three 4" ports.

View attachment Xmass 18 450 Liters 20 Hz.wpr
Re: Quijibo's Dual XMASS 18 build.

bought some wood today.
time to start making some sawdust.
I'll try to take enough pictures.
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