Subwoofer Design for the Max X MX15-22

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Dayton MX15-22 First Look

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The new Dayton Audio Max-X 15″ Subwoofer, the MX15-22 is now available.  I plan to get one, but before I do, I thought I would share some ideas for one of the best subwoofer box designs for deeps bass.  As always, the subwoofer box design is the most problematic.  And I honestly thought the MX15-22 could be really hard due to it’s High Excursion. Especially when you are trying to design the loudest subwoofer box design. Typically high excursion subwoofers will have some issues with port noise when you design your subwoofer box.  Or at least maintaining an inaudible port noise at full volumes. This was especially a challenge when I designed the Dinas.  But if all the specs are correct on this sub, here is a build option.

*when I say loudest subwoofer box design, i am talking about low end extension without the aid of dsp.


Home Theater Subwoofer Design


Subwoofer Design

ChevyChev ported subwoofer design tuned to 21hz in around a 5.3 cubic foot box. This should be a great subwoofer design for deep bass.   Simulation is with 800w


Projected Response of the Subwoofer Box:


Subwoofer design for the deepest bass and loudest subwoofer box for the MX15-22 Max

This Max15-22 has a projected F3 of around 20hz. This is exactly what we want for the deep bass that is necessary for a good home theater subwoofer.



With 800w, the subwoofer does have a problem excursion below 18hz.  Which we can take care of later. *In general this is an issue with all ported subwoofer box designs.


Subwoofer design for the deepest bass and loudest subwoofer box for the MX15-22 Max


Port Velocity

Port Velocity below 26hz does go over out target of 17 m/s and has a first port resonance of 226hz.  This subwoofer box is using a slot port of 15″ wide by 2″ tall and 30″ deep.  Some people might be okay with this, as the amount of sound there is negligible.  But I think we can get this down a little more.


Subwoofer design for the deepest bass and loudest subwoofer box for the MX15-22 Max

Most of the perceived problems of this subwoofer box design will go away with a simple high pass/subsonic filter on the subwoofer.  By just using a second order centered at 20hz, all your excursion problems go away and your port velocity doesn’t go over 17m/s except between 17-25hz.  Here it peaks at 20m/s.  And with a rear firing port, I don’t think this would be an issue at all.  But if you were concerned, you could increase that to a 4th order.   Why is this so important?  Most home theater plate amplifiers have a 2nd order high pass on them centered at 20hz.  So you wouldn’t have to do anything. And since this can take the full 800w, it will be the loudest subwoofer box design (assuming you want a flat response that is).


Suggested Amplifiers:

The amplifiers are going to be the most expensive part of this build. But if you want your subwoofer design to really shine, you will want to pick one that best suits your needs. There are a lot of pros and cons to each amplifier.  I’ll try to break it down for you.

*For Home Theater subwoofers it is highly suggested you use a dsp. You can use something as cheap as the DSP-LF.


Plate amplifiers

SPA1000 – This would be the most powerful plate amplifier that would get you the most SPL and deep bass out of the  MX15-22 right out of the box.  It is a class AB amplifier.  The biggest con here is the expense.  It is twice the cost of one subwoofer and will only work for this subwoofer.  But it does have really good dynamic power and will help your subwoofer see it’s full potential and has a 20hz 2nd order dedicated high pass.  It also is a sealed amplifier, so you wouldn’t have to design a separate amplifier compartment in the subwoofer box.  However, I still suggest it.

SPA500 – This is another Class ab amplifier, which some people prefer.  This would only give your subwoofer 500w of power and more dynamically.  It also has a very limited parametric EQ, but might help out if you have a huge peak due to a room mode.  This is a cheaper option, but there are less expensive and maybe even better amplifiers out there for the price.  This does have a 20hz 2nd order dedicated high pass as well. It is also sealed, but I would still recommend a separate amplifier compartment.

SPA500DSP – This is a class D amplifier with built in DSP.  This will allow you to pick your subsonic filter, dsp your room modes out using a laptop with usb. You can install limiters, phasing and eq.  This would be for someone that really wants the best sound out of their subwoofer and has a decent calibrated microphone to set it up.  It is probably my favorite plate amplifier.   This is not enclosed, so I would recommend a separate sealed enclosure for this.  This can be built right into the subwoofer.

SD500 – This is the cheapest option.  It is a class D amplifier.  It has not tested as well as the Dayton Audio AB amplifiers when it comes to dynamic power.  So do not expect much more out of it that the 500w even during short bursts. This is not enclosed, so I would recommend a separate sealed enclosure inside or outside the subwoofer box.  This can be built right into the subwoofer design we created..


Professional Amplifiers

Coming soon


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  1. Really nice design! I was about to pull the trigger on a pair of SQL 15s right when these were released. I decided to get a pair because the $120 per sub difference wasn’t worth the aluminum basket and lower inductance. I made 4.5 cubic foot enclosures for them with 1.5×18 inch ports tuned to 19hz. Maybe a little larger and lower with stuffing. The skinny aspect ratio might lower my output a little but I can manage. EQed up about 5dB I’m hoping for an f3 of 16hz. The port velocity is acceptable at 17 m/s at 22hz and a peak of 26 m/s at 16.5 hz. It should act as a warning that I’m about to clip my crown 2502. I just saw that these were available at musical instrument shoppe for $150 each plus $9 shipping. If the specs hold true that is robbery.

    I’m glad dayton is finally making a sub that fits in a relatively small box, but not too small that the port wont fit. The ultimax series might have went a little lower, but the box size needed was just too much. These are just right and they are hard to beat at the price.

  2. Since learned from my Cinema 6 build that cabinetmaking is not my Forte (although it turned out decent), My next project will be upgrading my Sub.

    For space reasons, I would love doing another IB sub, but since the loft is on the second floor and it on an outside corner of the house, it would have to be an attic system. My access hatch is too small to get the manifold through so I would have to build it up there. Between that and the high summer temps shortening driver life, I am canning that idea.

    I like the price/performance of the MX15 driver, but not wanting to deal with another build that is larger and would magnify errors in panel cuts, I looked around and saw that Erich at DIY Soundgroup is reintroducing the Ported Cube enclosures. He has a 15″ and 18″ version which appear to be the same except for the driver cutout. It is a 5.5 Net Cu Ft enclosure tuned to 18 Hz with a slot port. Seems close to what you did in your build so I tried playing with that in Win ISD ( really do not know exactly what I am doing on ported enclosures) and on the surface does not look to bad. Erich said I could raise the tune by shortening the port if I wanted to ( looks easy to do, just don’t cover all of the side rails).

    I know his flat packs are outstanding in precision, so glue up would be easy. Thoughts? Am I missing things to look at?