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
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:
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.
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.
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).
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.
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..