Thanks for the simple explanation.
How do I calculate the required mass for each PR? I know the mass effects the tuning but do not know/understand the math required to calculate. Would like the have good bass extension - but don't want to have extreme power requirements due the the sub producing the deep bass.
What tuning would you suggest and how much mass is required on the PRs to get to that tuning? With the extra funds required for the PRs will need an inexpensive subsonic filter - any suggestions?
Thanks again for the advice. I want to build the PR-version, just need some clarifications.
I'd push the size up a little if you go PR. You want about 7-9 cubic feet. You are going to load it up with mass based upon the size of the enclosure but your tune will be around 17-18Hz.
With this driver, you need power. Basically, if you have a lot of stroke, running in realistic sized enclosures and designed for 1st/2nd octave, you need the power to utilize it. There is no way around it.
A lot of people talk about efficiency but for subs, it is pretty much a non-issue. It isn't a transducers efficiency that is going to determine output down low. It is determined by the box and that is a point that very few people understand. Efficiency is solely dictated by the moving mass & BL motor strength. When you increase BL, you increase efficiency but you do so at the expense of bandwidth in a given box size. Same thing with Mms, if you decrease the moving mass, you increase efficiency but once again lose bandwidth for a given box size.
So... the box ultimate determines efficiency down low in the frequency range. As a consequence, if you want lots of output, you need lots of stroke & power. Since the efficiency is set by the box and choice of bandwidth, our power needs for a given output are set in stone. If you want more output, you need more stroke and to use it, you need more power and there is nothing that anyone can do to change that relationship.
In terms of inexpensive, I'd advise the following. I'd either build it with the right parts or build something else that requires less power. Personally, I'd not build a sub without EQ & room measurement tools. It can make a significant improvement in sound quality. The SMS-1 is my standard recommendation because of flexibility and ease of use and it has a variable subsonic filter for a resonant build. The EP-2500 is less than $300 street price. Between the two of them you have < $700 invested in power, room measurement, and all the signal processing you need. If that is out of your budget, I'd aim for a less expensive sub that doesn't require the power of the Maelstrom.
Kevin Haskins
Exodus Audio
