Compact Sub/Bass Module

[ruseriousclark]

I've been sitting on 4 M8N's amongst other things and will be keeping 2 for a 2 way build down the road but as for the other 2 I'm putting together a PC sub to match an m3n full range build I did years ago.

Looking to maximize low end extension and minimize size (I know, I know the two do not go hand in hand w/o sacrifice) anyway... I wanted to do something a little different but maintain some aesthetic appeal.

Design goals are to get the most from the M8Ns using the least amount of space possible.

Looking at a ~1 ft^3 compound loaded isobaric BR configuration. With what I've run, it should yield an f3 around 30hz. I've gathered that the knock on Iso's are the added expense, due to the added driver and their relatively inefficiency given the amount of power needed to drive them both within the same enclosure. Expense for me isn't an issue in this situation and I have a sub plate amp laying around with 240 watts at 4 ohms, well over what these things can handle.

I have no actual build experience with anything other than a standard sealed and BR configurations so any input or advice is greatly appreciated.

Should be a fun little project. Look forward to some input from those with more experience.

[ThomasW]

Other than how you mount the drivers isobaric subs are nothing but a sealed box so not to difficult.

The quick and dirty method is simply bolting the drivers together face to face. Only issues doing that are the exposed driver is ugly and this changes the center of gravity so the boxes tend to tip forward.

[ruseriousclark]

Thomas- Thanks for the input.

I have begun cabinet construction and will post photos closer to final completion.

In the process discovered a couple neat things some here may not know. Or I could just be showing my inexperience.

The Compound Isobaric arrangement cuts the Vas of the driver in half. Makes sense but why this is important is I find many times clearance items especially sub-woofers have larger enclosure requirements than their non clearance peers. If one were able to pick up two on the cheap you presumably can get the performance of a higher priced driver with the same volume at a lower cost.

Lots of problems with this theory but for budget builders, of which I presume there are many these days, this may be a driver arrangement for people to consider.

More later.