When using subs for prosound, use baltic birch. It's much more durable and it's lighter than MDF too.

You decision about whether to use one 12π hornsub or a small group (say four) of the three π subs should be entirely dictated by your intended usage. If you'll be playing mostly indoor events, small to medium size rooms, then the group of three π subs is better. If you'll be playing in very large rooms or outdoors, then the 12π hornsub is best.

I have lots of both models of subs in the field, and the lines are very clearly drawn about who uses what. I only know of one person using a 12π hornsub for home hifi. It's just too large and doesn't make sense for small and medium size rooms. The intended environments are outdoors or very large rooms like stadiums, auditoriums or large theaters.

Likewise, the three π subwoofer is mostly in homes. I have a few being used by DJ's and bands that do events in local clubs and other moderate sized rooms. In small to medium size rooms, it's much better to have a few three π subs than it is to have one or two hornsubs. With multiple subs, you can smooth room modes, so that makes it handy to have several three π subs to place around. They're pretty easy to carry too.

The 12π hornsub is 45x45x28 and weights 285 lbs. It is a big box, to be sure, but it rocks back on its wheels which fit perfectly on truck ramps of everything from 24' rentals to the biggest tractor trailers.

• 12π basshorn spec sheet

The mouth frontal area is large enough to make the basshorn directional at the top end of the passband, but down low it is acoustically small. That's why a single horn has approximately 6dB rising response through its passband. However, when used in small groups, the frontal area is large enough to provide directivity through the whole passband, and there no longer is rising response. You can see the difference even when just using a pair of horns, and by four, response is a straight flat line. Tons of power too, by the way.

You can build the horn without the heat exchanger, but I wouldn't recommend it. I've already done all the hard work, so to ignore it just doesn't make sense. We have the PI-12 woofers, already machined and ready to accept the cooling plugs. We keep them in stock, as well as the plugs and plates. I'm not sure if you read the write-ups of test results, but the improvement made by the plugs is incredible. Running the horn without the cooling plugs is like running a car without a radiator. Sure, it will start and run but it won't produce as much power and it won't last as long.

• Heat exchanger effectiveness