I got one of the JBL1500 sub speakers when they were on sale at PE and I'm wondering if they were implemented in a box like the pi corner horns would that be an enhansement to a typical sub box? Would there be more output per watt with the corner placement in a sealed box? I would like to integrate it with my pi-4's and wondered if this could be a way to increase output for that purpose. But would having a sub in a corner interfear with overall integration? Over at the lansing heritage forum, I read people putting them in just about anything from small cubes to large vented boxes. But I'd like to stay away from a bigger vented box. Thanks.

Rick

Just as a point of fact, I'd like to clarify something. There is absolutely no difference in the characteristics of a ported box and a sealed box that has equalization applied to extend response to match. If response is the same, then transient response and group delay are too. Please see the posts in the thread called "Resonance," which was an earlier discussion about this. A good T/S reference is the "Vented Speaker Systems" article written by Brian Davies. So you might consider these things when deciding on your implementation.

As for corner woofer placement, Dr. Floyd Toole describes the strengths and weaknesses nicely in his paper, "Loudspeakers and Rooms - Getting the Bass Right." The JBL1500 works very well in a seven π cornerhorn, slightly retuned for that woofer. The way this is done is to extend the vent on the Professional Seven π plans to fill the entire width of the cabinet. It's actually a simple mod that amounts to the removal of one side wall to gain a little bit of extra length, and it works very well. Those that have done it have been very pleased with its performance.

The π cornerhorn provides several benefits. For one thing, it increases efficiency. Another thing is that midrange and treble reflections are controlled because every sound source is horn-loaded, delivering energy into the room and away from the walls. Floor bounce and wall reflections are minimized and the directivity of all sound is equal.

Most speakers have omnidirectional bass and as frequency rises, it becomes more directional. There are often breaks where the pattern becomes more narrow as a driver becomes directional, and then at a crossover point, the pattern becomes wide again. This causes a non-uniform reverberent field and small "sweet spot." But seven π loudspeakers have uniform directivity and their sound is good everywhere in the room.

I trust your judgement, because the 4 pi's I made are so nice. Actually the discussions at lansing were rather confusing to me with all the different sizes and tunings and on and on. Your explanation makes sense to me. The paper by Dr. Toole is good too, though I must admit my limited pre-hansle mind of technical literature makes my eyes cross after a few paragraphs. But I follow instructions pretty good. Any chance of obtaining the professional 7 pi plans and the means to augment the tuning vent for this beast? Thanks.

Rick

Frode

Tommy