Practically 25Hz response in eigth space! Its because I ended up adding a little more length to it while keeping mouth area small to get lowest Fc. Excursion is also lower now down to a lower frequency than before, more power handling and SPL :D

A linkwitz riley crossover which is -6db at the crossover point, at 70Hz will get rid of the rising response curve and make it completely flat.

Hornresp doesn't predice room nodes of course (only boundry reinforcement as extension of length and mouth area) so I might get more bass than in the above graph.

2.80m long, 2000cm^2 mouth. Close approximation of real exponential flare (areas correct for expo). Schematic:

All wood is MDF, 25mm thick (=1"). External dimensions inc wood thickness is 100cm deep, 109.25cm high, and 53cm wide. Compact by my book :D

The 18LW1400 has a very stiff cone so it wont self destruct from throat pressure like some drivers do. Bassmaxx have also done work with the 18LW1400 and it survived all the tests, while other drivers the cones just crush (eg: Aura 1808). I think they are going to use the 18LW1400 in the new Bassmaxx B3.

As I said before JBL 2242, Eminence Magnum 18LF and Omega 18 also have the same response curve in this horn so they could be used too.

Adrian

Has the midrange horn from the cabinetmaker come back yet? Any pics so far? Or are you waiting for the box around it to be finished first?

Adrian

Midrange horn

Here's a little teaser. I really like it, it sounds great and it's easy to build. I've actually found some unintended additional applications that are pretty exciting to me. As you know, I planned this for use with a Delta 10 or JBL 2012 or 2123. I've drawn up a cabinet that's nice for use with many π speakers; You can use it as an add-on upgrade for existing speakers or install it right off the bat on new speaker systems. I've also drawn up plans for a cabinet that sits flush on top of a Klipschorn or Klipschorn clone.

But something occured to me when I was testing, and that was to use an Alpha 10 on this horn in a little mini-VOTT kind of cabinet of about 5 cubic feet, rear chamber port-tuned to 35Hz. Put a nice wood horn on top and make the cabinet shape so that it can be used against a wall or in a corner. That makes the horn smooooth, and the large cabinet makes bass response deep. It has a shelved response, but with corner loading, not only does the midrange horn become smoother and deeper, but bass is assisted by the boundary conditions too.

Conceptualized eight π loudspeaker

It's a pretty cool little deal that I'm planning to call an eight π speaker. I've got some more work to do, and with all the other stuff on my plate, it's going pretty slowly. But the horn itself is done and now I've just got to document everything and write it up.

I was thinking, maybe I should remove all reflectors but the bottom two? Because they keep the areas right for expo flare as in:

I think I'd rather just have them all out though, but it makes the bit in the middle a lot bigger area than surrounding bits:

But I dunno if it matters. Technically it should make my path length a bit longer I think if I remove the reflectors, so thats good (stays flat and just goes even lower according to Hornresp, all good!).

So should I forget about all the reflectors and leave them out? If you say it'll be fine I believe ya. Hornresp doesn't seem to show much change anyway with a fatter 3rd segment... It will be so much less effort to build.

Adrian

Will the JBL 2012 or 2123 also work like the Alpha with a vented rear chamber to below 100Hz? Whats the current low limit of the Alpha 10 unit? Maybe you could even rear load the Alpha 10 to 70Hz... something like 1.25m length with 2000cm^2 mouth using only a single fold with the mouth exit at the front, underneath the midrange horn. though I'm not sure if loading both sides of the driver with different horn types is a good idea, I guess it could be OK though just like loading one side vented and the other a horn, it works although I'm just speculating.

Do current Pi Corner horns provide horn loading to 300Hz? Or are they direct radiator by then?

In my experience the whole concept of flat reflectors as postulated by Huygens is flawed. Reflectors are only necessary above 200 Hz or so, and then to work properly they have to be round.

The horn itself doesn't go below 150Hz, even in a corner. If not in a corner, it won't go below 250Hz. Really, as it is intended for vocal range, that's fine. I wouldn't do the vented-rear chamber with a Delta 10 or JBL 2012, and would use them with a sealed back for their intended use as a midrange horn. But the Alpha 10 is a pretty good little midwoofer, and it delivers deep bass. It occured to me that it might be suitable for something like a mini-VOTT.

So the eight π is really an unintended exploration of the retro Altec style cabinets with short front midhorns and bass-reflex bass. It's cool looking, and should work well as at its price point, being somewhere around the cost of the higher priced Thermionics. In kit form, maybe even cheaper.