Yeah...more bass!

[sootshe]

"The bass was as deep as my Khorns and even tighter.

That is a pretty bold statement. If this is really doing that much for bass extension, than you definitely have my attention. Can we get any numbers to back up the subjective observations?

Daniel

I have a test disc (original Master Recording - "Sound Check by Alan Parsons & Stephen Court) that has amongst other things 1/3 Octave test bands. When the speakers were firing into the room I could just hear the 50Hz tone. Now that they are firing into the rear wall I can just hear the 31.5 Hz test tone & the 50 Hz test tone is much stronger.

Without any dedicated testing equipment that's the best I can do. I tend to agree with Greg though that if a trace was done it might not look all that great, but the proof is in the pudding!

[WMcD]

There is, IMHO, some theoretical support for what is reported.

PWK wrote a short paper showing that there is a finite amount of resistive loading of a finite length horn below cut off. [Edit, this is loadng at the throat.] It is in the Klipsch papers. Artto posted these lately. This was to justify the fact that the K-Horn could transmit sound below the 48 Hz or so fc of the K-horn. Of course everyone heard this but they were used to looking at graphs of throat impedance of infinite length horns.

More on point is Don Keele's article about optimum mouth size for finite length horns. It shows that when you have an optimum mouth size for a given fc the loading below cut off is very good, maybe optimum. [Edit, this is loading at the mouth.]

The bottom line here, in my view, is that when a reversed LS is "really in a corner" it could have better performance below fc than a K-Horn. This is because the mouth situation is more near optimum for the higher fc (about 63 Hz) of the LS.

To restate what I get from Keele is as follows. If you are looking for best performance below fc, you might be better off with a smaller horn with a good mouth match, than a bigger horn with a poor mouth match. [Edit, I'm here making an assumption that a good mouth match results in a better resistance at the throat.]

There are many other factors, of course. One is that, IIRC, the LS has higher resonance freq of the driver. The other is room modes.

Wm McD.

[greg928gts]

To restate what I get from Keele is as follows. If you are looking for best performance below fc, you might be better off with a smaller horn with a good mouth match, than a bigger horn with a poor mouth match.

Can you expand on this a little?

Greg

[doityourself]

I don't know about optimum mouth size is as critical as it sounds. I built a Table Tuba subwoofer that is horn loaded. It's a 13 ft length horn inside a 30x30 box 18inches wide. Mouth size is roughly 18inches by 22 inches. Sounds good down to 30 hz or so. Puts out more sound below 40hz than the khorn and it's only running an 8 inch Ford Explorer subwoofer! Corner placement is recommended but not necessary. Mouth size could be as narrow as 12 inches if used in a corner.

[JohnA]

is yours sitting something like this

Hmmmmmmm. Looks kinda like a University Classic, doesn't it?

[jwc]

is yours sitting something like this

Hmmmmmmm. Looks kinda like a University Classic, doesn't it?

agreed.....except a much easier build for sure

[8-|]

jc

[sheltie dave]

John, it certainly does!

http://www.hifilit.com/hifilit/University/plans-1.jpg

[WMcD]

To restate what I get from Keele is as follows. If you are looking for best performance below fc, you might be better off with a smaller horn with a good mouth match, than a bigger horn with a poor mouth match.

Can you expand on this a little?

Greg

Yeah. I went back and edited my original post. What I wrote was overly broad and failed to distinguish mouth conditions and throat conditions.. I'm not totally retreating though.

One underlying issue is just what is the acoustic resistance at the throat. We know that well above Fc we have increased resistance, and this is the good load which leads to efficiency.

Below Fc we know that the acoustic load is not nearly as favorable. I had run a simulation of my variation on a Jubilee in a corner. It showed that below Fc, the acoustic resistance is still higher than that experienced by a direct radiator, by about a factor of 2. Therefore, below Fc, bass horns can still work better than direct radiators, even if not by very much. (I'd love to use this as a master's thesis some day.)

But going back to the question, and my edits. I am thinking that a good mouth load makes for a good throat load, even below Fc. A jump in logic but not too big.

My comments on the LS in the corner arise from the following: Both the LS and K-Horn have the same mouth size in terms of square feet, they are both four square feet. I say that about the LS just because of the general dimensions. With the K-Horn, that comes from the Jubilee AES paper, though there it is in metric units (Dave Mallette has a post going about metric units. Smile.)

But the LS has a higher Fc.

Generally, this means that the LS has a larger mouth than the K-Horn when compared to their Fc. Maybe this part of what you'd like me to expand upon. It is a way of discussing just how "big" the big end of the horn really is when we can scale horn sizes. It gets a bit complicated. You see the Fc freq converted to a wavelenght. Then the size of the mouth (if round) is described in terms of its circumfrence as compared to that equivalent Fc wavelenght. Gosh, this is getting away from the issue.

So the LS is closer to a optimized mouth size. The situation of the reversed LS in a corner gets even better, for it. This is because, in a fuzzy way of thinking, we have added an additional length by the sound path coming around the box and out into the room. Now we have, again, fuzzy logic, a yet bigger mouth formed by the room walls and the back (now forward) box.

There is another issue here because horn functions above Fc are hurt by lack of lenght as well as small mouth size. The reversed LS has that additional path. And that is overall good, and I expect good below Fc.

Wm McD

[Marvel]

Nice explanation, Gil.

I've been meaning to post this for a few days...

Below is a picture of a Pi speaker, put on its side with an Oris horn on top. Notice how it looks like a DR pointed into a corner, to make a horn out of it. That is exactly what the LS pointed into the corner does. btw, this design isn't marketed by Wayne any longer.