Edgar

Probably NOT! See http://www.sanderssoundsystems.com/Speakers%20WP.html. The transformer is probably the audio stepup transformer, and the screw terminal is probably for the DC bias. Does your friend have a high voltage DC power supply to go along with the speakers? These might be the HV supplies. The large-diameter wire might be a few kiloVolts DC (caution!), the smaller wire probably ground. I recommend that you know EXACTLY how this all hooks up before you even consider purhase. Greg

You're welcome. I think that there's no doubt that the response of a full-length tractrix horn drops at a higher frequency than that of an exponential or hyperbolic horn. But for less than full-length horns the differences are not as great, because the various horn contours become more similar near the throat. I think that Bruce Edgar said that all horns with the same throat, mouth, and length dimensions respond within ±2 dB of each other, regardless of contour. (David McBean actually showed me a counterexample comparing a conical with a hyperbolic, but the statement is essentially true as long as you don't get too extreme with the contours.) The simulation programs like Hornresp can give you a pretty good indication of the general differences. Greg

It occurred to me that maybe you actually meant a 1/4-size horn mouth. So I reran Hornresp with a 1/4 mouth instead of a full mouth. This plot shows the 4Pi case (no walls or floor). 1/4-size mouth in black, full mouth in gray. The half-Pi case (floor-wall-wall corner) is much smoother. Greg

I wasn't quite sure what you meant by 1/4 space, so I took a shot and figured that you meant half-Pi space. Hornresp allows you to model 4Pi (no floor or walls), 2Pi (floor mounted), Pi (floor-wall corner), or half-Pi (floor-wall-wall corner, like a Klipschorn). If that is not what you meant, then I can try again, or you can run Hornresp yourself from the parameters that I posted last time. Greg

Here's what Hornresp gives for an answer. The mouth area ("S2", in cm^2) is 7200 square inches, and the length ("Tra", in cm) is 80 inches. "S1" is the throat area and "F12" is the cutoff freq. Greg

Best person to ask is David McBean himself. I have corresponded with him via email, and he is quite approachable. He hangs out at Audio Asylum and can also be reached through the Hornresp Website. Greg

If you have Hornresp, you can see it for yourself. Try the following test cases. Note that the only differences are the type of horn (tractrix, exponential, hyperbolic), the horn length (modified as appropriate to keep the same throat and mouth dimensions), and the rear chamber volume (set for appoximately "flattest" response). Greg

You can fit an almost perfect 39 Hz tractrix contour inside a Jubilee. I don't know that I'd want to do all that woodcutting, though. Hornresp says that it only subtracts a few Hz from the low frequency cutoff. Greg Edit: revised to say "subtracts from" cutoff instead of "adds to".

Yes.

Here. Actually, I think it's the opposite. With very short horns it is difficult to distinguish between exponential, tractrix, hyperbolic, or even conical. (Try your Hornresp model with a conical horn instead of a tractrix, and you'll see only small differences in response.) I think that it is only when the horns become long enough for the major differences in their contours to emerge that the response differences start to become significant. Greg (No, I'm not Bruce Edgar. Edgar is just my forum name. Maybe I'll change that someday, to avoid confusion.)

Nope. See Don Keele's paper, especially the conclusion. Greg

Bob, Except for Re (4.95 vs. 3.33), your measured "N1" numbers agree reasonably well with the numbers that I used. Fs 35 vs 34.46 Qts 0.403 vs. 0.39 Vas 8.8 vs. 10.65 Greg

Fs = 34.46 Hz Vas = 10.65 cubic feet Qts = 0.39 It looks like I'm using the post-1985 numbers It has been quite a long time since I created that Hornresp model, and frankly I don't remember where I found all of the other parameters. I think that someone posted a complete set in a forum message a while back. Greg

CW1526 (stamped) in black, CW1526C (cast) in gray.

When theory and reality disagree, I'd go with reality. CW1526 in black, PD1550 in gray.

Not quite. The graph shows each woofer's output for a 2.83V input. So the CW1526C plays a few dB louder than the K33E overall, but its frequency response in the horn is very similar to the K33E. If you look at the other graphs posted earlier, you'll see that those woofers are a little louder above 400 Hz or so than the K33E, but that their bass responses drop-off at a higher frequency ... maybe 46-47 Hz vs. 41-42 Hz for the K33E. Since low bass response is what we're trying to get out of the KHorn, this difference is significant. Greg

Sure. The dimensions represent my best estimates, based upon some old Speakerlab K plans that I have. While there is some debate as to the dimensional accuracy of these plans, for the Hornresp parameters they are probably more accurate than my ability to extract the data from them. Also, since all four woofers are being compared in the same context, at least the relative differences between them should be accurate.

Okay, here's what Hornresp gives for the CW1526. Again, K33E in gray for comparison.

Doesn't look like much difference, but they both lose 5-6 Hz on the low end compared with the Klipsch woofer. That's actually a lot. If you can post the Thiele/Small parameters, I can run it through Hornresp. Greg

And here's the PD1550.

FWIW, here's what Hornresp predicts for the PD158 in the KHorn (K33E in gray, for comparison).<\P>

I'd like to know the back story behind this. Was Verizon was sending him bills for 0.2¢?

Is that e^(2*PI) or e^(i*PI)? I can't quite make it out in the picture. If it's e^(i*PI) then it equals -1, and the check is made out for two-tenths of one cent. Greg

Everything that you could possibly need for these can be found at Great Plains Audio. In particular, see Note 5 on the page referenced. Greg

Marilyn, their niece.