Edgar

I think that, for the original purpose of the thread (as I understood it) -- i.e., finding the low and high frequency capabilities of the horn and finding an appropriate modern driver for it, the fact that the akabak and Hornresp models are so similar means that the results are reasonable. The truth is, as long as the throat area, mouth area, general contour, and path length are correct, the minute details don't really matter all that much with regard to the overall shape of the frequency response. For reflections and resonances, akabak is far superior to Hornresp, but the Classic is already an established design so I presume that any problems in those areas would have already been identified. I find it a little amusing (in a good way) that you are trying to evaluate the max SPL capabilities of a 100+ dB enclosure ... 135 dB SPL in your living room will melt your picture windows!

The triangle height cannot be 23.5" if the leg is only 21.75". The height should be 21.75*sin(67) = 20.02". Also, the base is not 18.375" wide -- that is the external dimension, and we need the internal dimension, which is closer to 16.375". That makes a triangle area of 20.02*16.375/2 = 163.9 square inches. (My CAD program puts it at 163.5 square inches, eyeballing the corner locations on the drawing.) That makes for a volume of 4917 cubic inches or 80.6 liters.

You are correct -- Hornresp nomenclature is very cryptic. It's evident that it started out as a simple program that got bigger and bigger and bigger ... As for the T/S parameters, I usually just enter Sd, Re, Bl, and Le, and use the wizards for the rest. If you double-click on Cms, Mmd, or Rms, it will prompt you for Vas, Fs, or Qes, and figure the rest for you. In the newer versions, it is possible to copy and paste driver parameters ... even from other files. (I have a whole library of variations upon the "Hornresp.dat" theme. The new versions of Hornresp can look inside those files and extract driver parameters from them.) I wish that it was also possible to copy and paste enclosure parameters, but the only way to do that is to use the "Add" facility, which is very inconvenient. The high frequency anomalies that you show definitely appear to be reflections and/or resonances. That could be due to the fact that akabak can model the folds, while Hornresp cannot. Hornresp assumes a simple, straight horn.

No LPF. Just pure Hornresp. Hornresp does provide for some backchamber damping, but I essentially nullified that (the "40000" numbers that I used for the "Fr" parameter). I also set the backchamber depth to a very small number ("Lrc" = 10) so that Hornresp's calculation of internal reflection effects would be negligible at all but the highest frequencies. I find Hornresp to be so much easier to use than akabak for "quick and dirty" comparisons like this. And the results usually agree pretty well. In fact I use akabak so seldom that I have to re-learn it every time.

And here is the C15W in the Hornresp model, using xrk971's T/S values. EDIT: revised "Eg" value in model. Second EDIT: revised "Fr" value in model. Lots of moving parts here. Easy to miss one or two.

Here are the Hornresp plots with the revised back chamber volume. As before, the plots in the lower tier correspond to the parameters in the upper tier.

Interesting. Your dimensions are almost exactly the same as what I used to generate the Hornresp plots in my earlier post. I did find one error in my models: somehow I calculated the back chamber as 80.43 liters but entered the model value as 173.2 liters (you used 106 liters for your akabak model). The smaller 80 liter value changes the response by about +1 dB at about 50 Hz, but otherwise has negligible effect.

You're welcome. I'm not certain that the Altec/GPA 515 will fit -- it's a 16" driver, and the woofer enclosure is only 16.375" wide.

You know, the Classic has an internal volume of 442 liters. In the same volume you could put 3 Eminence Sigma Pro-18A-2 woofers in a vented box, or 5 in a sealed box, and get similar 100+ dB performance with a much easier build. Just food for thought.

Here you go. Response graphs in the lower tier correspond to input parameters in the upper tier. EDIT: See post #23 for revised graphs.

Back in the Golden Era, when 20 Watts was considered "a lot of power", there were many viable horn loudspeaker designs. I haven't heard most of them, so I cannot comment from personal experience about their sound quality, but I have read reports that many of them sounded very good indeed -- perhaps even better than the Klipschorn. And the University Classic is often mentioned as one of the finer designs. So why did the Klipschorn survive and all of the others disappear? My opinion, and it is only my opinion, is that those other horn loudspeakers were just plain ugly. In fact, the only horn speakers that appear as "beautiful" to me are the top-line Klipschorn, and the JBL Paragon. I do not know why the Paragon disappeared, and even the Klipschorn is a rare item nowadays. Ah, you say, but doesn't sound quality trump appearance? Well, just consider how often WAF is discussed right here in the Forums.

I don't know if this one has been mentioned before: http://photo.qip.ru/users/tda-audio/182333/3269763/#mainImageLink

As do I, though "simplicity" is not in his repertoire. The wheels that he designs are ghastly.

Right now Windows 8 appears to be significantly cheaper than Windows 7. If you don't like the Windows 8 user interface, you can download Classic Shell for free, http://www.classicshell.net/, and it will emulate (and even improve) the Windows 7 start menu. I use Classic Shell because I have, simultaneously, computers running Windows 2000 (!), Windows XP, Windows Vista, Windows 7, and Windows 8, and I need to have a reasonably consistent user interface across all of them.

That is exactly my point.

No. This is the company that I was referring to.

The particular form of "more open sound" that you describe has already been mastered by a company headquartered in Framingham, Massachusetts.

There was a lot more to Time Windows than just the splayed drivers, with particular regard to the crossover network, interaction of driver polar responses, and woofer cabinet design (an early QWP, of sorts). Simply splaying a set of drivers in a horn-based design probably won't duplicate the effect. I bought a used set of Time Windows a few years ago for $175. I needed to replace the grill cloth, but otherwise they were just fine. In my opinion it was a very good investment -- they are definitely something special.

Here's a reasonable top-level description: http://www.pcs.cnu.edu/~fharlan/flac.html The big paragraph just before the end.

Flac is to audio what PKZip is to data. A flac file is just a compressed container. When playing a flac file, it is decompressed on-the-fly back into the original PCM audio samples ... exactly, bit-for-bit. Hence the term "lossless".

I actually grew up just a couple of miles from there. If I had some spare cash and a pickup truck I'd own them already.

I think that you're going to have to use a hydrocarbon solvent to remove a hydrocarbon. That said, I've found that Goop and similar hand cleaners work well in situations like this one. (Don't use the kind with pumice.) Make certain that the glass is perfectly dry when you apply the Goop, and rinse it off after 15 minutes or so, with lots of water and a little elbow grease. Afterward, you might have to remove the Goop residue, but that should be handled with mild detergent or even Windex.

For future reference, help is as close as the nearest Radio Shack: http://www.radioshack.com/product/index.jsp?productId=2062214, http://www.electronicspoint.com/threads/how-eliminate-this-earth-loop.166617/#post-1079600. I have used one of these in the past, and they are not bad -- at the very least whatever degradation they may introduce is not as bad as the hum that they eliminate.

My townhouse neighbor occasionally gets a little overzealous with the volume control. I'd be angry, except ... he plays such good music!

I once spent $200 for 64K of RAM! It was a kit that I had to solder. That was a very, very long time ago.