Edgar

The difference can be quite noticeable, even on "slow" systems. For example, whenever I download a file, I download it to the RAM disk first. Virus scan on the RAM disk runs a lot faster than on a regular disk. Also, if it's a compressed file, uncompressing it goes a lot faster on the RAM disk. It's perhaps a little thing, but on a 32 bit Windows system it beats letting 0.5 - 0.8 gig of RAM just go to waste.

Creates a blazingly-fast solid-state hard drive in a section of memory. The only caveat is that the RAM disk loses its contents when you turn off the computer, so consider it to be temporary storage only. I locate the Windows "tmp" directory on it.

Convert that unused half-gig into a RAM disk: http://memory.dataram.com/products-and-services/software/ramdisk; click on DOWNLOAD SOFTWARE under RAMDISK LITE. It's free and it works.

Yes, Bruce Edgar has been a strong proponent of the University Classic configuration, particularly for its 90 degree bends. http://volvotreter.de/downloads/Edgar-Show-Horn.pdf (No relation to Dr. Edgar)

OTHORN is 419 liters.

Yes, you have that right. But that is just a comparison of what can be done in the same volume as the SPUD. The other things that can be taken away from this are: 1. A single TS400D-4 in 1/2 the volume will still be competitive in frequency response and excursion. 2. A pair of RSS315HO-44 in 1/3 the volume will also be competitive in the same ways. 3. If you really want to use the full 296 liters, then you have many more options for enclosure shape with the vented boxes than with the SPUD. 4. It's easier to get a tapped horn to go below 20Hz than it is to get a vented box to go below 20Hz. (I had to experiment with a lot of woofers to find these examples.) 5. Since vented boxes tend to be much less finicky to build and tune than tapped horns, for systems that don't actually need to go below 20Hz the vented box may be a better option. 6. Vented boxes do not exhibit any of the high frequency "mess" that is characteristic of tapped horns, so vented boxes may be the better choice for use above 70Hz or so. A quick look at online prices puts the Ciare 8.50NDW at $135 each, the TS400D at $239 each, and the RSS315HO-44 at $156 each. So there are some definite price advantages to the SPUD with regard to drivers. As for the 2PI radiation angle, I did experiment a bit with that. The SPUD is somewhat less sensitive to the radiation angle than the vented box. That is to say, the cutoff frequency rises a bit more in the vented box than it does in the tapped horn, when the angle is increased from PI/2 to 2PI. But with the extra excursion capabilities of the larger drivers, EQ is an easy option. Overall it is not my intent to discourage anyone from building a tapped horn. But if you only need 20Hz or 25Hz, then there are other options that start to look better. EDIT: This does not address the sound quality issue. Personally, I like the sound quality of a tapped horn/transmission line/TQWP (all variations on the same theme). Just today I read on a forum somewhere that a person described the sound of a TH as "rumbly", as compared with the "woofy" sound of a vented box. That mirrors my own opinion, and I cannot think of a better way to describe it.

An icy day in the Midwest. I'm stuck inside, thinking (dangerous). I got to wondering how close a vented box could come to a SPUD. So I started experimenting with Hornresp. I have a SPUD model that I obtained somewhere on the Internet. I'm not certain exactly how accurate it is, but, frankly, an inch of error here, an inch there, doesn't make a lot of difference in the response. I tried several different 8" woofers in the SPUD model, and found that the Ciare 8.50NDW produced the flattest response. (There may be other woofers that perform slightly better; I just don't have models for them.) That model is shown in the upper left of the attached graphic, with the frequency response at the upper middle and the diaphragm displacement at the upper right. Hornresp tells me that the SPUD internal volume is 296 liters. So let's build some 296 liter vented boxes. Well, 296 liters is enough volume to produce approximately a B4 response (4th-order Butterworth -- very desirable) with two Dayton TS400D-4 15" woofers. The Hornresp model for that is in the middle left of the graphic, the frequency response in the middle middle, and the diaphragm displacement in the middle right, in both cases with the SPUD in gray for comparison. Two-hundred ninety-six liters is also enough volume to produce approximately a B4 response with no less than six Dayton RSS315HO-4 12" woofers. The Hornresp model is in the lower left, with frequency response lower middle and diaphragm displacement lower right. I'll leave the interpretation to the reader. But I will add the Hornresp says that the low frequency, excursion-limited max SPL of the two Dayton versions is between 16 dB and 19 dB higher than for the SPUD.

Original. Have the parameters changed in the newer models? I haven't kept up.

It can't predict how they will sound, but for what it's worth: here and here.

Here is everything I have for the Hornresp model of the Jubilee. You'll have to rename the file to "Hornresp.dat" and place it in the Data folder associated with Hornresp.exe. I built this file under the latest version of Hornresp (v33.5), so there should be no compatibility problems. Note the similarities in the responses of the EVM12L, PE31, PE32, and 12NDH-3. Hornresp - Corrected Jubilee alternate woofers.txt

I'd be glad to. But right now I'm on a completely different computer that doesn't have access to my Hornresp data. So I'll do that tomorrow morning.

The rules are a little different with horn loading. Light cones and strong motors work best. As direct radiators this leads to weak bass response. But in a bass horn, this leads to extended HF response, while the horn itself takes care of the bass.

The EVM12L is an exceptionally good driver. Originally designed for horn use, it has more recently been applied as a "guitar speaker". With horns, the LF response is largely controlled by the horn itself. It is the HF response where the woofer makes the most difference. In this the EVM12L excels among 12" drivers. Drivers with responses very similar to the EVM12L include the B&C PE31 and PE32.

K31 in gray, Delta 12LFA in black.

K31 in gray, Kappa Pro 12A in black.

K31 in gray, EVM12L in black; no other changes.

I've heard it. Not perfect, but quite impressive nonetheless.

They stopped importing them to the US after the 2012 model year, I think.

I did the hyperbike thing for over twenty years. Now I'm looking for something that is actually fun to ride at sane speeds. This looks like it would satisfy that need, but unfortunately it's not available in the USA. Perhaps someday I'll convert the enduro version.

Occasionally someone will reply to a specific post without quoting it. In the new forums they can only do that by clicking the generic "Reply to this topic" button, but then it is not clear exactly to which post they are replying. Would it be possible to augment the generic "Reply to this topic" button with individual "Reply to this post" buttons, alongside the existing "Quote" and "Multiquote" buttons, within each post? And along with that a way to see exactly to which post the response is linked? Maybe this capability already exists, but I have not found it. I believe it existed in the old forums.

Because it is a quote box. It's obvious, so the word "Quote" is superfluous. Not a big deal. Thanks.

OK... Close, but not quite what I hoped. In this message I attempted to do exactly what I described in my original message. It all worked except that I cannot find a way to eliminate the word "Quote". Good enough, I think. Thank you.

To add to that, previously the HTML tags showed up while editing, so that one could, for example, quote a sentence, reply to that sentence, quote another sentence, reply to that sentence, etc., by inserting the appropriate tags. Is it (or can it be) possible to see and manipulate the HTML tags while editing with the new editor? I have noticed that I can click "Quote" multiple times, then delete different portions each time, but it is then apparently not possible to eliminate the redundant "Jeff Matthews, on 08 Nov 2013 - 09:46 AM, said:" lead-ins.

And, in the neverending march of technological change, even though Voigt's tractrix has many wonderful attributes, it is being superceded by constant directivity designs because of their superior polar responses. So I guess we will soon have to thank D.B. Keele (who himself thanks John Gilliom for the original idea) for all CD horn variants. After a while one realizes that this is just the way that technology progresses. As they say, one stands on the shoulders of giants. (Full disclosure: despite my forum name, I am not Dr. Bruce Edgar, nor am I related to him or associated with him in any way. Though I sent him an email message once. Yes, he responded.)

OK; I can't really disagree with that. But I don't think that the omission was a sin of the magnitude that DeanG makes it out to be.