DIY Round Tractrix Horn

[Rudy81]

Interesting. It might be worthwhile to double check simple things like xovers settings, polarities, delays, and all that fun stuff. I'm wondering if maybe something got goofed somewhere?

Well, that is certainly possible and I will check today. However, as soon as I popped in the P. Audio horn with an identical driver, the problem went away, the dialog became crisp and clear.

Hey, what do you want for a horn made by hand? Who knows what those little sound waves are having to deal with before they exit the horn.

[Rudy81]

One thing I'm going to try today is to set the system up with the round horn on one side and the rectangular horn on the other, same driver, then run the system in mono, muting one side to in effect A/B the horns instantly. I think this is the only way I can quickly evaluate the sound of each horn. I had previously done my A/B comparrison by changing out both horns.

I am wondering now if my perception of a more open soundstage is not a similar issue that I experienced with the center. I can't beleive it is only dialog that would do that. Hmmmm?

[DrWho]

Well, that is certainly possible and I will check today. However, as soon as I popped in the P. Audio horn with an identical driver, the problem went away, the dialog became crisp and clear.

Could it be a voicing difference? A comparison of final frequency response would be interesting.

How much you gonna ask for your round horns? []

I would have expected better performance from the PAudio horns that you seem to prefer, but I'm actually surprised by how different they apparently sound - especially considering the measurements.

[DrWho]

Btw, who was sitting in the sweet spot during the movie? Do the other chairs sound good too?

[Rudy81]

Btw, who was sitting in the sweet spot during the movie? Do the other chairs sound good too?

I was originally sitting in the sweet spot. After my wife complained of the poor dialog, we changed seats and she mentioned it was worse in my seat....I found little difference in her seat vs. mine, they are right next to each other. However, all seats experienced the dialog issue. As soon as I swapped the horn we all agreed it was way better. It seemed to me the issue is that dialog seems a lot less 'defined' and more 'dispersed' with the round horn vs. a more centralized location with the P. Audio CD horn. I'm about to run my R vs. L experiment in a bit.

[Rudy81]

Could it be a voicing difference? A comparison of final frequency response would be interesting.

How much you gonna ask for your round horns?

I would have expected better performance from the PAudio horns that you seem to prefer, but I'm actually surprised by how different they apparently sound - especially considering the measurements.

Frankly, I'm not sure what I prefer at this point. I was leaning toward the round ones for stereo, but am not sure what to think now. The P. Audio are hands down way better for center channel dialog. The question now is how about music...they are much closer in that area, with the exception of a perceived soundstage openess with the round ones.

[Rudy81]

Very interesting results after today's experiment session. I did three things in order to evaluate the sound characteristics of the round horns.

- First, I replaced one speaker's horn with the P. Audio horn with an HF200 driver. The other had the DIY horn with same driver. Then set the system to 'mono' and used the mute function on my Ashly crossover to A/B the horns.

- Second, put back the system to all P. Audio, the way it has been for the last year or so.

- Lastly, put back the DIY horns and HF200 drivers.

I listened to quite a variety of music, but focused on male and female vocalists. I used the Ultimate Demonstration Disk extensively since I am very familiar with this disk, plus the recordings are excellent.

During the mono testing, it was easy to differentiate between horns. The DIY horn produces a more diffuse, 3 dimensional soundfield than the P. Audio horn. The difference is easily heard. I should have done this test to begin with. With music as a source, the round horn sounds more lifelike and less like a horn, in other words, it has more dimension than does the rectangular CD horn. With the P. Audio horn, your eyes are drawn to the horn when it plays in mono. The round horn does not have the pin point source the P. Audio seems to project....of course, this is in mono, same material, same driver.

That was good news, because it confirmed for me what I had been hearing as a much fuller and larger soundstage. I have mentioned that several times in my evaluation. I focused on male and female vocalists to see if I could note any of the problems we ran into with movie dialog. In fact, the voices were excellent and the round horns sound slightly more 'real' than the CD horns.....this, with musical material. There is just more 'life' to the sound produced by the round tractrix.

Interestingly enough, with center channel dialog, the problem I ran into last night persists. But, I beleive I have narrowed down the cause. It is not a ringing or resonance that I hear with the DIY horn and dialog. It is that the sound does not seem to eminate from the screen, but is more 3D and diffuse. I beleive that makes it slightly less intelligeble, but more importantly, it separates the 'voice' from the 'person' on the screen. Our brain is used to having a specific location with a persons' voice, not a larger than life soundfield. The P. Audio horns bring the person's voice back to the screen where the actors are, and that is much more of what we are used to hearing. I may be full of it, but that is the only way I can explain what I am hearing and the differences I have found between movie dialog, musical vocals and the center channel issue.

When I went to step two and went back to all P. Audio gear, the original setup, it was clear that the DIY horns have a much better soundield. Today's work is making my decision of which horns to keep easier. It is starting to look like both horns will have their place. For pure 2 channel music, the round horns create a much better soundstage with greater depth. The imaging is about equal for both horn systems. For movies, the P. Audio horn is a must in the center channel. It just sounds 'weird' to hear voices somewhat disconnected from the actors on the screen.

Although this has been a pain in the neck at times, it has been very instructive.

BTW, as an aside, the round horns seem to be slightly more 'efficient' than the rectangular horns. When comparing same horns with different drivers, the 16 Ohm HF200 actually sounds as loud as does the 8 Ohm P. Audio. I fully expected to need more power into the HF200 to get the same SPL. I don't know how to measure the efficiency of the horn/driver combination yet, but will get to that when I can.Thus far, I have plenty of headroom for the HF200 with my Hafler P3000 amp.

After some 2 channel listening to the original P. audio setup, I went back to DIY horns with HF200 drivers and am now 99% sure these round horns sound much better in terms of a large soundfield with excellent imaging. This was a weird turn of events with center channel dialog that I did not expect. Very instructive though.

[mark1101]

What I use to help myself voice a new speaker is an old original ( a reference). I have a pair of corns and a pair lascalas that I use in the same room to A/B my speaker experiments and adjustments (on my MCM-3 Grand). You can't go wrong if you are in the ballpark of a lascala for tone. Of course the newer drivers and horns will extend and disperse better, but using the reference has been a big help for me. It definitely helps me EQ my system since I'm using a parametric which is fine for corrections, but for voicing is more more difficult.

Are you using any type of professionally designed reference at all to help you voice? All you have done in these threads s interesting to me.

[mark1101]

Sorry double post.

[Rudy81]

What I use to help myself voice a new speaker is an old original ( a reference). I have a pair of corns and a pair lascalas that I use in the same room to A/B my speaker experiments and adjustments (on my MCM-3 Grand). You can't go wrong if you are in the ballpark of a lascala for tone. Of course the newer drivers and horns will extend and disperse better, but using the reference has been a big help for me. It definitely helps me EQ my system since I'm using a parametric which is fine for corrections, but for voicing is more more difficult.

Are you using any type of professionally designed reference at all to help you voice? All you have done in these threads s interesting to me.

No, I have no professional reference. Great idea to use a cornwall or something to help. However, the sound of any of these larger horns is rather far from any of the Heritage speakers and I'm only working on two way from 50Hz on up, so no tweeter. My center La Scala no longer has the mid horn or tweeter, those left here at least a year ago.

Next time I come across something suitable, I just may pick it up as a model, or known starting point.

[Rudy81]

Mark1101, one problem with using a stock heritage speaker as a model is that in my case, I have been moving away from the stock mid range sound for some time now. When I had my Khorns I changed horns out several times and eventually went to a two way setup with the P. Audio gear. Problem was getting a good crossover near 400Hz was really pushing the horn/driver combination.

For two years now I have been pursuing a sound I really liked, which I heard purely by accident. I listened to a pair of Oris 150 horns at a gentleman's home who had a set of DIY Jub bass bins for sale. I went to listen to the bass bins, but ended up listening for a few hours to the Oris horns. I have not heard many speakers with the sort of clarity and soundstage I heard at his house. No, I never did buy the Jub clones, but was left with the Oris horn experience as a goal.

Over the years I have changed many horns in pursuit of a sound more to my liking. When Dave started working on his elliptrac, I got interested in the DIY route again and started researching round tractrix horns....that led to this project, and so continues the journey. Now, I could buy a set of Oris horns and call it a day....but knowing me, that would open up another can of worms. Ideally I need to find a set to borrow, try them out at home and then see how they sound in my room. That's a tall order though.

[DizRotus]

Do you recall the drivers on the Oris horns?

[Rudy81]

Do you recall the drivers on the Oris horns?

No I don't. I should have paid more attention to that kind of thing. Back then I didn't even understand what an active crossover was.

[djk]

Most use Lowther drivers, some of which are very expensive.

Les Hudson has tried using Audio Nirvana and had good results at modest cost.

[Rudy81]

I recall the Lowthers are pricey. I also know some folks use other options. The horns themselves are not cheap. The Orphean II horns for 2" drivers were $2k delivered. I have not looked into the Oris horns, but they pricing is on the BD Designs site.

[Rudy81]

After living with these horns and the Faital Pro drivers, I thought I'd update the thread. I have been very pleased with the DIY horns, but always felt that perhaps a set of horns that had a more precise manufacture might add a slight improvement. I recently acquired a set of Jabo KH-55 exponential horns. Tonight, I finally got a chance to set things up and test the DIY Tractrix vs. the Jabo exponential horns. I also got a chance to test, once again, the Faital Pro driver vs. the P. Audio BM-D750 in each of the horns.

Here are a few shots of the Jabo horns and the test results. BTW, the tests were all run with REW 5.0 and my new calibrated ECM8000 mic.

[Rudy81]

Jabo side view with my DIY stand in its raw stage.

[Rudy81]

Driver view.

[Rudy81]

First off were various comparissons by ear only. The Faital Pro vs. the P. Audio driver does a little better in the very high frequency and that confirmed my previous tests. It was nice to then run those tests again since I had not listened to the P. Audio drivers in quite a while.

I had a difficult time deciding which horn sounded best between my DIY tractrix project and the Jabo horns. My only observation was that the Jabo's tended to handle the very high frequencies a little better than my DIY project. They seemed to beam less in the very HF, at least that was my impression.

Here is a plot comparing the Faital Pro vs. the P. Audio driver in the Jabo horn. The P. Audio does a very respectable job holding its own until above 14kHz and that is where the Faital Pro manages to respond slightly better.

[Rudy81]

Here is a comparisson between the Jabo and DIY horns with the same Faital Pro driver. I was pleasantly surprised that could manage this type of performance with the DIY horns. Is is pretty close until the response approaches 20kHz. and that seems to be the biggest place where my DIY project loses something.