Rudy81 Posted March 22, 2011 Share Posted March 22, 2011 In my never ending search for a better two way system, I started looking at the Faital Pro HF-200 on another thread. That led me to look at Dave's (GotHover) elliptical horns. I eventually wondered how a tround tractrix horn would sound with the HF-200. Not one to leave any stone unturned, I decided to try my hand at a round Tractrix horn for my mains and center channel. One of the best systems I have heard used Oris 150 horns. That led me to the round tractix idea. In retrospect, I should have just purchased them from Dave. Wow, I can't beleive how much work it was making these by hand. I have been at this for several weeks now and am almost done. They are turning out better than I expected, and I sure hope they will sound good enough to keep.....specially after all the work. Here are a few pictures of the effort. Once completed, I will run some sweeps on the horns with the new Faital Pro driver. This first shot shows one horn, put together but before cutting the router edges and sanding. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted March 22, 2011 Author Share Posted March 22, 2011 I decided on this outer design in order to make it easy to sit them on my bass bins. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted March 22, 2011 Author Share Posted March 22, 2011 After spending unending hours filing, sanding and sanding some more, this is the product after priming. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted March 22, 2011 Author Share Posted March 22, 2011 The horns are in the shop drying after two coats of paint. I plan on one more sanding and then a final coat of paint. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted March 22, 2011 Author Share Posted March 22, 2011 Oh, yeah, here is the trio after priming. Quote Link to comment Share on other sites More sharing options...
Guest David H Posted March 22, 2011 Share Posted March 22, 2011 Looks great Rudy. Dave Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted March 22, 2011 Author Share Posted March 22, 2011 Dave, coming from you that's a nice compliment. Thank you again for all the tips and suggestions, you have been very kind to help me with this mammoth project. I don't know how you keep doing this over and over. You must have a 'system' to get them done quickly. They sure are a heck of a lot of work! Quote Link to comment Share on other sites More sharing options...
jwc Posted March 22, 2011 Share Posted March 22, 2011 Badazz Rudy. Really. jc Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted March 22, 2011 Author Share Posted March 22, 2011 JC, this is all your fault. You got me on the DIY track with the DBB's. The good news is I am still enjoying the heck out of those bass bins. Quote Link to comment Share on other sites More sharing options...
greg928gts Posted March 23, 2011 Share Posted March 23, 2011 Very nice! Keep the pictures coming. Greg Quote Link to comment Share on other sites More sharing options...
DrWho Posted March 23, 2011 Share Posted March 23, 2011 How do you guys control the cross-sectional area with this method? Are you really getting all 3 horns to be within ~1/32" from each other? That looks like a ton of work. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted March 23, 2011 Author Share Posted March 23, 2011 DrWho, in my case, I'm sure they are not exact copies. I did the best I could cutting the circles and then sanding as accurately as possible. Withing 1/32"...I have no clue. I beleive they are close. I used a tractrix template to check my work as I went along, but even the template is not perfect. I'm sure Dave's horns are more accurate since he makes more, and more accurate, cuts with his CNC machine. Other than a machine doing the work, it is practically impossible to make it 'perfect'. Quote Link to comment Share on other sites More sharing options...
Marvel Posted March 23, 2011 Share Posted March 23, 2011 How do you guys control the cross-sectional area with this method? Are you really getting all 3 horns to be within ~1/32" from each other? That looks like a ton of work. You are assuming all the old Altec and JBL castings were the same? Some of the JBL adapters were off way more than 1/32" What freq. do you think this will impact?400Hz = 33+ inches approx. 15KHz = .9 inches approx. 20Khz = .67+ inches approx. Bruce Quote Link to comment Share on other sites More sharing options...
greg928gts Posted March 23, 2011 Share Posted March 23, 2011 I have an old K400 horn that has a 3/32" hump in the middle of the inside. What interesting is this is from the cut-a-way that was sent to dealers to show off the construction of the Khorn to potential customers. Greg Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted March 23, 2011 Author Share Posted March 23, 2011 Once I get everything hooked up and tuned, I will certainly report back. Once I get the volume levels balanced, I will run Audyssey Pro, and it will run plots, in room, for each speaker. I will then be able to easily 'see' if there are any major frequency anomalies due to shoddy horn construction. I don't expect that I will be able to hear any differences in horns, but you never know. I don't believe I have an ear exacting enough to be able to determine such things. I certainly can't tell one cable from another. The difference would have to be rather noticeable for me to hear it, so I will have to rely on electronic measurements to see if there are any major problems. My other option was to spend $1200 per horn for the BD Designs Orphean II horns. Just too rich for me. Quote Link to comment Share on other sites More sharing options...
DrWho Posted March 23, 2011 Share Posted March 23, 2011 How do you guys control the cross-sectional area with this method? Are you really getting all 3 horns to be within ~1/32" from each other? That looks like a ton of work. You are assuming all the old Altec and JBL castings were the same? Some of the JBL adapters were off way more than 1/32" What freq. do you think this will impact?400Hz = 33+ inches approx. 15KHz = .9 inches approx. 20Khz = .67+ inches approx. Bruce It's the 1/20 wavelength rule of thumb calculated at 20kHz. A lot of the other horns being mentioned aren't being used up to 20kHz. Obviously it matters less at lower frequencies where the wavelengths are longer, which is why many of the other horns being mentioned probably didn't feel the need to hold tighter tolerances. The accuracy is also going to impact the distortion (moreso the throat dimensions) and the polar response, so it's not just about the on-axis amplitude variation. I'd expect 1/32" at the throat to impact the SPL before 10% distortion by more than a dB at the lower end of the passband, and the HF polars could also get affected by several degrees. It'd be even worse if the wavefront loses its shape, causing it to finger out. I'm not trying to say that all of this will for sure be an issue with dramatic audible impact, but I know of several horn designers that work very hard to make sure the manufacturing imperfections don't cause these issues... Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted March 23, 2011 Author Share Posted March 23, 2011 Doing all this by hand makes me think it is full of imperfections, so we will see how it sounds. Not that I'm great at juding sound, but if I can note a problem, it will likely be a big one. Otherwise, I'm sure I won't notice it. The only way to manufacture those with super tight tolerances would likely involve a mold injection type of setup. Quote Link to comment Share on other sites More sharing options...
Marvel Posted March 23, 2011 Share Posted March 23, 2011 A lot of the other horns being mentioned aren't being used up to 20kHz. Obviously it matters less at lower frequencies where the wavelengths are longer, which is why many of the other horns being mentioned probably didn't feel the need to hold tighter tolerances. The accuracy is also going to impact the distortion (moreso the throat dimensions) and the polar response, so it's not just about the on-axis amplitude variation. I'd expect 1/32" at the throat to impact the SPL before 10% distortion by more than a dB at the lower end of the passband, and the HF polars could also get affected by several degrees. It'd be even worse if the wavefront loses its shape, causing it to finger out. I'm not trying to say that all of this will for sure be an issue with dramatic audible impact, but I know of several horn designers that work very hard to make sure the manufacturing imperfections don't cause these issues... I'm sure that manufacturers do their best to minimize the imperfections, ad realize also that the higher you go in freq. the greater the imperfections will cause problems. As Rudy points out, we'll have to see if he can hear any problems.We should always strive to do the best we can do and I'm sure that is the case with Rudy's work. After all, I'm not getting anything built right now. [] Bruce Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted March 23, 2011 Author Share Posted March 23, 2011 Looks like DrWho is right, and my handywork sucks! After reading his comments I decided not to wait until tomorrow to run the frequency sweeps. The horn I built does fine until you get in the high frequencies. At least the one I tested has a huge drop around 14kHz! I tried all sorts of mic placement and compared the driver response to the Faital Pro mounted on my P. Audio horns. Graphs to follow...what a bummer. Quote Link to comment Share on other sites More sharing options...
Rudy81 Posted March 23, 2011 Author Share Posted March 23, 2011 Ok, here are the REW test results, done outside, with my Behringer ECM8000 mic. The green line is the P. Audio 4525 horn with the Faital Pro HF200 driver. The red line is the DIY horn with the same driver. Not the most controlled and scientific of conditions, but you get the idea. I ran several runs at different distances and that 14kHz dip is there every time! I'm sure my wife can use them as flower pots.... Quote Link to comment Share on other sites More sharing options...
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