Rudy81

Now you're cookin' Edit: I am already looking around for an OB LF solution that can get close to 20Hz on the low end and cross two way with the AMT. I have previously built H frame, M frame and W frame OB's but could not get them down in the 20's with my current Kappalite drivers. I also tried building Ripoles, but they are very limited in the higher end of their response. If I could find a good OB system to get me into the 20's I'd be all over them. I am looking right now at the Eminence drivers used by the Pure Audio Project.

Each wing is 7 1/4" wide. I wanted to keep the build as simple as possible. I used Oak stock from local lumber big box. Each piece started at 7 1/4" x 3/4" x 6'. I then cut the wing pieces at just over 12" to span the stacked drivers. One edge was beveled at 45 degrees to sit flush with the driver. The other end I routed half-round purely for aesthetics. Super simple and inexpensive. I'm sure somebody can improve on my idea, but that was my starting point. I selected Oak since it was the stiffest hardwood they carry. Turns out the Oak selection helped in the paint area. Very minimal sanding was required with 320 grit to even the surface. Paint turned out really good on the Oak surface. The wings are then glued and brad nailed to a base. In this case, some scrap Baltic Birch I had from a previous project. I supported the wings with smaller oak pieces that also have a 45 degree bevel, which serve as a holder for the ends of the drivers. I will run two rods through the driver pre-drilled holes to keep the drivers in place. I also built a plywood top to finish the top and give it a standard 'horn' look. I plan on filling the voids you can see along the vertical edges of the driver/wing interface with black modeling clay, which I picked up from Hobby Lobby for $3. Frankly, I don't think I have ever built anything for my audio stuff that was this inexpensive. I plan on placing the waveguide on four isolation pads to keep bass bin vibrations from affecting the AMT structure. Not sure if that matters, but what the heck.

My efforts would have been in vain had it not been for Chris's tutoring and his deep knowledge of the subject. I certainly have learned a lot from all of you and Chris in particular as of late. The value of this forum is the cooperation and camaraderie everyone seems to enjoy. I am hopeful this "kit" will help those who seek just a little more than what stock units can provide. The waveguides turned out really nice and are in the shop offgassing those nasty lacquer fumes. Ten days from now, due to work schedule, I plan on getting back into this hot and heavy. If you guys are interested in my results and experience with my project I will continue posting pics and where I end up with the Xilica settings. My dual Kappalite 3105LF bass bin is pretty capable from 20hz-1.2khz, so I may end up crossing a bit higher than you would with a stock Khorn bass bin. But, we can get an idea of how it can work. I plan on extensive listening sessions and hope to get @Thaddeus Smith and anyone else that want to stop by to have an objective listen. Another set of objective ears will help in providing several, more valid opinions on the project.

I don't think the Xilica is 'minimum' for good sound. Having recently acquired one, it does offer more flexibility than other units. In my case, it has more EQ options than did my Ashly and has the convenience of control over IP. But, the Ashly was plenty capable on its own. The AMT doesn't need a huge amount of EQ, so even a basic unit should suffice. Of course, I defer to the expertise of others who are more conversant with active crossovers. I think what you have will be plenty to get you on your way should you decide this is a worthwhile option. As soon as I get mine up and running I hope you can stop by for a listen. Who knows, you may not feel it is that big a deal. Let your ears decide.

I asked about the 24dB/Octave based on my reading a comment by Dr. Heil's assistant. IIRC, he suggested that slope. However, I am gaining confidence in this driver setup we have and may start with the Danley Style non-crossover crossover. Since I don't listen at ear splitting levels, there shouldn't be any danger to the diaphragms.

I think that's a great place for me to start my setup. Chris, would you recommend a L/R 24dB/Oct crossover for this application?

Here is some homework.... You have much reading to do sir.....BTW, this is how I found what the AMT can do.

Do you know where the AMT is crossed in that speaker? 25Hz is pretty darn good for a 12" woofer. Tough to have a bottom end that can keep up with the speed of the AMT.

Grrr. Don't even say that! Chris posted the ESS link above. They are on sale, $155 and free shipping. What's not to like.

BTW, this speaker is at the ESS showroom. Ricky of ESS sent me the picture. As you can see, they too are working on the horn theory. I believe this speaker is a prototype. I will also say that the folks at ESS are superb. Very personable and responsive when I called. Actually spent quite a bit of time on the phone with Ricky discussing my project. Seem like ESS is working on a lot of stuff for the future. I sure hope it goes well for them. How do you like the crazy look of their bass section? Called a Transar.

The crazy thing is the price comparison between an AMT and the TAD TDD-4002 or BMS 4592ND....it just is a superb technology.

I'll let Chris handle this comparison. Although I have owned the Faital Pro HF200's and those very horns, it was a long time ago and my 'audio' memory is not long lasting. Chris has more gear similar to what most Klipsch aficionados own. FWIW, my wife who appreciates good sound, but is not 'into' it came in to the media room while I was doing A/B testing with my Oris vs. a single AMT. I asked her to sit and listen and give me her impressions. After just a couple of minutes, she looked at me and said "that's a no brainer and left". Mind you, she had been ribbing me over even contemplating selling my Oris. I'm honestly perplexed and can't understand why more people have never heard of this AMT thing. I never would have known had Chris not used that driver to help explain some measurements he was teaching us to make.

Possible. Will have to see what work has in store for me. If I can, I would be glad to take my DIY project up there.

I have not used compression drivers for many years now and currently use my Oris horns, so that is what I can compare with. Although, I do have a pair of Heresys in my workshop. The driver is not a perfect driver and does have some areas where it falls short. Keep in mind that I have nowhere the expertise that Chris does, although I have been messing with horns and speakers for many years as you can see by my many builds. These are just some of my impressions. Positive: - Incredibly 'open' and 'airy' sound compared to my very modest Fostex drivers. This driver is an Open Baffle lover's dream! It is OB sound on steroids. I have built and used many OB types and styles and loved the sound as compared to horns or other drivers. Problem is that a standard driver in an OB has some limitations. This crazy looking thing produces amazing soundstage with crisp fast, sound. The last time I was this impressed with any speaker was when I first heard the Oris horns. But, the Oris I heard had some very high end drivers. - Based on what Chris has taught me to look for in Group Delay and Spectrogram graphs, nothing I have comes close to this driver's performance. - Now that we have been able to lower the crossover point, this thing is a real winner when stacked. Although, it is plenty amazing with just a single per speaker. Negative: - It will need some EQ to get good performance below 1kHz. You can search and find folks that don't feel the driver has enough mid-range to satisfy. However, the use of an active crossover and EQ should make that complaint a mute point. - It's HF coverage is very directional, so sounds optimum if you are seated for listening vs. walking around the room and expecting great off-center performance. - If you don't have an active crossover, you will need to build a crossover for it I suspect. - It needs space behind it and I don't think it will sound good if it is too close to the wall behind it since it is a dipole type of setup. For me, the pluses way outweigh any negative. The sound these things make is just outrageous! You owe it to yourself to listen to one. 1970s technology to boot!

It was the performance at low listening levels that attracted me to these strange drivers. I ordered a pair just out of curiosity. I still can't believe how good they sound for such an inexpensive driver. Thanks to @Chris A, I have been able to get the driver to a place where I can comfortably cross with my bass bins and maintain a two way speaker. Originally I created a prototype which was a full horn type of device for the stacked AMT. That configuration showed some problems and also killed the incredible open and 'airy' sound these things make. When I removed the top and bottom, the performance returned and the sound was back to what I expected. I now have six of these drivers for my front mains and will start my listening tests in the coming weeks.

Any time sir! Should have them hooked up and running in about 2 weeks. Work keeps getting in the way, but just finished painting the waveguides.

Chris, thanks for running the EQ parameters. Based on the success of the very simple wing design, I am moving ahead with painting them. Today might be a good day to shoot lacquer on those if the humidity doesn't get up too high. Might as well finish them properly and then go on to more formal listening tests. It will, however, take a good week before I can bring them in the house. The lacquer can seriously stink up the house if I bring them in too soon. Don't want to upset the wife this early in the year.

Are you looking for this thread? https://www.diyaudio.com/forums/planars-and-exotics/171441-hornloading-heil-amt1.html Actually, I got my thoughts from that thread. I have been in contact with one of the guys there who had some success in their build. Although, they have gone on to other speaker types and builds. My current goal is to be able to lower the usable frequency of the driver just a bit and, using a horn, boost the performance at the 1-2khz region.

I'm well aware of that! It would be a boring hobby if we all found the 'perfect' speaker and never looked elsewhere for something else. I need a house with 4 or 5 listening rooms set up with different systems.

Hey, hey, hey.....I haven't decided yet. The Oris I believe are the speakers I have owned the longest. Although, I did change drivers a couple of times. 😎

What are you asking for the AVM-60?

I read that very article last night. I have been trying to find the AMT manufacturer but no luck yet. Good picture you found for size reference. Hopefully by end of next week i will have my dual AMT prototype built. Then we can see just what a similar horn will do. I don't plan on curbing the sides though.

In this video, Mr. Hawthorne indicates he crosses the AMT at 350Hz!!!????

Time to start cuttin'. I won't be able to follow you since I will be stacking two drivers per speakers, to will need to go the DIY route. Good luck. Do you have the ability to take measurements after you mount the horn?

The Beyma TPL 150-H also uses an AMT in a horn. https://www.usspeaker.com/beyma tpl150h-1.htm