Double Stack ESS AMT-1 with Wings--Possible Kit for Heritage

[Rudy81]

Always interesting to hear 'acoustic' opinions from different ears.  I will note that as a dipole driver, it is important to keep it away from the rear walls.  In my case, I have mine about 6' from the rear wall and about 3' from the side walls, which have absorbers on them.  

 

I have a set of 402's in my shop right now, and the sound is very different between the two systems.  IMHO, the AMT is spectacular for a stereo set up in most rooms.  My room is fairly large with quite a bit of acoustic treatment.  

[Schu]

I am happy...

 

 

[jjptkd]

34 minutes ago, Schu said:

I am happy...

 

 You're running your UJ's as 3-ways? What are your crossover points? 

[Schu]

...

[ARX]

There's a lot of useful information in this thread.

 

To be honest, I've never really cared much for AMTs, but I've always had a weak spot for the big Heils, of which I own a pair. Unfortunately, the diaphragms didn't survive years of abuse in a cafe. 

IMO the horn loaded twin/stacked ESS AMTs beg to be used in combination with a Bert Doppenberg's Orelo-style horn loaded OB. The crossover point (560 - 600Hz) isn't ideal for multiple 15s, but should be low enough for 4, or 6x 10 or 12".

Straight wings with a curved end flare could be used so that the stacked Heils can be integrated.

 

Cheap 12" with Fs: 34 Hz and Qts: 0.59:

[Rudy81]

A driver with a Qts of 0.59, to the best of my knowledge, may not work very well in an OB setup.  I would think a driver with a Qts above 1.0 would be better suited.  

 

Funny you mention Bert's Orelo.  I built a set of DIY Orelo horns paired with some 15" Eminence drivers I had and could never get the performance I expected or needed out of them.  I'm sure Bert's work well, but I won't be passing by the Netherlands anytime soon to have a listen.  

 

I have built and played with just about every type of OB setup and have settled on the very simple H frame configuration with dual 18" Goldwood drivers, it has the best performance when paired with the Heil AMT in a 2-way configuration.  I have other conventional Klipsch speakers, but for my room setup, the OB sound is my favorite.  

 

 

[rmlowz]

1 hour ago, Rudy81 said:

I have other conventional Klipsch speakers, but for my room setup, the OB sound is my favorite.  

I have really been enjoying my Lii Audio S10-W15 combo in an OB. The sound is amazing on my 300B that Nick built me.

Like you I have Klipsch also.

 

Rich

[hsbrock]

On 9/9/2022 at 1:42 PM, Rudy81 said:

A driver with a Qts of 0.59, to the best of my knowledge, may not work very well in an OB setup.  I would think a driver with a Qts above 1.0 would be better suited.  

 

Funny you mention Bert's Orelo.  I built a set of DIY Orelo horns paired with some 15" Eminence drivers I had and could never get the performance I expected or needed out of them.  I'm sure Bert's work well, but I won't be passing by the Netherlands anytime soon to have a listen.  

 

I have built and played with just about every type of OB setup and have settled on the very simple H frame configuration with dual 18" Goldwood drivers, it has the best performance when paired with the Heil AMT in a 2-way configuration.  I have other conventional Klipsch speakers, but for my room setup, the OB sound is my favorite.  

 

 

It has taken me some time to read this thread, and I have been intrigued. Are Rudy81 or Chris still available to answer some questions? Do you men mind if I run something past you? I'm a newby to this site, recently retired.  I have wondered about the problem of not being able to provide adequate spacing between the rear AMT drivers used dipole and the rear walls, and if the problem could be solved by inserting a labyrinth between the rear of the AMT and the rear walls. I understand why it is ideal to have about a meter spacing, but, like you, who has all that space to position their drivers out into the room? So, in wondering about this, I have asked myself about adding about 60" (5') in distance by having the rear of the AMT feed into a slow-growth exponential labyrinth of only 3 turns, and the end of the labyrinth being the throat of a Tractrix 7-9" horn (that would effectively duplicate the front horn radiating directly into the room). I understand that higher frequencies do not like turns, but why? And at what frequencies do they cease behaving similar to lower frequencies?

 

My understanding is that they don't, and from what I read, they bend/diffract around corners the same, based on their frequency, and if the labyrinth were 1 1/2" wide by (increasing from 8" to 16" high)...why not?

 

From my calculations, it seems to me that the frequencies should bend around a 1 1/2" corner up to about 9kHz, or would it? And what doesn't bend could be bounced/reflected with 45-degree corner blocks, providing solid waves into the throat of the rear horn. (Then the mouth of the rear horn would have lens/vanes/diffractors to spread the waveguide as best.) The inside of the labyrinth could be covered with either large, hard, smooth, glazed ceramic tile, which is harder, heavier & stronger than glass. On the other hand, the three most reflective / least absorbent materials, better than steel or glass, are silver, gold, and aluminum. So maybe the inside of the labyrinth could be covered with heavy gauge aluminum foil, spread smooth and attached with a fine-spray adhesive during construction.

 

My corner-horns are about 30" wide, so to insert a labyrinth in there would be: 15" to the right + corner + 30" to the left + corner + 15" to the right, to arrive at the throat of the rear horn.

 

This would add 60" to the length, plus 6-8" behind and back, would total about 85-90", or better than 2 meters, or about 6 ms to the time delay, which I understand is the time needed for ideal spatial positioning, thereby extending the spaciousness of the room, and with the diffusers inside the rear horn, it seems it could achieve the same effects as having the speakers a meter away from rear-side walls. It seems to me that the distance should be long enough there shouldn't be phasing issues. In order for the sound to not to lose its energy or be dissipated, it is both very reflective and has adequately heavy mass throughout the labyrinth.  Sound diffracts at the same angle it hits the barrier, so if it hits at 45 degrees it will bounce off at 45 degrees, and make it around corners, shouldn't it? Or, does it?  

 

This thread has posed to me a few questions like this one, but this is my first. I'm hoping to find some answers. I've had plans done on this and then I encountered this thread. Can either of you expand on anyone that has attached horns to an AMT? Do you know of anyone that has attached an exponential labyrinth to AMTs? (Must be expansion to avoid standing waves.) If soundwaves are not absorbed, they should travel the distance without dissipation just like in free-air, shouldn't they? One question I wonder about is, what could happen with IM distortion? What am I not thinking of? I lack the experience to answer these questions, and am hoping someone might have some answers or ideas. Thank you, gentlemen, for considering my questions.

 

[hsbrock]

On 1/2/2020 at 2:34 PM, Rudy81 said:

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.

 

@Rudy81 I have been studying your posts for some time now, and have a few questions, if you might help me? Assuming AMTs in a dipole Tractrix Bi-horn front & rear... and for dipole OB I should have 1m between the VC and the rear wall, and I so have been considering moving the mouth of the rear horn as close as 8" from rear wall, and adding distance/delay to the soundwaves with an slow-expansion exponential labyrinth between the rear of the AMT and the throat of the rear horn, with the mouth of the rear horn about 8" from the rear wall, but I wonder, How well might 400-10kHz soundwaves travel through an exponential labyrinth - if the soundwaves won't bend, will they reflect or bounce adequately and cleanly enough (presuming the walls are hardened) if I have curved corners or 45-degree blocks?  The goal is to enable placing the drivers closer into the corners without having them out so far into the room. With this much distance, would I run into phase issues and breakup? Can I keep an adequately clean sound feeding into throat of the rear horn? Surely the same principles apply as with sub horns.  With aluminum being the third most reflective surface to bounce sound waves (behind silver & gold), I was considering lining the interior of the labyrinth with a sheet of heavy weight aluminum foil before it feeds into the rear horn. There would also be diffusers within the mouth of the rear horn to spread the sound horizontally and vertically to expand the stage & prevent direct bounce-back. So my concerns deal with the sound progressing through the labyrinth because I cannot find anything about how higher frequencies propagate through a labyrinth. I've assumed an slow exponential expansion to avoid standing waves or back-waves, i.e., the throat at the rear of the AMT expands very gradually to the mouth of the labyrinth/throat of the rear Tractrix. I sure am hoping someone might have some insights!

[Rudy81]

Hmmmm. Placing the back of the speaker so close to the wall is likely to cause you problems and in a sense, defeats the purpose of the dipole design.  I don't have any experience with labyrinth use in such a scenario.  I suspect you are likely to have to use trial and error to see if that will work for you.  I suspect this concept is really adding complexity to your listening space.  

 

I would start with just placing the speakers where you want without anything modifying the rear propagation and listen to it.  It may sound ok.  As I'm sure you know, OB speakers are normally further from the rear wall.....but, trying it out will be the only way for your to figure out how it sounds.  

 

If not satisfied, you can the begin trying different options like absorption, diffusion or a much complex idea like the labyrinth. You actually may have good luck using some polycylindrical diffusers on the back wall.