I'm wondering if I can pay someone to design a waveguide for an AMT that I own?
Does anyone know of anyone providing that service?
Does anyone know of anyone providing that service?
Some of the best designers are right here. You may find you need to be at least partially involved in the process.
Which AMT do you have? I just installed waveguides on Beyma TPL-150 (now 150H), and I must say, waveguides do NOT automatically improve sound quality.
https://www.diyaudio.com/community/...ible-with-beyma-tpl-150h.403976/#post-7474697
https://www.diyaudio.com/community/...ible-with-beyma-tpl-150h.403976/#post-7474697
I am glad to help. I had assumed that I would just mail the AMTs to someone. But I can assist too.
I have owned/borrowed Mundorf, Aruum Cantus, Dayton, and a few others. But these are my personal favorites.
My goal is to see if a horn would possibly allow them to cross safely lower than 2400hz, have even better dispersion, and address any possible issues with FR.
I have owned/borrowed Mundorf, Aruum Cantus, Dayton, and a few others. But these are my personal favorites.
My goal is to see if a horn would possibly allow them to cross safely lower than 2400hz, have even better dispersion, and address any possible issues with FR.
I would LOVE to purchase those Beyma waveguides from you, if you end up not keeping them. This is for another project.
I always EQ response, waveguide or not. Often a waveguide changes response and sometimes makes it more in need of EQ, however this isn't automatically a problem.. though sometimes it is. It comes down to issues that respond well to EQ and issues that don't.
True. I am a huge disciple of DSP and proper EQ.
So I guess the goals are lower xover possibilities, better dispersion, and ... should efficiency improve with a horn? Not that it's needed.
So I guess the goals are lower xover possibilities, better dispersion, and ... should efficiency improve with a horn? Not that it's needed.
For example, an OS waveguide on a dome tweeter will widen directivity at the top end, thus lowering sensitivity overall once EQed. Efficiency is a different thing of course and the low end can be brought up, as you say.
The waveguide should be large enough to support those lower frequencies, then large enough to have a roundover as well. Avoid having one dimension that is especially short.
The waveguide should be large enough to support those lower frequencies, then large enough to have a roundover as well. Avoid having one dimension that is especially short.
Those appear to have the diaphragm quite far back in a kind of steep waveguide already. I'm not sure how the waveguide would mount? It ideally want to be as close to the sound source as possible. Can the front come off, or are the magnets integrated in there?
Look like I would have to trim the face plates flush. I thought the waveguide would mount to the round flange, with the rectangle showing through.
I figured the new waveguide would just continue the factory angles out to the roll overs on the edge of the new waveguide.
I just dont know the length to make anything. Including the diameter of the round overs.
But that's my ignorance speaking.
I figured the new waveguide would just continue the factory angles out to the roll overs on the edge of the new waveguide.
I just dont know the length to make anything. Including the diameter of the round overs.
But that's my ignorance speaking.
If you can find waveguides like the ones drjlo has and make them fit at the throat with a good overall shape and a good throat transition shape.. then you could extend the walls and add roundovers to any size you need.
BTW. Anybody know which AMT Martin Logan uses in Motion 40? I quite like how this speaker sounds, especially in the highs, although it's crossed over pretty high at 2.6kHz, in a funky, shallow waveguide/recess? Its size is 1.4x1 inch.
Okay, a wavelength of what exactly? How do I determine the width of the wavelength?
Are we speaking the wavelength at the desired low cut off frequency?
Yes.
A waveguide isn't going to have a cutoff frequency, strictly speaking.. that's a thing for regular horns and it's more than we need to look at now. What's important is how low it holds it's directivity control. A wavelength at the crossover frequency is a good place to start but there is more to it than that.
Use the standard formula, eg 345m/f=wavelength
A waveguide isn't going to have a cutoff frequency, strictly speaking.. that's a thing for regular horns and it's more than we need to look at now. What's important is how low it holds it's directivity control. A wavelength at the crossover frequency is a good place to start but there is more to it than that.
Use the standard formula, eg 345m/f=wavelength
Generally, in order for a horn to control its horizontal/vertical polars, a horn mouth size of 1/2 wavelength at the desired low frequency loss of directivity is required. For instance, for a 800 Hz horn, the horn mouth width should be ~8.5 inches/ 21.6 cm.
The fact that AMTs are line sources creates an increasing directivity index as the frequency rises, thus highlighting the only real Achilles heel of AMT performance. So the vertical directivity gets very, very narrow above 4-8 kHz (depending on the length of the ribbon diaphragm). One way to address this undesirable characteristic (counterintuitively) is to use stacked AMTs vertically to provide a more uniform band of coverage vertically, just like the old Magnepan line source tweeters used in the 1980s:
https://community.klipsch.com/index...s-amt-1-with-wings-possible-kit-for-heritage/
The idea is that the tweeter line source height covers the listener's head height directly on-axis, but not off-axis. Any concerns about ceiling/floor bounce are eliminated (just like for all planar dipole loudspeakers). This characteristic is one of the signature sound qualities of dipole loudspeakers--the only reflections of concern are from the front wall.
So you only really need wings, left and right--not a full horn--thus simplifying the task of making a horn considerably. Just place the AMT/horn on a flat surface above the loudspeaker, and leave the top of the horn aperture open in order to retain as much vertical "airiness" as possible.
![1610566149_WingsForward.thumb.jpg.fd23438a39ad84037a3f81e85856ec29[1].jpg](https://www.diyaudio.com/community/attachments/1610566149_wingsforward-thumb-jpg-fd23438a39ad84037a3f81e85856ec29-1-jpg.1221389/ "1610566149_WingsForward.thumb.jpg.fd23438a39ad84037a3f81e85856ec29[1].jpg")
Double stack Heil AMTs with wings
![646738597_DoubleStackAMT-1withFrontWingsSPLandPhase.jpg.64d6fb6af9293ea3e0f336ec64c62593[1].jpg](https://www.diyaudio.com/community/attachments/646738597_doublestackamt-1withfrontwingssplandphase-jpg-64d6fb6af9293ea3e0f336ec64c62593-1-jpg.1221390/ "646738597_DoubleStackAMT-1withFrontWingsSPLandPhase.jpg.64d6fb6af9293ea3e0f336ec64c62593[1].jpg")
A little DSP EQ on-axis and you're good to go.
Chris
The fact that AMTs are line sources creates an increasing directivity index as the frequency rises, thus highlighting the only real Achilles heel of AMT performance. So the vertical directivity gets very, very narrow above 4-8 kHz (depending on the length of the ribbon diaphragm). One way to address this undesirable characteristic (counterintuitively) is to use stacked AMTs vertically to provide a more uniform band of coverage vertically, just like the old Magnepan line source tweeters used in the 1980s:
https://community.klipsch.com/index...s-amt-1-with-wings-possible-kit-for-heritage/
The idea is that the tweeter line source height covers the listener's head height directly on-axis, but not off-axis. Any concerns about ceiling/floor bounce are eliminated (just like for all planar dipole loudspeakers). This characteristic is one of the signature sound qualities of dipole loudspeakers--the only reflections of concern are from the front wall.
So you only really need wings, left and right--not a full horn--thus simplifying the task of making a horn considerably. Just place the AMT/horn on a flat surface above the loudspeaker, and leave the top of the horn aperture open in order to retain as much vertical "airiness" as possible.
Double stack Heil AMTs with wings
A little DSP EQ on-axis and you're good to go.
Chris
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If you don't mind paying, someone that does that on a pretty regular basis would be member Joseph Crowe.
Check out his webpage, hes got several models available for different amt and ribbons.
There are also plenty of other skilled members on here that will give you tips and insight free of charge, and possibly will do it for a fee.
But do enough research first to know what you want, and can specify it.
Perhaps you could draw by hand (or whatever means), what you are picturing and we can give some feedback on the likely results before you get an item produced.
I get the impression what you really want is a smooth interface between the AMT which sits proud of the main plate and the baffle?
I get the impression what you really want is a smooth interface between the AMT which sits proud of the main plate and the baffle?