Thanks for the offer, Ron. I picked up a pack of gorilla mounting putty and I think I will give this a try first. Its very soft and tacky and easy to remove, leaving no residue.
I just think it is BS that I can spend that much and they are perfectly fine to let me pay $72 shipping to send me junk (was the cheapest shipping option). Reading their return and refund policy I can see I've made a big mistake. They have zero skin in the game. I'm out the shipping and would have to pay again to ship them back. I should have never tried this.
I removed the melted, 50 year old diaphragms and installed the two NOS (new old stock) diaphragms that @LifeOfBrian gave me. These diaphragms look like the yellow or bronze colored teflon ones that ESS sold as replacements many, many years ago. On-axis is kind of bumpy, but at 15 degrees off axis at 1 meter, the two NOS diaphragms measure reasonably flat (see pic below). Not perfect, but I can work with these to build a nice pair of tower type speakers. I don't think these tweeters are designed to be listened to directly on axis. You need to be at least 15 degrees off axis, in order to tone down the on-axis treble bump somewhat in the 4 to 7kHz region.
I haven't spent a lot of time tweaking a crossover on the pair I have, but brief listening, even with the peaks and dips of my pair was very enjoyable. Brief measurements showed very low distortion. The large Sd provides great dynamics.
But Chahly - Stahkist don't want speakers that look good, Stahkist wants speakers that sound good!
@ugly_woofer said:
Why not just call ESS and ask what putty to use?
Thanks, Nick. The web site lists Simply Speakers as an authorized dealer for replacement parts, so I submitted an email question and am waiting for a reply.
Got a reply. Apparently, any type of rope caulk, sold in the weatherstrip aisle of any hardware or lumber store, can be used.
I was initially offended when I read about Linkwitz' experiments with rear facing tweeters and omni designs. He said "it sounds interesting". And now that's what I think. I've heard the highly touted MBLs and they sound great, but they don't give the imaging of point source loudspeakers. If someone is happy, who am I to judge?
But Chahly - Stahkist don't want speakers that look good, Stahkist wants speakers that sound good!
@LifeOfBrian said: I believe they came form the AMT-1b's However, this is an interesting adaptation. Wonder what that cabinet design did to the imaging?
My design will be completely open, front and back. A thin, narrow tower with the same footprint as the big AMT tweeter. Almost like mounting the big AMT on top of a pole. No nearby type reflections will be possible from the enclosure, either front or back, except for the narrow tower itself. However, the old classic, 70's style AMT has four reflective cavities on the front and back that I will need to deal with. So I will be filling these cavities with 1/4" thick felt or demin.
@rjj45 said:
I was initially offended when I read about Linkwitz' experiments with rear facing tweeters and omni designs. He said "it sounds interesting". And now that's what I think. I've heard the highly touted MBLs and they sound great, but they don't give the imaging of point source loudspeakers. If someone is happy, who am I to judge?
So far, I have experimented with sealing the back with a 1/4" thick 6.75" x 8" sheet of closed cell foam rubber. Held it in place by press fitting it onto the back temporarity with gorilla mounting putty. Sounded horrible. And it produced a large number of nasty peaks and dips in the on-axis response in the 2k to 7k region. I didn't put damping material of any kind in the rear cavity, so maybe that was the problem. Don't know. Right now I am leaning toward the open back config for the final design unless I can come up with a closed back config that sounds and measures much better.
Got a reply. Apparently, any type of rope caulk, sold in the weatherstrip aisle of any hardware or lumber store, can be used.
Not a fan of rope caulk because the oil stains wood and some painted surfaces
I have noticed this too. In the past, I have mounted woofers on raw MDF using mortite rope caulk. Then, when I removed the drivers several years later, I noticed that the oils from the rope caulk had visibly stained the MDF a darker color. So I stopped using rope caulk to mount drivers and shifted over to custom cut 1/16" thick foam gaskets instead.
@4thtry said:
So far, I have experimented with sealing the back with a 1/4" thick 6.75" x 8" sheet of closed cell foam rubber. Held it in place by press fitting it onto the back temporarity with gorilla mounting putty. Sounded horrible. And it produced a large number of nasty peaks and dips in the on-axis response in the 2k to 7k region. I didn't put damping material of any kind in the rear cavity, so maybe that was the problem. Don't know. Right now I am leaning toward the open back config for the final design unless I can come up with a closed back config that sounds and measures much better.
I was going to try some 1/2" felt pressed in so it hugs the angled side contour, bent at the center close to the diaphragm.
@LifeOfBrian said: I believe they came form the AMT-1b's However, this is an interesting adaptation. Wonder what that cabinet design did to the imaging?
I see they have the sides mostly open with grill cloth. I wonder why they didn't do the same thing on the back panel.
@rjj45 said:
re: rope caulk.
I used blu-tak to connect an adapter to an XT25 and waveguide.
It will never dry out or stain. Looks perfect for this application.
I was looking for blu-tack, but couldn't find it at local stores. So I picked up a pack of gorilla mounting putty instead. Probably very similar to blu-tack, just a different color and packaging. Seems to hold the diaphragms in position very well.
I was asked about the vertical dispersion pattern of the classic AMT tweeters operating in dipole mode, so I put together a few graphs. Since we are looking at a full 360 degrees, the heat map seems to be the best graph to use.
This first graph below is a 360 degree horizontal heat map of the classic ESS AMT tweeter, using the NOS diaphragm and a double notch xover. You can clearly see the expected figure 8 response pattern with 90 degree null. From 1 to 2kHz it is +/- 70 degrees and from 2.5kHz to 20kHz it narrows to approx +/- 50 degrees.
The second graph is a 360 degree vertical heat map. Here you can clearly see how the vertical dispersion narrows significantly as you go up in frequency. From 1 to 2kHz it is +/- 60 degrees, from 2.5 to 6kHz it is +/- 30 degrees, from 6 to 10kHz it is +/- 20 degrees, and from 10 to 20kHz it narrows down to about +/- 10 degrees.
And here is my Vcad 6 pack screen with tentative 9 part double notch crossover. As you can see, I lose about 6.5dB with the filter, reducing the AMT's sensitivity down from 92dB to about 85.5dB. I'm planning on using two 8 ohm HiVi F5 mid/woofers, hooked in parallel, mounted just below the tweeters. After accounting for the parallelling gains and BSC losses, this should give me a good sensitivity match.
Comments
Thanks for the offer, Ron. I picked up a pack of gorilla mounting putty and I think I will give this a try first. Its very soft and tacky and easy to remove, leaving no residue.
Measured at 24", on my measurement stand. Close enough for me.
I think it is pretty awesome to see the evolution of these tweeters.
Excellent match. And really smooth looking for a 25dB/decade plot.
Not exactly happy with this. I expected better quality control for the prices these command.
I was a bit surprised seeing how the ribbons are ‘set’ in the unit. Perhaps take one out and reset, re-puddy, and re-measure ???
I just think it is BS that I can spend that much and they are perfectly fine to let me pay $72 shipping to send me junk (was the cheapest shipping option). Reading their return and refund policy I can see I've made a big mistake. They have zero skin in the game. I'm out the shipping and would have to pay again to ship them back. I should have never tried this.
I would share your findings with Heil and have them check to see if one unit is defective. Chances are they will stand behind their product.
I removed the melted, 50 year old diaphragms and installed the two NOS (new old stock) diaphragms that @LifeOfBrian gave me. These diaphragms look like the yellow or bronze colored teflon ones that ESS sold as replacements many, many years ago. On-axis is kind of bumpy, but at 15 degrees off axis at 1 meter, the two NOS diaphragms measure reasonably flat (see pic below). Not perfect, but I can work with these to build a nice pair of tower type speakers. I don't think these tweeters are designed to be listened to directly on axis. You need to be at least 15 degrees off axis, in order to tone down the on-axis treble bump somewhat in the 4 to 7kHz region.
I haven't spent a lot of time tweaking a crossover on the pair I have, but brief listening, even with the peaks and dips of my pair was very enjoyable. Brief measurements showed very low distortion. The large Sd provides great dynamics.
Got a reply. Apparently, any type of rope caulk, sold in the weatherstrip aisle of any hardware or lumber store, can be used.
Glad that you've got them and running.
Thanks, Robert. Plan is to build a new tower system with them and have them ready for demo at Indy next year as my non-theme pair.
Not a fan of rope caulk because the oil stains wood and some painted surfaces
My guess would be that there will be too many reflections from that box design, but who knows, and as always it comes down to individual taste.
I was initially offended when I read about Linkwitz' experiments with rear facing tweeters and omni designs. He said "it sounds interesting". And now that's what I think. I've heard the highly touted MBLs and they sound great, but they don't give the imaging of point source loudspeakers. If someone is happy, who am I to judge?
re: rope caulk.
I used blu-tak to connect an adapter to an XT25 and waveguide.
It will never dry out or stain. Looks perfect for this application.
My design will be completely open, front and back. A thin, narrow tower with the same footprint as the big AMT tweeter. Almost like mounting the big AMT on top of a pole. No nearby type reflections will be possible from the enclosure, either front or back, except for the narrow tower itself. However, the old classic, 70's style AMT has four reflective cavities on the front and back that I will need to deal with. So I will be filling these cavities with 1/4" thick felt or demin.
So far, I have experimented with sealing the back with a 1/4" thick 6.75" x 8" sheet of closed cell foam rubber. Held it in place by press fitting it onto the back temporarity with gorilla mounting putty. Sounded horrible. And it produced a large number of nasty peaks and dips in the on-axis response in the 2k to 7k region. I didn't put damping material of any kind in the rear cavity, so maybe that was the problem. Don't know. Right now I am leaning toward the open back config for the final design unless I can come up with a closed back config that sounds and measures much better.
I have noticed this too. In the past, I have mounted woofers on raw MDF using mortite rope caulk. Then, when I removed the drivers several years later, I noticed that the oils from the rope caulk had visibly stained the MDF a darker color. So I stopped using rope caulk to mount drivers and shifted over to custom cut 1/16" thick foam gaskets instead.
My go-to gasketing material:
McMaster Carr
I was going to try some 1/2" felt pressed in so it hugs the angled side contour, bent at the center close to the diaphragm.
I see they have the sides mostly open with grill cloth. I wonder why they didn't do the same thing on the back panel.
The top panel looks like grill cloth too.
Probably for cost cutting. Grill cloth is cheaper than wood.
I was looking for blu-tack, but couldn't find it at local stores. So I picked up a pack of gorilla mounting putty instead. Probably very similar to blu-tack, just a different color and packaging. Seems to hold the diaphragms in position very well.
I have used it many times before it should work well.
I was asked about the vertical dispersion pattern of the classic AMT tweeters operating in dipole mode, so I put together a few graphs. Since we are looking at a full 360 degrees, the heat map seems to be the best graph to use.
This first graph below is a 360 degree horizontal heat map of the classic ESS AMT tweeter, using the NOS diaphragm and a double notch xover. You can clearly see the expected figure 8 response pattern with 90 degree null. From 1 to 2kHz it is +/- 70 degrees and from 2.5kHz to 20kHz it narrows to approx +/- 50 degrees.
The second graph is a 360 degree vertical heat map. Here you can clearly see how the vertical dispersion narrows significantly as you go up in frequency. From 1 to 2kHz it is +/- 60 degrees, from 2.5 to 6kHz it is +/- 30 degrees, from 6 to 10kHz it is +/- 20 degrees, and from 10 to 20kHz it narrows down to about +/- 10 degrees.
And here is my Vcad 6 pack screen with tentative 9 part double notch crossover. As you can see, I lose about 6.5dB with the filter, reducing the AMT's sensitivity down from 92dB to about 85.5dB. I'm planning on using two 8 ohm HiVi F5 mid/woofers, hooked in parallel, mounted just below the tweeters. After accounting for the parallelling gains and BSC losses, this should give me a good sensitivity match.
Curious how this one turns out Bill , I have these drivers on hand