Rudy81 Posted January 31, 2020 Share Posted January 31, 2020 8 minutes ago, Thaddeus Smith said: OK, I'll admit that those are pretty sexy and refined.. They should look fairly nice when painted. Since I know how they will perform, I will hold off on measurements until I have a chance to finish them totally. Link to comment Share on other sites More sharing options...
Rudy81 Posted January 31, 2020 Share Posted January 31, 2020 I'm still in pain after having trashed that diaphragm. 😰 1 Link to comment Share on other sites More sharing options...
Rudy81 Posted January 31, 2020 Share Posted January 31, 2020 17 minutes ago, Pete H said: Agreed, and if he made an extra set, you would be willing to pay? LOL I'm sure he has templates and they certainly look fantastic! Ha! For reference, this took me two full days in the shop and I had the lumber on hand. Because the driver cases are not 'perfectly machined' it consumes time fitting each set individually....but, I think worth the effort. I think this will be the final solution until someone can come up with a true horn vs. a waveguide. Overall size is about 14" wide and 13" deep IIRC. Wings are made from stock Oak that is 7.25" wide. Used about a 4'x8' sheet of plywood for the base and sides. IMHO, the 12" sided symmetrical prototype I made before this is just too dang big and heavy. Closing off the sides certainly makes the whole thing look more 'finished'. Still brainstorming on how to close off the open top, yet make it accessible if you need to remove a driver. I will likely be crossing higher than where I am now....I'll see how they measure up and then go from there. Link to comment Share on other sites More sharing options...
Pete H Posted February 1, 2020 Share Posted February 1, 2020 12 minutes ago, Rudy81 said: Closing off the sides certainly makes the whole thing look more 'finished'. Still brainstorming on how to close off the open top, yet make it accessible if you need to remove a driver. To be clear, you don't like tops on them at all? Chances of you having to change out a driver are remote, so I'm assuming this is purely for ascetic purposes. I'll have to give all of that some thought as I go through the process as well. Link to comment Share on other sites More sharing options...
Rudy81 Posted February 1, 2020 Share Posted February 1, 2020 15 minutes ago, Pete H said: To be clear, you don't like tops on them at all? Chances of you having to change out a driver are remote, so I'm assuming this is purely for ascetic purposes. I'll have to give all of that some thought as I go through the process as well. I'm just hoping to have a more finished look when all done, yet be able to remove a driver if needed. I am currently leaning to cutting a piece that would fit perfectly in the void left at the top and just use double sided tape to stick to the top of the second driver. Not at all a big deal, but something to close the 'driver slot' and have a finished look. Link to comment Share on other sites More sharing options...
Pete H Posted February 1, 2020 Share Posted February 1, 2020 Still breaking in, cut some temp wings at 9.25 out of some epoxy BB scraps I had laying around and listening to some Bonnie Raitt, sounding pretty good, no measurements or eq currently, just a LW12 at 800 hz with the BB's. 1 Link to comment Share on other sites More sharing options...
Rudy81 Posted February 1, 2020 Share Posted February 1, 2020 @Pete H, how far is the stack from the front wall of your listening space? What HF were you using before for comparison? Link to comment Share on other sites More sharing options...
Pete H Posted February 1, 2020 Share Posted February 1, 2020 About 8" from the front edge currently. Sunday when I can run some tests it will be the 2 AMT's versus the Faital Pro HF200 in a 2 way. Currently running the Faital's and Daves LMAHL2 tweeters in a 3 way with the dual 12 BB's. Link to comment Share on other sites More sharing options...
Rudy81 Posted February 1, 2020 Share Posted February 1, 2020 5 minutes ago, Pete H said: About 8" from the front edge currently. Sunday when I can run some tests it will be the 2 AMT's versus the Faital Pro HF200 in a 2 way. Currently running the Faital's and Daves LMAHL2 tweeters in a 3 way with the dual 12 BB's. What I meant to ask was the distance form the back of the AMT to the front wall of your room. I suspect that if you are too close to a room boundary you will lose some of the openness and magic this driver exhibits in my room. The HF200 will be a worthy opponent for sure. Link to comment Share on other sites More sharing options...
Pete H Posted February 1, 2020 Share Posted February 1, 2020 They are out in my shop at the moment. It's where I do my basic swapping, listening and testing and then they will get moved in and set up for the room. The shop is about as bad as it gets with all the tools and equipment that are in here, but it allows me to do a lot of A/B listening easily. Currently there are the dual 12 mini's, KP250's, KI396's a Cornwall 2 and a split 3 way Cornscalaish speaker in the shop. Link to comment Share on other sites More sharing options...
pzannucci Posted February 1, 2020 Share Posted February 1, 2020 15 hours ago, Rudy81 said: Progress on the final design. Nice!! Link to comment Share on other sites More sharing options...
pzannucci Posted February 1, 2020 Share Posted February 1, 2020 On 1/30/2020 at 2:41 PM, Chris A said: Sorry for misinterpreting your question. Without having polar measurements (every 10-15 degrees off-axis out to 90 degrees with the microphone the same distance), it's difficult to answer your question about curved wings. You'd be looking for "waistbanding" of the polars and a phenomenon known as "mouth bounce" is encountered with the straight-sided wings...if the curved wings are appropriate to this application/effort. Marginal if you are thinking about playing them at higher SPL, i.e., at or near 100 dBSPL, or higher. The rise in harmonic distortion without stacking or added wing extensions is fairly sudden and relatively large, as if the diaphragm is suddenly running out of travel like in a subwoofer cone entering an xmax condition. I believe that's due to the lack of acoustic loading and polar directivity support of a horn (symmetric horn on both sides of the AMT-1 for the forward and rear waves) and the measurements that Rudy has done pretty much back up that assessment. Chris On the distortion front, I have a couple of extra diaphragms with thoughts of using some very strong N52 magnets I have to build a better motor structure. I was thinking better control on the diaphragms might help reduce distortion at lower frequencies and increase efficiency. Thoughts? Link to comment Share on other sites More sharing options...
Chris A Posted February 1, 2020 Author Share Posted February 1, 2020 Certainly if you can achieve higher B-field at the ribbon, that will also extend performance lower in frequency, albeit the ribbon itself will still be limited in its travel by the distance from the resting position of the diaphragm until the pleats "close up" on each other-in both directions of pleat motion. So the issue of the 100 dB "brick wall" is still there without wings if you're trying to play the AMT-1 below 1.5 kHz. The advantage of the wing extensions is that they reduce the total travel of the pleats in order to produce a flat SPL on-axis, by as much at a factor of 5 over the no-wing configuration (depending on frequency, of course). The frequency band where the wings come into play are below the 1/4 axial wavelength distance of the AMT-1 housing itself--which is below 1.5 kHz, where the ribbon runs out of horn loading (2.25 inch axial distance of the magnet structure covered by the polymer case of the driver), and is emitting into wider and wider horizontal angles below that point. You can see this in the spectrogram broadening below 1.5 kHz (a single AMT-1 without wings in half space): The AMT-1, double-stacked with 7" wing extensions at 1m: and with 12" wing extensions: The anomalies at 3 and 5 kHz in the last spectrogram are only a function of the smoothing used on the plot. At 1/24th octave smoothing, those bulges disappear, but the plot looks a bit more "busy" to the untrained eye. Chris Link to comment Share on other sites More sharing options...
Chris A Posted February 1, 2020 Author Share Posted February 1, 2020 To prove my point on the spectrogram for the 12" wing assembly: all that must be done to have a uniform spike of the spectrogram is to EQ the assembly to flat SPL response: It's the minimum phase nature of acoustic drivers and loudspeakers that causes most of the wiggles in the phase (i.e., peak energy time) curve as the stacked/winged AMT-1 assembly SPL goes up and down vs. frequency. Chris Link to comment Share on other sites More sharing options...
pzannucci Posted February 1, 2020 Share Posted February 1, 2020 Thinking of both wings/horn and higher field. Try the best of both worlds. Link to comment Share on other sites More sharing options...
Rudy81 Posted February 1, 2020 Share Posted February 1, 2020 Another wings set close to being done. Now I have to wait for the lacquer to dry and let the fumes die some before bring them in. One note. During my build I placed the small internal braces for the wings right up against the driver sides. During the final gluing and nailing, a couple of pieces moved in a few thousands of an inch....enough to require sanding to allow the driver to slide in.....Grrrrr....wasted of half a day fixing that mistake. Other than that, these should work for my room. Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted February 2, 2020 Share Posted February 2, 2020 How are you routing the wiring + placing the barrier strip? Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted February 2, 2020 Share Posted February 2, 2020 Another detail I'm hoping to clarify.. Impedance: 4 ohms, Re: 3.9 ohms Power: 40 watts RMS, 160 watts max Wired in series these power handling specs become 8ohms impedance, 80w rms/320w max, correct? Link to comment Share on other sites More sharing options...
babadono Posted February 2, 2020 Share Posted February 2, 2020 ^Looks correct. 1 Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted February 2, 2020 Share Posted February 2, 2020 Seeing how fragile the leads can be, just want to be sure I don't blast them with power. Although, Rudy is using his EP4000's so maybe it's a non issue. Link to comment Share on other sites More sharing options...
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