the sort of rough and too bright phenomenon you describe put's to mind of lower frequency modulating higher frequencies via a non rigid enclosure (think aural exciter like sound)
Hi Pano, Turk,
Yes, regular Home Depot Formular foamboard.
I've found it to be milled a bit better than the Lowes green stuff. Truer thickness, squarer edges, less bubbles inside etc.
The Formular comes in both scored and unscored versions.
You can see the scoring in the pict i posted.
If the horn had really added anything to the coax CD, I would have gone to an insulation wholesaler and bought unscored to get rid of the flaws.
The foam horn didn't really seem to help much, so i just cut the box down without it. Probably should have kept trying though....a Danley guy told me you can't match the cone and horn's angles the same, which i had been trying to do.
I use this hot wire cutter when i can: Hot Wire Cutter THERMOCUT 115/E – PROXXON Inc
A nice tool !!
Made a table to set it in, to cut bigger pieces.
Works great, with only caveat being it takes a little practice to get feed rate and wire temp coordinated.
Not hard to master though.
I think it would be super for making a conical (synergy) foamboard horn.
Yes, regular Home Depot Formular foamboard.
I've found it to be milled a bit better than the Lowes green stuff. Truer thickness, squarer edges, less bubbles inside etc.
The Formular comes in both scored and unscored versions.
You can see the scoring in the pict i posted.
If the horn had really added anything to the coax CD, I would have gone to an insulation wholesaler and bought unscored to get rid of the flaws.
The foam horn didn't really seem to help much, so i just cut the box down without it. Probably should have kept trying though....a Danley guy told me you can't match the cone and horn's angles the same, which i had been trying to do.
I use this hot wire cutter when i can: Hot Wire Cutter THERMOCUT 115/E – PROXXON Inc
A nice tool !!
Made a table to set it in, to cut bigger pieces.
Works great, with only caveat being it takes a little practice to get feed rate and wire temp coordinated.
Not hard to master though.
I think it would be super for making a conical (synergy) foamboard horn.
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Thanks Mark, that's a nice setup. 
Good to know that the pink foam cuts smoothly with the hot wire. Like you, I tried matching the horn flare to the cone flare, but found it not easily possible. And with a cone in a rectangular horn, there are other problems.
Next step is to build 12mm thick MDF horns. But which driver? The 3" or the 4"? Measurements are coming next posts.
Good to know that the pink foam cuts smoothly with the hot wire. Like you, I tried matching the horn flare to the cone flare, but found it not easily possible. And with a cone in a rectangular horn, there are other problems.True, I "think" that the foamcore is singing and that it doesn't have a very nice voice. Mentally separating that sound from the lack of bass and the driver's FR isn't easy.
Next step is to build 12mm thick MDF horns. But which driver? The 3" or the 4"? Measurements are coming next posts.
Graphs for the Holidays
OK, here are some measurements. I've tried to group them for easy visual comparison with never more than 2 curves per graph. Driver vs driver on and off axis and horn vs baffle on and off axis.
Starting with the FaitalPro 3FE25 3" driver on the Cosyn style waveguide made of foamcore vs the same driver on an open baffle of the same dimensions and same material. What is the waveguide doing that the baffle is not?
Dimensions are 60cm wide x 41.5cm tall. Measured at 1 meter from horn mouth or baffle surface (distance to driver is different). Height from concrete floor is 124cm. On axis and 30 degrees off axis horizontal. No rear chamber on the driver.
OK, here are some measurements. I've tried to group them for easy visual comparison with never more than 2 curves per graph. Driver vs driver on and off axis and horn vs baffle on and off axis.
Starting with the FaitalPro 3FE25 3" driver on the Cosyn style waveguide made of foamcore vs the same driver on an open baffle of the same dimensions and same material. What is the waveguide doing that the baffle is not?
Dimensions are 60cm wide x 41.5cm tall. Measured at 1 meter from horn mouth or baffle surface (distance to driver is different). Height from concrete floor is 124cm. On axis and 30 degrees off axis horizontal. No rear chamber on the driver.
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and in looking at mark100's speakers i would use burlap and pva glue to dress the baffle....diffraction is not the enemy of smooth response/good sound...
barbecue rotisserie motor with a drive yoke???
or some form of keeping the feed rate proportial to cut current via a comparator,perhaps??
This is the Faital 3FE25 vs the Faital 4FE35 on the Cosyn style waveguide both on and off axis. This is a little unfair to the 3FE25 because it has a 1L rear chamber vs the 4FE35 that has a 2.8L rear chamber. Both are heavily stuffed.
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what's the depth? and for giggles what's your best subjective approximation of point of origin to mouth of horn?
10 inch????
10 inch????
You know, i think foamboard sings too. One of the big syns i made has 2" thick secondary flares, and i just keep feeling like they add some voice that doesn't belong. Could just be airborn bass from subs vibrating them, though.
But I've also put a TC9 and 3fe25 in plain foamboard baffles for measurements, and even then pink sounds a little off...in a way i don't really know how to explain.
Have to say I may be done with foamboard other than for internal volume fill when needed.
Re your two measurements plots..
First one, horn vs baffle same driver...my coax was smoother without the horn too. (Twas why I ditched the horn rings).
On the second, OA vs 30 deg....you're using Bill's sheet for 90x60 right?
If so, i wouldn't expect too much difference at 30 deg, given a 90 deg pattern....maybe 45 deg would show the horn kicking in more?
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Yes, this is Bill's Cosyn as stock in the spreadsheet, 90x60 degree. Only the throat size has been changed to accommodate different size drivers.
Depth with 3FE25 and TC9FD = approx. 21.5cm. With 4FE35 depth = 20cm
Depth with 3FE25 and TC9FD = approx. 21.5cm. With 4FE35 depth = 20cm
ok i was an inch and a half off from looking at the graph....i bet a fifth of scotch i could have done better hearing it!!
Do you mean t/s specs? My impedance rig no longer works under Win10, so all I have are manufacturer specs. FR? On baffle?
Max width 24", max height 18" max depth maybe 12-14". Desired polar should be classic gently falling response about 630 Hz at listening position, meaning about 30 degrees off axis and 9-12 feet away. I"m currently testing at 5ft apart and 5 feet from the from front of the horn.
Listening with bass
To get a better idea of what these might sound like in real use, I dug out an old subwoofer and a little 3 channel Class-D amp that has a mono sub channel.
Made a huge difference. No longer harsh and bright, they are now somewhat mellow. No EQ was used this test.. I listened to whatever came up on my phone, some Les Baxter, the Symphonie Fantastique, Switched on Bach. All good. The Berlioz was remarkable. Good depth, especially with the garage door open, almost as deep as a real orchestra. Very nice location of instruments left to right and forward back. Switched on Bach was fun, but no real depth. There is no hint of the sound coming from the horns at all, which is surprising considering the rough build. The image width does not extend much outside of the speakers but can go deep if the recording has it. They get plenty loud with nothing more than a little chip amp running on 12 volts.
Then I listened to a good bit of YouTube for voice, mostly Techmoan. Good articulation, the sound of different takes is obvious, overall easy to follow. Sweet spot is fairly wide, no head in the vice listening, the phantom image shifts left to right some as I move, but doesn't pull quickly to one side or the other.
I'm now encouraged to do a real build out of better material. Still need to decide if the 3 or 4 inch would be better. I think either will sound nice and can be tweaked with a simple passive network.
To get a better idea of what these might sound like in real use, I dug out an old subwoofer and a little 3 channel Class-D amp that has a mono sub channel.
Made a huge difference. No longer harsh and bright, they are now somewhat mellow. No EQ was used this test.. I listened to whatever came up on my phone, some Les Baxter, the Symphonie Fantastique, Switched on Bach. All good. The Berlioz was remarkable. Good depth, especially with the garage door open, almost as deep as a real orchestra. Very nice location of instruments left to right and forward back. Switched on Bach was fun, but no real depth. There is no hint of the sound coming from the horns at all, which is surprising considering the rough build. The image width does not extend much outside of the speakers but can go deep if the recording has it. They get plenty loud with nothing more than a little chip amp running on 12 volts.
Then I listened to a good bit of YouTube for voice, mostly Techmoan. Good articulation, the sound of different takes is obvious, overall easy to follow. Sweet spot is fairly wide, no head in the vice listening, the phantom image shifts left to right some as I move, but doesn't pull quickly to one side or the other.
I'm now encouraged to do a real build out of better material. Still need to decide if the 3 or 4 inch would be better. I think either will sound nice and can be tweaked with a simple passive network.
Interesting! Seems to only give extra gain around 600-3kish. I would have expected more! Were these with the same input?
Yeah, sometimes it doesn't matter if it measures well it can sound nice. I wish I'd got round to making a second one of mine to do a sound test. Here was my go, might give you some interest.
1000hz Foam Board Conical Horn (SynergyCalc)
Yeah, sometimes it doesn't matter if it measures well it can sound nice. I wish I'd got round to making a second one of mine to do a sound test. Here was my go, might give you some interest.
1000hz Foam Board Conical Horn (SynergyCalc)
Yes, exactly the same input. Thanks, I'm looking at your thread now.
They sound good enough for me to build a pair out of MDF for a start. Here I can do that for about $15. Maybe later in walnut if I really like them. I don't think they'll be the best speakers I've ever had, but for the size and cost, why not?
They sound good enough for me to build a pair out of MDF for a start. Here I can do that for about $15. Maybe later in walnut if I really like them. I don't think they'll be the best speakers I've ever had, but for the size and cost, why not?