Hi Mark
I look forward to seeing your build. Yes the horns will be massive. I spent the day welding and grinding the steel (Universal beam 150mm2 @ 37 kilo a metre) for the lathe build. With some nice inch and a half bearings and 18" double belt pulley it should be good for 80 to 120 rpm. I am hoping to be able to cut the rings to shape and just use the lathe for sanding and fnishing!
I look forward to seeing your build. Yes the horns will be massive. I spent the day welding and grinding the steel (Universal beam 150mm2 @ 37 kilo a metre) for the lathe build. With some nice inch and a half bearings and 18" double belt pulley it should be good for 80 to 120 rpm. I am hoping to be able to cut the rings to shape and just use the lathe for sanding and fnishing!
Here we go again, another sim. I have reduced the size a little. Looks pretty good. Not sure if 2lt is too small for rear chamber? Compression is high as well but that is easily modified.
Attachments
Sawn-off tractrix
Nice data, Traskutis . Looks like it's valid to simulate as 1-Pi, on the basis of these measurements . I'm impressed how low the response reaches towards 100Hz .
Was this measured with the horn on the floor ?
Meanwhile, slightly hi-jacking 3GGG's thread , the attached data may be of interest. I have been playing around with a Hyperbolic design for the Fane for a while . Limited mouth ( 3500sq-cm ) and about 85-90cm long . Was concerned a bit about colouration - ripple. After seeing all these full-mouth Tractrix designs, I wondered ( today ) , how quickly does the response 'go bad' if you cut-off the mouth of a big tractrix early ? Seems it's a lot better than I thought . If I use a 120Hz TRA and cut-off at 3500 mouth, I get a BETTER result than using an exponential, and it's about 5-10cm shorter. See attached . Any comments ?
Nice data, Traskutis . Looks like it's valid to simulate as 1-Pi, on the basis of these measurements . I'm impressed how low the response reaches towards 100Hz .
Was this measured with the horn on the floor ?
Meanwhile, slightly hi-jacking 3GGG's thread , the attached data may be of interest. I have been playing around with a Hyperbolic design for the Fane for a while . Limited mouth ( 3500sq-cm ) and about 85-90cm long . Was concerned a bit about colouration - ripple. After seeing all these full-mouth Tractrix designs, I wondered ( today ) , how quickly does the response 'go bad' if you cut-off the mouth of a big tractrix early ? Seems it's a lot better than I thought . If I use a 120Hz TRA and cut-off at 3500 mouth, I get a BETTER result than using an exponential, and it's about 5-10cm shorter. See attached . Any comments ?
Attachments
I would not use the Faital on a 2" horn unless you make a phase plug for it. You will get a lot of reflections and the sound will be congested. I did not use an adapter, just bolted the Faital directly to the 4" throat. This makes for about a 1:1 throat. The sound was very smooth and coherent without any sign of congestion. The Faital is one of the few woofers that can get away with a 1:1 throat and still maintain decent high frequency gain.
This is how I do it in the real world:
I make the back chamber about 25% larger than what I figure out in Hornresponse. You can take your best guess at how much volume the basket & magnet takes up, but is not really needed. Mount up the woofer and close everything up. Measure the resonance. It should be too low in frequency. This is good because it is easier to reduce the volume than increasing it. Open the horn up and remove the woofer. Line the rear chamber with Great Stuff expanding foam. Slowly spray the foam out - DO NOT go fast. Go nice and slow so the foam will only expand a little bit. Let it dry over night. Put the woofer back in and remeasure the resonance. You want to push it just a little bit higher than your target maybe 5Hz to 8Hz high . You then get back the last little bit of volume back by stuffing the remaining volume in the back chamber with poly fill. This gets your resonace where you want it and provides standing wave absorbance. If for some reason you over shoot the amount of expanding foam, its very easy to cut some of it out with a knife.
Nice measurement. Looks very close to the measure I took about 5 years ago. I know you guys believed me when I said the Fane 8M went to 5KHz before it pooped out. However, I've had people tell I'm full of it and that there was no way the Fane could do that. The proof it right before us.
You'll be fine. Just try to round over the outer edge with something like a 3" radius. There should not be any problems if it is acoustically well coupled to the floor.
Look at the Electrical Impedance screen for your simulation. Adjust the rear chamber volume to where you need it. Follow my advice in one of my above posts when you go to build it.
The size doesn't matter, only the position matters. At least that's what she said.
All kidding aside, I generally find I get the best snap/punch when tuned slightly above the flare rate of the horn.
Hey JLH,
Hey,
Where is the compression "limit", 8M is 2,8:1 without phase plugs? About the Faital it was more of a hypothetical discussion as I already have the horns and 2441 for them. The Faital is very cheap so it would have been easy to do the test.
This is my friend hoktunas system where he tries out the LeCleach horns.
Hey,
Where is the compression "limit", 8M is 2,8:1 without phase plugs? About the Faital it was more of a hypothetical discussion as I already have the horns and 2441 for them. The Faital is very cheap so it would have been easy to do the test.
This is my friend hoktunas system where he tries out the LeCleach horns.
The size doesn't matter, only the position matters. At least that's what she said.
All kidding aside, I generally find I get the best snap/punch when tuned slightly above the flare rate of the horn.
So are you saying the Electrical impediance spike should be just after 125 hz for the 125hz horn I am building?
Misc
Thanks JLH for the encouragement .
I can start drawing-out the template at the weekend I think . It'll be a good way to celebrate the royal wedding .
3GGG - once you've defined the flare rate (eg. 120Hz) of the Tractrix the curve essentially exists 'on paper' from a starting point to the full mouth size. Then as you choose the S1 and S2 values you're effectively chopping the full shape off at the small and large end . You will see the length come down as you reduce the S2 mouth size.
Thanks JLH for the encouragement .
I can start drawing-out the template at the weekend I think . It'll be a good way to celebrate the royal wedding .
3GGG - once you've defined the flare rate (eg. 120Hz) of the Tractrix the curve essentially exists 'on paper' from a starting point to the full mouth size. Then as you choose the S1 and S2 values you're effectively chopping the full shape off at the small and large end . You will see the length come down as you reduce the S2 mouth size.
Hey JLH,
Hey,
Where is the compression "limit", 8M is 2,8:1 without phase plugs? About the Faital it was more of a hypothetical discussion as I already have the horns and 2441 for them. The Faital is very cheap so it would have been easy to do the test.
This is my friend hoktunas system where he tries out the LeCleach horns.
Cool picture. What are the bass bin designs? Maybe that is something I should consider with my JBL2226J bass horn build.
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