pinkmouse said:
Here are some thoughts of mine, based on modeling these for a few months.
- Traditional "horn subwoofers" don't work well in a tapped horn. Usually a driver with low QMS and QES likes a horn, but not with a tapped horn.
- A low FS isn't really necessary. This is one of my favorite things about a tapped horn. In a typical sub, you need a seriously low FS to get deep bass. The big problem with low FS drivers is that their sensitivity is too low. It's Hoffman's Iron Law haunting us ("You can have low end extension, high efficiency, or small enclosure size. Pick two."). I'm not saying that the tapped horn VIOLATES Hoffman's Iron Law, but close
- If anyone is wondering why we can get away with this, it's because the tapped horn resonates at a number of frequencies. It's not just a quarter wave horn; it also resonates a full octave lower. So when you create a 40hz tapped horn, it also resonates at 20hz (the reflected wave from the mouth.)
- This is great stuff. Everyone on this forum keeps making tapped horns with giant drivers, but it's really not necessary. You could probably make a decent tapped horn with a 170mm or even a 130mm woofer.
I'm experimenting with what works best in a tapped horn. For instance, I've posted a design that shows what happens when you use series resistance to raise the QES of a tapped horn. Here's my tapped horn project.
"I was also not able to figure out how this TH for the 3015LF looks like."
Waveguide 'W1' Node=20=21
STh=750cm2 SMo=2200cm2
Vf=10L Len=2.5m T=0.9
Horn 'W2' Node=21
STh=2200cm2 SMo=2444cm2
Len=35cm Conical
Try 571 for S1, 750 for S2, 17.5 for L12
Try 750 for S2, 2200 for S3, 250 for L23
Try 2200 for S3, 2444 for S4, 35 for L34
If you model one in 1Pi it will be about what two are in 2Pi, add 6dB and that will be about what four will look like in 2Pi. Very close to the AkAbak script results (within 1dB or so).
Waveguide 'W1' Node=20=21
STh=750cm2 SMo=2200cm2
Vf=10L Len=2.5m T=0.9
Horn 'W2' Node=21
STh=2200cm2 SMo=2444cm2
Len=35cm Conical
Try 571 for S1, 750 for S2, 17.5 for L12
Try 750 for S2, 2200 for S3, 250 for L23
Try 2200 for S3, 2444 for S4, 35 for L34
If you model one in 1Pi it will be about what two are in 2Pi, add 6dB and that will be about what four will look like in 2Pi. Very close to the AkAbak script results (within 1dB or so).
Greets!
FWIW, I got to looking a little harder at what's going on in a tapped pipe and if you haven't cut any wood yet, then I'd like you to use a 349 cm^2 area pipe with the 322.9 cm dim increased to 344.42 cm. I doubt there's any audible difference, especially in-room, but it just seems more technically correct when I sim it as a BP:
GM
FWIW, I got to looking a little harder at what's going on in a tapped pipe and if you haven't cut any wood yet, then I'd like you to use a 349 cm^2 area pipe with the 322.9 cm dim increased to 344.42 cm. I doubt there's any audible difference, especially in-room, but it just seems more technically correct when I sim it as a BP:
GM
Attachments
Well I have a pile of wood cut to size. Time to set up the dado blade for some rebates.
Thanks to advanced topological theories and lots of work with a pencil, paper and calculator, I managed with one sheet of mdf, but the line is 2cm shorter than the ideal. I think I can cope with that.
Thanks to advanced topological theories and lots of work with a pencil, paper and calculator, I managed with one sheet of mdf, but the line is 2cm shorter than the ideal. I think I can cope with that.
Attachments
Don't bother, it's no big thing. I mean there's more than one way to lay it out depending on the desired gain BW, though a simple pipe's options are somewhat more limited than a true horn expansion, but as there's nothing intrinsically wrong with the one you planned and as you can see in the sim, not alot of difference.
If just the extra length is the problem, then go ahead and use the larger CSA or whatever is the largest you can get up to ~400 cm^2 though.
GM
Oops! Never mind, didn't see your latest post until after I posted, so you used ~349 cm^2 CSA, 53.82 cm/342.42 cm/53.82 cm?
If just the extra length is the problem, then go ahead and use the larger CSA or whatever is the largest you can get up to ~400 cm^2 though.
GM
Oops! Never mind, didn't see your latest post until after I posted, so you used ~349 cm^2 CSA, 53.82 cm/342.42 cm/53.82 cm?
Darn!
That's a bummer PinkMouse....
I wouldn't mind having your (Metric..?) dimensions, as I too have 1 pair of B139 lying around, and my new festool circular saw (TS55) is on it's way to my home, so I need to make some sawdust!!!
(Beautifull cordless drillS(!!) thou hast, PinkMouse, I've only got one...)
Good luck buying a new jigsaw, I read somewhere shinobiwan found a nice bosch (blue ofcourse).
Cheers, Paul
That's a bummer PinkMouse....
I wouldn't mind having your (Metric..?
) dimensions, as I too have 1 pair of B139 lying around, and my new festool circular saw (TS55) is on it's way to my home, so I need to make some sawdust!!!(Beautifull cordless drillS(!!) thou hast, PinkMouse, I've only got one...)
Good luck buying a new jigsaw, I read somewhere shinobiwan found a nice bosch (blue ofcourse).
Cheers, Paul
Hi Paul, dimensions are no problem, as soon as it's confirmed working, I'll post them. I also have to draw them up properly first, (rather than my indecipherable scribblings that confused me at times!).
Battery drills. I have four, and sometimes find myself whilst doing a job wanting another...
As for the jigsaw, it's not a tool I use a lot, or heavily when I do so, so nice as the blue Bosch are, I'll probably just get a cheap one for the time being.
edit: Oh and I'll also post a suitable crossover and power amp layout as well.
Battery drills. I have four, and sometimes find myself whilst doing a job wanting another...
As for the jigsaw, it's not a tool I use a lot, or heavily when I do so, so nice as the blue Bosch are, I'll probably just get a cheap one for the time being.
edit: Oh and I'll also post a suitable crossover and power amp layout as well.
Pinkmouse,
Looking good. You have posted three dimensions earlier in cm that made little sense to me excepting that it appeared to indicate a path length of 134.81 inches. I was wondering if you could post inch dimensions of your project and let us know what driver (size?) you have chosen as well.
Looking good. You have posted three dimensions earlier in cm that made little sense to me excepting that it appeared to indicate a path length of 134.81 inches. I was wondering if you could post inch dimensions of your project and let us know what driver (size?) you have chosen as well.