jbell, how do they sound with the cabs standing upright, stacked beside one another and the horn mouth firing on to the floor?
I have a pair of 3015LF drivers and a pair of Lab12 drivers. I plan to start next week with Wayne Parham's 12Pi design using Lab12 drivers. I'll probably make about 6 cabs.
I want to use 3015LFs in a TH and plan to make 6 of these as well. However, I have not yet found a fold which is portable for PA duty.
Could someone please help with a portable fold for the 3015LFs going down to about 35 Hz?
If nothing else comes up then using the same fold and dimensions as yours would be good. Could someone in the know draw out a rough sketch with dimensions and angles, scan the image and post it here. I am sure it will be of help to many.
Thanks,
I have a pair of 3015LF drivers and a pair of Lab12 drivers. I plan to start next week with Wayne Parham's 12Pi design using Lab12 drivers. I'll probably make about 6 cabs.
I want to use 3015LFs in a TH and plan to make 6 of these as well. However, I have not yet found a fold which is portable for PA duty.
Could someone please help with a portable fold for the 3015LFs going down to about 35 Hz?
If nothing else comes up then using the same fold and dimensions as yours would be good. Could someone in the know draw out a rough sketch with dimensions and angles, scan the image and post it here. I am sure it will be of help to many.
Thanks,
Jim has posted everything you need above - it is literally a connect-the-dots type build. All dimensions are in inches, the hornresp parameters are in centimeters.
From jbell's post:
Point 1 is at the left side of the picture of the open horn, point 2 is in the middle, and point 3 is at the right. These three are the only points required for layout, the rest is connect the dots.
Good luck with your builds.
edit: clarification of units and measurements
From jbell's post:
Point 1 is at the left side of the picture of the open horn, point 2 is in the middle, and point 3 is at the right. These three are the only points required for layout, the rest is connect the dots.
Good luck with your builds.
edit: clarification of units and measurements
The 3015 LF is one of the more popular drivers for TH's used for PA. There are several other designs for this driver in the "collaborative" thread, as well as a number of different folding topologies discussed. If you expand your search beyond the diyaudio site, there are a number of other pertinent discussions and designs that are well-documented on the web.
Jim's design plays to 40 Hz with authority (102 dB 1W 1M 2pi). It is -5dB @ 35 and -12dB @ 30 Hz. It uses an efficient folding pattern (no wasted internal space), and is already too big for your use. Physics and basic horn theory tell us that a 35 Hz horn will (with all else being equal) be even larger, regardless of the folding pattern used.
Taking the 3015 LF driver, placing it into a lower-playing tapped horn, then designing that tapped horn with a smaller mouth will cost you efficiency through the passband as well as increase the driver's excursion. It can be done, and may even yield a flatter response, but you will most likely not get the same SPL capability and you will reach driver excursion limits sooner. Jim's design was chosen based on maximum output within a given passband and a given amount of space for the installation.
In fact - a TH for the 3015 that is -0 dB @ 35 Hz is also 5 dB less efficient than Jim's through the passband, but requires essentially the same cabinet size. Additionally, 1W excursion increases approximately 20% due to the lower frequency. There is no free lunch.
If the 3015 is too big, consider the 4012HO. It also performs very well in a tapped horn, will reach the frequencies you want, and requires a cabinet that is approximately 1/2 the size. The efficiency is similar for the two drivers in a cabinet capable of an honest 35 Hz.
Once the driver is chosen, there are only four variables in the simplest form of a TH (which Jim's is L12=L34, conic flare). Area at the throat, area at the mouth, length, and location of the tap.
Jim's folding technique?
Simple, but brilliant.
Draw up a scale model of the horn's taper, cut it into sections, and slide them around on the paper to see how it all fits together. (Sorry about letting your super-duper top secret folding technique out into the wild Jim....)
Lots and lots of options out there. There are lots of examples, and lots and lots of screenshots. Learn to use hornresp. It is not hard to figure out.
We'll show you the trail, tell you about our trips, share our maps, provide assistance and encouragement where we can, but we're not gonna climb your mountain for you.
Design, build, test, evaluate, redesign.....
Jim's design plays to 40 Hz with authority (102 dB 1W 1M 2pi). It is -5dB @ 35 and -12dB @ 30 Hz. It uses an efficient folding pattern (no wasted internal space), and is already too big for your use. Physics and basic horn theory tell us that a 35 Hz horn will (with all else being equal) be even larger, regardless of the folding pattern used.
Taking the 3015 LF driver, placing it into a lower-playing tapped horn, then designing that tapped horn with a smaller mouth will cost you efficiency through the passband as well as increase the driver's excursion. It can be done, and may even yield a flatter response, but you will most likely not get the same SPL capability and you will reach driver excursion limits sooner. Jim's design was chosen based on maximum output within a given passband and a given amount of space for the installation.
In fact - a TH for the 3015 that is -0 dB @ 35 Hz is also 5 dB less efficient than Jim's through the passband, but requires essentially the same cabinet size. Additionally, 1W excursion increases approximately 20% due to the lower frequency. There is no free lunch.
If the 3015 is too big, consider the 4012HO. It also performs very well in a tapped horn, will reach the frequencies you want, and requires a cabinet that is approximately 1/2 the size. The efficiency is similar for the two drivers in a cabinet capable of an honest 35 Hz.
Once the driver is chosen, there are only four variables in the simplest form of a TH (which Jim's is L12=L34, conic flare). Area at the throat, area at the mouth, length, and location of the tap.
Jim's folding technique?
Simple, but brilliant.
Draw up a scale model of the horn's taper, cut it into sections, and slide them around on the paper to see how it all fits together. (Sorry about letting your super-duper top secret folding technique out into the wild Jim....)
Lots and lots of options out there. There are lots of examples, and lots and lots of screenshots. Learn to use hornresp. It is not hard to figure out.
We'll show you the trail, tell you about our trips, share our maps, provide assistance and encouragement where we can, but we're not gonna climb your mountain for you.
Design, build, test, evaluate, redesign.....
Not sure what you're asking? I was outdoors, over grass (not hard surface, like typical 2pi readings) and the closest building was 5-7 meters away. I didn't measure it, but that's about where my driveway ends. (garage was behind, nothing either side for acres) I used a spl meter, not software, so I didn't have to worry about calibration. Nothing more than a 5mph wind that I remember.
So, if anything, my readings are a little understated. A true groundplane measurement over hard surface would be higher.
does that answer your question?
So, if anything, my readings are a little understated. A true groundplane measurement over hard surface would be higher.
does that answer your question?
Good stuff, Guys -
I'm surprised that it's so wide (24" inside). Most tapped horns on the BIG thread are barely wide enough for the speaker.
I've done some CAD, and I get a path length that's 30-40 cm longer than the 17/230/17 that Jim reported here. Not a problem, as length is a good thing.
Am I doing something wrong?
I'm surprised that it's so wide (24" inside). Most tapped horns on the BIG thread are barely wide enough for the speaker.
I've done some CAD, and I get a path length that's 30-40 cm longer than the 17/230/17 that Jim reported here. Not a problem, as length is a good thing.
Am I doing something wrong?
Attachments
The football stadium at USC (columbia, SC) uses 16 TH 115's for the sound system there. Apparently it was just installed. My brother was at the game and he said the output capacity was easily doubled. I'm not 100% sure they are TH 115's, but my brother saw them from a distance when the coverings were off during band practice, and the guy who does the on field sound system said they were using some sorta new horns. I am assuming that they are using danley products. From where he was seating, he said there was so much output he had to cover his ears, yet it was still clean. I guess they are not used to having TOO much output capability at USC.
Here's my version of Jim's Tapped Horn. I ran this by Jim, and he suggested that I share it with the forum. This thing is BIG, over 600 liters, but that's not a problem for a fixed install.
The average guy should be able to get all of the saw-work done at a decent lumber yard, and complete it in an afternoon. If all the 24" cuts are actually 23 3/4", and cut with one set-up, he can even use PVA and everything will fit perfect. If he's got a router and a laminate trimmer bit, he can even make it pretty.
The angle cuts on the front and the baffle are a little over 8 degrees, but Jim said he left them square and used PL Polyurethane expanding adhesive. No bracing is shown, which is either brave ... or foolish. Jim put triangles in the two back corners (see pic earlier in thread).
This is a great project !!!
~Don
The average guy should be able to get all of the saw-work done at a decent lumber yard, and complete it in an afternoon. If all the 24" cuts are actually 23 3/4", and cut with one set-up, he can even use PVA and everything will fit perfect. If he's got a router and a laminate trimmer bit, he can even make it pretty.
The angle cuts on the front and the baffle are a little over 8 degrees, but Jim said he left them square and used PL Polyurethane expanding adhesive. No bracing is shown, which is either brave ... or foolish. Jim put triangles in the two back corners (see pic earlier in thread).
This is a great project !!!
~Don
Attachments
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.