Check some T.H. calcs for me?
a very helpful forum member ran some numbers for me, if you could have a quick look and see if you agree with them and if the box is a good one to build (for a single box outdoor low end beast) of if for the cost and effort i could build something significantly better,
id appreciate it
http://img862.imageshack.us/img862/2115/60ndownth.jpg
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-469
also, i have no idea from looking at the charts what the box size and shape and layout should be,
any help there would also be greatly appreciated. 🙂
a very helpful forum member ran some numbers for me, if you could have a quick look and see if you agree with them and if the box is a good one to build (for a single box outdoor low end beast) of if for the cost and effort i could build something significantly better,
id appreciate it
http://img862.imageshack.us/img862/2115/60ndownth.jpg
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-469
also, i have no idea from looking at the charts what the box size and shape and layout should be,
any help there would also be greatly appreciated. 🙂
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If you want the best bang for your $$$ Horn sub then build the F20 fround here....
http://www.avsforum.com/avs-vb/showthread.php?t=1329971
The driver is the 15" MFW-15 and its 1/2 the price of that Dayton choice.
You can buy it here
http://www.diysoundgroup.com/MFW15_Group_Buy.htm
Find a cheap pro amp (EP1500 is perfect) and you will have the highest performance/$$$ 20Hz horn design period.
Everything is done for you, just follow, build and enjoy!!!
http://www.avsforum.com/avs-vb/showthread.php?t=1329971
The driver is the 15" MFW-15 and its 1/2 the price of that Dayton choice.
You can buy it here
http://www.diysoundgroup.com/MFW15_Group_Buy.htm
Find a cheap pro amp (EP1500 is perfect) and you will have the highest performance/$$$ 20Hz horn design period.
Everything is done for you, just follow, build and enjoy!!!
At about 92 dB one watt one meter, fairly low sensitivity, but that goes with such a low F3.
Goes low, but the dip at 80 Hz (the bottom end of your K quad) is a problem, unless you are planning to cross at 60 Hz or lower.
The large peaks at 90-400 Hz will require out of band EQ in addition to the crossover to tame.
231 liters is a big cabinet, but within the size range you suggested in your BFM post.
You can fold it any number of ways to fit the shape you desire.
Art
Actually, in the last 40 years of mixing live and recorded music, I have only spent a short period of time using Hornresp.
But I designed and built dozens of PA systems without.
Computer programs get you into the ballpark, you have to build and test to get on the playing field.
in real world use,
would the dayton T.H. smoke the F20 in every way?
or is there less then 20% in it?
for the extra $75, if i get 12 hz lower and 12 db louder
its money well spent.....
would the dayton T.H. smoke the F20 in every way?
or is there less then 20% in it?
for the extra $75, if i get 12 hz lower and 12 db louder
its money well spent.....
I studied the LABhorn design a lot, specifically to improve upon its weaknesses. It isn't that I thought it sucked, but I did think its front/rear chamber size and its mouth weren't ideal, causing more response ripple than I would like, particularly from such a large horn. I changed the front and rear chamber sizes and made the horn 5" wider to improve these things.
I also thought that having two drivers gave an opportunity to incorporate push-pull drive, which reduces distortion particularly at the lowest frequencies, where horn loading is reduced. The improvement is measurably dramatic.
Finally, the side panels being aluminum provide an excellent opportunity to improve cooling. The "stock" design has no real benefit from the aluminum panels, because the only transfer mechanism is through the air in the chamber, i.e. basically no thermal transfer at all. By adding a cooling plug, the power handling is more than doubled. This is important, because the failure mode of most LABhorns is thermal, provided the proper high-pass filter is employed to prevent over-excursion from out-of-band content.
Information below (including Hornresp models, acoustic measurements and other technical details for both the LABhorn and 12Pi hornsub):
The 12Pi is another DIY design, by the way, with plans free for the asking. We do provide flat pack kits, driver kits and cooling plugs and plates, but I think the DIY nature of the design and the fact that plans are freely available for all, makes this link in the spirit of the forum (i.e. not overly commercialized). The whole point of the 12Pi was to be a statement, not to build a career, It does indeed put the petal to the metal, more than any other portable basshorn subwoofer I have ever seen.
I'm also the one that did the measurements at the 2005 and 2007 Prosound Shootouts, where the charts shown in the first page of this thread came from. I've measured several of Bill Fitzmaurice's designs, and I would have to agree with the sentiments expressed here. They are very easy to build, and pretty lightweight. They work well above about 60Hz or so. But below 60Hz, all of them are 100x lower than most other hornsubs, like 20dB down. The mouths are just too small.
There's really no substitute for mouth size, in my opinion. if you try and make a "horn" with a small mouth, what you really have is a transmission line, not a horn. That's not terrible, but it is a very different animal. The efficiency isn't really increased except at odd multiples of the fundamental standing wave, set by the length of the line. You can do the Transflex "tapped" thing, but then you are just filling in some of the holes, not really increasing efficiency. And if you start putting that sort of device in groups, then by the time you have enough to work well, you're back to a large mouth area.
Seems to me the biggest advantage of smaller bass "horns" is they're easy to carry. That's a worthwhile goal, to be sure. But I think that it compromises other areas, in most cases, so you pay for that portability. Put castor wheels on a large basshorn and transport it with a truck that has a ramp. That makes movement easy, and doesn't present a compromise.
I also thought that having two drivers gave an opportunity to incorporate push-pull drive, which reduces distortion particularly at the lowest frequencies, where horn loading is reduced. The improvement is measurably dramatic.
Finally, the side panels being aluminum provide an excellent opportunity to improve cooling. The "stock" design has no real benefit from the aluminum panels, because the only transfer mechanism is through the air in the chamber, i.e. basically no thermal transfer at all. By adding a cooling plug, the power handling is more than doubled. This is important, because the failure mode of most LABhorns is thermal, provided the proper high-pass filter is employed to prevent over-excursion from out-of-band content.
Information below (including Hornresp models, acoustic measurements and other technical details for both the LABhorn and 12Pi hornsub):
The 12Pi is another DIY design, by the way, with plans free for the asking. We do provide flat pack kits, driver kits and cooling plugs and plates, but I think the DIY nature of the design and the fact that plans are freely available for all, makes this link in the spirit of the forum (i.e. not overly commercialized). The whole point of the 12Pi was to be a statement, not to build a career, It does indeed put the petal to the metal, more than any other portable basshorn subwoofer I have ever seen.
I'm also the one that did the measurements at the 2005 and 2007 Prosound Shootouts, where the charts shown in the first page of this thread came from. I've measured several of Bill Fitzmaurice's designs, and I would have to agree with the sentiments expressed here. They are very easy to build, and pretty lightweight. They work well above about 60Hz or so. But below 60Hz, all of them are 100x lower than most other hornsubs, like 20dB down. The mouths are just too small.
There's really no substitute for mouth size, in my opinion. if you try and make a "horn" with a small mouth, what you really have is a transmission line, not a horn. That's not terrible, but it is a very different animal. The efficiency isn't really increased except at odd multiples of the fundamental standing wave, set by the length of the line. You can do the Transflex "tapped" thing, but then you are just filling in some of the holes, not really increasing efficiency. And if you start putting that sort of device in groups, then by the time you have enough to work well, you're back to a large mouth area.
Seems to me the biggest advantage of smaller bass "horns" is they're easy to carry. That's a worthwhile goal, to be sure. But I think that it compromises other areas, in most cases, so you pay for that portability. Put castor wheels on a large basshorn and transport it with a truck that has a ramp. That makes movement easy, and doesn't present a compromise.
This is where the "...it's really this hard to answer comes into play...."
What is real world use? You've said outdoors PA single box. Littlemike's F20 is a Home Theater box made to go really low. I think he'd be one of the first to say it's not a single box outdoor PA sub...
Define "real world use" (in real terms, spl, distance, frequency range) and then the really hard to answer questions start to get easier.
Wayne,
As far as mouth size, on a “normal” horn, I agree with you completely.
As far as tapped horn design, you seem to ignore that they are capable of more smooth LF output per cubic foot than a single standard horn, in single units.
The OP asked for a single unit approximately half the size of a 12Pi.
Having done distortion measurements on Lab 12s loaded in ported cabinets and tapped horn cabinets, I found distortion to be lower in the ported cabinets and similar in the tapped horn cabinet to the 12Pi.
As far as I know, you have never done a side by side comparison of the push-pull drive 12Pi compared to the Lab sub distortion specifications, yet you persist in saying “the improvement is measurably dramatic”.
Same goes for the claim that the cooling plug doubles the power handling.
Any data to back those claims up?
Art Welter
re: driving with sine, my brand new and never abused nor used Yorkville UCS1 computer optimized pipehorn had lots more distortion than a K15 size coupler loaded with something like a Sigma 18 - 20+dB more on H2! I almost bet Louis Bellson and Ray Brown didn't worry about bass :^)
An externally hosted image should be here but it was not working when we last tested it.
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The Dayton T.H. is a lot smaller the F20, and does not go as low, and has about the same output level.
Hoffman’s Iron Law says speakers with lower extension always have a sensitivity drop, as the efficiency of the woofer is proportional to the cabinet volume and the cube of its cutoff frequency.
Simply stated: You can have low end extension, high efficiency, or small enclosure size. Pick two.
For PA type use, trying to have a low corner below 35 Hz results in a very large and heavy cabinet for very little improvement, as there is very little content below 30 Hz in most music, some EDM excluded.
I made the change from subs that rolled off around 45 Hz to subs that rolled off at about 35 Hz when I started noticing what I could hear in headphones went lower than the PA, and the amps were clipping and speakers flapping trying to get those 10 Hz.
After making the change, the PA goes pretty much as low as anything I hear in my Ultraphones, Sony 7506 elements in Peltor deadphones.
The 30 dB or so attenuation they offer allows you to tell if what is coming in is what is coming out of your speaker system, even with the headphone level set well below the speaker level.
Invented by a great drummer, Gordy Knutsen, the Ultraphones have been the best investment I have made in over a million dollars of audio equipment.
But they were responsible for me realizing my subs were not cutting it...
Art
ill take low end extension and small enclosure size, power is cheap.
i think your saying its not worth chasing 35 hz for a powerful outdoor sub? better to call it a day @ 45 ish.
my headphones also have -30db attenuation
Sennheiser Worldwide - HD 280 PRO
45 Hz was OK back in 1985, but is "lite" today.
35 Hz is a good compromise now.
No need to go much lower, except for specific EDM types of music.
Power is cheap, but real estate is not. Large cabinets cost in transportation and storage.
If you want the maximum low end and small enclosure size, ported cabinets rule, but cost more in drivers and power.
Unless you are tapping in close to the power mains, your cheap power is often compromised by voltage drop, reducing the cheap power to a fraction of it's rated output.
again, small boxes.
im only looking for a fun 'much bigger then your average guy is likely to own' sub to break out once in a while,
im not doing the sound for a pink floyd concert.
but honestly, i have had so many differing answers over the last week (TH, ported, horn, Air suspension), i now believe there is no real outstanding design that everyone agrees is the way to go, which translates into,
all designs perform about the same.
ive decided to stay away from a complicated design/build to avoid the possibility of a mis aligned front and rear wave, ill keep my eyes open for something on the www thats getting a lot of very positive reviews,
and build that.
im in no hurry, and am only having fun.
music should be fun right?
im only looking for a fun 'much bigger then your average guy is likely to own' sub to break out once in a while,
im not doing the sound for a pink floyd concert.
but honestly, i have had so many differing answers over the last week (TH, ported, horn, Air suspension), i now believe there is no real outstanding design that everyone agrees is the way to go, which translates into,
all designs perform about the same.
ive decided to stay away from a complicated design/build to avoid the possibility of a mis aligned front and rear wave, ill keep my eyes open for something on the www thats getting a lot of very positive reviews,
and build that.
im in no hurry, and am only having fun.
music should be fun right?
People here like to slam BFM designs, but I built them with pretty good results and made money using them. Four 24" Tuba 30s loaded with Eminence 4012s did pretty well when stacked together, moved plenty of air and driver for driver handily beat a pair of TCS 2800 with B&C drivers and powered with 6kw Camco Amp. A stand alone single does sound anemic, but groups of four come to life, especially in limited power situations.
Good music is fun.
There are large differences in performance between between basic designs, and differences between designs in each category.
Acoustic suspension can be the smallest enclosure to reach low, but is the least efficient.
Ported is next in line for size, but some listeners don't care for the phase inversion, but most will trade the efficiency for sound.
Tapped horns can be 6 db more efficient than ported cabinets, but require a larger cabinet.
Bass horns can be the most efficient, and can sound similar to acoustic suspension, but have to be huge to go low.
Have fun in the search!
Art
do Tapped horns or bass horns suffer phase inversion? (if designed/built correctly)
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