A few days ago I posted the measured response inside my car. (Which is where I'll use it.)
Here's the measured response outside:
The orange and the red graphs are the tapped horn. I took two measurements, at equal distances, to isolate high frequency peaks.
Note the SPL levels aren't calibrated whatsoever; I just crank up the volume to get plenty of clean signal.
For comparison's sake, the blue lines are my old sub, which is a transmission line that uses dual 12" woofers.
The interesting part is that they're practically identical below 50hz! Hoffman's Iron Law at work
The transmission line uses dual woofers, and is built LIKE A TANK. In addition to the serpentine construction, it also has cross braces and it's metal plated!
The pic shows three of my subs. The old transmission line, the new tapped horn, and my bandpass subwoofer from my home theater.
The tapped horn is basically an unqualified success. It's more efficient, uses one woofer instead of two, is easier to build, and weighs less than HALF as much. The TL is 73lbs, the TH is 35lbs. The bandpass clocks in at a svelte 28lbs, thanks to it's sonotube construction
http://www.diyaudio.com/forums/showthread.php?s=&threadid=114340&perpage=25&pagenumber=3
Here's the measured response outside:
The orange and the red graphs are the tapped horn. I took two measurements, at equal distances, to isolate high frequency peaks.
Note the SPL levels aren't calibrated whatsoever; I just crank up the volume to get plenty of clean signal.
For comparison's sake, the blue lines are my old sub, which is a transmission line that uses dual 12" woofers.
The interesting part is that they're practically identical below 50hz! Hoffman's Iron Law at work
The transmission line uses dual woofers, and is built LIKE A TANK. In addition to the serpentine construction, it also has cross braces and it's metal plated!
The pic shows three of my subs. The old transmission line, the new tapped horn, and my bandpass subwoofer from my home theater.
The tapped horn is basically an unqualified success. It's more efficient, uses one woofer instead of two, is easier to build, and weighs less than HALF as much. The TL is 73lbs, the TH is 35lbs. The bandpass clocks in at a svelte 28lbs, thanks to it's sonotube construction
http://www.diyaudio.com/forums/showthread.php?s=&threadid=114340&perpage=25&pagenumber=3
Just a heads up
Hi Patrick
You inspred me to see how small I could get a tapped horn. As well as a tapped horn that worked with cabin gain and gave you a semi-flat response all the way down to 18hz.
http://www.diyaudio.com/forums/showthread.php?s=&postid=1856932#post1856932
Mark
Hi Patrick
You inspred me to see how small I could get a tapped horn. As well as a tapped horn that worked with cabin gain and gave you a semi-flat response all the way down to 18hz.
http://www.diyaudio.com/forums/showthread.php?s=&postid=1856932#post1856932
Mark
You've modelled it for 0.5*PI space. Model it for 2*PI space to get figures that are more comparable to those produced by box modellers for sealed / vented systems.
Based on the research that I've done, the smoothest response and widest bandwidth is to be found when you use an array of small high excursion woofers.
The array spreads out the resonances, reducing the peaks and dips inherent in the tapped horn design. It allows us to use a box size that's incredibly small.
I had a hunch that Danley is using multiple woofers in his new tapped horns to smooth the peaks and the dips that appear when you use a horn that's too small.
The results of my experiment can be reviewed here:
http://www.diymobileaudio.com/forum/diy-mobile-audio/65945-small-tapped-horn-car.html#post837001
Here's the measured response of a tapped horn using three $25 woofers from MCM, with smoothing applied:
Pretty darn smooth, if I do say so myself...
The results of my experiment can be reviewed here:
http://www.diymobileaudio.com/forum/diy-mobile-audio/65945-small-tapped-horn-car.html#post837001
Here's the measured response of a tapped horn using three $25 woofers from MCM, with smoothing applied:
Pretty darn smooth, if I do say so myself...
Based on the specs on their site, a pair of these will give you more SPL than a trio of MCM woofers. The MCM woofers give you a little more efficiency, but the ID8s kill them with all the excursion they have.
Nice find!
Pix are here:
http://www.diymobileaudio.com/forum/diy-mobile-audio/65945-small-tapped-horn-car.html#post838712
Here's some pics showing the relative size.
The smallest box is the "triple-8" tapped horn, which is chronicled on diymobileaudio.com. I posted frequency response measurements five minutes ago. It measures 24" x 24" x 9.5" on the outside.
The box with the twelve is chronicled in this thread, and it measures 24" x 24" x 13.5" on the outside.
The "monkey coffin" is a clone of the autotuba that I was running in my Accord in 2005. It's the exact same volume, except I moved the mouth to couple it with the pass-through in my trunk in the Accord. Moving the mouth extends the pathlength and lowers the F3.
Here's some pics showing the relative size.
The smallest box is the "triple-8" tapped horn, which is chronicled on diymobileaudio.com. I posted frequency response measurements five minutes ago. It measures 24" x 24" x 9.5" on the outside.
The box with the twelve is chronicled in this thread, and it measures 24" x 24" x 13.5" on the outside.
The "monkey coffin" is a clone of the autotuba that I was running in my Accord in 2005. It's the exact same volume, except I moved the mouth to couple it with the pass-through in my trunk in the Accord. Moving the mouth extends the pathlength and lowers the F3.
I found this pic on my hard drive, which shows the response of the 4.5cf tapped horn with a 12" woofer (dark red), the 3.1cf tapped horn with three eights (purple), and a 4cf horn with a single eight (red).
Measurements are outside; in car expect a big bump below 80hz thanks to cabin gain.
All three are measured at the exact same volume level on the amplifier, but the twelve is drawing the least current, due to it's higher impedance. The twelve has the highest efficiency of all of them, since Hoffman's Iron Law rules the day. The triple8 has the highest power handling and the smallest size of all of them, because it has the highest displacement. Note that the SPL level on this measurement is more accurate than the previous measurement. (IE, the twelve is more efficient than the initial measurements showed. When it comes to efficiency, bigger = better.)
Oh sorry little late for a reply
Because it smooths out the predicted response a little.
I don't know if it will be like that in reality but It would take a real build and test to know for sure.
Patrick,
Did you have a post with more details of your transmission line design and construction? I would be most interested.
Thanks!
Hey Patrick,
Wanted to ask if you built the dual MCM 55-2421 tapped horn? How does the real response compare to the predicted? Are you using it in your HT?
I am looking to build a TH for HT. I would rather go for multiple distributed THs that are reasonable in size then one gigantic one.
Would there be any advantage to using the T8-740P instead of the MCM? You say it has more excursion, so will it bottom out less quickly?
I see your drawings, but they don't show angles, I guess I have to work them out.
Has anyone else built THs with the MCM or T8?
A while back there was someone in europe that did a small TH with a 6.5" driver, but I can't seem to find it anywhere.
Wanted to ask if you built the dual MCM 55-2421 tapped horn? How does the real response compare to the predicted? Are you using it in your HT?
I am looking to build a TH for HT. I would rather go for multiple distributed THs that are reasonable in size then one gigantic one.
Would there be any advantage to using the T8-740P instead of the MCM? You say it has more excursion, so will it bottom out less quickly?
I see your drawings, but they don't show angles, I guess I have to work them out.
Has anyone else built THs with the MCM or T8?
A while back there was someone in europe that did a small TH with a 6.5" driver, but I can't seem to find it anywhere.
If you search the main TH thread, JLH (I think it was JLH) built a dual-W8-740 20Hz TH that was "banned from the house" due to excessive output. slightly complicated build relative to other versions due to the push-pull mounting and a throat chamber, but looked impressive.
I've played around with Hornresp and the W8, and the dual driver versions seem to work significantly better than single driver versions. Conversely, single W6 designs seem to work a bit better than dual W6 designs, although I haven't played with those too much.
That was volvotreter. Tapped Horns (scroll down)
Last year I built an "improved" version of this sub, using three of the MCM 55-2421s.
Small Tapped Horn For a Car - DIYMA.com
In a lot of ways I prefer the original sub; while it's bigger, it's also a lot lighter. It's nice to be able to remove the sub easily if I need to haul stuff in my car. With the MCM that's not practical, because the sub is so heavy.
I'm thinking about redesigning it so it will play half an octave lower. Before doing that, I thought I would post some more data on the sub before I tear it apart.
The pic above shows the predicted response of the subwoofer I've documented in this thread. On the left is the response with a P-Audio SN-12MB. On the right is the response using a Faital W12N8. I am using the P-Audio, but I've noticed that Loudspeakersplus doesn't sell it any longer. The Faital looks like a good replacement. I tried modeling it with the new Dayton prosound twelve, but the response didn't look good.
You'll notice that the predicted response is a *little* different than what I posted earlier. This is because the finished subwoofer's dimensions were slighty different than what's in the plans I posted. The difference is only a db or so.
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