The Smallest Tapped Horn

[Patrick Bateman]

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

Tapped Horn for Dummies

[P4z1f15t]

Originally posted by sumsound

Same the B&C 12PS100-
I did add~ 5mH of inductance
Am I close with the internals??

Hi sumsound,

why did you add 5mH of inductance?

[mwmkravchenko]

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/showt...32#post1856932

Mark

[brsanko]

Hey Patrick thanks for letting us know about the 8" MCM driver it really does model exceptionally well in a TH. It outshines the 6" Tang Band I was looking at and is about $15 cheaper! It will be my next Sub project.

[Brian Steele]

Originally Posted by brsanko

well here it is tapped horn for TB 6.5" sub. System Volume about 30 liters. Response down to 30Hz. Volume above 120db.

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.

[winslow]

Wonders if my JBL 2204Hs would be worth a shot in a TH in the car?

In case you missed it on DIYMA, can the TH for the car play realistic sub-bass levels?

[Patrick Bateman]

Originally Posted by winslow

Wonders if my JBL 2204Hs would be worth a shot in a TH in the car?

In case you missed it on DIYMA, can the TH for the car play realistic sub-bass levels?

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.

[Patrick Bateman]

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/...tml#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...

[Brian Steele]

Originally Posted by Patrick Bateman

Pretty darn smooth, if I do say so myself...

It would be, if you apply smoothing

[mwmkravchenko]

Hi Patrick

Are you using ARTA to do your measurements? Kind of looks familiar to ARTA anyway.

Industry standard smoothing is 1/3 octave by the way.

Nice application of design sleuthing.

Mark