The Smallest Tapped Horn

[winslow]

The Image Dynamics v3 ID8 might be a good woofer too. 2x the displacement of the MCM, cost more to the general public though.

[Patrick Bateman]

Originally Posted by winslow

The Image Dynamics v3 ID8 might be a good woofer too. 2x the displacement of the MCM, cost more to the general public though.

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/...tml#post838712

[winslow]

Wonder if I could fold one of these in a 20x20x10 space. Probably not....

[Patrick Bateman]

Originally Posted by winslow

Wonder if I could fold one of these in a 20x20x10 space. Probably not....

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.

[Patrick Bateman]

Originally Posted by Patrick Bateman

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.)

[sumsound]

Originally Posted by P4z1f15t

Hi sumsound,

why did you add 5mH of inductance?

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.

[rhapsodee]

Originally Posted by Patrick Bateman

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!

Patrick,

Did you have a post with more details of your transmission line design and construction? I would be most interested.

Thanks!

[JoshK]

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.

[dwk123]

Originally Posted by JoshK

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?

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.

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.

That was volvotreter. Tapped Horns (scroll down)

[Patrick Bateman]

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.