LittleMike's Anarchy Tapped Horn - Home Theater Forum and Systems - HomeTheaterShack.com

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post #1 of 32 Old 03-28-10, 02:48 PM Thread Starter
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Mike
 
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LittleMike's Anarchy Tapped Horn

I'll admit that I did not get this one built by myself, but it is my design. I've got the wood cut, just been too busy with other things. Much thanks to Todd (radman12) for taking the plunge and building this on my simulations and speculations alone. I was able to visit with Todd on Friday and measure the results.

This is the design I posted in the Shiva TH thread, it is a single Anarchy driver in a folded tapped horn.

Remember the three fundamental parameters we get to choose two of at the expense of the other?

Loud
Low
Small

I chose low and small. Heresy - I know - I sacrificed SPL.

The idea was a "rest of the world" type of sub - reasonably sized with respectable performance. A pair placed along walls or in corners should be adequate for 99% of the potential users. That last 1% all post in the forums I frequent, and are all reading this, so this is not a high-powered monster home theater sub for you. It should be a decent little sub and it really is designed to be used in multiples. A pair of these in corners or along walls should get to 100 dB at a typical LP from 25 Hz on up with under 100 watts per driver. Four should do reference levels plus.

He's got a build thread over at AVS, I am working on plotting the measurements now.

Last edited by littlemike; 03-28-10 at 02:49 PM. Reason: typo
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post #2 of 32 Old 03-28-10, 05:16 PM Thread Starter
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Mike
 
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Re: LittleMike's Anarchy Tapped Horn

Measured 1W 1M 2pi response:



THD:



2nd Harmonic:



3rd Harmonic:

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post #3 of 32 Old 03-28-10, 05:20 PM Thread Starter
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Re: LittleMike's Anarchy Tapped Horn

There are full plans and drawings posted over at AVS for anyone interested.

This is a relatively simple build (lots of parts, sure, but no bracing!!!) that you could do with a skilsaw, straightedge guide, router or jigsaw, and a screwgun.

It takes a 5X5 or a partial 4X8 of 1/2 inch material.
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post #4 of 32 Old 03-28-10, 05:42 PM Thread Starter
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Re: LittleMike's Anarchy Tapped Horn

Todd (radman12) took my sketchup layout and made it look really nice. The following is his work:









There is also a nice PDF plan attached.
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post #5 of 32 Old 03-28-10, 07:03 PM
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Re: LittleMike's Anarchy Tapped Horn

Glad to see you posted over on this forum also.

I keep going between the two forums all the time and at times I forget where I saw what and who.
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post #6 of 32 Old 03-29-10, 11:27 AM
Kevin
 
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Re: LittleMike's Anarchy Tapped Horn

Wow.... knock-out job. These would make for a great distributed subwoofer build.... one on each wall and you have reference level output and the smoothest possible in-room response.

Great work... both of you.

Kevin Haskins
Exodus Audio
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post #7 of 32 Old 03-29-10, 03:35 PM
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Re: LittleMike's Anarchy Tapped Horn

Nice Mike! I think this is a good project for someone who wants multiple subs in a small room to smooth out response, but doesn't need huge output. One could easily drive 4 of these off an inexpensive amp like the Tapco Juice J800. I don't know what plate amp options there are out there.

I started looking at smaller drivers like this for exactly that reason. My livingroom is all of 1,700 cf. I don't need the output of a THT and two of these would offer a much better solution.

I wonder how much of an improvement you would see in the low corner with the sub pointing into the corner?

What does the damping material at the ends of each fold do to/for the frequency response curve?
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post #8 of 32 Old 03-29-10, 04:21 PM
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Re: LittleMike's Anarchy Tapped Horn

I'll be building a couple of these.....

Great job.....
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post #9 of 32 Old 03-29-10, 04:33 PM Thread Starter
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Re: LittleMike's Anarchy Tapped Horn

We put the damping material in to attenuate the upper frequencies, namely the 106 Hz spike. I tried using less than I have used in the past, and we got good results, taming the spike by ~10 dB relative to the model, with little to no impact to SPLs anywhere else.

Tucked in a corner, room gain might make the apparent low corner drop down a little bit, but to be honest, horns cease behaving like horns below fc, and tapped horns are even worse, as there is no back chamber to provide a load on the driver. Look at the distortion plots I posted - the lines cross when THD = SPL, and that happens within 1/2 octave below fc. Boundary loading is not room gain.

More importantly, SPL will definitely increase with boundary loading, expecting real world increases of 4 dB along a wall, 8 dB in a corner is fair for most cases. If you live in a concrete bunker, you might see the full 6 and 12 dB that theory predicts. I don't, I have measured +6 to +8 dB as a result of corner loading. So - with 86 dB at 1W 1m 2pi, fair values would be ~90 dB 1W 1m for wall placement, max 1 m SPL ~108 dB, and 94 dB and 112 dB, respectively when placed in a real corner.

No - this is not reference levels, but that was never my goal with this. I targeted max SPLs of 95 dB at a typical listening position (-10 dB from 1m).

The measured fc of Todd's build corresponds to the model very well, I measured -3 dB at ~23 Hz. Remember, this is a 6.5" midbass driver being asked to do subwoofer duty (and shaming a lot of drivers in the process ).

Seriously. -3 dB @ 23 Hz. Flat from 25 to 100.

Max SPLs of over 110 dB at 1m when placed in a corner (~100 dB at a typical LP).

All from a single 6.5" midbass driver and less than 3 cubic feet.
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post #10 of 32 Old 03-29-10, 05:35 PM
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Fred
 
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Re: LittleMike's Anarchy Tapped Horn

Thanks for the reply Mike. I used the wrong term. I was thinking of what the corner loading would do to the length of the horn (thus dropping its tuning slightly) pointed in to the corner vs out into the room).

Quote:
If you live in a concrete bunker,
Funny you should mention that. Though my landlord insists on calling it an apartment, it really is a concrete bunker...
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