Tapped Horn for Midrange

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Wouldn't it be great if we could extend the response of a horn?

While building my unity horn I had an idea:

In the unity horn, there are four mids that are ported into the horn. What if I ported the rear wave of the speaker into the horn, instead of a seperate driver?

So I went about building one yesterday. Here are some pix:

An externally hosted image should be here but it was not working when we last tested it.

It's the same mold from my Unity, but a LOT bigger.

An externally hosted image should be here but it was not working when we last tested it.


An externally hosted image should be here but it was not working when we last tested it.


Here's my train of thought, if you're interested in the idea.

The Unity works fantastic, and it sounds wonderful. However, there are a lot of variables in a Unity horn. The idea with this experiment is to find out if we can get a bit of the Unity goodness, without resorting to five drivers and a HIDEOUSLY complex crossover.

Another great element of this design is that there's no crossover in the midrange. Perfecting the crossover on a 'real' Unity is incredibly challenging, because the transition is right in the midrange, so any little problem stands out like a sore thumb.

An externally hosted image should be here but it was not working when we last tested it.

And here's the waveguide that I built. Yes it's ugly, but I only spent an afternoon on this.

So how does it sound you ask?

Like a 'real' Unity, it has an ability to resolve nuances like a good set of headphones. I've heard "And I Was a Boy From School" at least 50 times, and I never noticed until today that there's someone singing in the background. Little details in the noise floor are brought to the surface, but in a good way. This isn't a case of hyped up treble; it's all about good timing.

I hate to admit this, but the midrange on this is better than the midrange on my 'real' Unity. It sounds so good it makes me angry! I absolutely HATE IT when something that I spent four hours on can compete with projects that I've spent MONTHS on. Having said that, I can assure you that the 'real' Unity will sound better once I get the crossover sorted out.

Though the midrange IS spectacular, this speaker isn't perfect. I can hear that my OTHER Unity has lower levels of distortion. Which makes sense, considering it has a compression driver and three mids. My OTHER Unity, with three mids, can take more power AND is more efficient. Having said that, the Aurasound Whisper handles an outrageous amount of power. I have a single cap to roll off the low end, and I'm feeding it with a 50 watt amp. (Triple the rated amount.) The raw driver is only 78db efficient, but in a WG, it's something like 86. My OTHER Unity plays lower, but I have a solution to that problem that I'll post soon.

To sum it up, this is a spectacular sounding mid, it's inexpensive, and it plays surprsingly loud.
 
It's very, very simple -

A aurasound "Whisper" mounted at the apex of a waveguide. That's it.

By itself, the Whisper can't get very loud, but the gain from the waveguide helps the efficiency quite a bit.

I did add one "twist" to the design: The Whisper is in a 1/4 wave transmission line that terminates 4" from the throat of the waveguide. The idea is to reinforce the low end.

Last night I measured the response. I'll post the measurements later. It measured *remarkably* well. I wasn't expecting such smooth response and wide bandwidth.

:: PB ::
 
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