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Don Snyder 22nd December 2010 10:16 PM

Elements of a Tapped Horn
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Let's build a Tapped Horn, element by element. Figure 1 is a tube with a speaker capping the left
end and the right end open. Driving the air in the tube with a one watt signal, beginning at 10Hz
and sweeping up to 3000, and results in the response shown in figure 2.

It's easier to make a Tapped Horn if the speaker is near, but not at, the left end. Moving the
speaker to the side (fig.3) results in changing the response (fig.4), but only the response above
150 Hz.

Next, let's keep the volume the same (500 Liters) while we taper the tube (see fig.5). This
changes everything. While the curve (fig.5) is shifted slightly to the right, the response on average
is smoother and louder between 30 and 150 Hz.

Last, we add in the Tapped Horn effect! We add the input from the back of the driver near the right
side in figure 7. This raises the response (see fig.8) in the 40-70 Hz area while it lowers the peak
at 85Hz. The peaks at 135 and 200 Hz are much weaker than shown.



j.michael droke 23rd December 2010 03:31 AM

Hi there Don: Can the four steps you showed be turned into a general method for starting a TH design for a specific driver? IE the tube must have an area slightly larger than the OD of the driver and the length should be related to the quater wave of the the chosen low corner hz, as a starting point. ...regards, Michael Droke

Don Snyder 23rd December 2010 02:13 PM

No ... the process shown helps understand the effects of the various elements, but is little help in creating a new design.
While some general rules can be used for a starting point, HornResp does the heavy lifting for us.

littlemike 23rd December 2010 07:15 PM

Nice explanation.

Don Snyder 28th December 2010 12:03 AM

Hi littlemike – Working thru this example helped me. Should I put this in a “sticky”?

Hi Michael – In a tapped horn, everything is so interdependent, that tweaking one
Parameter (ie length between front & back of horn) seems to change many things.

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