Making round horns
version francaise
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Round horns are more and more used in hifi.
Many people think that a lathe is necessary to make wooden round horns but very few of us
own one and furthermore they could be used for small horns only. This web page shows how to
make a round horn unlimited in size and without a lathe. I encourage you to make one much bigger
than mine, then please tell me if it works well. Why not a horn whith a diameter of 1.5m? It is feasable since
you can build them slice by slice.
drawing the plans
-choose a curve (tractrix, expo or another), the length, the throat
diameter, the mouth diameter. Many books or web pages tell how to do it.
-choose the slice thickness which is the tickness of the wooden boards used,
16mm for exemple.
example: the curve designed by Lecleach
-some softwares allow to display the horn. Here is an exemple for a 150Hz tractrix horn, it is 860mm large:
building a wooden round horn
First draw the slices with a large compas on the MDF boards. Draw the inside and outside circles
on both sides of the boards. Then use a jigsaw to roughly cut the slices. The maximum cut angle is usually
45 degres and that is not enough for most tractrix horns.
Here is an example of slices on top of each other to build a 300Hz horn for a 2 inch compression driver.
The outside diameter is about 550mm.
Because the slices have been roughly cut with a angle limited to 45 degres, a diy milling machine can be used
to improve the shape of each slice as shown in the next picture:
Then this is what you get after putting the slices on top of each other:
Then use glue and screws to put the slices togeter. Don't use screws for the largest slice and
don't use glue for the smallest slice because it has to be removable to fix the compression driver.
When the glue is dry rasp to swooth the horn, this is a painfull task:
Then file down, varnish and then sand the horn.
Another example: a 150Hz tractrix horn for a 6 or 8 inch cone driver with a 2 inch adapter.
Response of the 150hz tractrix horn with a 2 inch Radian 950PB compression driver, almost 220Hz-16KHz with no EQ.
tweeter horn, Lecleac'h curve:
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