A-290 Wood Horn


Grand Teton National Park, WY, USA (Photo by Yuichi)

A-290 Specifications

= Horn Type : Hyperbolic horn
= Cut-off frequency : 290Hz
= Frequency range : 600Hz to 20KHz
= Driver : 2 in or 5 cm throat Pioneer TAD 400x or JBL 244x or
equivalent
= Size : W 656mm, H 230mm, D 405mm (inclu. 25mm throat adapter)
= Material : Chinese quince laminated lumbers (3.0cm thickness)
= Finish : Two coats of oil based clear polyurethane varnish

= Color : Not applied
= Others
- Four fins (separators) inside the horn

....Mar. 1989 MJ Magazine....

Building and assembly process


Transfer template on a laminated lumber by pencil. Cutting of the lumber by
hand circular saw
Addition of both wings Application of glue by
fixing wings
Completion of coarse formation process Adjustment of side curve
of the plates
Verification of side curve
alignment among three
Application of epoxy glue
(12 Hrs to cure)
Lamination of three horn plates by fixing clamps
and four screws
Obtain vertical contour
by a electric plane
Fine adjustment by a
rotary sander and a belt
sander or sandpaper
Completion of top and
bottom horn pieces

Gaining thickness of the
side horn walls
Contour making of the
side walls of the horn
Completion of internal fins
Belt sander may be used.
Location of four fins
Epoxy glue is applied.
Side walls are assembled
with epoxy and screws.
Final assembly and filling
process by epoxy and
wood powder mixture
Driver adapter (circle -
square converter)
Epoxy coating inside
Surface treatment by a
hand router, a rotary
sander and sandpaper


Measurement and Data


Left hand data is frequency
response curve.

TAD 4001, 2 in throat, driver is mounted. The response shows very flat sound pressure level from 350Hz to almost 20KHz.

This horn with TAD 4001 or
JBL 2441 or equivalent driver covers mid to high
frequency range in 2 way
or 3 way construction.
However,
very high frequency response depends upon the driver capability.

To set the crossover frequency as 300 to 400Hz is a little risky. Therefore, 600Hz above is safe to use.
Right hand data is a impedance curve.

This data shows that the diaphragm of the driver is horn loaded from 320Hz.

Therefore, it is a good idea to use this horn from 600Hz with enough guard band.

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