Arai 290


  • Horn Type : Hyperbolic (T=0.7) Constant Directivity (CD) horn
  • Coverage : H 95°, V 40°
  • Cut-off frequency (Fc) : 290Hz
  • Frequency range : 540/600Hz to 20KHz
  • Driver : 2"in throat like TAD 4001/4002, JBL 2446/2450 or 1.4" driver with adapter
  • 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
  • Four fins (separators) inside the horn


Drawing files: 


Yuichi recommend to use drawing file for  re-draw your own at 1:1 scale on a hard paper as a construction template.
These templates are very important to make accurate horn curves or contours.

For now it's the original PDF, as see in Horn Design section some information is not strictly exact :
A290 PDF

There is a easier version to build of the A290, the 290S :
A290S PDF
It's not really interesting to build this against the regular A290 but it highlights the fact that the sides are just another fin, because in this version it's truly the case.

Building:


A more modern way to do it is visible here (in french but there is a lot of pictures) :
http://www.cinetips.com/viewtopic.php?f=40&t=698

Yuichi Arai original content:
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:




 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 2" 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.

Directivity coherence with 15" is around 650hz.