Auror
MTM 2-way
Floor-stander
Transmission line
RCM Akustik 5.25HE*
Seas 27TDFC
RCM Akustik 5.25" FS = 54Hz (1/4
wave = 62 in)
Auror Line Length = 58 in
Sd = 88 sq cm x2 = 176 sq cm or 27 sq in
Taper = 1.25 to 1.00 or 33 sq in to 27 sq in
Enclosure = 7.25" wide, 12" deep, 45" high
Made from .75" MDF; Front baffle .75" MDF + .5" birch ply
Tweeter height = 36"
Internal Volume = 1.4 cu. ft.
Stuffing = approx. 9 oz (give or take) polyfil
Pieces parts
Woofer template: Mount woofer on 1/4 mdf.
Trace around woofer with two-part inlay collar and 1/4 bit
Mount template on front baffle. Cut flange recess. Cut through hole
(not shown)
Enjoy.
Two part inlay collar set. Trace woofer with bushing removed. Add
bushing and trace inside of template to cut woofer flange recess.
Back chamfer.
The TL.
If necessary I can get to almost any part of the line
This wont hurt a bit
A lining of half inch Dacron batting was not enough to smooth out the
response. I later added Dacron polyfill.
Ready for crossover testing
Crossover testing was a bit hectic.
Crossover finalized. Milling the crossover circuit board.
Crossover boards milled and drilled.
and populated.
Veneer. No matter what people say there's just no easy way to veneer 3
sides of a long box all at once.
How did I trim the veneer around the odd shaped flange area?
With a low-profile bushing on the SRB!
Follows the inside of the flange recess not the through hole.
Danish oil being applied to the walnut veneer.
Crossover mounted on back wall behind woofer.
A second pair of Aurors being stuffed for Paul Pickard.
The narrow footprint of the Aurors made them a bit tippy. Here I'm milling
some outrigger footies.
Mounting holes drilled and spike holes tapped.
New spiked footies mounted.
No more tippy.
The RCM woofer with and without low pass filter. The notch is most
effective at 6.6k - almost midway between the 6k and 7.5k humps. This
breakup above 5k is attenuated almost 30dB - totally inaudible to my ears.
Frequency response taken at 1.5 meters.
Auror impedance. 9 ounces of polyfill looks about right to me.
Final impressions? I don't plan to sell these anytime soon. Easily the
second best sounding speaker I've ever built. A moderately complicated but
EXTREMELY cost effective design. Email me if you want me to blather on
about things like crisp treble, taught bass, neutral midrange.
The Auror hovering at 5500 feet above sea level.
* To purchase the
RCM Akustik 5.25HE please send an email to Paul
Pickard
** Ms Rowling, please don't sue me for
using the name "Auror"