Continious max SPL:
Est. build cost:
40 Hz-20 KHz (in-room)
90 dB / 2.83 V / 1 meter
110 dB (pair, 1 meter, from 45 Hz)
Updated April 16th 2008 - Construction details and filter added
when auditioning a small stand-mounted speaker you will overhear the
line "Where's the subwoofer?". Well, where is it? It's not there
becuase your impression of "deep" bass is likely just strong
harmonics (which isn't always bad, just saying) and even such a
speaker can produce the lowest notes of most instruments at low output
I'm tired of all these small speakers with five inch
woofers that "don't need a subwoofer". Well, you never "need" a
subwoofer, but do you want one? I'm going to build a speaker that's
smaller than yours and that's capable of playing deeper, cleaner and
louder than yours. And it shall be named 'Scimitar'.
from earlier experiences, I will pair a dedicated woofer with a
fullrange driver and do it with as few filter components as possible.
Basically a stand-mount 'Bellicose'. It is something I have always
wanted to do since I consider 'Bellicose' to be my most succesful
speaker to date (although they are still just prototypes - working on
prefer this configuration because you can use a woofer that's optimized
for the lower frequencies rather than having to play the low end and
the midrange. Todays modern fullrange drivers can match some of the
domes out there in the high range, and you get the benifit of being
able to place the crossover frequency where it hurts the least, where
the ear isn't as sensitive and where the wavelengths are long. You also
get a very controlled dispersion without unmanagable humps or dips in
the off-axis response due to different drivers directivety patterns not
Basically, it rocks, and more people should do it.Drivers
a surprising move, I am once again going to use drivers from chinese
Tang Band. Why? Because they make unique and interesting drivers using
new materials and technologies that others dare not try. QA is really
good now a days and they keep improving even old drivers with new stuff
they come up with. I like this company. Oh yeah, the price is a factor
five inch woofer because I got a good deal, and a three inch fullrange
for a good compromise between dispersion and sensitivity.
little beauty has been around a while and is highly popular. It is the
first time I build with it, though, and I think it will be a pleasure.
ferrite motor, paper cone, aluminium phaseplug, very low mathematical
Xmax but in reality they can move way past the stated 0.5 mm before
distorsion kicks in. Xmech is huge for a 3-inch driver!
cone curves inwards to face the voice-coil former at almost zero angle.
It is coated on both ends, with very lossy coating on the rear side. A
damn good cone, actually.
woofer isn't very exotic either. Just a standard motor on a standard
frame. It has a strong pentagonal dustcap and a thick paper cone.
The multiroll surround is a Tang Band patent and I find it to work very
A healthy 5 mm of mathematical one-way Xmax
and a strong voice-coil should give it the edge it needs against
traditional five inch midwoofers.
Also, this is why we need
more neodymium in the world. That magnet is just ridicilous and I fear
it's going to bend the frame just by hanging there.
The enclosures are built from 19 mm MDF and a bit less than half a standard 1200x2400 sheet is used for all the parts. The
ports are slotted and runs along the back, exiting at the bottom-rear
of the cabinet. This means you'll have to put some feet on the speakers
so they come up at leastt 1.5 cm from the surface they are placed on.
the roundovers on all the parts that form the port, and on the outer
vertical edges of the side panels. This should be done with a 12 mm/
half-inch radius bit.
Click image for full size.
When assembling, I recommend gluing all
the parts together on one of the sides, leaving the other side off
until the last moment. More on that below.
The port is
12 mm high and to be on the safe side, have a piece of 12 mm thick wood
in the port opening as you work, so that it won't bend or crack
the joints should an accident happen. Once you have both sides on
the port will be very stable.
fullrange driver has its own chamber and it's made from a 90 mm
inner-diameter paper tube, cut to 12 cm length with a MDF lid (can be pretty thin) at the rear.
This should provide an internal volume of 0.5 liters, and if you fully stuff the chamber with
soft acoustic filling (polyester or wool), the resonance will be damped
enough to not be a problem in the crossover.
If you left one
side off, installing this chamber should be no problem. Just glue it
against the inside of the baffle and make sure it's aligned with the
driver cut-out. Don't forget to drill holes for the wiring (and seal
The chamber for W3-871SC, made out of a paper tube and a lid.
don't need much sound absorbation material in the rest of the box. Line
the walls behind, below and at the sides of the woofer aswell as the ceiling with some thin foam
and that should be it The filter should fit on the wall behind* the
woofer that forms the port, and the terminals above the port,
behind the fullrange driver's chamber.*
(Don't recommend putting it at the bottom as it will be closer to the big iron mass that is the woofer motor.)
The final measurements will be (WxHxD) 218x340x250 mm.
components and somewhat 2nd order electrical filters. The
crossoverpoint is 400 Hz. Notice that the fullranger should be
inverted. The 2.2 mH should be aircored 1.4 mm wire, the 1.5 mH should
be aircored too but with 0.8 mm wire. 68 µF and 56 µF can be big
polyester paralleled with small polypropylene to reach the
correct value. Pure polypropylene would be too expensive. Resistors
should be simple metaloxide.
Click for full size.
picture above shows on-axis response of the drivers and their sum at
2.83 volts / 1 meter, power response within +- 45 degress, the
acoustical phase of the drivers and the electrical phase and impedance.
Notice that the port will have higher output in reality due to boundary loading.
dip in the response at 3 KHz is baffle diffraction I couldn't get rid
of. Should be pretty harmless. On-axis has a rise that evens
out slightly off-axis. Phase response shows that the drivers are
friends all the way up to 5 KHz, which is a good result considering the
low crossover point. Impedance never drops below 4 Ohms and is stable
upwards in frequency with some reflex-peaking in the low end.
Yeah, you can put them on their side without affecting the sound. Pretty neat.