Loudspeaker Designs and Articles for the DIY Enthusiast
|A high sensitivity / high SPL
design offered for PA, Music
and Home Theater
Some audio enthusiasts tout the advantages of a single driver speaker design.
Others eschew these designs, suggesting the advantages of more drivers
overcome their obvious physical design limitations. -Then there are those who feel
that more is never enough. If you count yourself in the later group, this design is
dedicated to you.
A 2.5 way sealed design with 6 Aura NS6-255-8A paper cone neodymium drivers in series
parallel configuration paired with a Vifa BC25SC06-04 textile dome tweeter.
Nominal Impedance: 4 ohms The impedance is above 5 ohms in the midwoofer’s pass band,
but drops to around 4 ohms at frequencies above 5 kHz.
Dimensions: external: 8.5” wide, 43” tall, 15” deep
Basic sensitivity: Conservatively rated at 92 dB / 2.83v / 1 meter
Max SPL: (Modeled at woofer published Xmax)118 dB / 1 meter
Main / Design Goals
This project is a bit different than our normal proclivity for
designs. Our design goals are generally tasked for as full
range as possible, often trading sensitivity for extension.
This design is aimed at high sensitivity and maximum
SPL. The system sensitivity at somewhere around 92-94
dB approaches the pro sound arena, and could easily be
used as a PA system in small venues. The basic
sensitivity suggests for home use it could be paired with a
small 4 ohm capable chip amplifier or other low power
source for acceptably high SPL’s on a flea budget.
Modeling suggests that 20 watts will drive this design to
109 dB, making a mobile battery powered system feasible.
Another departure from my normal penchant is the slight
response peaks at the speaker’s frequency extremes.
The low end peak is due to the higher Q of the sealed
enclosure, which was chosen to power handling and limit
the enclosure size. This also helps to augment the
apparent bass when used as a stand alone speaker.
Used with a sub, I’d suggest high passing the speaker to
ameliorate the bass hump. The tweeter peak
compensates for its inherent roll off when listened to off-
axis. The result is a fairly balanced power response, and
reasonably flat response when listened to on the design
While the max SPL model’s somewhere around 118 dB,
there is another advantage to using six midwoofers per
line: The combined surface area of the six drivers nearly
equals that of a typical 15” woofer. This design exhibits a
surprising amount of tactile presence.