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Frequently Asked Questions about the
NaO Loudspeaker
What is NaO?
NaO is a high performance, open backed (dipole) speaker systems using conventional drivers with
a hybrid active/passive crossover. The acronym NaO is derived from the Portuguese word Não meaning
"not" or "no" as in "No box".
How much does the a NaO speaker system cost?
If you buy just the plans and the required printed circuit board and build a stereo system yourself the cost can be
as low as $1700. A NaO Mini system can be built for less then $1300, including subwoofers and plate amps.
What are the features of the NaO II approach?
1) NaO II is a hybrid bi-amplified system using a simple passive crossover between the midrange and
tweeter and an active crossover/equalization unit between the main panel and woofer system. The NaO II
speaker systems require 4 channels of amplification (two channels per side).
2) NaO II uses two 18 cm midrange drivers in an MTM format with a 1 inch, fabric dome tweeter.
3) NaO II was designed from its inception in 2003 with a switchable rear tweeter.
4) NaO II employs a compact U-frame woofer (link opens in new window) system that achieves nominally 6dB greater
sensitivity on axis than a conventional H-frame dipole woofer of similar bulk size (length) while reducing rearward
low frequency radiation.
5) NaO II uses a custom designed active crossover/eqaulization unit (ACEU) which adds flexibility in
tuning the system to your tastes and to your room.
6) NaO II woofer system can be operated in user selectable modes as either a U-frame or a sealed box woofer.
There is no need for an additional subwoofer when used in home theater applications unless extremely high
low frequency SPL is required. This avoids the introduction of additional group delay associated with a
woofer/subwoofer crossover.
Why a passive/active hybrid?
The hybrid design philosophy achieves many of the same advantages of a fully active system; greater efficiency,
improved linearity and increased dynamic range, without the need for excessive channels of amplification thus
reducing the system total cost while maintaining a high level of performance.
I really prefer an all active crossover. Can the NaO be adapted to that format?
Yes. The NaO II can be built as a fully active system with an optional midrange/tweeter active crossover
module for those who desire to have a full active system. The fully active system requires an additional stereo
amplifier and the resulting increased cost.
What are the unique features of the U-frame woofer system?
The U-frame woofer system produces a radiation pattern that reduces the bass energy radiated
to the rear of the speaker. Additionally, the U-frame woofer system does not behave
as a pure pressure source, a characteristic of a sealed box woofer system. The result is that the
U-frame woofer potentially interacts differently with the listening room. The U frame woofer system is also
capable of producing greater on axis SPL that an H frame dipole woofer of similar size.
How much power does the NaO require?
It is recommended that the NaO II be used with high quality power amplifiers rated in the range of
60 to 100 w/ch into 8 ohms. The amplifiers used should be capable of driving a 4 ohm load.
The ideal setup for the NaO II is to use identical stereo amplifier with one amplifier placed directly
behind each speaker to minimize the effects associated with longer runs of speaker cables.
However, identical amplifiers are not required.
Can Tube amplifiers be used with the NaO?
Yes, provided they meet the power and impedance requirements noted above. It is suggested
that the use of tube amplifiers be limited to then main panels and that solid state amplifiers be
used to drive the woofer system. Additionally, it is recommenced that the optional impedance
compensation network for the main panels be used if the output impedance of the tube amplifier
is high.
How much active circuitry is used in the NaO II ACEU?
Every effort was made to minimize the number of active stages in the NaO II ACEU. There
are only 4 active stages in line with the main panels, including the high pass filter block, and 3
additional stages in line with the woofer.
What size listening room is suited for the NaO?
The NaO is best suited for rooms of at least 200 square feet floor area.
Is the NaO a transient accurate design?
No.
Where can I hear the NaO?
You can contact Music and DesignTN at the email address below to arrange a visit to the Hartford
area to audition the NaO II/III or to determine if someone in your area has a NaO II or NaO III system
and would be willing to have you stop by. Whether you hear the original NaO or the NaO II or the NaO III
you can be sure that your audition will be representative of the NaO speaker system.
If you have questions about NaO speakers please contact: info@musicanddesign.com
NaO Loudspeaker
What is NaO?
NaO is a high performance, open backed (dipole) speaker systems using conventional drivers with
a hybrid active/passive crossover. The acronym NaO is derived from the Portuguese word Não meaning
"not" or "no" as in "No box".
How much does the a NaO speaker system cost?
If you buy just the plans and the required printed circuit board and build a stereo system yourself the cost can be
as low as $1700. A NaO Mini system can be built for less then $1300, including subwoofers and plate amps.
What are the features of the NaO II approach?
1) NaO II is a hybrid bi-amplified system using a simple passive crossover between the midrange and
tweeter and an active crossover/equalization unit between the main panel and woofer system. The NaO II
speaker systems require 4 channels of amplification (two channels per side).
2) NaO II uses two 18 cm midrange drivers in an MTM format with a 1 inch, fabric dome tweeter.
3) NaO II was designed from its inception in 2003 with a switchable rear tweeter.
4) NaO II employs a compact U-frame woofer (link opens in new window) system that achieves nominally 6dB greater
sensitivity on axis than a conventional H-frame dipole woofer of similar bulk size (length) while reducing rearward
low frequency radiation.
5) NaO II uses a custom designed active crossover/eqaulization unit (ACEU) which adds flexibility in
tuning the system to your tastes and to your room.
6) NaO II woofer system can be operated in user selectable modes as either a U-frame or a sealed box woofer.
There is no need for an additional subwoofer when used in home theater applications unless extremely high
low frequency SPL is required. This avoids the introduction of additional group delay associated with a
woofer/subwoofer crossover.
Why a passive/active hybrid?
The hybrid design philosophy achieves many of the same advantages of a fully active system; greater efficiency,
improved linearity and increased dynamic range, without the need for excessive channels of amplification thus
reducing the system total cost while maintaining a high level of performance.
I really prefer an all active crossover. Can the NaO be adapted to that format?
Yes. The NaO II can be built as a fully active system with an optional midrange/tweeter active crossover
module for those who desire to have a full active system. The fully active system requires an additional stereo
amplifier and the resulting increased cost.
What are the unique features of the U-frame woofer system?
The U-frame woofer system produces a radiation pattern that reduces the bass energy radiated
to the rear of the speaker. Additionally, the U-frame woofer system does not behave
as a pure pressure source, a characteristic of a sealed box woofer system. The result is that the
U-frame woofer potentially interacts differently with the listening room. The U frame woofer system is also
capable of producing greater on axis SPL that an H frame dipole woofer of similar size.
How much power does the NaO require?
It is recommended that the NaO II be used with high quality power amplifiers rated in the range of
60 to 100 w/ch into 8 ohms. The amplifiers used should be capable of driving a 4 ohm load.
The ideal setup for the NaO II is to use identical stereo amplifier with one amplifier placed directly
behind each speaker to minimize the effects associated with longer runs of speaker cables.
However, identical amplifiers are not required.
Can Tube amplifiers be used with the NaO?
Yes, provided they meet the power and impedance requirements noted above. It is suggested
that the use of tube amplifiers be limited to then main panels and that solid state amplifiers be
used to drive the woofer system. Additionally, it is recommenced that the optional impedance
compensation network for the main panels be used if the output impedance of the tube amplifier
is high.
How much active circuitry is used in the NaO II ACEU?
Every effort was made to minimize the number of active stages in the NaO II ACEU. There
are only 4 active stages in line with the main panels, including the high pass filter block, and 3
additional stages in line with the woofer.
What size listening room is suited for the NaO?
The NaO is best suited for rooms of at least 200 square feet floor area.
Is the NaO a transient accurate design?
No.
Where can I hear the NaO?
You can contact Music and DesignTN at the email address below to arrange a visit to the Hartford
area to audition the NaO II/III or to determine if someone in your area has a NaO II or NaO III system
and would be willing to have you stop by. Whether you hear the original NaO or the NaO II or the NaO III
you can be sure that your audition will be representative of the NaO speaker system.
If you have questions about NaO speakers please contact: info@musicanddesign.com
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