Music’s Finest Conductor
The Audio Note Absolute Zero AZ-Three Loudspeaker.
INTRODUCTION.
First of all thank you for buying an Audio Note product, I hope that it will reward you
with many years of good quality music and reliable service.
As a company our main aim is to design and manufacture equipment which gives you
the maximum sonic performance for the price and to do this we use many
unconventional solutions and the AZ-Three speaker is no exception to this, so it is
important that you read this brief manual carefully, in order for you to get the best
performance and sound from your new speakers.
The AZ-Three is designed to be used without a front cover or grill, and is therefore not
supplied with one. A cover can be easily made from transparent foam and four dots of
Velcro!
As with all Audio Note speakers, no corners have been cut in terms of component and
driver quality despite the modest price of the AZ-Three, the well tried and tested AN-E
tweeter and woofer feature in the two-way line-up together with a heavy duty crossover
with air core inductors, silver plated speaker terminals and Audio Note AN-D internal
wiring.
All the Absolute Zero models share the following design features,
1.) Rear loaded folded quasi parabolic horn with rear facing mouth.
2.) Floorstanding with built-in spikes.
3.) High efficiency, and more importantly best possible dynamic power transfer
behaviour to maximise acoustic output to power input.
In our quest to deliver a compact high sensitivity speaker with good room interface we
have reinvestigated and re-evaluated all the main principles of horn loaded cabinet
designs, and this knowledge coupled with our expertise in system dispersion and
associated crossover design, has resulted in a speaker system that redefines not only
the quality-price relationship at any level which is important when making basic
comparisons to the competition, but more importantly the AZ Series speakers offer an
emotional quotient of reproduced acoustic performances that is quite in a class of its
own.
The vast majority of directly radiating diaphragm designs have very poorly matched
acoustic impedance resulting in the characteristically low efficiency, in contrast a horn
loaded system where a suitable geometric design of the horn mouth and internal
expansion rate allows the acoustic impedance to be optimised to match that of the
driver across several octaves, resulting not just in higher efficiency but also in better
dynamic power transfer from the amplifier..
This better matching achieves two important benefits, firstly the efficiency is greatly
increased and secondly, the resistive termination presented to the diaphragm reduces
the amplitude of any response anomalies.
The greatest problem of horn loaded systems is physical size. For a simple horn the
lower cut-off frequency is directly proportional to the effective diameter of the mouth
when radiating into free space, for example a cut-off frequency at - 3dB of 50Hz would
require a horn mouth area of 3.8 square meter!!
Clearly unsuitable for most domestic purposes.
The most important consideration must therefore be to first reduce the size requirement
whilst maintaining the low frequency response. To do this the rear of the diaphragm
needs to be loaded by an inductive impedance component. This can be designed by reconfiguring the parameters of the horn flare to off-set the increasingly capacitive throat
impedance below the cut-off frequency. This, in combination with a speaker position
that takes advantage of close proximity to room boundaries (wall or corner) reduces the
radiation impedance further. With corner positioning the bass horn mouth area is
effectively increased by a factor of x16 or x8 when placed against a wall, providing a
substantial boost at low frequencies.
In the Audio Note AZ-Three Quasi horn, rear diaphragm radiation is controlled by
critically positioned acoustic impedance matched foam, further aiding low frequency
performance by levelling out the amplitude of standing waves.
ROOM PLACEMENT.
In common with our more conventional ported speakers, the Zero AZ Series speakers
are designed to be placed very close and at an angle to a rear wall or preferably with
the rear horn mouth firing assymetrically into a corner close to the side walls, this
positioning has been chosen because being a horn it improves bass response and low
frequency cut off for reasons already discussed.
It is vitally important to understand that the proximity of the AZ-Three to the rear wall
or corner, if you experience problems with the bass, try moving the speaker closer to
the wall, or try to change the angle of the speaker.
The best performance is achieved by corner placement and if placed in a corner, the
AZ-Three should be angled so that the on-axis line of the drive units crosses about 1 - 2
meters in front of you, with the back corner of each speaker almost touching the side
wall (see diagram 1). Even in a hotel room it is possible to reduce to boom and bass
resonance to a more than acceptable minimum, whilst still retaining good attack and
depth of bass.
If only a rear wall is available, it is still possible to get a fine boom-free bass response,
and experimenting with the angle and distance to the rear wall is absolutely necessary
inorder to get a good result. The inside rear corner of the speaker can be very close to
the wall, as little as 5 centimeters is acceptable, with the speakers placed as far apart
as the room allows, (see diagram 2.).
With only a wall behind the speakers the bass output will roll off quicker than in the
corner position, as the acoustic amplification provided by the room boundary (the wall)
is less than half of that of the corner.
GENERAL.
As with most Audio Note product concepts, this design philosophy is in stark contrast to
conventional speaker design dogma which creates speakers that as a main placement
consideration dictates that the speaker should be as far away from reflecting walls as
possible, a design philosophy which in my opinion is as illogical as it is unpractical, all
rooms have walls, so you might as well design them into the equation when looking at
the time constants between the direct versus the reflected sound and the rooms main
resonans modes which are only excited more by generating the sound far from the
walls, in addition to the fact that having speakers placed in the middle of the room is
physically obtrusive and does not endear your partner to your music system.
So to briefly sum up the advantages of placing the speakers near the room boundries,
A.) Improves room compatibility (variation in sound from room to room) by minimising
the speaker's sonic variability to different rooms, being close to the room boundaries
gives a far more predictable relationship between direct and reflected sound and in
addition reduces the influence of the room's standing wave behaviour.
B.) Improves bass response, by reinforcement against room boundaries, which makes
it possible to, by adjusting speaker's distance from the wall/corner, regulate the bass
quality/quantity to further minimise room influence on the sound.
C.) Wall or corner positioning makes the speakers less obtrusive in most room settings.
The exceptional dispersion performance of the drivers which is further supported by the
crossover network allow for considerable flexibility of listening position by creating a
wide, deep and high listening "window" and by maximising the coupling between horn
and room creates an acoustic pressure behaviour similar to that of live instruments
bringing you closer to the musical event.
The AZ-Three loads its 8 inch paper cone driver with a quasi quarterwave horn and
combines this with a 1 inch dome tweeter and an efficiency of around 94dB, in a 100
cm high floorstanding dynamic speaker, available in black satin, cherry. beech or
rosewood finish only.
The Zero Series speaker range will eventually consist of 3 models, the AZ ONE (90dB),
AZ TWO (93dB) and the AZ THREE (94 dB).
As with our existing speaker range we have spent a lot of time making sure that the
power transfer interface between the amplifier (The P ZERO's, naturally, but also our
other low power amplifiers such as the OTO, MEISHU and Conqueror) and the AZ
speakers' load to maximise the acoustic power output to the greatest possible extent
and it is important to appreciate in this regard that good efficiency ratings are one
thing, but in themselves they are no guarantee that you are able to play loud with a
small amplifier; this requires good wideband dynamic acoustic output conversion to
input power applied through the crossover to the drivers and that is quite another
matter which the common efficiency rating does not adequately describe, and the AZ
Three really does go loud with the 8 watts of the P ZERO's.
Specifications for the AN AZ-Three,
Dimensions Height 1,000 mm, width 280 mm, depth 320 mm
Sensitivity 94 dB at 2.83 volt @ 1 meter
Impedance 6 Ohms nominal
Crossover Frequency 2.8 KHz
Finish Black Satin, Cherry, Beech or Rosewood
Weight 24 kgs
UPGRADING.
Any member of the Audio Note AZ-speaker range is easily upgraded, the copper AN-D
internal cable can be changed to AN-SPa silver cable or a better variety of Audio Note
silver speaker cable.
The standard crossover compliment consists of a pair of chokes wound with copper
wire, these can be exchanged for a silver wired version (this will be quite expensive),
and a pair of bipolar electrolytic capacitors which can be upgraded to Audio Note
copper foil paper in oil caps of the same value (1 x 4.7mF/50 volt and 1 x 6mF/50volt),
which will be a considerable improvement and cheaper than the silver chokes.
A silver wired version of the woofer is also available and a silver wired version of the
tweeter will be available by the end of 1999.
All Audio Note products are designed with upgrading in mind, this is a central part of
any product specification/design, and allows you, our customer, to improve your
purchase over time, hopefully improving your enjoyment of and interest in reproduced
music.
Peter Qvortrup 01.05.2000.
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