HFC_issue31 10.indd
Avalon Compás
eil Patel, head and chief designer at Avalon
Acoustics, thinks deeply about how his
creations should sound. Whereas some
operations have a notional idea of accuracy, and try
to maintain it over a range of products scaled for size,
price and power, Patel frequently adopts a different
approach. Through the selection of customised
drivers and components, he often seeks to express
a particular acoustical idea which best exploits the
individuality offered by a particular kit of parts.
This is true for the new Compás, which is allegedly
‘inspired by the musical style of flamenco’. Indeed,
in the flamenco tradition the Spanish word compás
effectively translates as rhythm in the strictest sense.
In a brief extract from my interview with Patel he
explained: “Each completed loudspeaker system
design is its own entity, hopefully with a distinct and
yet truthful character.”
Although I knew that these speakers would be
quite large, I was not really prepared for an imposing
physical presence, nearly 1.2m tall. Our samples had
a faceted front and grille, the latter covered in almost
black fabric. A satin finish had been applied to a
really dark, highly figured burr walnut veneer, which
would suit classically furnished decors; more modern
arrangements will benefit from the lighter toned
Cherry or Maple alternatives, or even the anticipated
gloss colours.
Avalon describes the Compás as designed for fine
rhythmic and dynamic sound reproduction, aided by
“control of all pertinent time constants to an ‘overdamped’ condition”, and free of ringing or overhang.
Fortunately our review pair were demonstrators
that had undergone significant use, so an extended
running in period wasn’t necessary.
Priced from £33,500/pair (depending on
finish), one has the right to expect an impressive
performance profile. An above average sensitivity
of 91dB/W is claimed, alongside a commendably
truthful 4ohm load impedance and a 50 – 500W
power rating. The latter is an indication of the size of
amplifier suitable for speech and music reproduction,
rather than the possible damage limit of the
loudspeaker itself. This wide power range also reflects
the low rated impedance, and a 500W peak input
should deliver good in-room sound levels of about
110dB for a pair.
HFC_issue31 10.indd 26
Avalon speakers carry a three year guarantee, and
finish options include figured Walnut quilted Cherry,
curly Maple, Myrtle cluster burl, Walnut cluster
burl (the review pair), and birds eye Maple. Gloss
automotive colours are also available. The base price
is £33,500 for standard woods in satin or high gloss
finish; premium woods cost £37,000, and a painted
finish is £35,500. A very detailed instruction manual
has good guidance on room acoustics, treatment and
loudspeaker placement, and suggests a toe-in of 3-10
degrees (ie not directly at the listener), with which we
A single wire connection is provided via Cardas
insulated clamp terminals. Heavy duty threaded
sockets are supplied under the base for spikes, along
with hardwood floor interface accessories.
All the drive units come from the new Accuton
‘CELL concept’ range of pure piston designs. These
represent a unified line, and the midrange and treble
units in particular are inherently time aligned. All
have ceramic diagrams (coloured black here rather
than the more common natural white alumina
finish), and the bass units include a honeycomb core
sandwich construction with inherent damping for
the diaphragm’s primary structural resonances. These
drivers also have high Qm (a parameter that denotes
the mechanical losses in the suspension), and may
well offer a shorter running-in period here.
Avalon uses customised versions of specific
Accuton production drivers. The bass uses a pair
of S220-6-221 units with die-cast chassis and a
38mm diameter long-throw voice-coil wound on
a high power handling titanium foil former. The
midrange is based on a variant of the C90-6-724,
a driver of modular appearance with a pistonic
ceramic composite cone. This has a well controlled
first break-up at 9kHz of only 6dB magnitude, and
claims very low distortion, partly due to the magnet
geometry and partly the underhung voice-coil
design. The laser-machined resonance control cutouts of earlier diaphragms have been engineered out
here. This driver will actually do bass in a compact
enclosure but is very capable when employed for
midrange only duty. The 25mm ‘ceramic’ C25-6158-based inverted dome tweeter is driven by an
alloy former with copper voice-coil. The whole
moving assembly measures just 0.17gram and it
11/9/13 20:14:54
delivers a high inherent sensitivity of 92.5dB at
6ohm, using double neodymium magnets and a
treated fabric surround. Avalon’s version is custom
terminated in order to interface with the heavy duty
internal wiring.
All the diaphragms are relatively sensitive to
careless touch, so come permanently fitted with
hexagonally perforated rigid steel grilles with large
‘windows’. The midrange driver is used between
500Hz and 4kHz, and the pistonic tweeter extends
beyond 30kHz (going beyond this hardly matters
in my view). The paired bass drivers are nominally
220mm units, almost equivalent to a single 13in
(330mm) example, so this speaker has ample bass
radiating area. It’s a step up from the Eidolon in
this regard, for example, and the combined power
handling of two voice-coils will improve the thermal
behaviour. Patel has developed proprietary crossover
alignments to achieve the acoustic responses
responsible for the character of the loudspeaker. He
notes a non-ringing Q of 0.5 for the acoustically
pertinent crossover filters and also for the bass
alignment .
Sound quality
Running it in for a while after delivery, this well used
demonstrator still showed significant settling-in over
the first five and then a further 100 hours of use. At
this point dynamics and clarity had improved and
bass lines sounded deeper and more articulate.
This tall loudspeaker has a high apparent sound
source, performers appearing to be standing rather
than seated. The name is intended to reflect a
character influenced by the flamenco – powerful
music with foot-stomping and expressive rhythmic
appeal – and this formidable floor stander gave
us a rollercoaster ride, at times thrilling, at times
disturbing. It differs from smaller Avalons in its
strikingly impressive and articulate dynamics,
which imbue powerful music with detail, scale and
excitement. It can be thrilling, providing large scale
performances which are superbly focused, together
with qualities of fine width and depth to the sound
stage illusion.
Its dynamic performance on percussion is
undeniable, and here it was upbeat, involving and
exciting. Interestingly, our view of its sound quality
varied rather more than usual with different types
of programming. A well balanced cathedral organ
piece sounded rather dark, and was considered a little
too forward on reed pipes. Orchestral material too
showed some forwardness on violins at times, and
mixed woodwind was somewhat unevenly voiced
between different instruments, with resulting shifts
in perspective.
HFC_issue31 10.indd 27
Some interaction with programme production
values was also evident. Classical, rock and jazz
pieces which were more distantly and spaciously
recorded, with significant reverberant energy, played
well on the Compás, demonstrating great scale,
massive detail, abundant power and an alluring sense
of vibrancy. A little ironically perhaps, other more
‘immediate’ and ‘dryer’ recordings sounded subtly
altered, sometimes to the extent that its rhythm and
timing elements were disturbed, seemingly slowed
and delayed.
Familiarity with certain such tracks indicated
that this speaker had a somewhat uneven midrange
frequency response, leading to perceptible if mild
colourations, such as a ‘hardening’ of midrange
timbre, some ‘nasality’, and a less than smooth treble.
Some singers, such as Eleanor McEvoy, showed a
degree of added huskiness, together with mildly
altered vowel sounds, different emphases and shifts in
perspectives. Its character therefore differs somewhat
from the well judged tonal balance found with
Avalon’s Idea (reviewed Vol6 No4), and for that matter
that classically neutral if slightly sleepy sounding but
oh so sophisticated Eidolon Diamond, which spent
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many years resident in my listening room.
Tonality notwithstanding, and by way of contrast,
Music for Six Mallet Instruments – an old warhorse
piece by Steve Reich – sounded quite exceptional,
the Compás bringing out both the essential percussive
qualities and the vital separation of the complex
layering of multiple instrument voices. Likewise,
mid-dominant percussion tracks, including of course
flamenco material, sounded very well focused and
were found most involving. However, the sense
of coherent timing experienced by listeners varied
with the piece chosen, and more general rock, folk
and R&B material seemed a little out of time, with
potentially strong, tight bass lines nonetheless lagging
the more forward, projected – even accelerated and
over articulated – upper midrange.
Some experiment with side wall absorption
suggested that more heavily furnished and damped
rooms might well suit it better than mine.
Test Results
Review System
Krell Evo 402E, D’Agostino
Momentum Stereo, Naim
NAP300 power amps;
Audio Research REF5 SE,
Townshend Allegri control
units; MSB Platinum Signature
IV DAC with Diamond
supply, Metrum Hex DACs;
Naim UnitiServe network
server and S/PDIF source;
NAIM NDS Streamer/
DAC/555 PS, Wilson Audio
Sophia 3, Quad ESL63,
Spendor D7 speakers; Finite
Elemente Pagode Reference
racks; Cardas Golden Reference,
Transparent XLmm2 and
Naim NAC A5 cables.
KOG Audio
Tel: 02477 220650
HFC_issue31 10.indd 28
The mildly uneven measured frequency response
made estimating the sensitivity problematic; 88.5dB
was considered a fair assessment, which is somewhat
less than the 91dB claimed. With an impedance
which does fall below 4ohms in places (in fact to
2.8ohms at both 25 and 60Hz), while averaging
about 5ohms elsewhere, this may be rated a 4ohm
loudspeaker, as specified. This result actually sets the
true sensitivity (ref 1W rather than the usual 2.83V
input) at 85.5dB, which is rather below average. Full
loudness potential will therefore be best obtained
with current-capable solid state amps, and the latter,
true sensitivity figure is likely to apply when driven
by valve amps. Some mitigation is available because
the phase angle of the load (indicative of the reactive
content) is low in the low impedance regions (eg just
18degrees at 25Hz), so its worst case combination of
phase and magnitude is not as taxing as some of the
Correctly judged, frequency response
measurements can often be a useful indicator of
performance, even though the designer suggests that
they can also be misleading in this case, and are often
not a good guide to sound quality or loudspeaker
character. This Compás measures nominally ±4.5dB,
40Hz - 32kHz, which is a larger amplitude tolerance
than usual.
The relevant frequency response graphs are
notable for significant local 1.1kHz and 3kHz
prominences of about 3dB (considered an audible
threshold), while the treble, 5kHz - 12kHz, also
looks a bit ragged. Characteristic if moderate
associated colorations could be heard on relevant
programme for all three of these aberrations: ‘hard’
in the midrange, ‘nasal’ in the low treble and ‘grain’
in the upper treble respectively. A hard dome tweeter
generally has an upper resonance, but in this case it
peaks around 11dB at a high 32kHz, and is probably
inaudible. Pair matching was generally very good
with mild ±0.5dB variations 1kHz - 15kHz, rising to
±1dB at lower frequencies.
Albeit with consistent ‘echoes’ of the axial
response features, the lateral off-axis responses were
tidy with a smoother if mildly decaying upper treble.
Off-axis consistency is undoubtedly very good thanks
to the powerful diffraction countermeasures, even if
the aforementioned primary response features remain
evident. Tidy off-axis behaviour certainly aids image
precision, as we heard during auditioning.
However, the Compás is rather sensitive to vertical
axis variations and hence listener ear height, as the
vertical responses reveal. The orange trace is for 15
degrees below axis and highlights a more rapid falloff
above a relatively inaudible 13kHz, while the aboveaxis trace (yellow) shows a strong phase cancelation
between mid and treble units that sucks out the
response above 4kHz to an average of -12dB. It is
therefore inadvisable to stand up (or use a higher
than usual seat) when auditioning these speakers.
This off-axis feature will also dull the overall power
response to some degree.
The described innate character is also revealed in
the multi-position in-room averaged response, where
the overall acoustic output as it’s coupled to the room
is seen. Here that aforementioned response ‘character’
is also evident. The smooth, extended, mildly rich bass
precedes a ‘cooler’ midrange, then those noted and
audible prominences at around 1kHz and 3kHz, the
latter highlighted by the steeper than usual subsequent
treble roll-off. In my view this is a mildly idiosyncratic
tonal balance, likely to lead to the distinctive timbre
and colour that we felt we heard on audition.
Randomised ‘pink’ noise (a waterfall sound) is our
usual stimulus for deriving the in-room response, and
under these conditions the noted speaker response
characteristics were quite audible.
The waterfall representation of output decay
over frequency and time revealed impressively rapid
clearing and near linear phase character of the early
response up to 0.5ms, though the noted, mildly
wayward upper frequency ripples are also evident.
However, there is also some clutter from secondary
resonances, likely emanating from the stop band of
the largely pistonic mid driver.
The grille and the related felt absorbers beneath it
are essential to this design and their removal results
in excess treble, with a further 4dB of response
aberration and a substantial loss of stereo focus.
The vestigial port is weakly tuned to about 30Hz
11/9/13 20:14:57
and plays little part in the overall response, its main
purpose being to align the phase response. Close to
a sealed box alignment, the bass is smooth, extended
and well damped, with a fast time signature. Bass
output is well tailored, and at moderate power
extends to a low 22Hz in-room, and to a good 33Hz
at higher powers.
Rapping the enclosure sides showed more decay
resonance than expected – more than my old Eidolon
Diamonds for example, or for that matter a Wilson
Audio Sophia 3. However, build quality is clearly
very high, judging by various construction details,
the heroic wiring and not least the fine finish.
In view of the low frequency driver excursion
required, some distortion was expected at moderate
powers, but the measured results were good. For
example, at a low frequency extreme of 20Hz
(86dB), distortion was about 3%, and it achieved
an amazing 0.3% at 35Hz. At a higher level and
frequency (a pretty loud 90dB at 50Hz), second was
a harmless 1% and third a remarkably low 0.26%.
With rising frequency (still at 90dB) the distortion
figure improves first to 0.3% and then remarkably to
just 0.15% by 100Hz. With the sound level reduced
by 6dB, second and third now averaged a remarkably
low 0.05%, which will be completely inaudible. At
higher frequencies, irrespective of power, my results
were in the 0.08% range regardless of frequency or
sound level up to 90dB. That claim for low Accuton
driver distortion is thus confirmed, except at 10kHz
where 2nd harmonic showed an innocuous isolated
rise above 88dBspl to 1% (though 3rd harmonic was
still held to a low 0.1%).
Avalon Compás Frequency Responses
Avalon Compás Impedance (blue) and Phase (orange)
Avalon Compás Waterfall response for amplitude/time/
This powerful loudspeaker has bags of character,
and ought to be experienced if considered a
contender. Tall and prismatically contoured, it
offers unusually detailed, powerful and deep bass,
tightly focused, audiophile quality stereo imaging,
and exciting expressive dynamics, together with
a heightened rendition of percussion. There is
also some midrange coloration and related tonal
emphases, the subjective impact of which will vary
with listener taste, the matching system, and not
least the room acoustics. (A rather live room, such
as my own is probably less well suited than a more
highly damped example, with some side wall and
corner absorption.) The overall standard, including
build quality and finish, and taking into account
the exceptionally low overall distortion, meets the
standard for recommendation, but do note that
its typical 4ohm impedance loading and moderate
efficiency renders it better suited to solid state than
to valve amplification.
HFC_issue31 10.indd 29
HIFICRITIC Loudspeaker Laboratory Test Results
Make, Country
Avalon Acoustics, Boulder, USA
Compás: moving-coil floorstander
Price per pair
From £33,500 depending on finish
Various standard and luxury veneers in satin or high gloss, or painted
Size (HxWxD); weight
117x28x43cm; 68kg
3-way, 2x220mm bass, 115mm mid, 25mm treble,
quasi-bass reflex loaded
Sensitivity for 2.83V
88.5dB/W measured (8ohm 2.83V watt)
Amplifier loading
4ohms typical, 2.8ohm min., ‘below average loading’
Frequency response, axial
40Hz to 32kHz ±4.5dB (listener axis)
response off- axis Good + (see graphs and in-room response)
Bass extension
39Hz for -6dB, (25Hz in-room)
Max Loudness
107dBA for a stereo pair in room
Power rating (max, min)
500W, 50W
Floor; spike coupled
11/9/13 20:15:00
NP: First may I make a brief statement regarding my
personal design philosophy: all technical decisions are
made in the context of achieving an aesthetic result.
The sonic picture I want to paint is fully formed in
the mind before the process begins. Each completed
loudspeaker system design is its own entity, hopefully
with a distinct and yet truthful character. Like the plays
of Shakespeare, each illuminating an integral aspect
of human nature, ultimately I would like our work
to focus a ray of light on the opaque nexus of music,
intellect, and emotion.
Avalon designer Neil Patel
Q: The description for the Compás mentions design
Q factors of 0.5, which is rather lower than the
industry norm, here perhaps trading transient
accuracy over matters of simple efficiency and
A: The desideratum here was first and foremost to
achieve transient accuracy throughout the bandwidth.
Technically, Q is defined as the ratio between energy
storage and dissipation at resonance, and is indicative
of transient behaviour, but is not its sole determinant
or descriptor. The actual numerical quantity is
actually closer to Q= 0.57 in our case, reflecting a
composite of proprietary Avalon bass tuning and
crossover filter alignments that produce the desired
transient behaviour.
Q: For the bass, is this achieved by ‘Bl’ or magnet
strength control, or by partly damped ‘bass line’
loading, or both?
A: The four general variables that are manipulated
in achieving our overall desired result are: driver
parameters, cabinet volume and internal labyrinth
length, electrical damping, and finally, venting
For the driver alone it is magnet Bl product; the
force applied to the moving system, the moving
mass, while voice coil inductance, capacitance, and
resistance are all essential quantities in our overall
mathematical modelling for low frequency design.
Each of the previously discussed variables must also
be quantified, with their respective components
added to the overall mathematical model for the
desired alignment.
Q: Or, is Avalon referring to the crossover transfer
functions at Q = 0.5?
A: Again, simply designating a specific transfer
function for the crossover does not necessarily address
the desired goal. In our case we have developed
proprietary functions which maximise our most
desired characteristics, namely phase and transient
accuracy for the radiated sound.
Q: What factors are primarily responsible for the
subjective gain in dynamics experienced with the
HFC_issue31 10.indd 30
A: The previously mentioned transient and phase
accuracy combined with low noise floor. Phase noise
and energy storage will blur dynamic contrasts, both
macro and micro dynamic.
Q: What could a purchaser expect to hear from
the more costly Compás Diamond version, once
acquainted with the standard Compás?
A: The primary function of a less deformable
membrane such as super rigid diamond is an
extension of bandwidth without the introduction
of break-up by-products; thus lower noise. Simply
substituting a stiffer diaphragm will not automatically
get you more frequency response extension or better
sound; in fact you must also preserve this gain in low
level information from within the crossover circuitry
and internal wiring.
The sonic benefit of the diamond diaphragm is
similar to that found between the Eidolon and its
Diamond version, a more open and relaxed high
frequency presentation, and that in a certain sense it
feels “less bright”. Of course maximum benefit will
be realized when the entire system of electronics and
front-end possesses extended and accurate bandwidth.
Q: The bass port is short and small, with relatively
little output, what is its purpose in this design?
A: Considering the port as a variable in the previously
discussed LF tuning question, coupled with internal
baffling, it is an essential design variable used for
extending the in-phase behaviour at low frequencies.
This concept goes well beyond the usual simplistic
discussion of group delay error, but instead gets to
the heart of our sonic philosophy, that the subjective
sense of time is the most important quantity in music
and must be preserved.
My feeling to describe where loudspeaker design
has gone generally in this regard is that of “disgust”.
As a verifiable quantity and essential aesthetic quality,
I feel that the valuing of the representation of time in
sound reproduction has been unceremoniously left by
the side of the road.
Q: Is it correct to say that the Compás is a 4ohm
speaker but that the quoted sensitivity is scaled to an
8ohm watt, relying on a current reserve from a (solid
state) amplifier?
A: This is correct. I’m still not quite sure that
efficiency per se has much place in high-end audio
as a quoted specification. Except for those who
mistakenly think that efficiency is related to dynamic
contrast. In my view issues of drivability are vastly
more important than this single specification.
Q: Is achieving for the purchaser the inherent
Compás timbre, its innate tonal balance, more
reliant on room absorption than say an Eidolon
Diamond or an Idea?
11/9/13 20:15:01
A: An excellent question for which I have only this
answer: If the absorption of the room is smooth
and even over frequency, the quantity of absorption
should be irrelevant. Technically speaking, if a room
is highly absorptive and there are no suck-outs
that significantly color the sound, then only more
amplifier power would be required to achieve a
similar subjective result. Unfortunately in the real
world the results of incompetently conditioned rooms
will be blamed on the transducer.
Q: Compared with the Eidolon Diamond, are the
larger mid and treble drivers in the Compás to do
with the goal of increased dynamics and efficiency?
A: That wasn’t my intention. The idea was to present
a more open soundstage by carefully smoothing the
polar response lobes. Stage width and depth are better
defined in the new design through careful attention
to detail regarding phase and the 3D, lateral off-axis
lobing behaviour.
In my view the suggested increased dynamic
impact in this design is little affected by those slight
increases in driver diameters.
Q: I note that great advances have also been
made for distortion in the new driver technology
employed in the Compás
A: Improvements for intrinsic driver distortion
parameters are significantly due to the radial magnetic
structures, and then the type of crossover and bass
tuning alignment avenues they open. Once again,
I consider that the actual radiation area is a less
significant parameter.
Q: Are those Accuton drivers modified or special to
A: Over the last 25 years or so we’ve developed a
close working relationship with those who produce
our most technically demanding components. We
have encouraged and participated in many of the
innovations you see in these particular drive units.
Above and beyond this, controlling each of the
driver parameters I have previously discussed requires
custom specification and structures. Many of these
characteristics, while essential for our proprietary
combination of electroacoustical elements, would
render them unusable and unsuitable for off the shelf
Q: Will the traditional Avalon crisp veneer edges
and corners be softened slightly to accommodate the
new gloss finishes?
A: No. More ‘shine’ (when available) will be done
without compromising the crispness of the form.
Q: And a range of matching grille cloth colours?
A: Don’t press your luck; we’re still trying to run a
business here!
Panda Feet!
anufactured for Dave Jackson at High
End Cable by established audio stand
maker Atacama, these renewableresource eco-friendly ‘carbonised’ bamboo cable
supports cost £100 for a set of four. The modus
operandi is a reduction in the coupling of floor
and frame vibration to the cable that is in contact
with them, especially speaker cable where longer
lengths may be exposed to a vibrating surface.
In addition, if there’s a dielectric effect on the
cable, the supports will provide a largely airspaced environment. The main premise is that by
reducing conducted vibration, its consequences
will be rendered less audible. The type of flooring
HFC_issue31 10.indd 31
is relevant, for example whether plain wooden
flooring or carpeted, and the latter is likely to have
less effect. One face of each Panda Foot is slotted,
the better to suit cables of ribbon construction.
We tried them in a high end system with both
Transparent XLmm2 and Naim NACA5 cables
and found some improvement in clarity, focus and
particularly in musical timing. The sound was less
congested (already very good here) while subtly
clearer transients and firmer bass sharpened the
beat. On a mail order, return-intact-if-they-don’tsuit basis, these cable supports represent a win win
High End Cable
Tel: 01775 761880
11/9/13 20:15:01
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