home entertainment 2007

“Measurements” sections knows.
Adding to the Diablo’s weight are its
top-shelf drivers. The 1" tweeter, made
by ScanSpeak (another Danish company),
is a low-compression design that
does without ferrofluid cooling or a
phase plug. It has an neodymium
motor, and its nonresonant backwave
chamber and machined faceplate are
both made of aluminum.
The 5" midrange unit and two 9"
woofers (which feature “huge” magnets,
per Peak Consult) are custombuilt
to the designer’s specifications by
AudioTechnology, yet another Danish
MEASUREMENTS
PEAK CONSULT EL DIABLO
Although Peak Consult claims a very high sensitivity
of 94dB for the Diablo, my estimate of the
speaker’s sensitivity was somewhat lower, at just
under 90dB(B)/2.83V/m. This is still usefully
higher than average, however. Its impedance (fig.1) resembles
a 4–5 ohm resistor over much of the audioband, with
a very small electrical phase angle, though this is significantly
lower than the 7 ohms specified. There is a combination
of 3.8 ohms magnitude and –34° capacitive phase
angle at 27Hz, but given the low frequency, where music
will rarely have high energy, this will not give rise to any
current-delivery problems with good amplifiers.
The traces in fig.1 are free from any of the small wrinkles
that would indicate the presence of cabinet resonance
problems, and indeed, investigating the panels’ vibrational
behavior, I found almost nothing of interest. Fig.2, for
example, is a cumulative spectral-decay plot calculated
from the output of a simple accelerometer fastened to the
cabinet sidewall level with the midrange drive-unit. Only
two modes can be seen, and even the lower one, at
480Hz, is high enough in frequency and low enough in
level to be subjectively irrelevant.
The small saddle centered on 32Hz in the impedancemagnitude
plot indicates that this is the tuning frequency
of the two large-diameter ports on the Diablo’s rear panel.
The ports appear to behave very similarly; the red trace in
Fig.1 Peak Consult El Diablo, electrical impedance (solid) and phase
(dashed). (2 ohms/vertical div.)
company, which was cofounded by
Ejvind Skaaning (and his son), who also
founded Vifa/ScanSpeak and Dynaudio.
AT drivers are used by Rockport
Technologies and Sonus Faber, among
other brands that don’t blush at selling
expensive loudspeakers.
The Diablo’s second-order crossovers,
set at 200Hz and 4.8kHz, are
hardwired with silver solder and use
cost-no-object electrical components
chosen for their sonic characteristics.
The network is sealed at the cabinet
bottom to eliminate microphonics and
to shield it from electrical and magnet-
ic radiation. Internal wiring is from
Stereovox, an American company
owned by Peak Consult importer Signals
SuperFi. The biwire terminals
comprise two pairs of WBT Platinum
Signature binding posts.
Designer Per Kristoffersen claims
the Diablo is easy to drive, with a gentle,
low-current-drawing phase angle, a
sensitivity of 94dB/W/m, and a load
of close to 7 ohms across its entire
claimed in-room response of
20Hz–45kHz, –3dB.
Clearly, its build and parts qualities
are high, but to really appreciate the
fig.3 is the sum of their outputs, scaled with respect to the
outputs of the woofers (blue trace) and midrange unit
(green) in the ratio of the square root of the radiating
areas. The ports’ output does indeed peak in the region of
30Hz, though the corresponding minimum-motion notch
in the summed woofer output (where the back pressure
from the port resonance holds the woofer cones stationary)
occurs a little higher in frequency, at 34Hz. Of more
Fig.2 Peak Consult El Diablo, cumulative spectral-decay plot calculated
from the output of an accelerometer fastened to the cabinet’s side
panel level with the midrange unit (MLS driving voltage to speaker,
7.55V; measurement bandwidth, 2kHz).
Fig.3 Peak Consult El Diablo, anechoic response on tweeter axis at 50",
averaged across 30° horizontal window and corrected for
microphone response, with the nearfield responses of the midrange
unit (green), ports (blue), and woofers (red) plotted below 1kHz,
1kHz, and 2kHz, respectively, along with their complex sum plotted
below 300Hz (black).
www.Stereophile.com, May 2007 91