HEADPHONES
L
egendary. It’s a powerful and emotive
word, but it is one that every audiophile
applies to Stax headphones... or, as
Stax prefers to call them, ‘earspeakers’.
In fact, in reality, they are essentially minia-
turised full-sized loudspeakers... even the shape
of the headpiece is rectangular, rather than the
circular form usually employed for headphones.
(The three most expensive — and most recently
designed — models in the Stax range have circular
rather than rectangular earpads, but traditionally,
Stax headphones have had rectangular ear pads.)
What makes Stax earspeakers especially unusual
is that instead of a dynamic driver element where a
coil of wire interacts with a magnetic field in some
way to move a diaphragm to create sound, Stax
earspeakers instead use an electrostatic system,
where high-voltage electrical charges move the
diaphragm. How high a voltage? Around 400 voltsAC for the drive voltage, and around 600 volts
DC for the bias voltage. How do you safely create
such high voltages? With what Stax calls a ‘driver’,
of which the SRM-D50 Driver/DAC is the newest
addition to the Stax driver line-up.EQUIPMENT
Stax has been in the business of building electro-
static (ES) earspeakers since 1960, and since all
earspeakers require special electronics to ‘drive’
them, Stax has also been building ‘drivers’ since- Of the models in the current range, the
flagship is the SRM-T8000 and the entry-level
model is the battery-powered SRM-D10, also
the only other model in Stax’s range that has an
inbuilt digital-to-analogue converter. So there
are two gold-plated RCA analogue inputs on
the rear panel of the SRM-D50, but also digital
connections — one coaxial on a gold-plated RCA
input, one optical Toslink input, and a USB-B
connector suitable for playing via USB from a
computer. Switching between the inputs is
accomplished via the rather interesting toggle
switch at the left of the SRM-D50’s front panel,
alongside which is a single five-pin DIN socket
to which you connect the earspeakers (only
‘PRO-Bias’ Stax earspeakers can be used). Unlike
many other headphone drivers in Stax’s range, this
means that only a single pair of headphones can
be used at a time.
At the extreme right of the D50’s front panel
is a small, smooth-rotation volume control
and, to its left, an equivalently-sized VU meter
with a rather old-fashioned look, right down to
the ‘orangey’ colour of the meter illumination.
(The last time we saw a meter like this, it was
on an über-expensive hi-fi component made
in Switzerland by Nagra. Good company toEARSPEAKERS+DRIVER
STAX SR-L500
+SRM-D50
Once you’ve heard Stax, there’s no
going back, they say. So what’s
the magic ingredient here?