TORUS AVR2 POWER CONDITIONER ON TEST
Australian Hi-Fi 51As you have probably guessed by that
parenthesised comment, you can connect the
Torus AVR2 to the internet, using the Ether-
net port provided on the rear. If you do this,
a whole new raft of features appears.
Once your computer is connected to the
Torus AVR2, you can check its status from
anywhere in the world, as well as operate it
from anywhere in the world. And, once a
computer is connected, you can individually
switch the rear power sockets on or off. You
can do this switching manually, or you can
program them to turn on and off at specific
times, on specific days of the week. You can
also program the Torus AVR2 to send you
an email if the AVRs experiences what the
instruction manual calls ‘an issue’, in which
case it will send you an email notification of
the specific fault condition that took place.
Although these capabilities are impressive,
I wondered why all this functionality had
been provided. If I am on the other side of
the world, why would I want to be able to
switch my system on or off, or have it do
so in my absence? Whilst pondering this, I
discovered that whenever the Torus AVR2
switches on, it switches on each power outlet
(aka ‘zone’) in order, starting with A. This
is really useful, because it means you can
connect (say) a disc or network player to
A, your preamplifier to B and each of your
mono power amplifiers to C and D. This will
correctly sequence your system power-up pat-
tern to prevent potentially damaging turn-on
transients from reaching your loudspeakers.
However, I have to note that this won’t be
so useful if the components in your system
switch to standby power when they’re not
being used.
Later on I also found that with your
computer connected you can actually
calibrate the Torus AVR2, but since this
process necessarily involves using a calibrated
voltmeter and the operator of that voltmeter
potentially being exposed to lethal voltages
whilst measuring, this process is not included
in the otherwise totally comprehensive and
unnecessarily lengthy Owners’ Manual.
IN USE AND LISTENING
SESSIONS
There are many very obvious reasons you
might want to use a power conditioner.
First would be to stabilise the mains voltage
reaching your components because there’s a
possibility that surges and low-voltages could
do them some harm. It is, however, only a
possibility, as most components are built to
cope with surges and low-voltages.
Another reason for using a power condi-
tioner would be to eliminate high-frequen-
cy noise spikes from the mains power, as
these can adversely affect the operation of
digital-to-analogue converters, for example...
though, once again, most components that
could be sensitive to noise on the power line
are designed to remove that noise themselves,
to ensure proper performance.
However there is one not-so-obvious
reason for using a mains power conditioner,
which is to remove audible transformer hum
from your components.
Transformer hum used to be quite an issue
in the past, particularly here in Australia,
because most transformers were made by
laminating plates together and winding
coils around those plates. The problem was
that most transformers were designed for
operation at a mains frequency of 60Hz and
a mains voltage of 120V. Here in Australia,
when those same transformers (with different
taps to accommodate the increased voltage)
were used, the higher voltage combined with
the lower mains frequency (50Hz) caused
the laminated plates to vibrate, causing an
audible hum at 50Hz. In some cases the
transformer vibrated so much that it actually
caused a buzzing sound.
It was largely because of this hum problem
that most equipment manufacturers have
switched over to using toroidal mains power
transformers, which are not made by lami-
nating plates together. Which is not to say
they made the switch to toroidals simply to
solve this issue...toroidal transformers have
many technical advantages over standard
transformers, plus a smaller form factor, so
using them also allowed manufacturers to cut
costs in many cases.
However, although toroidal transformers
are intrinsically acoustically quiet (very little
hum) when fed from an ideal 240V source,
they can become noisy under adverse line
conditions, which will result in the com-
ponents they’re being used in generating
audible hum in the listening room... usually
at 50Hz, but sometimes also at 100Hz and
150Hz. If your components produce an
audible hum when they’re operating as a
result of sub-standard mains power, using a
power conditioner should reduce or eliminate
it. One complication with assessing audiblehum is that the level of hum will vary de-
pending on the music being played, and the
volume at which it is being played, because
hum levels will always be higher when a
transformer is being stressed than when it’s
just idling along.
Another reason you might want to use
a power conditioner is if you’re running a
high-power amplifier. In many cases, depend-
ing on the supply voltage in your area, if your
amplifier is running flat out, it could be pull-
ing so much current from the mains that the
mains voltage will drop, resulting in reduced
amplifier performance. A power conditioner
such as the Torus AVR2 will maintain the
correct supply voltage even under conditions
of peak demand.
Yet another reason is ground loops. If
your mains connections are such that there
are multiple paths for electricity to flow to
ground they may form a ‘loop’ which may
then pick up stray current via means of elec-
tromagnetic induction, resulting in unwant-
ed current in a conductor that’s connecting
two points that are supposed to be at the
same potential. The result of a gound loop is
hum. With all your components plugged into
the AV2, all the earths will be at exactly the
same potential, eliminating the possibility of
hum-generating ground loops.IN USE AND PERFORMANCE
I thought I’d check the Torus AVR2’s voltage
control ability before I commenced my
review, so I connected it to a variable mains
power transformer (Variac) I use when I am
reviewing 120-volt products, as it allows
me to adjust mains voltage from 110 volts
up to 270 volts. I first set the Variac at 230
volts, because this is the voltage the mains is
supposed to be here in Australia. I say supposed
because although the Australian government
committed to switching from 240 volts down
to 230 volts to harmonise with the European
mains voltage several years ago, it has never
happened. Or, perhaps, it has happened in
some regions and with some suppliers, but
not in others... and certainly not in my
suburb. Anyway, with the Variac set at 230
volts, the Torus AVR2 put out a constant 235
volts. This seemed a little strange, and after
a few emails with the Australian distributor,
it transpired that the operation of the Torus
AVR2 is somewhat dependent on the load
that’s connected to it, and for my initial tests
I’d connected a load that was drawing only
0.1-amps. When I increased the load to 2.8-
amps, the voltage dropped back to 230 volts,
right on the money.
With the bigger load connected I ramped
up the Variac to 234 volts, for which the AVR
delivered 237 volts. I then wound the Variac