Volume Control - T+A P 1260 R Mode D'emploi

Symmetrical outputs (XLR)
(P 1260 R only)
The principle of symmetrical connections has its origins
in studio technology, where the highest possible quality
and best possible interference suppression are required.
The principle is based on the idea of transferring two
mirror-image (inverted) signals instead of a single signal.
The receiving device generates the difference signal
between these two signals, with the effect that all traces
of interference are eliminated, and only the pure, un-
coloured signal remains for further processing. Of
course, symmetrical signal transfer is of particular inte-
rest where large distances are involved, e. g. with active
speakers, or where the audiophile listener wishes to set
up the power amplifiers directly adjacent to the speakers
in order to keep the critical loudspeaker cables as short
as possible.
However, symmetrical amplifier technology offers further
advantages: no currents are transferred via the earth
conductor, which would otherwise result in a decline in
earth voltage, which would in turn offset the vitally im-
portant earth reference potential. Since the amplitude of
the effective signal is doubled by the difference genera-
tion process, the voltage amplitude per unit of time is
also doubled, thereby doubling the slew rate of the
signal.
An additional advantage is that distortion and back-
ground noise tend to cancel each other out. The im-
provement in noise is around 3 dB, which equates to a
reduction in hiss of around 30 %. Fact: symmetrical
signal technology does require considerably greater
complexity, since some parts of the amplifier have to be
duplicated, but in our opinion the gain in fidelity justifies
the effort every time.
The external sign of the extra investment we have made
in this technology is the presence of indestructible, pro-
fessional studio XLR sockets. The pre-amplifier can be
retro-fitted with an XLR output module.
TASI ( Surround Interface)
This interface, normalised by , enables you to loop a
 surround decoder between the source select switch
and the amplifier's volume control.
If a decoder is connected in this way, the interface
automatically detects it and switches to surround mode.
In surround mode the amplifier's volume and tone
controls are disabled, as these functions are assumed
by the decoder.
Update / Upgrade
This  unit can be kept up to date with the current
state of development by fitting an update or upgrade.
An Update expands the unit's operating facilities by
•
the installation of a new program memory.
An Upgrade involves the installation of replacement
•
sub-assemblies or auxiliary modules. The installation
or conversion work is carried out by your specialist
 dealer.

Volume control

The amplifier features a two-stage volume control which
enables the unit to work at a high level of amplification in
the input stage of the pre-amplifier, without risking over-
loading the pre-amplifier.
This is the responsibility of the first volume control. In the
subsequent stages of signal processing the amplifier has
a higher-level signal to handle, and this in turn signifi-
cantly reduces hiss and crossover distortion where the
signal passes through zero.
The second volume control reduces any hiss generated
in the pre-amplifier at low levels directly before the out-
put stage.
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