TL Audio A3 - Manual (Page 5)

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The Equaliser has 3 bands. The HF and LF controls are shelving whilst the mid
control is a swept, peaking filter.
Comprehensive switching (via relays) allows the A3 to be configured with the
equaliser pre or post the compressor, or with the equaliser in the sidechain, for de-
essing or frequency variable compressor effects.
A VU meter is provided, which can be selected to either input or output signals. It may
also be selected to display the compressor Gain Reduction. In this mode the meter
normally indicates 0dB, falling back as the signal is compressed. The amount of
compression may be read directly from the dB scale. The meter is also provided with a
“+10dB” switch, which keeps the reading on the scale when driving a high level out
(to a DAW, for example). In the +10 mode, 0VU is calibrated as +14dBu out.
Why Class-A?
Class A circuits are designed with a constant current flowing through all of the
transistors, which is sufficient to drive the peak output required from each block of the
circuit. This ensures that every transistor is kept at its optimum operating point,
minimising non-linearities due to changes in current and internal thermal effects, and
eliminating the objectionable “cross-over” distortion typical of class AB circuits.
Due to the higher steady state (or “quiescent”) currents used, the power dissipation of
class A circuits is substantially higher than can in general be handled by integrated
circuits. It is also possible to design discrete transistor circuits to operate at higher
voltage rails than are available for audio integrated circuits, adding the benefit of
greater headroom and improved dynamic range. For these reasons, there are no
integrated circuits in the audio paths of the Ebony Series.
The outstanding audio quality is reflected in the technical specification of the units,
with particularly low noise and distortion, and wide frequency response.
Why Tubes?
Valves - or “Tubes” - have long been associated with excellent audio quality,
recognised as adding “warmth” or “depth” to a signal. Driving the valves harder
results in an increasing level of mainly second harmonic distortion, which is
responsible for the characteristic overdriven valve sound.
The Ebony Series feature variable drive valve circuits, which may be switched into the
audio paths, or bypassed completely. The valve drive control varies the signal level
through the valve stage, without affecting the overall gain from input to output. It is
therefore possible to vary to the degree of harmonics added by the valve, from subtle