Tech Notes

amplification, imbuing the sound with pure tonality, open imaging and natural fluidity.
The resulting low-level signal then passes to the power amp stage – iFi’s ‘current multiplier
circuit’. This is a highly efficient switching power amplifier, a description it has in common
with Class D amplification – but there the similarity ends.
Class D amp modules are often used in audio products because they are energy efficient and
able to generate relatively high current from a small device. However, in terms of sound
quality, typical ‘off-the shelf’ Class D amps leave a lot to be desired, not least because
switching occurs at varying frequencies which may be within the audible range – the higher
the power level, the lower the switching frequency.
iFi’s current multiplier circuit is entirely different because the switching frequency is fixed at
an ultra-high level – around 1.5MHz, far beyond the audible frequency spectrum. This results
in a high level of efficiency, multiplying the current supplied by the valve several thousand-
fold, whilst maintaining far greater linearity and lower noise than typical switching
amplifiers. Coupled to this is a low-pass circuit and a feedback loop, the latter ensuring the
output frequency is ideal for the load, and everything is ‘clock-locked’ via iFi’s GMT (Global
Master Timing) circuit to ensure unerring precision.
This ingenious fusion of amp technologies enables a sound that combines purity of tone
with a high level of engagement, speed and dynamic gusto, ensuring the emotive quality of
music is delivered in full effect.
Custom drivers, uniquely configured
The PureEmotion amp stage delivers a total of 320W to power the Aurora’s custom-made
speaker drive units. The main drivers, of which there are four – two firing from the front and
one from each side – sport a 120mm cone made from coated long-fibre paper, a material
selected for its optimal balance between stiffness and self-damping. This is coupled to a
large magnet, a basket that resonates above the audible range and extensive measures to
ensure excursion is controlled and damped mechanically, so that clarity and control are