Sidebar 3: Measurements
Based on the company's earlier FLS4 power amplifier, the genes of Audia Flight's FLS10 can be traced right back to the inaugural Flight 100 model, launched in 1997. In this current model, eight pairs of power transistors are deployed in bridged mode (per channel) across substantial heatsinks, supported by a huge 2kVA toroidal transformer and 144,000µF of supply capacitance. Regulation is impressively stiff, so the FLS10 not only exceeds its 200W/8 ohm rating by delivering 245Wpc into 8 ohms (23.9dBW) but then offers a +2.5dB uplift to 440Wpc into 4 ohms (23.4dBW).
Fig.1 Distortion versus time at 1kHz/10W/8 ohms for 30 minutes (1800 seconds) after initial switch on. Left channel, black trace; right channel, red trace.
Fig.2 Dynamic power output versus distortion into 8 ohms (black infill), 4 ohms (red), 2 ohms (blue), and 1 ohm (green) speaker loads, all ref. 1kHz/10ms. Maximum current is 37.2A at 1% THD.
Moreover, there's sufficient capacity in that huge PSU to sustain 265W, 500W, 885W, and a full 1385W (37.2A) into 8, 4, 2, and 1 ohm, respectively, under dynamic conditions (see fig.2). Having established its credentials as "no ordinary 200-watter," it's also worth remembering that this bridged/floating output stage should never be connected to a grounded "black" speaker terminal (Quad 'statics and some older Tannoy models spring to mind).
A passing reference is made by the brand for a limited "class-A" operation and, indeed, the FLS10 is fairly power hungry, drawing 170W from the wall at idle and consuming 700W at the rated output. The thick alloy chassis does warm up to around 100.4°F (38°C) and the black heatsinks to 113°F (45°C) after several hours, but the amplifier is sufficiently well compensated that there's barely any drift in distortion over this time (see fig.1). In practice, the right channel had some marginal advantage in all distortion versus level and frequency measurements, but the differences are not especially significant.
Fig.3 Distortion versus power output from 1W to Audia Flight's rated 200W into 8 ohms at 1kHz (left, black; right, red).
Fig.4 Distortion versus frequency at 10W into 8 ohms from 5Hz–40kHz (left infill, black; right infill, red).
Distortion is low, although typically lower at moderate 10–100W outputs (0.001%) than at 1W into 8 ohms (0.0035%) and 200W (0.002%). Again, these are not large variations (see fig.3). There's arguably greater change in distortion versus frequency (see fig.4) from the lowest bass frequencies, where distortion is just 0.0004%/20Hz rising to 0.009% at 20kHz and 0.03% at an ultrasonic 40kHz (all at 10W into 8 ohms). This is primarily second harmonic distortion, I might add.
Other advantages of Audia Flight's circuit topology, as discussed in Rogier's review, are also realized in the usefully low 0.007 ohm output impedance (20Hz–10kHz, rising to 0.02 ohm at 20kHz and 0.19 ohm at 100kHz) and a very extended frequency response that stretches from 1Hz-100kHz with a mere –0.6dB rolloff (–0.035dB a 20kHz, all ref. 10W into 8 ohms). Any further treble loss into lower impedances, amounting to just –0.08dB at 20kHz into 2 ohm, is of academic interest only. Meanwhile, the amplifier's (near) dual-mono construction leads to a fine ~100dB channel separation through the midrange, falling to a perfectly acceptable 75dB/20kHz.
However, overall gain is a high 46.2dB (via the balanced XLR inputs)—unnecessarily so for use with contemporary 2V line sources—requiring just 196mV to raise the rated 200W into 8 ohms. So, while few users will not from the full range of the digitally governed volume control, it offers a fine 0.03dB channel balance over the top 60dB of its dynamic range. If there is a small fly in the FLS10's otherwise exceptionally load-tolerant ointment, it's that this manifests as a moderate –63dBV hum—possibly caused by switching (rectification) pulses from that huge PSU in close proximity to the audio stages.
As a result, while the A-weighted S/N ratio remains a below-average 73dB (ref. 0dBW), its spectral content is more likely to inject a subjectively pleasing warmth than an annoying hiss or buzz. In use, the grip exercised by the FLS10's low source impedance/high current output will doubtless prove its dominant feature. This Italian flagship is no shrinking violet.—Paul Miller
