Pre/Power Amplifiers

In practice, the ’800 has much in common with its Relentless parent including a total +26.3dB gain, a very wide 91dB A-wtd S/N ratio (re. 0dBW), a response that’s not quite ‘DC coupled’ (–1dB/1Hz) and that rolls gently away at HF to –0.7dB/20kHz and –7.0dB/100kHz. The difference in ‘character’, not power, is realised by an increase in distortion – mostly 3rd/5th harmonic – and output impedance. In practice, while the 800’s distortion generally increases with frequency – as expected – from 0.014% to 0.055% from 20Hz-20kHz at 10W/8ohm [see pink trace, Graph 2 below], its trend of distortion versus power is less linear. In fact the 800’s minimum 0.011%/1kHz distortion occurs at 200-300W/8ohm but is equal, and higher, at 6W and 600W (0.022%/1kHz).

This unusual trend of THD vs. output – seen with previous D’Agostino amplifiers – is clearly illustrated in Graph 1, all of which brings us to the 800’s prodigious power output... Like the parent Relentless, the ’800 is not only monumentally powerful – delivering 1170W/8ohm and 1990W/4ohm – but also sufficiently load-tolerant that it’ll surely drive (read, melt) the most ‘difficult’ of loudspeakers with its dynamic output of 1403W, 2658W, 4901W and 8290W into 8, 4, 2 and 1ohm loads, respectively. This is equivalent to a maximum current of 91.1A (10msec at <1% THD) – the original Relentless had 106.4A in the tank! Otherwise, D’Agostino’s conservative 800W/8ohm rating allows the brand to suggest a doubling of power into each halving of load impedance. And what of the power meter? Well, 1.3W/8ohm will register as 300W on the scale and 4W as 500W. And the magic 800W marker? That’s achieved at 18.5W! PM