Integrated Amplifiers

Denon DCD-1700NE
SACD has the edge over plain vanilla CD in this player, right down to its maximum 2.50V output and 110.6dB A-wtd S/N ratio which, in both cases, is some +0.5dB ahead of its silver stablemate. Distortion too, while already a low 0.00085%/1kHz with CD [see Graph 1] is squeezed further to 0.00017%/1kHz in SACD mode. Above 10kHz the situation reverses as the requantisation noise associated with SACD/DSD64 causes an uplift in THD+N with the golden disc – so 0.0007%/20kHz with CD becomes 0.04% with SACD, increasing to 0.07%/30kHz. Of course, CD is limited to a ~22kHz bandwidth, its response subject to the adaptive qualities of Denon's 'AL32 processing' where the digital filter shows less ringing with transient signals at the expense of an early treble roll-off of –6.5dB/20kHz. With non-transient/steady-state signals the digital filter delivers a flatter and more extended response that reaches out to –1.8dB/20kHz. SACD data is retained as DSD rather than downsampled to LPCM (as we have seen in many players) and so the response sails out to –0.5dB/20kHz, –1.2dB/40kHz, –2.5dB/60kHz, –6.0dB/80kHz and –13.6dB/100kHz.

The 1-bit format also offers improved low-level linearity from the ±0.2dB error at –100dBFs associated with CD to ±0.1dB with SACD, the latter drilling down as far as –130dBFs with a resolution of ±0.8dB. Jitter is at the 16-bit limit of measurement at 114psec with CD (rather intriguingly increasing to 118psec in 'Pure Direct' mode) and reduces to 56psec with SACD [see Graph 2, below]. Other performance parameters, including the fine 125dB/1kHz and 101dB/20kHz stereo separation, the 97ohm (single-ended) output impedance and 0.02dB channel balance are all features of the shared analogue output stage. PM

Denon PMA-1700NE
Although the DCD- and PMA-1700NE are both equipped with TI's PCM1795 DAC, the amplifier's implementation features an alternative 'hybrid' digital filter with asymmetric pre/post ringing and a slightly reduced 73dB stopband rejection. Via the tape recorder outputs, the A-wtd S/N is a couple of dB shy at 108dB but distortion – with 24-bit rather than 16-bit CD data – is significantly lower at 0.00015-0.0008% over the top 30dB of its dynamic range than that achieved by the DCD-1700NE [compare Graph 2 with that on p59]. Low-level linearity is good to ±0.1dB over a 100dB range, jitter is a little less 'tidy' at 120psec and 165psec (48kHz and 96kHz, respectively) while the line responses reach out to –0.5dB/20kHz, –3.7dB/45kHz and –12.8dB/90kHz with 48kHz, 96kHz and 192kHz files.

These responses will be superimposed onto the 'analogue' response of the main amplifier which is flat to within –0.4dB/1Hz and reaches up to –0.1dB/20kHz and –0.79dB/100kHz. The 0.028-0.037ohm (20Hz-20kHz) source impedance should maintain this response into all but the most violent of speaker loads just as the FET amplifier's robust 97W, 186W and 348W dynamic output into 8, 4 and 2ohm loads, respectively, indicates good driving ability. Into lower, 1ohm, loads the PMA-1700NE is protected beyond a 265W/16.3A output [see Graph 1]. Overall gain is a high +46.6dB while the A-wtd S/N ratio is a generous 91dB (re. 0dBW) and distortion consistently low at ~0.0025% from 1W-50W/8ohm through the midrange (up to 0.015%/20kHz), only increasing to 0.003%/1kHz at the rated 2x70W/8ohm. In practice the amplifier's true power output is closer to 2x92W/8ohm and 2x175W/4ohm. PM