Cambridge Audio 751BD - Measured performance

MEASURED PERFORMANCE

Frequency response of CD via the analogue outputs, shown in our analysis, was flat to 20kHz whichever filter was selected. Because there is no onboard DSD convertor PCM must be selected to output SACD, forcing DSD to be converted to PCM before going through the DACs. There was still benefit though, SACD frequency response reaching out to 32kHz before rolling away slowly, analogue fashion - see our analysis below. With high resolution 24/192 PCM the analogue outputs reached 48kHz (see our analysis below), so again high sampling rates are done justice.

Linearity of the onboard DACs was a bit below top rate CD players as is to be expected, since this is not a dedicated analogue player, but 0.29% at -60dB via the analogue outputs is still a good result and this allowed a good EIAJ Dynamic Range value of 98dB to be achieved. With high resolution 24bit PCM distortion dropped to 0.15% at -60dB (see our analysis below), against 0.02% or so possible, so there’s improvment over 16bit. Similarly, SACD gave 0.21% at -60dB so measured better than CD, and at -90dB just 0.6% - but DSD code is very linear at low levels, hence SACD’s smoothness.

Random jitter on the digital signal measured less than 20pS above 100Hz (see our analysis below). Signal related jitter was 80pS on a -60dB, 1kHz test tone, a very good result. There was a little low rate clock wander but it was not high at around 200pS maximum. All in all the 751BD was as clean in this area as the 650BD and will give fine sound quality through an external S/PDIF connected DAC.

The 751BD measured well through its analogue outputs and via its S/PDIF digital output. It provides audio of good quality. NK

Frequency response (-1dB)

CD          2Hz-20kHz

SACD     2Hz-32kHz

Blu-ray    2Hz- 48kHz

Distortion (%)

0dB       0.0008

-6dB      0.0008

-60dB    0.29    (24bit  0.15)

-80dB    3.8

Separation (1kHz)    108dB

Noise (IEC A)         -111dB

Dynamic range        98dB

Output                    2.0V

FREQUENCY RESPONSE, 192kHz PCM    (what it means)

FREQUENCY RESPONSE, CD    (what it means)

FREQUENCY RESPONSE, SACD   (what it means)

DISTORTION, 24 bit, -60dB     (what it means)

JITTER    (what it means)