For stations untrammelled by pirates, the FM sound is remarkably noise free and extremely well-balanced in frequency response, entirely without the plague of multipath adding enharmonic distortion to the treble. Multipath distortion must still be there – no-one’s knocked down all those buildings between my house and the nearest mast – but is effectively suppressed better than many on this tuner.
The rare product that bests the NAD (Magnum Dynalab springs to mind again) does so by taking the next step in tuner thoroughness, rolling its own tuner head. This is a considerably more costly implementation than simply buying an off-the-shelf tuner head as MAD has done. The improvement can be likened to the difference between an Armani Black Label suit and something made for you by a Savile Row tailor; the custom-made route is a better ‘fit’ for the rest of the tuner circuit and makes a big difference to those who notice these things. Specifically, it’s this ‘roll your own’ approach that moves you out of the listening room and into the studio with the Eddie Mair, or knee deep in silage with Eddie Grundy. You don’t get that level of detail on the NAD, but this detail is at the sharp end of the 95% rule, though and unless you gain an awful lot of pleasure listening to radio on a very regular basis with an extremely good aerial, the custom tuner head may not prove the draw it might first seem. Certainly, if the choice came down to either a NAD M4 as it stands, a rudimentary version with a more expensive tuner head or a £5,000 version with the best possible FM stage, most would go with NAD’s current offering.
DAB is somewhat harder to suss out, given the variable quality of bit rate on offer. It is perceptibly louder than FM in this model, and that built-in DAC upgrade did appear to bestow a significant benefit on the M4’s digital radio output. The sound had considerably better separation and a more open midrange on anything at 128kbps and beyond and even 96kbps mono talk radio was mercifully free from the chestiness that seems to trouble male voices on DAB. The sound of the on-board DAC was as good that of the M4 and a separate DAC, so there seems to be no point in aftermarket upgrades; cheaper DAB devices sometimes need a good DAC, so that’s less of a saving in comparison.
It pains me to say this, but I suspect DAB imposes its own price ceiling in audio quality terms, and this was something that doesn’t happen with analogue FM radio. And that price ceiling happened several hundred pounds below the price of the M4. So those expecting a huge jump in DAB sound quality between this and the entry-level DAB tuners will be disappointed. In DAB sound quality alone, the M4 is better than cheaper models, but not as significantly as the price might imply.
This is not NAD’s fault, though and the M4 raises the bar for FM replay on a DAB tuner, which is going to be a major source of quality audio for at least the next decade. And that’s a major feather in the M4’s cap – it represents the perfect transition product, from excellent FM to great DAB. And it’s well-built enough to live out the last years of FM… However long that ends up being.
NAD M4 Masters Series Tuner
Type: AM/FM/DAB tuner
FM Tuner Section
Capture ratio (FM): 3dB
Image Rejection: 85dB
Signal/Noise (mono): 72dB
Signal/Noise (stereo): 66dB
IF Rejection: 78dB
Channel separation @1kHz: 42 dB
Frequency response: ±1.5dB (20Hz-15kHz) ±1.0dB
AM Tuner Section
Usable sensitivity: 30dBµ
Image Rejection: 28dB
IF Rejection: 36dB
Signal/Noise Ratio: 38dB
Harmonic Distortion: 3%
DAB Tuner Section
Tuning Range (Band III): 174MHz-240MHz
Tuning Range (L Band): 1452-1492MHz
Sensitivity Range Band III: -100dBm typical
Sensitivity Range L Band:-97dBm typical
Frequency Response: ±0.3dB