Sennheiser, like many microphone manufacturers, has its eye on the digital market. Rightly so, as digital has a nasty habit of exposing weaknesses in the audio chain.

Like all analog devices, microphones exhibit greater distortion at higher pressure levels. The wide dynamic range of digital has meant that this distortion is clearly audible as a microphone characteristic.

No longer masked by tape hiss, the noise generated by the microphone must be kept to a minimum. The MKH 40 generates an equivalent noise of 12dBA (21dB as per CCIR 468-2), which should be quiet enough for anyone.

As Sennheiser points out, it is the distortion content, rather than the SPL, that is important. Nevertheless, the two are bound to be related and the MKH 40 does rather well at 134dB at the 1kHz (142dB with the pad in).

Apart from the pad, the only other variable is a 3dB roll-off, effective from 120Hz. The unit comes with a windshield, clamp and padded box.

Sennheiser does not state the capsule diameter of the MKH 40, but it appears to be around 20mm which is ideal for an acoustic guitar. Between the mic and recorder (I used a Revox B77 for testing) there was only a Sennheiser MZN 16 P 48 U power supply and a balancing transformer. I would not normally have bothered with the transformer but the literature with the power supply stated that the audio outputs should always be connected to balanced amplifier inputs.

Oddly enough, the same unit is described in the microphone handbook as matched to balanced and unbalanced microphone inputs.

I created a pseudo stereo with my aged AKG CK1/C451EB providing ambience. Later on, I reversed the roles for comparison.

My first reaction on donning the headphones was: 'My God, the noise!' Not mic hiss, but the squeaking of shoe leather, peeling of paint, anything that moved. This microphone is sensitive. I had been warned by an MKH 40 convert that this would be the case. He also told me to watch out for feedback in the cans. Foolishly, I used an old pair of open backed AKGs.

The clarity of this mic is astonishing. It picked up everything and reproduced it with a sparkling brightness. I also found the bass roll-off useful as my acoustic guitar has a slight 'wolf note' on the low G and no amount of repositioning the mic will ever get rid of it. In fact, the Sennheiser reproduced the fault with a precision verging on the satirical.

Although I preferred the Sennheiser to the AKG, it is fair to point out that my 451 has gone 10 years without a service. Comparison with the new AKG C460 may be more valid.

I also tried the Sennheiser on vocals, overdubbing a track I had created with the Akai MG 1212. For this application, the windshield was very useful but there was no trace of overload, even without the pad in.

I never use my 451 for vocal because it is so easy to overload. The Sennheiser can be used without reservation and the sound quality is phenomenal. It was even able to enhance my own throaty growl.

In terms of pure clarity, there is very little to touch this microphone and I believe that, even without a digital recorder, it would be a worthwhile investment.

Contact: Hayden Laboratories Ltd, (Contact Details).