In true German style, these mics are built to last, and they offer a high degree of performance for a comparatively modest outlay.

Sennheiser has been in the audio business for over 40 years and has gained an enviable reputation for producing high quality microphones and headphones. Their legendary MD421 has been in production for as long as 25 years and, with more than a quarter of a million already sold, is still one of their most popular models. Three of its more recent companions keep it company.

Popular with studios around the world as a general purpose and drum mic, the 421 is offered in three versions: 421 N, 421 2 and 421 U. As if this weren't confusing enough, the MD421 U itself, is available in several variations of finish and adaptor thread size. This is not the most convenient of arrangements; as the mic has an integral stand mounting which won't fit into a conventional clip. However, leaving aside exterior considerations, the only significant difference is that the MD421 2 does not have an integral, low-frequency, roll-off filter whilst the others do. Our review sample was an MD421 U-5.

MD421 U

This dynamic mic has a cardioid response and, in common with most of Sennheiser's pro models, comes with its own individual frequency response plot. The transducer incorporates an extra hum-bucking coil to cancel interference from nearby transformers and the like, with a useful frequency response extending from 30Hz to 17kHz, making it suitable for many varying applications. The shape of the response is neither completely flat, nor typical of the type with a built-in presence peak as might be found in a dedicated vocal mic. It is flat from around 80Hz to 1 Khz, but it gently rises from there. This basically means that the top end is emphasised slightly, without the unnatural quality that characterises a narrow peak response. This gives a cleaner top end than would be expected from a mid-priced dynamic mic, and must be a factor that has contributed significantly to its continued popularity. Below 80Hz, the response gently falls away down to the minimum usable frequency which is around the 30Hz mark.

In physical terms, the mic is housed in a black anodised aluminium case, and feels a little on the weighty side. Though popular for drum work, its large size could prove a problem on those occasions where space is tight in this application. The actual construction standard though, gives no cause for concern. This is a well-finished mic but also a very rugged one as its long history without major redesign testifies.

Incorporated into the mic, in the form of a ring around the socket, is the roll-off switch. Because pressure gradient mics of this type exhibit a degree of proximity effect, by virtue of their physical design, in some cases it is desirable to curtail the low-frequency response when close miking instruments, or when using the mic for vocals. The switch offers five settings varying from no cut at all, to around 6dB/octave for frequencies below 500Hz. For vocal work, this facility helps to reduce popping, despite the mic having a built-in windshield; which is more a help than a complete cure. For vocal or outdoor work, a separate windshield is generally considered essential with most mics.

In electrical terms, the mic has a balanced output available on its conventionally wired XLR connector with an impedance of 200Ω. The difference in sensitivity between the front and the back of the mic is around 18dB at 1 kHz which gives a reasonable resistance to unwanted feedback in live sound applications.

Personally, I found that it worked particularly well on brass, and all kinds of drums: even the bass drum. However, it's also a good all-rounder and I've heard them effectively used as vocal mics before now.

MKH4O6 P-48

To me, this seemed the most exciting of the four mics. Perhaps I should have left it until last. Like the other mics, it is available in several different formats which basically represents a choice of finish and connector. The one we have here is the MKH406 P-48 U-3; which basically means that it's black with an XLR connector.

Unlike the other mics on review, this is a directional condenser mic and, unusually amongst condensers, this ones capsule is biased by RF, rather than DC. This RF (radio frequency) is generated by an integral 8MHz oscillator. Its big plus that it reduces the susceptibility of the mic to operational difficulties in humid climates, (like 2" away from a rock singer's mouth) by presenting a lower capsule impedance. Power is provided by standard 48v phantom powering and the output impedance is extremely low: around 10Ω.

The MKH406 P-48 is a pressure gradient instrument mic, though it will work well on vocals in conjunction with an external windshield. It has a usable frequency response from 40Hz to 20kHz and a flat response with only the smallest of humps at around 6kHz. Physically the mic is a simple slim-line 150mm black cylinder that fits into a conventional mic clip. A shock mounting is designed to minimise handling noise, and the low output impedance means that no additional special screening precautions have to be taken, even when using long leads.

When you record an acoustic instrument using this mic, and compare the results with a similar recording made with a good dynamic mic, the difference is obvious. The tonal balance is flawless, and no scratching, booming or honking is present... but you still have to learn to point it in the right place. The clarity at the top end, and the sheer amount of air around the sound, proves that the right choice of microphone is one of the most important aspects of sound engineering. The ability of a good condenser mic to respond to transients, is what sets it apart from a good dynamic mic. Their tougher diaphragms have to drag a heavy copper coil around with them wherever they go, which adds to the mechanical inertia.

On vocals too this mic performs very well, though a pop shield is essential, especially as there's no low-frequency roll-off control. The old pair of tights over the coat hanger is quite adequate; but don't use the fish-net type! Like all good condenser mics, this one does cost that bit extra, but it's definitely worth having at least one good condenser mic in your locker, and I wouldn't mind this one being in mine.

MD4O9 U-3

Back to the land of the moving coil (dynamic) mics. We now come to the MD409 U-3 which is a cardioid design capable of handling very high sound pressure levels. It's therefore eminently suitable for use with percussion, guitar amplifiers etc. The design, a little dated in appearance, utilises a high area membrane to handle these high levels with the minimum of distortion and its directional nature gives it a reasonable immunity to feedback, whilst preserving separation. A stainless steel sound basket and a carefully designed shock mounting system, make this a rugged mic which doesn't suffer unduly from handling or structure-borne noise.

The microphone is coloured black with a grille at each end, and as it's naturally vital to choose the right end, one is gold plated.

Electrically, the output is rated at 200Ω, balanced via an XLR connector. The frequency range covers 50Hz to 15kHz, and although the frequency response is not specifically tailored to colour the sound, there is a slight peak in the region of 12kHz, which may help to preserve the top end brightness before the cut-off, which starts at around 15kHz. At the low end, the response starts to roll off at 150Hz so it is unlikely that this mic will be suited to punchy bass drum work.

MD918 U-3

Last and by all means least expensive, is the MD918 U-3: a budget dynamic mic, again with a cardioid response. Designed for close-up work with instruments such as percussion and brass, the usable frequency response extends from 50Hz to 15kHz. In accordance with the previous mics, this is a toughly built device with integral shock mounting and coloured black. This mic is of the, by now familiar, configuration of low impedance (4Ω) with a balanced XLR output. The response rises smoothly to a peak at around 4kHz and the bottom end rolls off below 150Hz, but as this mic is designed for close-up work, the proximity effect should help to counteract this roll-off to some extent.

Summary

Of all these sensibly priced mics, the MKH406 P-48 is my favourite. It's also the most expensive. Likewise the old 421 is still excellent value for money, especially as a drum, brass or general purpose studio mic. Every studio ought to have some.

The remaining two mics work well within their recommended areas and again lend themselves to any general uses that don't require a hefty bass response. The more microphones you try, the more you realise how different they all sound. The most difficult job being, to select a mic with exactly the right characteristics to complement the sound source you are working with at the time. Sennheiser certainly give you a wide choice in this area.

Most German goods tend to be expensive by the time they reach Britain, but I was pleasantly surprised by the prices of all these mics. It's not hard to see how Sennheiser won their reputation.

Prices including VAT are as follows: MD421 U: £143.18 MKH406 P-48: £315.79 MD409 U-3: £99.59 MD918 U-3: £63.25

Further information can be obtained from: Hayden Labs Ltd, (Contact Details).