Sennheiser HD 540 Headphones
The German company Sennheiser have built up a reputation for high quality and reliability in professional circles with their studio microphones and headphones, including a popular range of infra-red 'wireless' types. Amongst domestic users too, the name Sennheiser has been practically synonymous with good, and highly practical, headphone design ever since they launched the world's first successful open-backed model, the lightweight HD414. I have written about a succession of these excellent lightweights over the years, and they have been best sellers on account of their wearing comfort, pleasing sound balance and (almost) indestructibility.
This HD540 'Reference' design is in a different league, as might already be guessed from its indicated average dimensions. The outer diameter of the ear-piece is a full 105mm so that the soft ear-cushions fit over the whole ear (circumaural) though without introducing very much in the way of isolation from external sounds, since the slotted plastic housing is open-backed. The relatively large (5Omm) diaphragm is driven by a coil of new design and construction using very fine and light aluminium wire in place of the traditional copper. Impedance is quoted as 600 Ohms, which is a medium value compared with the low impedance often found in headphones, but should provide a good match for most sorts of equipment.
The main headband consists of a single arc of springy plastic to which the ear-pieces are attached allowing a small amount of swivel in all planes to ensure a snug fit. Final settling on the head is adjusted by an inner padded headband which rides up and down on click-stops. The straight two-wire replacable cable is 3 metres long and divides at the headphone end to separate push-on plugs carrying L/R identification. The jack plug is of the versatile type which seems to be a Sennheiser speciality. It is essentially to the (little used) DIN 5-pin standard but comes with a plug-on adaptor to fit the universal 6.3mm jackplug. It also carries a DIN socket on the back which would allow further headphones to be stacked for communal, or anyway duet, listening.
How they performed
These HD540 headphones are certainly comfortable to wear, though nobody could call them inconspicuous and one's ears do get quite warm after a while. Their 250g weight can be forgotten even after long periods of wearing, and the long cable lets you sit well away from the equipment if you want. I t is worth taking a little trouble to ensure that the inner headband rests properly on the top of your head and that the ear-cushions are clear of your ears and pressing evenly on the sides of your head. This affords maximum comfort but is also helpful in ensuring proper bass/treble balance.
The sound is characterized by a very extended treble end and of course is therefore very analytical. You may be surprised at your ability to hear pages turning and people moving about on your favourite CDs. On the plus side is the pleasantly open perspective, with musicians more distanced than one hears from many headphones or indeed loudspeakers. This would seem to confirm that this is a new generation Sennheiser design, and justify the description 'Reference".
Of course the familiar in-head effect is still there to some extent, and the stereo stage is not the 60° frontal arc we aim for with loudspeakers. Yet I soon came to like the way that instruments could be separately located and the musical thread s became easily identifiable. Transients were clean and undistorted, and speech was natural in tone-so important if you want to have a private listen to BBC stereo plays on VHF/FM, or if you have a set-up which allows you to listen to television sound on headphones.
At £69 the Sennheiser HD540 offers very pleasing sound quality at any sensible listening level. Sensitivity is high, and I applaud the maker's warning in the leaflet that too loud listening for long periods may lead to fatigue and even hearing damage. If your programme sources are low-fi, these headphones may reveal the shortcomings all too clearly; but if you have a decent LP, CD, cassette or tuner system you will find listening via these well engineered headphones a very satisfying experience.
