Back in 2003, Sennheiser spent millions of Euros on researching and developing the new HD650, taking technology developed for its £1,000 MKH40 broadcast microphone to reduce distortion and deliver clarity – while the sound balance was said to be based on the £10,0000 Sennheiser Orpheus. It all made for one of the company’s most enduringly popular hi-fi headphones ever…
These phones feel great. At 260g they’re fairly substantial, but are superbly finished with damped fibre frames, black stainless steel grilles and a high-quality titanium-silver finish. Inside, each side sports Sennheiser’s patented Duofol transducers with two Mylar films per side to make one rigid diaphragm, with specially developed acoustic silk for precise, uniform damping. The coils themselves are ultra-light aluminium (Copper Clad Alloy Wire), with neodymium iron magnets in a sophisticated magnet/diaphragm design for controlled long excursions with very low distortion. Three metres of connecting cable is used, which is detachable, made from highly conductive OFC copper for maximum signal transmission and Kevlar-reinforced for strength. Sennheiser says this gives very low handling noise (i.e. sensitivity to structure-borne sound. The result is that the capsules are made to high tolerances (within ± 1dB), and used in hand-picked pairs. Sennheiser claims a frequency response of 16-30,000 Hz (± 1dB), and quoted impedance is 300 ohms.
All this would be of dubious use if it was painful to wear – I still remember the coiled cable of Beyer’s DT990 causing me considerable amounts of grief as it constantly tugged at one side of my head! Fortunately the HD650s are about as comfortable as big hi-fi headphones can be. The elliptical design sits firmly on the ears with the soft padding excerpting a reasonably 2.5N of contact pressure – not as sylph-like as Sennheiser’s £29.95 PX-100s, but not bad at all!
Sonically, they’re better than their HD600 predecessor by no small amount. They actually sound quite soft at first – which the ‘600s do not – and seem to open up and get more expressive as the listening continues. Daft Punk’s All Around the World showed their wonderfully musical nature. Bass was slightly stronger and fuller than the HD600s, but more fluid and articulate. Midband was smoother and more subtle, with better low level detailing and a greater sense of atmosphere. Again though, it was a softer tone, allied to greater expression that impressed me. This made for a more emotional listen on jazz recordings such as Herbie Hancock’s The Prisoner – it was more beguiling and seductive, rather than being just plain ‘impressive’ as the HD600s are. Another boon was the treble, which was by no means as perfunctory as the HD600s. Again, it’s more atmospheric, ‘spacey’, lucid and ever so slightly sweeter.
Essentially, they’re comfortable, musical and reasonably neutral – precisely how it should be. True, in absolute terms there are now more open and transparent designs around – the HD650s sound more cuppy and congested than they first did, reflecting the rising standards of the competition from Audio-Technica and Philips. But you still get a very fine sounding design which sounds better still with the addition of one of the many aftermarket headphone leads now available. The popularity of these modern classic headphones also makes them a second-hand bargain, because there are so many around from £150 upwards; replacement earpads are around £50, so any HD650 you buy should work long into the future.