Launching a £1000 pair of headphones in the midst of a global recession wouldn't have been the first choice for Sennheiser, but after experiencing its new HD800 flagship (pictured above) in action, we're sure they'll find an audience.

We won't get a review sample of the Sennheiser HD800s until April – which is when the headphones hit UK shops – and you'll be able to read our full review, including comparison with the Grado GS1000s, in our issue out in May.

However, after getting excited by the January launch, followed by a sneak preview in the UK recently, we jumped at the chance for a longer listen – and to see how Sennheiser headphones are made – at the company's HQ near Hanover, Germany.

Why new high-end headphones?Sennheiser's previous flagship headphones – the awesome £10,000 electrostatic Orpheus, complete with tube amp – were launched back in 1991, and haven't been available new for almost ten years. That's left the HD650 as the top Sennheiser model: fine headphones for around £250, but no match for lovers of higher-end hi-fi (and higher-end headphones!)

The HD800s have been in development for years, with Sennheiser's designers going back to basics – and registering a clutch of patents on the way – to build a modern high-end headphone.

For example, the 56mm transducer in the HD800 is the largest currently found in dynamic headphones, designed for incredibly pure sound reproduction with exceptional detail. Its vibrating element is a ring, rather than the conventional circular style, which allows more of the surface area to vibrate without distortion. Sennheiser claims total harmonic distortion of less than 0.02 percent (at 1kHz and 100dB sound pressure level).

Here's how it all fits together:

 

Headphones that act like speakersAnother headphone rethink is the way the earcups fit on your head and direct sound into your ears.  The HD800s are designed so the soundwaves are directed into your ear at a slight angle – more as they would be when you're listening to speakers. Sennheiser claims this results in a more natural sound, with good spatial extension, but with a purity of reproduction that far exceeding that of speakers.

 

Try before you buyWith so much behind these new headphones, it's perhaps not so surprising that Sennheiser will only be selling the HD800 headphones via dealers who've been trained on all the new model has to offer, and who also sell suitable headphone-amplifier partners. Sennheiser is really keen that prospective purchasers experience the HD800s first, so don't expect to see these headphones for sale online anytime soon...

How are headphones made?All Sennheiser HD800 headphones are hand-made at the Hanover production facility. In theory, they could make 5000 pairs a year, but manufacturing capacity is flexible to meet demand.

If all components are to hand, it takes around 45 minutes for a series of skilled workers to assemble a pair of HD800s – after which each set of Sennheisers is tested (of which more later).

First up is the build of the patented HD800 transducer, which involves attaching the voice coil to the ring-shaped membrane (see below). The HD800's voice coil is capable of taking more power than previous Sennheiser designs:  it'll handle up to 4W of thermal power compared to the 1-2W of the HD650, for example.

 

Sennheiser's technicians – who work flexitime (80 percent start at 5am!) – check components at each stage in the process to reduce failure rates further down the line.

 

And a closer look at the heart of the headphones:

The main body of the headphones are then built up, with workers wearing special gloves (see below) to protect the components. The latter includes specially tooled magnets, which Sennheiser claims are the largest in the headphone world.

You'll also note that the earcups aren't covered (with fabric, for example), as Sennheiser believes adding an extra layer could increase the potential for sound-impairing vibrations.

The care and precision involved in the manufacturing process is clear. The woman below working on connecting the cabling would take on all-comers at the game Operation, we can tell you (and we would have told her, if our German was up to it...)

 

More earcups await their turn – incidentally, the batch below were sitting alongside a production line for in-helmet headphones for soldiers. This Sennheiser facility makes a wide range of specialist and consumer products, including recording-studio microphones to noise-cancelling headphones (of which more in another blog).

More after the break

Next up, the HD800 headbands – a patented, multi-layered design combining metal and high-quality plastic in yet another combination designed to minimise vibrations.

Each pair of headphones has an individual serial number – Professor Dr Jorg Sennheiser owns pair No1 (and you'll see him wearing them later)...

 

And it's then onto the next stage of production, where cabling is added. Sennheiser doesn't weave its own wires, but the HD800 cables are made to its specification from another German supplier.

The four-strand, high-performance cable is made from silver-plated, low-oxygen copper, shielded against electromagnetic disturbance. The HD800's earcup connectors and 6.3mm jack plug are gold plated for optimum contact.

The picture below of almost-finished headphones shows quite clearly how those ear-cups are set at a slight angle, to tilt those tunes into your ears.

Finished headphones go through a series of quality-control tests, including time in a reduced-sized anechoic chamber (think a sensory-deprivation-experiment version of the cupboard-under-the-stairs) – the test equipment is pictured below.

Finally, our chance to listen From here, the next step for the headphones that pass the quality tests is their new satin-lined home – an impressive presentation box that's befiting that four-figure price tag.

Back in the Sennheiser HQ's presentation room, we were greeted by a row of these boxes (see below, open and shut), each housing a pair of HD800 headphones hooked up to a T+A SACD player via a Lehmann Black Cube headphone amplifier (£750).

 

 

As you may just about to make out from the top one of those two pictures, we were provided with a  'sturdy' selection of test discs – being Germany, there was a rather predictable preponderance of AOR, including Toto – then left for an extended listen.

Standing up in a presentation room, as the world's press squabble over sets of headphones and the most in-demand discs, is no substitute for the longer-term, comparative test we'll soon put the Sennheiser HD800s through, but it gave us an impressive flavour of these £1000 beauties.

For these are great-looking, superb-feeling headphones. They look modern, are incredibly comfortable, and have the fit and finish their price-tag demands. Everything from the main body to the cable and connectors seems solid without being clunky or heavyweight.

Open to detailAs you'd expect from an open-backed design, they neither particularly block out external noise nor stop their own sounds from leaking out into the room: in so many ways (not least the mugging risk!) these are not the headphones for public transport. On the plus side, they produce an open and airy sound: the comparisons with speaker- rather than headphone-listening are not idle claims.

Listening to the SACD of The Who's Tommy, there was the pomp, presence and detail you'd expect a high-end pair of headphones to deliver. Even more poorly-produced, modern pop CDs – thank you, Mark Ronson – fared surprisingly well. We can't wait to hear them against those direct-rival Grado GS1000 headphones – that'll be a shootout our whole team (with their assortment of ear sizes and musical tastes) will want to be involved in.

Meet the Sennheiser teamAnd talking of teams... Sennheiser has its own golden-eared listening panel that tests every prototype – and finished model – it produces. "It's a group of 16 people: a range of ages, both male and female, and including those with plenty of listening experience and those without – all with good hearing," explains Axel Grell, Sennheiser's senior acoustic engineer (pictured above right, with Professor Dr Jorg Sennheiser)

 "We look for a range of ear-shapes, too," Grell adds, before cheekily adding "but we don't have anyone with ears like your Prince Charles – perhaps we should!" 

He notes that different countries can prefer different sounds, too, but decided not to explore an idea to offer alternative versions of the HD800 'tuned' for specific markets around the world.

Will HD800 technology trickle down to cheaper headphones? Axel and his team continue their testing and development work – which includes laser-testing of components, as shown below – and he doesn't rule out some of the patented technology from the HD800 appearing in more affordable headphones. Or indeed it being scaled up to even higher-end products. Orpheus MkII, anyone?