Hifi Pig’s « Headphone Month » wouldn’t really be complete without taking a listen to the Stax Earspeakers. In her review Janine Elliot takes a listen to the £1695 Stax SR-407 headphones.

Talk about headphones, and there is one name that always springs to mind. When I was a teenage hi-fi fanatic I always wanted to own a Stax. I remember then the company were adamant that they should actually be called ‘Ear Speakers’, and I could see why with the Lambda. These monsters of the day looked more like speakers tied to the head with a vice rather than headphones. Whilst the original conventionally shaped Stax was in 1960 it wasn’t until 1979 that the Lambda – if you like, the original baby of the SR-407 – was born. Indeed, many of the original exterior parts, such as headband, driver yokes, earpads, and outer casing still play a part in the current 207, 307, 407 and 507 incarnations. Only the Jecklin Float offered an alternative electrostatic design, but that particular offering was prone to fall off your head if you leaned forward. Koss, Sennheiser and PWB did produce electret and electrostatics, but that’s for another day. These ear speakers couldn’t be plugged directly into your standard headphone socket but rather had to be connected to a special electrostatic generator, known as an ‘Energiser’, in the case of the Stax using a 6 pin, and later 5 pin, connector. The energiser was itself connected to the line output of your pre-amp. Quite unique in design, the high voltage Lambda transducers were angled inwards, rather than being parallel to the ears like most cans. This gave it a distinctive soundstage, as if the instruments were in front of your head, rather than cramped inside between your ears. This made listening to music all that much more realistic and less tiring than most others, particularly when listening to centralised vocals. Coupled with the electrostatic diaphragms, it made for a quick and extended frequency response. Many years later I bought my first pair, and have never looked back. Having been brought up on Quad ESL57 and 63’s these cans could do everything that those speakers could, only much louder.

Looking more like something from the Second-World War with its distinctive rectangular brown plastic scaffolding to keep weight down and faux leather ear-cups, the 2011 Stax SR-407 usually gets mated up with the two 6FQ7 valve SRM-006ts energiser to make up the SRS-4170 system. Interestingly, both parts can be bought separate though they are useless unless mated together, and when bought as a pair aren’t any cheaper, either! With a specification to die for (frequency response 7-41,000 Hz) and the prospect of a fully balanced audio path from the XLR output of my Krell CD all the way to my ears via the custom-made double axis 4-gang volume controller I knew this was going to be special. After a long run-in to get some flexibility in the tight 1.35 micron plastic membranes, I began to listen. By the way, the human hair is at least 40 times thicker! Compared with the original Lambda, the 2011 model has many changes to the inside, making for a much better bass end, though the slightly more expensive SR-507 (which is black, with real leather) gives a much more confident lower end than this model, and is £250 more as a consequence. With that extra bass this psychologically makes you feel the top end is inferior, which of course it isn’t. Perhaps the original Lambda was a little bit more comfortable, but with its large design fitting around my ears I was still able to listen for extended time.
Listening to the Dadawa ‘Sister Drum’ it was evident that my ears would probably hurt before the electrostatic membrane did. The thud of the bass drums was very quick and precise and the wide dynamic range made my Krell KPS20i, renowned for its excellent bass production, sound better than I ever thought it would. Everything was there, crystal clear. Listening to my own album ‘Get Over It’, I could hear elements of my recording that had not been apparent when I made it; things like slight level changes or changes in perspective mid-verse. This led me to Dire Straits ‘Love Over Gold’, an old favourite that I know has a few bad edits in it that many headphones and speaker systems will miss out. The opening track ‘Telegraph Road’ has a terrible sound stage shift of Knopfler singing at 3’38”. The SR-407 precision was still very musical, however, and that finding this spot on the music was a doddle. These were musically clinical, if you hear what I mean.

As well as the extended horizontal sound stage, with their large curved rectangular diameter fitting over the ears these ear speakers had a massive vertical soundboard as well. The sound was all around my ears, not just a centralised pin-point. This made it much more realistic to listen to. Their size was particularly evident playing J.S. Bach organ tracks which made this sound like St Pauls, rather than the local village church organ. Conversely quiet decays of instruments were allowed to do so in their own time, not being quickened by the limitation of a conventional heavy cone driver. This was precision stuff. My ears felt like I was listening again back in my twenties. I wish. The soundstage of The David Rees-Williams Trio ‘Classically Minded’ had always confused me with its width and multi-pianoforte ‘layering’, which sounding quite claustrophobic and confusing. The Stax made it far easier to discern the different piano melodic lines, which don’t sound correctly placed as if you were listening in the audience, making me wish I’d actually done the mix myself. It just didn’t sound natural; a fault of the 2001 album, and not the Stax. Nothing could get past this kit! Also, as is often in a lot of recordings, the drum kit had a “large” fingerprint, but not as wide as had the diaphragms not been angled to my ears, as they are on the Stax. The valve energiser gave a precise velvety sound to the badly mic’d piano that was quite compelling. I just didn’t want to stop listening.

Time to switch over to vinyl. To test the power and bass I listened to the last two tracks of the new re-master of Pink Floyd ‘The Division Bell’. There was no end to the musicality, with precise cymbal highs and a bass just went lower and lower. Finally I put on Patricia Barber ‘Live in France’. I felt like I was in the audience, and I listened tirelessly to all four sides of the disc. I was in love with these cans, I mean, Ear Speakers. The sound was transparent and focused. It was ‘so easy’, that the only problems were the slightly incorrect bias on my Rega arm distorting the vocal to the left channel a tad. Easily rectified whilst 580 volts between my ears.
If I have to criticise this product it is the slightly plasticky feel, though this keeps down the weight, and weight of the ribbon cable if left dangling. With the prospect of balanced all the way through, two XLR inputs rather than just one in the Energiser would for me be preferable. Small price to pay. Combined with the energiser this outfit costs five pounds short of £1700, and for me is the starting point for serious listening in the Stax family. Cheaper outfits including the SR-207 or SR-307 ear speakers lack much of what is possible. The SRS 3170 combo, for example, comprises the SR-307 with a less able transistor energiser. The price of the SR-407 on its own is £495, but useless without an appropriate energiser. But, at little more than the cost of a very decent pair of headphones and headphone amp, this weird contraption is to my ears easily the winning combination.

Janine Elliot

Sound Quality – 9.2/10
Value for Money – 9/10
Build Quality – 8.2/10

Overall – 8.8/10

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