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Stax SRS-3100 electrostatic ‘earspeaker’ system

Stax SRS-3100 electrostatic ‘earspeaker’ system

Stax holds a special place in the music lover’s heart. It’s the high-performance electrostatic headphone that even those who don’t like headphones enjoy. But, goes the logic, only a select few can get to enjoy them, because they are very expensive. The rest of us have to make do with high performance dynamic designs because we don’t have thousands to blow on headphones.

This argument, however, suffers from being complete nonsense, as evidenced by the SRS-3100 system. You see, the SRS-3100 is the Stax entry point, made up of the SR-L300 Earspeakers, and the SRM-252S energiser, at an extremely competitive package price.

The SR-L300 Earspeakers are based on the popular Lambda design, the classic rectangular over-ear speaker-shaped models similar to ones Stax designed back in the 1970s. In order to keep them price competitive, the heavier grade ABS design of the more up-market models from the same Lambda line is slimmed down considerably.

, Stax SRS-3100 electrostatic ‘earspeaker’ system

This makes the SR-L300 lighter on the ear than previous designs (by a few grams), but it also makes the overall headphone/earspeaker feel flimsier than bigger models in the Stax range. That being said, the new slide-type adjustment for the headband is a boon, and should be seen on later iterations of the more upmarket designs in my opinion.

The SRM-252S also shows its inexpensiveness, thanks to a wall-wart power supply and a very small form factor indeed. Where most Stax energisers look like someone cut an integrated amplifier in half, the SRM-252S is small enough to be hidden by a decent sized paperback book. Nevertheless, for all its ‘CD box set’ size, it hides a small, solid-state Class A amplifier. This isn’t the kind of amplifier that could greatly benefit from the ‘Kimik’ mods found in more upscale Stax energisers (and in fairness, the SR-L300 isn’t the kind of earspeaker that would be improved by a significant upgrade in energiser).

The two are designed to act as amp and headphone as a complete package, and there is no provision for a DAC. Just the one input, in fact. Power and volume are combined in the single volume pot, and a little green LED tells you when the power is being fed to the headphones. There isn’t much in the way of run-in required here. They just work out of the box without fuss. I used them hanging off the end of the Hegel Mohican CD player and the Weiss DAC501 tested elsewhere in this issue.


Back when my own experience of wine was limited to cheap ‘plonk’, I had dinner with a friend who was exceptionally knowledgeable about wine. He – naturally – chose the wine. Until this time, I thought the florid descriptions of wine tasting sessions were the result of pretentious nonsense and hacks being paid by the word, but this bottle of wine changed all that for me. I discovered a complexity of nose, palette, and ‘mouth feel’ that made me view that flowery prose of wine writers with greater respect. It was, quite simply, the best glass of wine I’d ever tasted. To my fellow diner, however, it was an OK wine, but nothing special.

The point of this little tale is that how you view the SRS-3100 system is somewhat governed by your viewpoint. And this speaks to a potential problem for reviewers, professional and especially amateur: if you view the SRS-3100 in the light of My First Electrostatic, then for many the reaction will be “Oh my God! Where have you been all my life!” But, if you look at this from the point of someone who has tried several seriously up-scale electrostatic designs, you’ll think it a fine and inexpensive unit with some understandable limitations in absolute clarity and the bass due to the structural design of the earspeaker itself. In fact, both aspects of the SRS-3100 performance are true, but I’m coming down on the side of the newbie, here.

The fascinating thing about the SRS-3100 from that newbie’s position is just how good it is. I mean, really, ear-openingly, oh-now-I-get-it good. If you are used to dynamic headphones – even really good ones that cost a lot more than the SRS-3100 system – the first time you hear this Stax sound, it’s a revelation. Yes, there will be people who hear that revelatory midrange and treble and conclude that they still need that powerful grip and weighty physicality of the sounds from a dyamic, but equally there are more who will be reaching for their credit card within minutes. For many, the SRS-3100 will be their first time with electrostatic headphones, or ‘earspeakers’ in Staxlish, and for some it will be the gateway to a world of electrostatics, and for others it will be the beginning and end point for that electrostatic musical exploration.

OK, so recent advances at the top end of dynamic and planar magnetic headphone design have levelled the playing field, so that the best of dynamic designs (like the HD800S from Sennheiser, or the Focal Utopia) and the best of planar dynamic designs (such as the HiFiMAN Susvara, the Audeze LCD-4 or the MrSpeakers Ether Flow) now provide much of what the electrostatic user craves, but none are as affordable as the Stax SRS-3100.

, Stax SRS-3100 electrostatic ‘earspeaker’ system

What the SRS-3100 does is define the electrostatic earspeaker experience for the user, and while the only way from here is ‘up’ that initial exposure is something you will never forget. In essence what that initial experience does is make is make it seem like you have music in the space around you, only slightly attenuated by the device you wear over your ears.

Perhaps the most telling part of the SRS-3100 performance is what happens when you take them off and try a dynamic headphone you are very used to. For most new-to-electrostatics listeners, suddenly what used to be acceptable now sounds arch and uneven. A sound you thought expressive and natural will sound blurred and false. Vocals you thought understandable now sound like they are being sung through cloth. That’s a no going back moment, and even if you don’t buy the SRS-3100 there and then, its conversion process has begun, like a sonic reprogramming.

The thrill of hearing a pair of electrostatic ‘earspeakers’ for the first time really should not be attenuated, and if the SRS-3100 is your first time you drink from the cup of Stax, get ready for a heady brew. I’m not even going to call out musical examples here because it may make you reach for the same and that might spoil the experience. Choose your own weapons here; play music, and enjoy what could be the start of a serious Stax addiction.

The more critical faculties kick in when you have a few more miles on the odometer, and know what good electrostatics (Stax and others) are capable of. The SRS-3100 tries hard – and let’s be honest, at the price, that trying hard is more than admirable… it’s astounding – but the limitations made to bring this system down to a manageable price take an audible toll.

The SR-L300 is only some 17g lighter than the next Lambda model in the range, but it feels both lighter and less substantial than its stablemate. And that relates to control over bass and depth of bass. Hopefully no one expects SR-009 bass slam and drive at this price level, but what you get on playing ‘Surfin’’ by Ernest Ranglin [Below The Bassline, Island] and Ira Coleman’s solid, yet almost louche bass underpinning has more of an accent on the ‘louche’ than the ‘solid’. It also lacks some of the absolute depth needed to give this beautifully recorded slice of reggae-meets-jazz a foundation of bass and drums. Dynamic drivers will show up this difference all too readily, but here even the lithe and live beauty of Monty Alexander’s piano playing may not win everyone over.


This time in closer scrutiny with more upscale electrostatic headphone systems, there is a very mild veiling across the midrange. Again I need to stress this is from above down; looking at the SRS-3100 in absolute terms set against headphone systems that cost many times more than this. Nevertheless, plying the first Contrapunctus Bach: The Art of Fugue played by the Emerson Quartet [DG] there is a mild sense of restriction of recording space and tonality of instrument, but this feels picky at the price.

, Stax SRS-3100 electrostatic ‘earspeaker’ system

The Stax SRS-3100 system is all about getting new people to experience electrostatic headphone (sorry, ‘earspeaker’) sound, and it achieves that goal brilliantly! People erroneously discount electrostatic headphone systems because ‘they are too expensive’, and then spend thousands on their dynamic headphone system. This deserves to be better known, because so many of those people would never look back. This really is ‘My First Electrostatic’ and if that fits your place in listening, the SRS-3100 is a joy to try.



  • Type: push-pull electrostatic, oval sound element, rear open-air type earspeaker
  • Frequency response: 7–41,000Hz
  • Electrostatic capacitance: 110pF (including attached cable)
  • Impedance: 145kΩ (including attached cable, at 10kHz)
  • Sound pressure sensitivity: 101dB / input 100Vr.m.s. / 1kHz
  • Maximum sound pressure level: 118dB / 400Hz
  • Bias voltage: 580V DC
  • Ear pad: high-quality artificial leather
  • Cable: parallel 6-strand, 2.5m full length, low-capacity special wide HiFC cable Weight : 448g (including attached cable), 322g (without cable)


  • Type: energiser/amplifier for electrostatic headphone
  • Frequency response: DC – 35kHz
  • Rated input level: 125mV (at 100V output)
  • Gain: 58dB
  • Harmonic distortion: 0.01% or less (100Vr.m.s. / 1kHz output)
  • Input impedance: 50kΩ(RCA)
  • Input terminal: RCA × 1
  • Maximum output voltage: 280Vr.m.s. / 1kHz
  • Standard bias voltage: DC580V
  • Power consumption: 4V
  • Operasting temperature/humidity: 0-35°C/less than 90%
  • Dimensions (W×D×H): 13.2 × 13.2 × 3.8cm
  • Weight: 540g
  • SRS-3100 system price: £795

Manufactured by: Stax

URL: www.stax.co.jp

Distributed in the UK by: Symmetry

URL: www.symmetry-systems.co.uk

Tel: +44(0)1727 865488

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