Audeze LCD-S20

Closed-back Headphones

Monitors / Monitoring > Headphones

By Sam Inglis

The LCD‑S20’s braided cable can be plugged into whichever of the two earcups is most convenient.

With their latest model, Audeze aim to solve one of the harder problems in headphone design.

From music to lifestyles, anything ‘alternative’ that’s successful enough eventually becomes mainstream. Planar magnetic headphone technology seems to be following the same course. Since its revival by Dr Drag Colich at Audeze, its combination of low distortion and superb transient response has made planar drivers increasingly popular in high‑end open‑backed headphones. However, manufacturers still have some problems to solve before they can compete with conventional moving‑coil technology in other markets.

One is cost, and we’re already seeing progress on this front. Makers such as Hifiman are bringing planar designs to market at highly affordable prices, and we shouldn’t forget that Fostex have been selling mass‑market ‘orthodynamic’ headphones since the 1970s. Another is size. Flagship planar models such as the Audeze LCD‑X have always been much larger and heavier than typical dynamic designs, but that too is changing. Audeze themselves have successfully miniaturised the planar driver to the point where it can be used in IEMs.

Perhaps the biggest obstacle standing in the way of the planar juggernaut, though, is isolation. I’m a big fan of many Audeze models, notably the LCD‑X, MM‑500 and LCD‑MX4, but what all of these have in common is that they are open‑backed. The same goes for the Avantone Planars and for all of the really good‑sounding models in Hifiman’s range. Whereas it seems to be possible to make closed‑back moving‑coil headphones that sound very nearly as good as the best open‑backed models — AKG’s K812 come to mind — that just hasn’t happened with planar magnetic ’phones. Yet.

Out of all the models I’ve heard, the design that came closest to solving all three of these challenges was Oppo’s PM3. Compact and lightweight, relatively affordable and surprisingly balanced in tone, these closed‑back cans have been a mainstay of mine since I reviewed them exactly a decade ago. Unfortunately, however, my own PM3s have long outlasted Oppo’s headphone division, and any hope of further development in that quarter seems forlorn. Which leaves the field open for the latest attempt to pull this particular sword from its stone: the LCD‑S20, from the OGs of the modern planar revival, Audeze themselves.

LCD Soundsystem

With a sub‑£500 retail price, the LCD‑S20s are quite a bit more affordable than most Audeze models, if not quite an impulse buy. They employ the latest generation of the company’s planar magnetic driver, dubbed SLAM and housed in circular, circumaural earcups. Although more compact than those of the LCD‑X, these are still on the large side, and are augmented by some pretty chunky cushions, which are about an inch deep at their thickest and get some distance between driver and ear. The cushions are replaceable and attach magnetically. Although circular on the outside, they have an inner cutout that is more rectangular, and angled to accommodate the pinnae. On the outside, the earcups are finished in a matte black fabric that covers a hard inner shell.

The earcups are suspended on yokes that provide plenty of movement in both the up/down and fore/aft planes. The main headband is of fixed length, but the top of your head makes contact only with the inner band, which can be adjusted to accommodate larger or smaller skulls by moving holes onto different pegs. All of the structural parts are made of metal, which gives the LCD‑S20 a reassuringly robust feel, but also means they weigh more than half a kilo. Despite this, I found them pretty comfortable. No case is included, and they don’t fold down for easy transportation.

Both of the LCD‑S20’s earcups have a 3.5mm jack socket in the base, but the cable only needs to be connected to one side, so you can choose whichever feels most convenient. The supplied 2.5m cable is made of smart and tough braided wire, and has a fixed quarter‑inch jack at the other end. A short adaptor cable terminating in a 3.5mm jack is also included.

Tone Quest

The LCD‑S20s boast an alleged frequency response of 10Hz to 40kHz, but as no tolerances are given, this is not a terribly helpful specification. More meaningful figures include an 18Ω nominal impedance and a THD figure of less than 0.1% for a 100dB SPL signal at 1kHz. This is impressive, although it’s a shame Audeze don’t supply the same measurement for a 100Hz tone too. At 93dB per milliwatt, the LCD‑S20s are significantly less sensitive than typical modern moving‑coil headphones, but not so much so as to require a special headphone amp in most circumstances.

These really do shut out the world outside.

Although they’re passive, purely analogue headphones, Audeze describe the acoustic dampening within the LCD‑20 earcups as being a form of noise reduction that delivers “heightened isolation”, and this is immediately obvious when you place them on your head. These really do shut out the world outside. For music listening purposes, this can even feel a little oppressive, but for studio work it’s an obvious benefit.

When it comes to reproducing rather than blocking sound, Audeze claim that the LCD‑S20s retain the usual benefits of planar magnetic design, notably a deep bass, low distortion and “pinpoint impulse response”. However, they say little about the overall frequency response, and words such as ‘neutral’ or ‘flat’ are noticeably absent from their description. That is perhaps reflected in the tonality, which demonstrates a fairly obvious forwardness in the midrange, centred somewhere in the 500Hz area.

This sort of character is perhaps all the more noticeable because it’s relatively unusual in headphones, which tend more often to have a ‘scooped’ tonality. Personally I find the mid emphasis more useful and also more tolerable for lengthy listening sessions than the more typical 5kHz boost, although that’s not to say I wouldn’t prefer it to be ruler flat! From a music listening point of view, it makes some mixes sound boxy, but adds substance to anything thin. And from a production standpoint, it is handy for scrutinising the meat of a guitar or snare tone, but elevates the risk of cutting more mud or honkiness than is really necessary.

20:20 Hearing

In other respects, the LCD‑S20s do indeed have the good qualities we have come to expect from planar designs. Although the true low end is sometimes a bit overshadowed by the midrange emphasis, it’s also fast, accurate and deep in a way that most headphones aren’t. There’s no flab, and bass drums retain their punch even when you filter off all of the top end. In fact, presentation of musical dynamics is excellent all round. One of the pitfalls of mixing on headphones is that it can be hard to get the level of the lead vocal right, or to judge the amount of compression that needs to be applied. I found the LCD‑S20 significantly more helpful for getting to grips with this sort of issue than typical moving‑coil headphones. And if drums and percussion don’t quite have the same visceral impact that they do on Audeze’s premium open‑backed models, they get pretty close. Once again, this is of genuine benefit when you are evaluating mix levels and compressor settings.

Finally, the ability to plug the cable into either the left or the right side has obvious, if modest benefits. However, it also introduces a potential asymmetry between the two earcups, because the cable entry port will be open on one side and plugged on the other. Some manufacturers who use this arrangement thus ship their headphones with dummy plugs that can be used to block the unused port. Audeze don’t, but I was convinced the LCD‑S20 sounded better this way. It’s subtle, but the stereo panorama seems more clearly defined, and some of the boxiness in the low midrange gets tightened up.

At the time of writing, none of the major headphone correction packages offers a preset for the LCD‑S20. Even without calibration, they have many positives, but I feel they will really come into their own when the likes of Sonarworks, Realphones and IK’s ARC On‑ear get to work. To my mind, the ideal pair of closed‑back headphones would have great isolation, low distortion, true and deep bass, a punchy dynamic response, and a perfectly neutral tonality. Audeze have nailed the first four of these, and I’m confident that software calibration can help the LCD‑S20 deliver the fifth.

Summary

With excellent isolation, great dynamics, minimal distortion and a revealing, mid‑forward sound, the LCD‑S20s demonstrate that planar tech has a place in closed‑back headphones.