ZMF Eikon Sealed Around-Ear Headphones Measurements

Click on graphs image to download .pdf for closer inspection.

Raw frequency response plots show mild changes in level with movement, but very little change in tonality. Raw frequency response is essentially linear with a warm tilt to the notch at 16kHz. The neutral target would have it gently rising from 600Hz to 1.5kHz. The concha peak at 3-4kHz is about the right height and frequency, subsequent response about right on average, but quite rough. In listening, the peak at 6kHz seemed to annoy only occasionally, but the notch from 7-9kHz did seem to reliably remove some sparkle from cymbals.

Looking at the measurements my biggest initial concern was the large feature at 1.5kHz in the frequency, impedance, and distortion response plots. I did spend some time listening to sweeps and pink noise to see if I could hear anything going on here. The only observation I could make was the slight dip in level seen in the FR when running a sweep. Otherwise, this feature appears to be benign to my ears.

30Hz square wave has a little too much shoulder and too small an initial spike indicating a warm headphone. Waveform top has good shape and is quite horizontal backing up the good bass extension of the FR plots.

300Hz square wave shows a low initial transient and a generally upward trend subsequently indicating a slight warm tilt to the treble range. This plot and the impulse response show quite a bit of noise subsequent to initial stimulus transients. Normally, I would have assumed this would be a grainy sounding cans from these plots. I didn't hear these cans as grainy. I heard them as not enunciating some things well due to the missing stuff 7-9kHz, and maybe a tad bright 5-6kHz, but not grainy. Noise seems strongly periodic and not random; CSD plots show some ridges between 5-10kHz that may be the source.

The THD+noise plot is dominated by the strong spike previously mentioned at 1.5kHz and a significant rise in the bass. I have to say the bass distortion puzzles me. Normally, you'd see some lack of bass extension and/or sway-back 30Hz square waves to go along with it. I heard the bass as a little gruff and lacking a bit of punch compared to the best, but it didn't sound loose or slow.

Impedance plots shows a nominally 330 Ohm headphone with a broad primary driver resonance at about 35Hz, and a strong resonance at 1.5kHz probably due to the tube-shaped structure behind the driver.

With broadband isolation at -26dB the Eikon seals very well against outside noise.

Needing 291mVrms to achieve 90dBspl at the ear, the Eikon may not achieve satisfactory listening levels from portable devices.

ZMF Headphones

thefitz's picture

I'm surprised how home-made these things look when you take them apart. Is this a hallmark of small builders? Does the Ether C look like that once taken apart?

sacredgates's picture

I am dismayed by some of the rather unsubstantial negative comments here. It looks like some folks just enjoy criticizing and I even doubt they actually heard this headphone.

As an Eikon owner I can relate to what Tyll says, but that means also to the many positive qualities he mentions! From my high quality tube amp they definitely make for a very fine listening experience. Yes they are smooth, and the "BBC" dip together with the slightly recessed upper treble make for a more relaxed non-fatigue tuning.
I do find them resolving; it is just not so directly obvious in your face because of Zach´s specific tuning.

Also imho dynamics do not lack with the right amplifier and soundstage is fine; tubes do give a helping hand here. They are closed headphones for sure, and don´t have the airy open presentation of good open headphones.

I consider the Eikon a great addition to the small pack of TOTL closed cans. An in depth and insightful comparison review worth reading can be found on

This review is much more refined than just trashing one headphone and glorifying another. The perfect closed headphone being the best in every aspect for everyone just does not exist. Get to know what qualities are important for you and which tuning suits your taste and equipment (and even that might change with music and mood). Zach has provided us with a very musical and seductive headphone; he never tried to tune them to be be a purely reference neutral tool (and please note that many many other headphones are actually way less neutral than the Eikon). I feel they are one of the most interesting cans at the moment and absolutely worth checking out!

Karalhoin's picture

That's that interesting review that placed the MDR-Z1R in dead last (out of 7 models) in "Overall Performance". A curiosity indeed.

Considering the other 6 models, I had already assumed the reviewer has some exotic preferences (calling people deaf would be rude). It's a very puzzling taste, to say the least. Sadly, it mines the credibility of the rest.

Bobs Your Uncle's picture

From context I believe the intended word is "undermines" rather than "mines".

And to advocate for developing balanced assessments in the manner promoted above by sacredgates:

It's worth remaining mindful that any critical conclusions one may espouse (ostensibly without any undue bias) may be undermined simply by an unfortunate turn of phrase; a result, perhaps, of an incuriously narrow perspective, or indeed through the assertion of unsupported / unsupportable claims. And such espousal will only serve, ultimately, to undermine the credibility of the critical thinker themselves.

Karalhoin's picture

Well spotted. However, we're not all native English speakers in this hobby and to be fair, the thinkers are discussing headphones, not necessarily requiring a perfect mastery of the language. Perhaps like some models can still be a bit amateurish and clumsy made, but we still kinda like their sound and get the message.

Karalhoin's picture

*clumsily, I meant clumsily!

Bobs Your Uncle's picture

No worries, & I fully get the challenges posed by moving between languages; especially when the 2nd language is English. The English language presents some pretty high hurdles to be cleared, but ... at least it's still somewhat more logical & consistent than our politics.

Jazz Casual's picture

The Eikon certainly looks artisanal. Is Sony making any attempt to provide you with an MDR-Z1R for review? I'm most interested in your opinion of it and how it measures up.

Tyll Hertsens's picture
Supposedly....I've contacted them numerous times.
kman1211's picture

Hope you can get a Z1R in for review soon. Do you have any of the new Beyerdynamics coming in for review?

JVG's picture

Thanks for this review, Tyll. Is an Atticus review forthcoming as well?

etrec's picture

I really don't understand your reluctance too review the Audioquest Nightowl Carbon, especially after your fine review of the Eikon. The Nightowl seems to share some of the same traits and type of driver that you describe in the Eikon, but at half the price and at a lower weight.

dynamo's picture

I bought ZMF Eikon this year. And I think this review lacks some important elements of Eikon's sound. First, Eikon's sound is fast, and have good response. Yes, it's warm sounding, but not slow. Lack some detail? I don't think so comparing with my STAX SRM-007tA SR-L700 combo. Reading the review, ZMF Eikon looks like slow and dull one. It is not a fact.