Low Cost, High Value, the $25 Xiaomi Piston 2 Measurements


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

Uncompensated frequency response plot shows a curve with a pretty good match to the Harman response curve, but bass bump is about 5dB too much and the increase starts at 400Hz as opposed to the more desirable 120Hz giving it a bit excessive upper-bass, lower-mid-range emphasis. Compensated response FR plot shows relatively good linearity, but somewhat excessive tilt, and a slight excess at 10kHz yielding what I would call, and what ljokerl identified in listening as a slightly "v-shaped" response.

30Hz square wave has a humped shoulder that looks slightly too slow to me (longer and more rounded) than ideal. Very little "sway back" curve is shown; the region from after the shoulder is quite linear, which normally indicates tight bass response. Similarly, THD+noise shows very low distortion in the bass, overall indicating tight, clean bass. ljokerl's comments regarding poor bass are rightly identified as excessive bass.

300Hz square wave shows a nice clean initial spike with little subsequent noise. Sharp following rise is indicative of a slight lack in mid-range response relative to the bass.

Impulse response, like the 300Hz squarewave, show a very speedy impulse followed by very little noise. This headphone should provide excellent detail and resolution without too much harshness according to the measurements. Imaging should likewise be good.

Impedance plot shows an 18 Ohm headphone, which could be bad for amplifiers with an output impedance higher than 2 Ohms, but the impedance plot is quite flat indicating the high output impedance amplifiers shouldn't change the FR of the headphones too much.

Isolation plot show an IEM with only modest isolation. Should be fine for walking around purposes when some awareness of outside noise and traffic is desirable for safety sake, but this might not be the best IEM for duty on airplanes and subways.

With 41mVrms needed to achieve 90dBspl at the ear, this headphone should have no problems achieving loud listening levels from portable players. These measurements indicate a good headphone for general purpose portable use in up to moderately loud environments.


avens's picture

What in-ear or portable headphone in general would you recommend at the $200-$250 price point...with a microphone?

Seems like an easy topic at first, but when I researched it seems there's so many complications these days that there are very few headphones available that offer good to great sound and convenience at the same time, in the form of all basic functions being compatible with your phone (Android in my case), no amp required, having a microphone is of the essence and hopefully three buttons. Weird, isn't it.

olc's picture

Can someone recommend a source for these that are not knockoffs? Apparently that's a real problem with these.

Impulse's picture

There's plenty of good options if you can settle for a one button remote, if you really must have a three button remote your choices will diminish by several orders of magnitude.

My Ety hf5 (three button but only one works on Android, same as 1 button hf3) were one of the better buys at their price point according to joker (at least they were a few years ago when I got them) and also one of the few with a button/mic at that price at that time...

You can always control volume with a single button by using an app like Headset Button Controller which lets you map extra shortcuts, like press and hold for volume (it sets it down to the minimum and ramps up until you let go).

Another alternative would be sourcing or making your own three button cable and pairing it with some of the portable headphones that take standard removable cables... V-Moda's M-80 or XS (highly acclaimed by Inner Fidelity) would be one option.

I've got the M-80 and even tho the one button remote never bothered me I still replace the stock cable often to use a shorter one when I pair them with a Bluetooth receiver clipped to my sleeve.

I'm actually looking to upgrade to the XS for the collapsible design, ever since the first M-100 leaks came out I said an M-80 with Cliqfold would be my ideal portable on ear headphone... Just gotta sell my M-80 first!

ljokerl's picture
3-button Android remotes are incredibly rare, which is part of what makes the Piston special. With a regular 1- or 3-button remote you have more options but still not too many. I would go with the Etymotic HF2 or HF3 for balanced sound and the RHA MA750i for enhanced bass. I'm still waiting for someone to sell a good-quality aftermarket MMCX headset cable to convert any of the current detachable-cable earphones into a proper headset.
tonylee5566's picture

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Downforce's picture

Wish I could. There's an earlier comment about the inset mesh screen on the ear tube on genuine ones, but obviously this can't be determined until they're received, so this seems to be a deal breaker re the Pistons.

The website http://www.xiaomiworld.com/ no longer works. The link to the Xiaomi English home page leads here: http://www.mi.com/en/ Perhaps this is a source for the genuine Pistons.

Impulse's picture

Sweet find joker, excellent review as always. I take it these are already a FotM at Head Fi? If they aren't they're bound to be...

Two questions, did anyone on Head Fi mention what EBay buyer they used? Would help in tracking them down... More to the point of the review, did I miss it or did you not mention what tips they come with?

Is it just the usual three sizes of silicons or what? I think you said on the first page the latest version come with different tips, but not what those are.

ednaz's picture

Just got my set, they're the second generation. Picked up on Amazon, where the vendor gives a really good piece of info... "if they're not over $20, they're probably fake, because of what they cost initially."

I just ran them through a bunch of my "take THAT, speakers or headphones" selections and these little earphones punch way, way above their weight. Jaco Pastorius' bass on Cotton Avenue; the bass on CSN's Dark Star - both have been champs at sorting out blat from bass, and every bit of bass musicality came through clean, clear, and precise. That open back is clearly at work there - I listened to a couple of things alternating between covering the opening on the back with my fingers, then letting it be open, it makes a huge, huge difference.

Listened to some Cubaton, some samba, a little new folk, some be-bop, and I'm completely amazed at the sound quality. Yes, a little U shaped, but not much, voices didn't sound veiled. Most impressive to me was imaging and size of soundstage. At this price I'd expect the whole band to be in my head, but instead they were all around me - I could point to each player.

Put on some binaural recordings and had one of those "binaural moments" where I sat up sharply in my chair thinking I heard someone whispering in my front hall, and I'm the only one home... then remembered that same moment had messed with my head before, but only with my CIEMs and my best headphones.

They are lovely, the packaging is very smart and well done. The silicon tips don't fit me well - the large were too loose, but I think part of that is because they're soo small that you're stuffing the metal into your ear to get a seal. Need to work on that a bit. But for what they cost - even not considering cost - these are going to be heavily used when I don't want to use my CIEMs.

Hugely impressed.

ljokerl's picture
long before I got wind of them, in the original iteration. The first generation wouldn't have impressed me much, though, so I'm glad I got to try the 2.0 right away. This was the eBay seller I was recommended for legit Pistons: http://www.ebay.com/itm/380861393335 There are just the standard 3 sizes of tips on all versions, just different quality from what I understand.
Long time listener's picture

I have both the Xiaomi and the Philips TX1, and to my ears, the TX1 provides a more pleasing balance overall. And I think reference to Tyll's measurements shows why.

Even though the levels of bass--relative to treble at around 10kHz--are identical, the Xiaomi sounds like it has "too much bass." The TX1 doesn't, however, because the levels of the low bass and the midrange have been lifted slightly. The TX1's balance sounds natural and without undue bass emphasis due to this slight shift.

The TX1 is also just a tiny shade lower in level in the treble just below 10 kHz, which I believe makes it slightly more forgiving in that area as opposed to the more treble-forward Xiaomi.

I think the Xiaomi is amazing at its price, but if I had to pick another at that price to listen to, it would definitely be the Philips TX1. More solid low bass, more pleasing treble, better balanced overall.

The TX1 also has a nozzle that is shaped slightly differently than the S1 or S2 nozzles, making it more snug-fitting in the ear and providing a better seal.

Long time listener's picture

Having said the above, I've gone back and forth on these ever since I got them. Listening again to the Xiaomis, I'm not sure if the TX1s are clearly superior. Both have some inevitable flaws, given their price, but both are pretty outstanding.

And maybe I'm just a late-blooming basshead, but I'm not inclined to say that either one has too much bass.

Khairil's picture

Can't choose between the two, the Xiaomi Piston 2 or the Sony MH1C. I am leaning towards Piston at the moment, but concern about the isolation, comfort level and performance differences. Can someone compare them two?

ljokerl's picture
I've used both quite a bit and have come to the conclusion that I prefer the sound of the MH1C but can't recommend it over the Piston because of how much the flat, rubberized j-cable of the Sony bothers me. The MH1C has less mid-bass and sounds tighter and more controlled at the low end. It's smoother and more refined up top, too. The Piston is bassier in the conventional sense, suffers from a bit of bass bleed/bloat, and has a more energetic top end. The presentation of the MH1C is more laid-back and it is less sensitive by a good margin.
Long time listener's picture

"I prefer the sound of the MH1C but can't recommend it over the Piston because of how much the flat, rubberized j-cable of the Sony bothers me..."

Isn't it all about the sound? I myself have never been bothered by any aspect of cables, including microphonics, for a second, and can't imaging why everyone is so concerned with that stuff. It seems bizarre to me to recommend a worse-sounding IEM over a better sounding one over cable concerns.

And after another day of listening, I do find that its the Philips TX1s that are staying in my ears, rather than the Xiaomis.

Impulse's picture

Microphonics can kinda ruin the experience for anyone that actually uses IEM while doing anything but sitting down calmly... What good is it if you can't hear it over all the rustling cable noise?

I always appreciated the way joker values the overall experience and not just SQ, but I use my IEM mostly while doing twenty other things so...

Long time listener's picture

Yes, you're right.I listen almost exclusively sitting at a desk or in bed, so microphonics will be less of a problem for me. But based on my experience in other situations, it still won't ever matter much to me.

I too appreciate Joker's reviews, here and on Theheadphonelist, and they've helped me find one or two IEMs I really like. But I also hear things very, very differently than he does (and I can't be the only one), and one or two of his recommendations have also been disasters for me--the Philips S1 being a case in point. Further, I strongly disagree that the Philips TX2 is better than the TX1, since I feel the TX1 is the only one of their four IEMs where they solved the problem of harsh treble, and it's the only one of the four I like. I also think it's subtly better than the Xiaomi.

So I hate to see his word taken as some kind of final, objective description of what's best and what's inferior, and I think second opinions are important. As someone who has several decades of experience listening critically to sound equipment and headphones, I like to get my two cents in.

Seth195208's picture

Microphonics in a cable isn't about sound?

SleepModezZ's picture

I'm a fan of the sound of the MH1C. Still, I won't use them them. The heavy asymmetric cables are pulling the phones out my ears with only the suction force of the tips keeping them in place.

Maybe foam tips could make the situation better but to my knowledge there are not any fitting Comply foam tips for the MH1C.

Maybe you can enjoy good sound quality even when pummeled with pain, discomfort and frustration - most people can't.

Seth195208's picture

..in two days. Had them for a month now. Absolutely love them. The easiest way to tell a counterfeit is an inset mesh screen on the ear tube. On the real ones, it's flush.

Hal Espen's picture

The only thing that bothers me about this excellent review is the failure to mention, even just in passing, that Xiaomi has been widely criticized for cloning many aspects of Apple design and marketing. I'm not suggesting that a headphone review needs to wrestle at length with the rights and wrongs of alleged knock-offs and patent rip-offs coming out of China. But when the review talks about how "the company will undoubtedly face many challenges expanding out of Asia... if it can be successfully introduced in other markets, of course," this seems like an excessively coy reference to the difficulty Xiaomi confronts if it wants to grow beyond the safe haven of China and India, and compete in regions where intellectual property rights are rigorously protected. And this aspect of Xiaomi's story makes the review's warning about avoiding pirated Pistons extra-ironic. I think your readers deserved a heads-up.

Impulse's picture

The Pistons are clearly not a rip off from anything Apple and virtually every other smartphone OEM has also been accused of ripping off Apple at one time or another (plus Google).

Who cares? The entire PC industry was built upon companies imitating and copying each other for decades before this ultra litigious age, and that included Apple and MS practically stealing design concepts wholesale from Xerox's PARC.

I don't see any reason such a warning should have any place in the review or why a writer reviewing something (that's only tangentially related even) should be that concerned with tech sector politics at large.

The warning about knock offs is more about protecting the readers from wasting their money than about any morality or preference over X brand's strategy.

Hal Espen's picture

Solid rebuttal, and I'll just add that your somewhat downplaying the issue with an air of world-weary indifference and maybe being overly scornful of what I thought was a pretty mild-mannered and reasonable comment. The story of how Xiaomi is navigating these ethical lines is one of the most distinctive and interesting things about the brand, even if you don't care.

JacktheMac's picture

Apple didn’t steal anything from Xerox PARC. They adopted and licensed it with Xerox’s permission.

It’s true that Microsoft spent the eighties and nineties ripping off Apple wholesale, but Apple have come up with more original products than any other tech company, ever.

So please don’t lump Apple and MS together: one innovates, the other copies; badly.

bhazard451's picture

Xiaomi is one of the companies that will start a revolution of sorts of direct to consumer, high quality goods from China.

"Affordable" and "Quality" are two words corporations like Apple despise seeing together. Most corporations would have no problem having a chinese oem like the one that created the Piston, and would charge $99 for the same IEM with their own "branding".

Instead, now we are starting to be able to get these items direct, and are getting very good quality at prices previously unheard of.

Think of the Piston as the new "Monoprice IEM". It's a small taste into the world of quality audio that people may want to jump into (and get addicted to). It's the entry drug. A good thing for everyone IMO.

Seth195208's picture

Is an interesting thing. Twenty five years ago, I purchased a velodyne subwoofer. After equalizing it, I noticed that the bass was so clean, that it sounded like it wasn't there. I actually had to turn it(subwoofer)way up to compensate for a lack of harmonic distortion in the bass that we expect to hear during playback. I also noticed the same thing with these headphones. The bass is very elevated but does not sound like it, probabably due to the almost complete lack of harmonic distortion in that area.

Copacetic's picture

I too own (and love the sound of) the MH1C, but detest the cables.
I use them on the move (rarely since I bought better, but much more expensive 'phones) and have resorted to using self amalgamating tape to 'tie down' the shape of the cable to more closely resemble a conventional 'Y' cable.
I agree that the MH1C is barely useable in it's stock form.
It provides fantastic sound for the £17 or so that I paid for it, but even at that price I would not use them as the cable constantly pulled one side out of my ears, even with a shirt clip.
'Microphonics' aren't a problem now that I've modded the cable and wear them over ear.
Just my 2c

jeckyll's picture

I might have missed this, but how is the sound isolation? I'm quite interested in these, but I work in an environment where I don't want sound leakage and appreciate sound isolation.

Thanks in advance.

ljokerl's picture
I would say it's average in this price range. There's not much in the way of leakage and of course they isolate better than EarPods and such, but if high noise isolation is a top priority I'd pick something else.
jeckyll's picture

Thanks for the quick reply!

Arvan's picture

I have both the Piston 2.0 and the vsd1s and I very much prefer the Vsonics. The piston has a huge WOW-factor at first listen. The sonics is perfectly tuned for use when out and about. A little bump in the bass, nice peaky treble but they sound to metallic to my ears. The trebble feels hard in some weird way. The vsd1s is smoother, has better midrange and is the iem i choose fore more critical listening while still on a portable device. However, the convenience with the android remote and the rather good cable on the piston makes them a winner to and from work.

l2blackbelt's picture

InnerFidelity Reviewer, what the heck link did you give me. I didn't feel like getting a knockoff so I ordered from the link provided. It did something beyond sketchy with paypal, confirming the order in paypal, saying it was going to be $25, then suddenly redirecting me back to the site, asking for me to pay more for shipping after I'd already confirmed my price on PayPal!

Since I wasn't sure if they were just going to hold my money hostage at this point, since to the best of my knowledge I'd already paid them, I agreed to the high $8 shipping, and somehow they updated the amount I owed PayPal to $32 something and I got an email saying they charged me that. What the heck site did you send me to? Really not happy about this.

Down_South's picture


Different types of shipping available with prices clearly marked.

sammydude's picture

I second Down_South on that. Safest site to buy original Xiaomi phones and accessories. I bought my Xiaomi Mi2S and it was an original. Was able to verify based on info available on the internet. I've ordered my Piston earphones from this site. I'm from India and the Piston earphones available in India website have been custom manufactured by Xiaomi. Lots of difference in sound quality and the chocolate smell is missing. So, I cancelled my order and have opted for ibuygou. Not affiliated with that site. But just want to share this info. Genuine guys and good customer care!

h1a8's picture

Is there going to be a review on the Piston 3? I'm very eager to see the frequency graph of these. Several reviewers say they are more balanced and somewhat clearer. Some say they beat the Piston 2 for best iem under $60.

Lastly, what about soundmagic e50s (and e10s)?