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[review] Celsus Sound - Gramo One - a fantastic open backed earbud

  1. Armaegis
    One only has to go through my profile to notice that I've gone through a lot of Nuforce gear over the years. I never got into their high-end stuff, but I've owned or tried most of their budget and midrange setups. Since Nuforce has been bought out by Optoma recently though, their future remains unclear. On the other hand, Jason Lim (co-founder and former CEO of Nuforce) has left and started up two new companies: NuPrime which will carry on the high end home theatre toys, and Celsus Sound which (for now) appears to be focusing on the portable world.
    So that brings us to the Gramo One, the new earbud by Celsus that is the subject of this review. Now if you're like me, you're thinking “an earbud? really?” and I don't blame you. Headphones have come a long way in terms of public awareness and sound quality and what people are willing to pay for (with some rocketing boutique pricing to match). IEMs and customs have also gone through a surge as well, putting a dent in many wallets along the way. Earbuds though, are sort of the forgotten stepchild of the headfi world. They're often that first piece of [redacted] that came with your mp3 player that you chuck into the drawer of forgotten wires and dead batteries.
    We've all probably read about a couple good earbuds though. Yuin comes to mind, and maybe some of those Sennheiser sport models, but really there aren't that many options out there, and hardly any in the “high-end”. So along comes Celsus with this fancy doodad called the Gramo One which at first glance really doesn't look like all that much... but hey first things first, here are the specs from the website:
    MSRP $249 (USD, EUR)
    The Celsus Gramo One is a reference-grade open-back* in-ear headphone that sits comfortably on the outer ear.
    One’s first – and enduring – impression is of an overwhelming, three-dimensional audio experience that can fairly be described as a virtual live event. The proprietary 16 mm Celsus Sound transducer produces a sense of space, depth, detail and dynamic as impressive as that of an audiophile’s dream sound system. A mesmerizing midrange and dynamic bass are among the more impressive of the Celsus Gramo One’s signature qualities. And no IEM we’ve ever heard can match the Gramo One’s production of seductive vocal textures.
    The term reference-grade typically connects with a few widely celebrated over-ear and on-ear headphones. Their drawback – and it’s a serious one – is weight and size as principal contributors to listener fatigue. In recent years, a few in-ear headphones (IEM) have achieved reference-class status. Again, as a drawback, IEM devices suffer from an ultimately fatiguing “music-in-the-middle-of-one’s-head” phenomenon along with the excessive ear pressure that inevitably accompanies prolonged listening. With the portability of an IEM, the Celsus Gramo One’s exceptional sound quality equals or betters the most highly regarded over-ear headphones.
    *Open-back earbud is specifically designed for use in quiet environment


    1. A proprietary 16 mm Celsus Sound transducer produces a sense of space, depth, detail and dynamic as impressive as that of an audiophile’s dream sound system
    2. A mesmerizing midrange and dynamic bass
    3. Seductive vocal textures.

    Included with Gramo One are

    1. 3 pairs of ear tips
    2. Genuine Leather pouch


    1. Transducer principle: Dynamic Open
    2. Size of driver: 16 mm
    3. Impedance: 32 Ohms
    4. Frequency Response: 15 to 23000 Hz
    5. Sensitivity: 100 dB
    6. Sound pressure level (SPL): 125 dB
    7. Ear coupling: Intra-aural (ear buds)
    8. Connector: 3.5 mm
    9. Cable length: 1.20 m
    So with that out of the way, let's talk a bit about this new toy of mine. I'll start off with TL;DR version: Holy crap, this... is really good for an earbud. Scratch that, it's pretty good even against IEMs in the price braket.
    Alright then, now that you've gotten the short of it, let's start from the top.
    Surprisingly heavy packaging. There's an abundance of cardboard to make everything solid and presentable. It's literally three boxes nested within each other before you get to the actual product. Once you're past that, you wrestle it out of the cardboard housing holding everything in place. Maybe I'm just being pedantic, but I feel like it could have all been put into a box a quarter the size which would reduce packing and shipping costs etc. Anyhow, the packaging is nice, if somewhat excessive. At least there wasn't an overabundance of tape like previous Nuforce iems had.
    The Gramo One comes with a leather pouch roughly the size of a deck of cards (more square-ish). The inner compartment has two slots (one large, one small), and the flap doesn't have any securing mechanism other than tucking in like a belt. Overall it's functional, but I would have felt better with a semi-hard case that could at least protect whatever is inside.
    Other than that, um, it comes with three foam covers/tips. The foams don't cover the driver so don't affect sound directly, but do serve to help hold the Gramo One in place in your ear. So it's not quite part of the seal per se, but sorta is. In my case, they wouldn't stay in my ears without them. Reportedly, future shipments will also come with rubber/silicon tips.
    Build Quality
    Overall the quality seems good. The lack of strain relief on the buds and plug is slightly worrisome, but the wires aren't flimsy so I think they should withstand a reasonable amount of use. The wires do have slight memory, so you don't want to pinch them or tie them into bows, but you shouldn't be doing that with your gear in the first place.
    Otherwise, the body of the Gramo One feels nice. Seems like metal for the main body, and plastic for the trim. Everything is smooth; no burrs or dents. There aren't any adjustable nozzles or anything like that, so unless you're going to reenact an episode of Will-it-blend, nothing should be coming apart. The rear is actually open backed with a metallic mesh covering. It's soft to the touch, so don't go sticking a pen into it and you should be fine.
    The foam tips are just... plain 'ol foam tips. They go around the front edge and help hold it in place in your ear with some cushioning. Nothing fancy, really they're disposable. You get four pairs in total (one already on, and three extra).
    Sound Quality
    Going in, I honestly wasn't expecting much. I'll admit I still had the preconception of earbuds being tinny sounding throways, so when I first put the Gramo Ones in I was quite shocked.
    Right away there was a healthy amount of bass greeting my ear, and I don't mean the flabby wubwub kind. Slightly boosted but clean, and strong down to about 60Hz before I noticed any significant rolloff. There was still decent response down to 40Hz. Seriously, out of an earbud? That's ridiculous. The open back gives the bass and good distortion performance. Covering it with your fingertips immediately drops the bass and cranks your distortion up
    The midrange is relatively flat-ish with a gentle slope down, so you feel it being a little bit recessed and vocals start to feel slightly distant. From the uppermids into the treble it shelves up, not super sharp but there are still a couple peaks in there. Much more noticeable with a sine sweep but not so much with music. It adds that sense of “detail” to the top end, though not necessarily in the most accurate manner. That extra energy in the top top end feels like it's in the 3-5kHz range, so it avoids the shouty range for me (which is more 2-3kHz) but provides that feeling of articulation and detail.
    Overall, with the slightly boosted midbass and midtreble, the Gramo One has a gentle V-shaped sound to it. As a side note, apparently these were tuned without the foams, but since I can't get a good fit without the foams I did not evaluate it as such (I tried briefly, but with a loose fit I lost all bass response and the treble became uneven). There will be extra silicon tips provided in future shipments, which may or may not change the sound.

    The ad copy intimates that the Gramo One offers an immersive soundstage, and in my experience it really does. Surprisingly wide, though somewhat shallow in depth. I'm sure much of the soundstage has to do with the open back. While covering the opening with a fingertip drops your bass and drives up distortion, it also crushes any sense of staging. On the other hand, hovering your finger over the back does not change the sound, so the chamber inside is at least isolated from external reflections, unlike typical open backed headphones.
    While we're on this subject of open-backed-ness, the Grado One has absolutely zero isolation. Zip, nada, zilch. It wasn't designed for that, and doesn't even block out incidental ambient sounds. In that sense, you can't treat these like typical IEMs where you want to block out the world. So what good are they then? Celsus Sound knew they were aiming for a particular niche market. Users who want the simplicity and compactness of earbuds (let's face it, some people never get used to putting iems into their ears or always feel discomfort), but still want good sound and don't require isolation. It may seem like a fairly marginal market segment, but after listening to these for a couple weeks, I can see their appeal.
    Obviously they won't work for crowded noisy places, but they're great for a casual setting where you still want to have awareness of your surroundings (a household with kids running around, or a pot on the stove, etc). I could go for a walk and still hear the subtle sounds of nature, or incoming traffic. I could sit in a quiet coffee shop or cafe and have my music going while settling into the familiar and comforting clatter of a kitchen. It's great for all those times where you want to have a little bit of music, but don't want to lose the acoustic ambiance of your surroundings.
    Or perhaps you just want the sound of an open headphone but don't want to wear a headphone. As someone with glasses and a wide head and who's reference is a big honkin' the HE-6, yeah sometimes I just want something simple I can put in my ear without putting it *in* my ear and still hear the world around me.
    I really do forget that I'm wearing them, and it's like I simply have a nice soundtrack backing up my life.
    In the public/outdoor settings in particular, I found the V-shaped sound very helpful. It provided that extra energy to hear the music over ambient sounds without getting too loud. Know what else was nice? bumping into a friend and stopping to chat, and all I had to do was hit pause. I didn't have to fiddle with wires to pull them out of my ears or put them back afterwards.
    Finally, the Gramo One likes to go loud and does so merrily. If anything, the bass becomes more prominent and lively as you turn it up and doesn't seem to break apart. So be careful with your headbanging ways.
    Vs Apple Earpods
    The ubiquitous Apple Earpods (the one step up from their generic buds) are going to be the most obvious comparison here. I know it's a completely different price point so the comparisons are moot, but I haven't heard any other earbuds so that's the best I can do. Now to be fair, I think the Earpods are decent and a huge leap up from the buds, though frankly it's not hard to step above the original buds.
    Grain and distortion on the Earpods feels much higher than the Gramo One. The Earpods also shelf the treble earlier, and subjectively feel much brighter and more fatiguing. It has a hollower sound and significantly narrower stage which just feels congested in comparison. However, the Gramo One does feel a little more distant while the Earpods are closer in.
    The Gramo One overall has a more laid back sound, and the Earpods are more in your face.
    Closing Thoughts
    Headphones and iems have come a long way in terms of public acceptance and what “typical” consumer pricing should be, but earbuds still have this stigma of being poor both in price and sound quality. Well, I hope the Gramo One will start changing people's minds on that (yeah yeah, probably nothing will actually do that unless your name is Apple or Sony).
    I consider the sound quality on par with IEMs in roughly the same price bracket.
    The applications of an open backed earbud may seem very narrow at first, but take a moment to consider when you'd like to have music playing but don't want to lose awareness of your surroundings. It may be more useful than you realize, and if that appeals to you, definitely keep the Gramo One on your shopping list.
    nick n likes this.
  2. Armaegis
    Here are the pics. If you were hoping for some pretty pics to showcase the Gramo One in all its glory, that's not gonna happen. There were taken with an ancient point'n'shoot camera of questionable quality, from a (notreallya) photographer of even more questionable background.
    Unwrapping at the beginning is always exciting.
    The second box slides out of the top. Yeah you like that. Oops the picture came out sideways; deal with it.
    A third box from the side? I guess if you're into that freaky sort of thing.
    Well here it is with a little bit of leather on the side for when things get frisky.
    Look, no one likes to cover up and those tips ain't pretty, but always gotta have protection right?
    Contrary to what you do in your spare time, you'll probably want to untie before you play.
  3. Armaegis
    A few pics have been uploaded to the second post.
    A feel a comparison vs other headphones would be difficult since it's an apples/oranges thing, but someone can always click on my profile to see what other gear I've gone through over the years to get a sense of where I'm coming from. My current reference point is a modded HE-6, and other iems that I have lengthy experience with are the VSonic GR07, Shure SE215, Etymotic ER4p.
  4. tomscy2000
    Nice job. I've been dawdling on my own write-up of these. They make pretty great sound; I prefer the prototype's sound signature because it had a superior center image, but I understand why they made the signature changes in the retail version --- the retail sound is more balanced overall and won't scare off as many mainstream people, because they might think the prototype lacks some bass and has too much upper midrange. I've compared these to the MX985, and while the Sennheiser sounds great too, I think the Gramo One holds better detail and texture.
  5. Armaegis
    Interesting. I never heard the prototype; so you're saying the proto was a bit more mid-centric?
    Incidentally the Gramo One was missing a product page, so I made one earlier this evening.
  6. tomscy2000
    Yes. The prototype was a bit more midcentric, but for me, that played to its advantage, because the midrange sounded incredibly life-like out of them. The retail version, which I'm still using now, has a smaller center image. It's still good, but I do prefer the prototype. These were some of the notes I gave Celsus when I tested out their prototype.
  7. mochill
    Damn, these are off my list because of the midrange is smaller :confounded:
  8. tomscy2000
    Yes, it's smaller than before, but it was HUGE before. They changed it because they wanted people to be able to use it without foams and at all insertion angles. Sometimes, on the prototype, at the wrong angle, the sound would be a lot harsher, so even though the midrange was amazing (seriously), it did have some drawbacks. They balanced it out for the production version. I still think it's very good. I just have not had the experience of other popular earbuds like the Yuin and Blox to come out and say unquestionably that this thing's a better earbud than any other I've heard before. But right now, it's still the best earbud I've come across.
  9. Armaegis
    I do wonder what the fit with the silicon tips will be like. They don't fit properly in mine without the foams.

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