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Celsus Sound Gramo One: Is It Really Worth $250?

The Celsus Sound Gramo One is an open-back reference-grade earbud. Considering the hefty price tag, how does it compare to its more affordable peers?

The AudionistThe Audionist

The Celsus Sound Gramo One—released in January 2015—is a reference-grade open-back earphone. It’s not an IEM, even though Celsus Sound calls it an “in-ear headphone”. This is an earbud, and an expensive one at that.

How much does the Gramo One cost? The recommended retail price is USD$249, varying between $200–$300 depending on whom you buy it from. Some of you might be wondering: $250 for an earbud? It better be one hell of an earbud then. So is it worth the price?

First of all, we need to understand that earbuds have come a long way. Earbud lovers will agree we’ve seen a sharp rise in the number of audiophile earbuds in the past five years or so. Take these for example:

Boutique Earbuds

  1. Baldoor Earbell E100
  2. Blox BE3, TM7
  3. CrossRoads HR1
  4. Dasetn MC5
  5. DUNU Alpha
  6. FiiO EM3
  7. Final Audio Piano Forte II
  8. HiFiMan ES100
  9. HiSoundAudio PAA-1 Pro, Living
  10. Marshall Minor
  11. MusicMaker MrZ Tomahawk
  12. SoundMagic PH-10
  13. Sunrise Audio Charm, Dragon2
  14. Tingo TC-100
  15. Yuin PK 1, 2, 3

It doesn’t end there. These are just the popular ones that came to my mind. I left out many that deserve to be on that list. You’ll notice I sorted them by alphabetical order too. I didn’t want to give the impression that one was better than the other.

Today, more boutique brands are finding ways to spin off the humble earbud into something new. The MusicMaker Tomahawk, for example, released just recently in March 2016.

A Brief History of Earbuds

Earbuds have come a long way, but the past five years have been important. IEMs rose in popularity thanks to brands like Shure, Etymotic and Ultimate Ears which paved the way. Because of IEMs’ popularity, manufacturers shifted their production focus to concentrate on in-ear monitors.

Sennheiser—a common headphone brand—used to manufacture plenty of earbuds up till 2005 or so. Now you’d be hard-pressed to find one in store. They still manufacture a few entry-level earbuds, but the days of the MX 985 are long gone. By the way, you can find out-of-production MX 985s on Amazon for over $200, a case of demand over supply.

But, there remains a group of headphone enthusiasts who still enjoy the good old earbud. They don’t carry the weight of headphones, and they don’t suffer from the fatigue of IEMs. Earbuds are comfortable and easy to use.

Yuin enjoyed huge success with their PK series—nondescript earphones that offered big, audiophile sound. Luckily for them, they entered the market early. A lot of people bought these relatively cheap earbuds. Boutique manufacturers soon realized there was a strong demand.

I won’t go into detail of the history of earbuds, but suffice to say, there are plenty of options now. From the Baldoor E100 ($13+) to the Yuin PK 1 ($150+), there is almost an earbud for everyone.

Then came along the Celsus Sound at a whopping $250. I’m open to testing out new products, so I didn’t want to judge the Gramo One based on its price. Recently I was lucky enough to demo the Gramo One. I’ve heard a lot of good things about this earbud. Was I impressed?

Gramo One: TLDR

The short answer: Yes.
Is the Gramo One worth $250? No.

Why? Read on to find out.

Celsus Sound Gramo One

The Gramo One

The Celsus Sound Gramo One is an open-back earbud, so I expected some sound-leakage. I tested it in a quiet environment to achieve the best response. Bearing in mind its open-back design, I expected good soundstage and proper midrange reproduction.

I fit donut foams on it to achieve a proper seal in my ears. I expected the bass to benefit from this mod (I wouldn’t exactly call this a mod though). The 16 mm driver should provide a big sound and help with the soundstaging. But above all, I expected the Gramo One to sound “big”.

I’ll cut to the chase and leave out the technical babble from Celsus Sound’s product specs. I’ve never bought into audiowoo marketing hype. I don’t care if it was fashioned out of Amazonian wood or rare-earth metals. I’m only interested in tone.


The Gramo One has plenty of bass, no doubt about it. It’s got a big sound, but definitely not thundering or earth-shattering. Although I did feel as if something was missing in the low-end. It doesn’t have a deep, low-end thump, most likely due to the open-back design. Forget about electronic music—it won’t work. On rock or metal tracks, the bass just doesn’t cut it.

Pop, jazz, soul, and everything else in that vein works fine. I believe Celsus Sound designed the Gramo One for a particular type of sound. The bass sits well in acoustic, lounge, piano, and vocal-type of music.


Mids are smooth, nothing artificial about it. No boxy mid-range tone boost here as well. There is a slight boost in the upper-midrange around 3 kHz, which helps to enhance mid-centric music. Midrange is not too forward but neither is it lacking. It sits well in the overall mix.


The Gramo One is not a glassy sounding earbud. There is a slight top-end roll-off, but not as much as the Final Audio Piano Forte II. The boost in the upper-mids and low-highs brings out vocals well without extreme hiss. I would describe the highs as transparent-sounding.


Soundstaging is articulate, with a wide, expansive sound and proper instrument separation. It doesn’t sound too analytical, the kind that confuses you, if you know what I mean.

Other than that, there’s nothing impressive in the soundstaging department. The Gramo One did its job well, and nothing more.

Overall Vibe

The Gramo One is great for any genre of music that includes plenty of vocals, piano, and acoustic instruments. It works well for ambient music as well. For rock music, it’s too fatiguing. The sound is too aggressive. Tracks mastered to emphasize midrange frequencies sound overly edgy and hard.

The Gramo One doesn’t track fast music too well. Double-bass kick drums and technical guitar sweep-picking gets lost in the mix.

The top boost is something to consider. What genre of music do you listen to? This is important because if you don’t enjoy music that has too much presence, you are going to hate the Gramo One. You’d be much better off with the Piano Forte II instead.

I compared the Celsus Sound to the Yuin PK 2, and I found the Gramo One’s tone thicker, but less trebly. The Gramo One’s midrange is more aggressive as well. As for soundstage, the Yuin PK 2 wins. The PK 2 has a more airy and shimmery ambience to it.

Celsus Sound Gramo One Package


In short, the Gramo One is a one-trick pony. It’s a good consideration if you want to add another earbud to your collection. But if you’re looking for a general do-it-all earbud, the Gramo One is simply not it.

And that is why I don’t think it’s worth the $250 price tag. There are other earbuds that can do the same for much less. I’m not knocking on Celsus Sound—I respect them for contributing to the earbud genre, and the Gramo One does sound amazing. But if you ask me, $250 is too much for a one-trick pony. I’d rather consider these earbuds below $150 instead.

Technical Specifications

Transducer: Dynamic Open
Driver: 16 mm
Impedance: 32 Ohms
Frequency Response: 15 to 23000 Hz
Sensitivity: 100 dB
Sound Pressure Level: 125 dB
Ear Coupling: Intra-aural (earbuds)
Connector: 3.5 mm
Cable Length: 1.2 m

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