7HZ Eternal Dynamic Driver IEM Review: Ace Of Bass

Linsoul 7HZ Eternal HiFi 14.5mm LCP Polymer Diaphragm Driver in Ear Earphone

Linsoul 7HZ Eternal HiFi 14.5mm LCP Polymer Diaphragm Driver in Ear Earphone







What We Dig

  • Beautiful Design
  • Comfortable Fit
  • Detailed, Open, Exciting Sound

What To Think About

  • Bass Can Be A Little Too Lively


If you believe that neutral=boring, then the 7Hz Eternal may be right up your alley…


7HZ took the portable hi-fi world by storm with their Timeless Planar Magnetic IEM, as it was one of the first affordable large-format Planar IEMs to hit the market. Many reviewers loved them for their detail and balance.

Now they have the IEM I’m looking at today, the $249 7Hz Eternal. It has a 14.5mm dynamic driver, which is enormous as far as IEMs go. According to the marketing materials, this IEM commemorates 7Hz’s 10th Anniversary, and its elegant design, complete with dazzling Sapphire colored glass panels (literally) reflects that.

So, will you be in a celebratory mood once you pop these shiny buds in your ears? Well, read on, and I’ll give you the scoop!

Disclaimer: This unit was sent to us by Linsoul in exchange for our review. No outside input was given or promises made regarding the content contained therein.


  • Impedance: 30Ω.
  • Sensitivity: 109dB/1kHz.
  • Frequency response range: 10Hz-20kHz.
  • THD+N: <0.2%@1kHz.


The 7Hz Eternal IEMs come tucked in a nice aluminum storage box, which itself is tucked inside an ornate cardboard carton. I was impressed with the metal storage box lined with velvet to keep the earphones from getting scratched.

There are some rough edges and excess glue on the lining, but overall the box is sturdy, and the rich bronze color matches the IEMs to a T. I also like the strong magnetic closure, which keeps the earphones from falling out.

Along with earphones and case, you also get tons of ear tips (10 pairs in addition to the pair pre-installed) and paperwork. The tips are a little thin, so not the best quality, but they do the job.

As alluded to earlier, the aluminum earpieces look quite elegant, with a turbine-shaped imprint in the center. In addition, that pattern is covered with a brilliant sapphire color glass panel that looks nice in the light, as it transitions from a blue tint to a mirror finish.

According to the company, the glass cover is made of the same glass used for watches, so it’s said to be durable.

The earpieces connect to the matching braided cable via an MMCX connection, which isn’t my favorite. MMCX connections usually get loose over time, and the earpieces fall off.

In this case, the connections seemed secure out of the box, and I had no issues in the few weeks I used them. The model I received has a 3.5mm plug, but you can get one with a 4.4mm cable.

While the cable looks nice, it’s a little stiff, and I’m not a fan of the over-ear loop. I prefer a loop that has more of a curl over the ear. As it is, the pre-formed loop is a bit loose and doesn’t stay in place when you wear it.

As far as fit goes, I found the fit to be quite comfortable despite the oversized housings. They’re lightweight (6g each) and contoured on the backside, so you barely feel them when worn. I should mention that I have pretty large ears, so if your ears are on the small side, YMMV.

The only thing that bothered me initially was the coldness of the metal against my inner ear, but that went away once they warmed up.


For my sound tests, I connected the 7Hz Eternal to my Fiio M11 Plus LTD DAP and played a bunch of music from the “Audiophile 101” MQA playlist on TIDAL.

The Eternal is relatively easy to drive, and you should have no issue playing them from any dongle or even directly from a cellphone. However, the better the source, the better they sound.

The first thing I noticed upon listening to the Eternal was a very robust low end, which added a bit of weight to the presentation. After that, I picked up a bit of boost in the upper mids, which added some presence to balance out the lively bass. Finally, the center mids were clear and open, albeit just a bit recessed, especially on songs with heavy bass drums and the like.

Overall, this equates to a very lively V-shaped sound with good detail from top to bottom. I liked how articulate the bass was, even if I found it a little excessive in quantity.

Similarly, I liked the upper mids/treble detail even though there was a slight hardness there. Overall, they provided some welcome spatiality to the sound. The main body of the midrange had excellent detail as well, adding some pleasing naturalness to both instruments and vocals.

The dynamics for the Eternal were good as well, as the deep bass drives the rhythm nicely, and the large driver does an excellent job of covering transitions from loud to soft and vice versa.

Listening to “Jesus, Etc.” by Wilco, I heard good separation between the various instruments and good soundstaging both right to left and front to back. The bass drum was nice and weighty, and the strings were placed nicely around the lead vocal.

I was impressed at how big and wide-open the Eternal sounded. At times I felt like I was listening to some open-back over-ear headphones. Songs like “Theme From Jurassic Park” sounded downright speaker-like.

On the other hand, I can’t say the sound was perfect. I found there was just a little too much emphasis in the mid-bass, which became distracting when listening to certain songs, especially Jazz and Acoustic tracks. I also found the upper mids to be just a touch exaggerated at times, especially with string parts.

That said, I found myself living with the boost in the upper mids because it added so much air and space to the presentation, something I liked.

The Wrap Up

In summary, I found the 7Hz Eternal to be both a good-looking and comfortable wearing set of IEMs. They have great soundstage and detail, but I found their bass (and upper mids to an extent) to be a little too elevated for my taste (I prefer a more balanced presentation). However, for those who like a livelier (read: fun) tonal balance combined with a bit of refinement, they may be just what the Dr. ordered.

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