Review: Acoustune HS1551 CU – Luscious

Acoustune HS1551 CU

Disclaimer: The Acoustune HS1551 CU came directly from Acoustune in exchange for this review. Headfonia is not related to Acoustune. This is the CU model of the HS1551 series, which costs around 500$.


Another day and another dynamic IEM is here at HFN. This time we have Acoustune’s beloved creation, the HS1551 CU. I love dynamic monitors and it’s good to see more of them in the market. They offer a more natural bass (most of the time, not every time) and spacious sound as a whole.

Single dynamic driver monitors have been quite popular recently, and they offer really good performance in the entry level region. But it’s not entirely limited to low budget levels, as there are also some single dynamic in ears targeting higher performance standards like the Acoustune HS1551 CU.


Acoustune operates in Japan since 2013, and focuses on delivering dynamic high resolution monitors to the market. They have 5 different models at the present time, all having single 10mm dynamic drivers. Acoustune believes that they have one of the best dynamic drivers in the market, and they remark that “the number of driver units cannot guarantee the sound quality“. Thus, seeking a complex solution would be pointless and unnecessary to them.

They’re using a diaphragm called “Myrinx” which comes from medical grade materials. This diaphragm was chosen because of its long term stability, and its benefits to get more resolution from the dynamic driver. The downsides of the dynamic IEMs are the resolution and clarity, but Acoustune planned to overcome those with their application. By implementing the medical grade material Myrinx on the dynamic driver membrane, they tried to achieve a dynamic and detailed sound with great staging and overall organic presentation.

Realizing the dreams of the Japanese audio engineers, the team is organized with audio industry veterans who all are experts at their job.

But have they achieved their goal? We will soon find out but give them credit, they tried something different haven’t they? Take Saegusa is their director of development and I was in contact with him all the time. Take-san is very responsive and communicative, and working together with him was very easy and smooth. I wish the best for our Japanese friends there.

Let’s begin.

Acoustune HS1551 CU

Acoustune HS1551 CU


I did not receive the full package of the earphones. Acoustune sent it with the leather carrying case and the tips only. In the complete presentation you get the package in a big briefcase which looks fantastic and premium. You can find its pictures on the web. It’s not that you can carry it around occasionally though. Still, it’s a great presentation of a product.

There are lots of silicone and foam tips supplied in the box with different sizes and types. If you’re going to purchase the Acoustune HS1551 CU, there is a process of tip rolling waiting for you. The leather carrying case is very practical and looks classy. It’s stylish, compact and protective at the same time. I absolutely loved it.


The Acoustune HS1551 CU has one of the most interesting designs I’ve seen in this market. It resembles to nothing I can think of, it certainly is unique. That sticking out thing on the outer body looks like a volume pot of some kind. The earphone is really an interesting piece to look at because of its shape and eye catching color scheme.

The structural design of the body consists of an inner chamber which has the dynamic driver inside, and an additional outer metal shell, enclosing and protecting it. This is done for less interference and for having a robust build. Acoustune gave the chamber a shape that can provide less resonance. The result is a consistent sound overall.

This is a %100 CNC milled brass housing, looking very durable and assuring. There’s also an “AL” version of this earphone, having an aluminum housing and by the comments I saw, it sounds different to this one. Brass is an interesting material. It’s not very popular and wide spreading among manufacturers, but some of them are into it and I saw it on the FiiO FH1 lately, although it was limited to the nozzle only.

Acoustune HS1551 CU

Acoustune HS1551 CU


The Acoustune HS1551 CU has a phenomenal build quality. The shell, the nozzle and mmcx sockets are all exceptional in terms of build and I think this IEM can be used for years without a problem. The OFC cable is also built perfectly, and it even feels like a headphone cable of high quality. It’s quite thick and it perfectly completes the unique and sturdy impression of the earphones overall. I have absolutely no complaints regarding material quality.

It’s not the most flexible and easy to carry cable however, so there’s a trade off right there. And because the cable doesn’t have memory wires, it’s not easy to wear the earphones over the ear and move around freely. The cable usually slides off from behind your ears where it should stay, and you find yourself adjusting it and getting it back to position. That is the case until you use the cable for quite a long time. When it gets its shape like a memory wire because of extended usage, the problem is over.

Fit is not the best and a little loose, and I actually thought the unique shape was going to be the cause of it. But it isn’t the shape that causes the loose fit. It’s because of the nozzles being rather short, and the silicone tips provided by Acoustune, although being very high quality and generous, don’t really help to achieve a deep, flush fit. The foam tips help in this regard and provide a deeper seal than silicone. Of course this is only my experience, everyone has a different ear anatomy and it will depend on the shape of your canals. Apart from that, the IEM surprisingly fits good to the other parts of the ear, especially the outer parts. It’s just the canal part that I didn’t find very good but as I said, your experience might be different.

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4.2/5 - (39 votes)

A keen audiophile and hobby photographer, Berkhan is after absolute perfection. Whether it is a full-frame camera or a custom in-ear, his standpoint persists. He tries to keep his photography enthusiasm at the same level as audio. Sometimes photography wins, sometimes his love for music takes over and he puts that camera aside. Simplistic expressions of sound in his reviews are the way to go for him. He enjoys a fine single malt along with his favourite Jazz recordings.


  • Reply April 17, 2018

    ohm image

    Wonderful photos, B.

  • Reply April 20, 2018

    Jonathan Z Bernabe

    Where can I get these in America?

    • Reply April 23, 2018


      I don’t think you can. But you can order from overseas.

      • Reply April 23, 2018

        Jonathan Z Bernabe

        I figured haha, thanks anyway

    • Reply April 23, 2018


      only online I think.

  • Reply April 21, 2018


    Great review. The Acoustune has a nice, wide soundstage accompanied by a smooth and warm sound. It does have its fair share of flaws, but it is a good value at its asking price.

    • Reply April 23, 2018


      Thank you and thanks for the comment. It’s very nice.

  • Reply April 23, 2018


    Wow this is an awesome review… thank you very much for this!! Also if possible, can you plse do a review on JVC’s new iem the FD01? Heard that its quite nice too

    • Reply April 23, 2018


      You’re welcome.

      Let’s see what we’re going to get. Lots of gear 🙂

  • Reply May 25, 2018

    Kevin Glimmersten

    I’ve ordered this IEM and I’m supremely excited.

    One question; does the imaging and soundstage depth allow for that alluring 3D-sound that’s in higher end earphones?

  • Reply December 8, 2018


    Will this pair great with the QP2R?also what do you think of the QP2R?is it a good dap?

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