STEREO GUIDE verdict
+ ultra transparent, high resolution
+ insane grippy speed and fine dynamics
+ deep, powerful yet fast bass
+ well adjustable, very comfortable fit
- mercilessly transparent for vintage recordings
- Capsules protrude far from the ear
Sound: tonal balance / transparency9.5
Sound: Bass / Dynamics9.4
Ease-of-use / Connectivity9
Price / Performance9
The last decade saw new headphone brands spring up like mushrooms after listening to music became an important thing after the rise of iPods and smartphones. That might be one reason why Japanese manufacture Acoustune appearing on the market in 2013 went mostly unnoticed. In Japan they are mostly famous for more or less expensive passive in-ear monitors. And the hype was all about Bluetooth, True Wireless and noise-canceling, was it not? So anyways, the new Acoustune HS1750Cu, which we had the chance to review after they were introduced to the European market, is anyways a pretty special product.
The elaborate construction and the unique, technology-driven design also play their part. Because the IEMs, which are handcrafted in Japan, are by no means inconspicuous. Even the HS1750Cu model, which represents something like the entry into Acoustune´s high-end league coming in at an ambitious retail price of 700 bucks. One might think these wired things in your ears evolve directly from some science fiction cartoon. And if you happen to read the specs and technical whitepaper of their diaphragm structure and choice of materials, you might think we are dealing with high-end loudspeakers.
The technology is in the material
While other high-end in-ears try to justify their four-digit price tags with electrostatic tweeters, a whole bunch of drivers and crossover filter, Acoustune declare a pretty down-to earth electrodynamic full-range transducer to be their preferred choice in terms of maximizing sound quality.
Thus, the HS1750Cu also contains a single dynamic driver unit with a 10 mm diaphragm. However, this one has it all in the truest sense of the word: Acoustune use an exclusive called Myrinx. This is said to be a special polymer of the type used in the medical field, for example during operations to replace human membranes. The transducer itself is designed to combine the precision and long-term stability of high-tech materials with some bionic touch of a human eardrum´s principle. And eardrum is exactly what “Myrinx” translates to.
But the quest for special material science does not end there: The developers are convinced that shape and material of the enclosure behind the diaphragm have a decisive influence on the sound character. The addition of “Cu” in the product name HS1750Cu stands for copper and is intended to provide maximum bass power and impulse accuracy in the lower frequency range. In fact, the entire inner volume is made of some brass-like solid copper alloy.
A new level of manufacturing
However, such an alloy, in turn, is not suitable for making the entire in-ear-monitor from it. Therefore, Acoustune´s developers unceremoniously designed a two-part outer casing made of aluminum. It is created in-house at Acoustune´s factory from the solid aluminum block using ultra-high precision CNC milling. The ingenious design ensures that it clamps the inner capsule without influencing it acoustically. This is also the reason for the somewhat science fiction-like look of the overall construction. From some perspectives, the design even resembles an engine.
So we should talk about efficiency: Despite their rather modest impedance of 24 ohms, the Acoustune S1750Cu are among the loudest in-ears we have tested so far. Even at the dynamically limited output jack of modern smartphones max SPL itself was pretty satisfying. From an audiophile point of view, this would of course be a senseless waste of potential. However, this could be an argument for temporary operation on the smart device for all those who sometimes travel without an additional DAC.
Amazingly comfortable to wear, 9-fold
Admittedly, we were skeptical as to whether the in-ear-monitors, which are milled from aluminum and have an eye-catching shape, could be placed comfortably and securely in the ear canal. In practice, however, this was super easy and left nothing to be desired from any of our test staff.
This is ensured on the one hand by the nine different adaptors included. The manufacturer proudly points out that all pads were designed and tested by the in-house development department. The adapters are not only finely differentiated in size, but also come in from different material and shape so we can very well imagine that every ear will find its matching one here.
Lord of the rings
First, there are memory foam rings that adopt temporarily to the shape of the ear canal. Many users might prefer those because they avoid the feeling of isolation. The classic rubber adapters turn out to be a bit stiffer. However, they are included in five sizes and should have the best chance of a tight fit. Those who prefer a compromise will still find three variants made of softer, thinner silicone. To avoid confusion, these are made of semi-transparent material while the aforementioned ones are black.
If you just halfway hit the size of the ear canal, the Acoustune HS1750Cu are easy to insert without any difficulty, twisting or pressing. The braided connection cable has to be routed behind the auricles, the rather wide aluminum constructions blend in amazingly ergonomically. Since the capsules stick out quite a bit and don’t rest against the inside of the ear, you practically don’t feel them. However, this also means that you can no longer lie on your ear sideways with it. If you like to fall asleep with in-ears or rest your head on a pillow on an airplane, you won’t be happy with the Acoustune.
This is what the Acoustune HS1750Cu sounds like
In the listening test, the HS1750Cu set off on a triumphant march. From tonal balance point of view, they somewhat resemble the Sennheiser IE 600 and Sennheiser IE 900 at first. They deliver highly accurate impulses and ultimate dynamics like you would expect it from a stage monitor. In addition, there is very exalted but superclean brilliance and a driving, ultra-deep and rich bass.
From hip hop to classical, no matter which genre you might want to listen to, Acoustune´s HS1750Cu amazed with a grippy, fast sound and ultimate resolution. We would describe it as a real pick-me-up that immediately transports the emotions of the music to your brain instead of lulling the listener. Those who are used to other, warmer-tuned in-ear-monitors might find them to be a bit on the bright side. But as this was accompanied by an amazing cleanliness, transparency and never hissed, we can recommend the Acoustune HS1750Cu without reservation even for sensitive audiophile ears.
Compared to the aforementioned Sennheisers, this was also the main difference: Despite all tonal and dynamic similarities, the Acoustune sounded a touch more elegant and refined, and also offered a bit more fundamental warmth. It only didn’t help with the somewhat hefty treble of some pop and rock recordings from the 1970s and 1980s. Peter Gabriel’s III and Led Zeppelin’s “Houses Of The Holy” sounded as they have to sound over high-resolution studio monitors: Solidly, aggressively brilliant on the one hand, a bit overproduced on the other.
Diving deeper into the music
The fact that the Acoustune is powerfully equipped in the low bass is actually only noticed in recordings in which corresponding frequencies occur at all. In other words, there is no artificial bass emphasis. But if the recording is up to the task, you will experience an abysmally deep, rich bass that is perfectly integrated timing-wise.
Staging and imaging were less attuned to the directness of a stage monitor. It rather resembled an optimized mastering studio: tending to be close but never intrusive, with implied spaciousness but no exaggerated staggering in all three dimensions.
Thus, at the end of the listening test, we can only express our appraisal: Acoustune´s developers composed top-notch high-resolution in-ear-monitors with audiophile qualities and grippy emotions. This immediately makes you forget all even more complex constructions. Especially if you are an in-ear fan looking for the virtues of a monitor without having to accept the disadvantages like harshness and directness.
Alternatives to the Acoustune HS1750Cu
There is a lot of renowned competition in the IEM segment between 500 and 1000 bucks. Our top recommendations in the passive segment and the references for listening comparison are the Sennheiser IE 600 and the Beyerdynamic Xelento 2nd generation (The latter used without its bluetooth neckband).
Those who prefer a softer, more sober tuning or like to listen to older pop/rock recordings with a shot of beautifyed sound will probably be happiest with the Beyerdynamic. The Sennheiser IE 600 and the Acoustune are quite similar. Here, it’s ultimately a matter of taste: a slight loudness and unfiltered directness like the Sennheiser? Or even more resolution and a slightly richer sound with the Acoustune HS1750Cu?
Technical data Acoustune HS1750Cu
- Retail price: 700 dollars/pounds/euros
- Type: In-Ear
- Transducer principle: Dynamic
- Weight: 7.6 g each without cable
- Features: 8 pairs of silicone ear adapters (S, M, L), 1 pair of foam adapters , hardcase.
- More at: www.cma.audio