Acoustune HS1750CU
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Introduction ~ preferences
Let's make no mistake, each person who's into the hobby of listening to gear has a reason for doing so. Be it to gain new experiences or perhaps, to find the mythical creature known as the all elusive 'Endgame'. Regardless, the joy of the hunt is something to be had.
My approach towards this (seemingly) endless quest is a path trekked by many, perhaps in futility, towards the imminent arrival upon the latter. What I look for in an IEM is versatility and uniqueness. A set should have its own flavor of sound and execute it well without compromise in other respects to achieve this.
I try to keep a small and manageable collection ––for each must contribute something different–– which gives me time to appreciate how an individual set shines in its own way. After all, what good can an IEM do if its sitting pretty but neglected?
I understand that this may be an unpopular sentiment in a hobby oft associated with consumptiveness, however, as it is as personal as it is subjective, let's just say that...to each their own.
A short note
All reviews are biased to a degree because reviewers are human, each with their own preferences and ears.
To give some context to the following points, I tend to prefer V-shaped to Neutral-bright IEMs. Treble-head is not a term I would use to describe my tastes but depending on how you define it, that may not be far off––the IE600 has nice treble.
Staging, imaging and technicalities-wise, what I really value is how engaging, how immersive the imaging and stage of an IEM is. Having good detail retrieval in a set is always great and also a good differentiator of quality.
Do note that I any references made are based on the Harman target (2019) for ease of reference.
Disclaimer
This is a personal set which I purchased from Zeppelin & Co. in Singapore. As such all opinions expressed are my own. My view may differ from yours, it is a subjective hobby after all, but I would be happy to know what you think below.
Lastly, this is my first time posting here so do bear with me if there are some areas that need brushing up
)
.
.
Now that we've established these, let's get on with it, shall we?
.
.
Build quality:
Nothing to complain about here. The machine work and finishing by Acoustune is a whole act on its own. What they've done here is just excellent work ––and that would be the same if this existed at any other price point–– their reputation for build quality is unquestionably on display yet again.
Accessories are rather superfluous, with the metal case and all, but it does sell the whole unboxing experience and communicates strongly to the customer that their purchase ––and by extension them–– are being thought of and regarded with care and attention.
Stock cable is robust with minimal memory, however, I did find it to be uncomfortable for prolonged use. Your mileage may vary on this.
Fit is the issue for me, it requires some playing around to get the IEMs to fit comfortably and even then, I do come off listening sessions with pain in the tragus. Thankfully, a good seal with the stock tips was quite easily achieved, though I can't say the same about fit comfort.
Tonality:
This set is warm. The bass boost is centered on the mid bass and that means Brass instruments, Bass guitar, Piano and Drums are all imbued with a satisfying sense of fullness. Drum hits are commandingly planted and strings have a deep and lush resonance. Bass guitars are visceral but also audibly separated from the drum machine.
On the right track, this thing can really slap.
Treble isn't smoothed like HT, rather, it is elevated at certain points (as seen from the FR). At times instruments can come across as slightly plasticky which goes both ways. At best this makes skin instruments (toms, bongos etc.) sound elastic in an ever so slightly exaggerated manner, at worse it imparts an unnatural "thwang" not dissimilar to the effect that you get from messing around with a tensioned rubber band. Upon first listen, I thought that this single DD IEM had the uncanny ability to replicate BA Timbre!
Air and extension in the higher registers is sufficient but lacking to my preference. Cymbal crashes are rich but lacking shimmer which makes them sound a tad dryer than they really should be. The lack of airiness ––which is what gives a sense of height–– is lacking and consequently, the set struggles in this regard as well. I must say, though, that extension is not lacking, just that the quantity present leaves more to be desired.
Staging & Imaging:
As for soundstage, most music sounds intimate, like being in a basement with a live indie gig. It gives a sense of being in a chamber and the edges of the stage are well diffused which avoids the feeling of being boxed in.
This set does a complete flip when playing tracks recorded in large, cavernous venues (Theatre, Dome etc.) wherein the set's tendency to diffuse the edge of its soundstage makes such recordings sound quite holographic. That's a term I will only associate with sets like the Andromeda 2020 and something that Harman tuned sets cannot recreate at lower listening volumes (or so I've experienced).
The imaging is inverted front to back. While conventional Harman tuned sets have treble and vocals upfront with bass and drums pushed back, this does just the reverse. This leaves us with a strange sound stage where vocals are pushed back, drums and bass are distinctly further behind the vocals but the thumps and visceral qualities that they possess are very forward ahead of them, all without muddying the most forward elements of the treble (voices, percussions etc.). It can be described a 'colored' since this emphasizes specific elements of music more than reference.
This set doesn't have the largest stage but is noticeably strong in one aspect, the ease of imaging. It images instruments rather strongly, helped along by its good dynamics and thus macrodynamic contrast, and does so at lower volumes as well. Each track requires careful volume balancing to get the most out of its imaging and staging. Due to how our ears' sensitivity to various sound frequencies varies relative to volume (equal loudness curve), this set's bass shelf will completely drown out details and compress the sense of staging at higher volumes. As an oversimplification, this is because for every unit increase in volume (dB), we become more sensitive to bass than treble so a set will sound more and more bassy as we crank the volume up.
What this leaves us with is quite a queer set indeed, very track dependent, very volume dependent. keep a DAC with good linear volume control or a mobile EQ app around to help make quick fine adjustments.
Music pairings & Technicalities:
This depends on what you define technicalities as. It is technical in that it separates individual instruments well. Every element of sound sounds distinct and contrasting. These macro details are well resolved but lack the 'edge' which gives that sense of clarity. This set is analogue sounding and relaxing, I would liken it to the audio equivalent of applying a mild bokeh effect to your music. Everything is there, distinct but blurry with only the key parts (vocals, main instruments) are in focus, the rest (synth etc.) dances around.
This set does not fit libraries with lots of high frequency details (cymbals etc.) as they don't have the airy resonance of BA sets. They also tend to perform poorly with bass heavy tracks (metal etc.), the sheer amount of double peddling and how the bass is usually mixed in this and similar genres usually ends up drowning the already recessed treble.
What this sets does well is jazz, indie music, post rock, funk, classical, EDM and Disco. I find that these genres generally tend to have the right instruments, mixing levels and acoustics that play into this set's strengths.
That is the gist of this set, it sounds great when played with tracks that synergize with its quirks and sort of falls apart and very quickly regresses into Je ne sais quoi when used otherwise. Though whatever that may be, it will certainly be a far cry from what its asking price commands as well as its full potential.
Conclusion:
This set may or may not be for you so it is highly recommended to try and get a demo for it before committing to a purchase, especially with the aforementioned issue regarding fit comfort.
The HS1750cu gives you a unique experience in a market saturated with Harman and other similarly tuned sets. While it may often be caught out on the wrong foot by competitors from the increasingly competitive chi-fi space, it is a niche set that offer something...different, in a good way.
Now, that's something which makes this an interesting one to check out.
Let's make no mistake, each person who's into the hobby of listening to gear has a reason for doing so. Be it to gain new experiences or perhaps, to find the mythical creature known as the all elusive 'Endgame'. Regardless, the joy of the hunt is something to be had.
My approach towards this (seemingly) endless quest is a path trekked by many, perhaps in futility, towards the imminent arrival upon the latter. What I look for in an IEM is versatility and uniqueness. A set should have its own flavor of sound and execute it well without compromise in other respects to achieve this.
I try to keep a small and manageable collection ––for each must contribute something different–– which gives me time to appreciate how an individual set shines in its own way. After all, what good can an IEM do if its sitting pretty but neglected?
I understand that this may be an unpopular sentiment in a hobby oft associated with consumptiveness, however, as it is as personal as it is subjective, let's just say that...to each their own.
A short note
All reviews are biased to a degree because reviewers are human, each with their own preferences and ears.
To give some context to the following points, I tend to prefer V-shaped to Neutral-bright IEMs. Treble-head is not a term I would use to describe my tastes but depending on how you define it, that may not be far off––the IE600 has nice treble.
Staging, imaging and technicalities-wise, what I really value is how engaging, how immersive the imaging and stage of an IEM is. Having good detail retrieval in a set is always great and also a good differentiator of quality.
Do note that I any references made are based on the Harman target (2019) for ease of reference.
Disclaimer
This is a personal set which I purchased from Zeppelin & Co. in Singapore. As such all opinions expressed are my own. My view may differ from yours, it is a subjective hobby after all, but I would be happy to know what you think below.
Lastly, this is my first time posting here so do bear with me if there are some areas that need brushing up
).
.
Now that we've established these, let's get on with it, shall we?
.
.
Build quality:
Nothing to complain about here. The machine work and finishing by Acoustune is a whole act on its own. What they've done here is just excellent work ––and that would be the same if this existed at any other price point–– their reputation for build quality is unquestionably on display yet again.
Accessories are rather superfluous, with the metal case and all, but it does sell the whole unboxing experience and communicates strongly to the customer that their purchase ––and by extension them–– are being thought of and regarded with care and attention.
Stock cable is robust with minimal memory, however, I did find it to be uncomfortable for prolonged use. Your mileage may vary on this.
Fit is the issue for me, it requires some playing around to get the IEMs to fit comfortably and even then, I do come off listening sessions with pain in the tragus. Thankfully, a good seal with the stock tips was quite easily achieved, though I can't say the same about fit comfort.
Tonality:
This set is warm. The bass boost is centered on the mid bass and that means Brass instruments, Bass guitar, Piano and Drums are all imbued with a satisfying sense of fullness. Drum hits are commandingly planted and strings have a deep and lush resonance. Bass guitars are visceral but also audibly separated from the drum machine.
On the right track, this thing can really slap.
Treble isn't smoothed like HT, rather, it is elevated at certain points (as seen from the FR). At times instruments can come across as slightly plasticky which goes both ways. At best this makes skin instruments (toms, bongos etc.) sound elastic in an ever so slightly exaggerated manner, at worse it imparts an unnatural "thwang" not dissimilar to the effect that you get from messing around with a tensioned rubber band. Upon first listen, I thought that this single DD IEM had the uncanny ability to replicate BA Timbre!
Air and extension in the higher registers is sufficient but lacking to my preference. Cymbal crashes are rich but lacking shimmer which makes them sound a tad dryer than they really should be. The lack of airiness ––which is what gives a sense of height–– is lacking and consequently, the set struggles in this regard as well. I must say, though, that extension is not lacking, just that the quantity present leaves more to be desired.
Staging & Imaging:
As for soundstage, most music sounds intimate, like being in a basement with a live indie gig. It gives a sense of being in a chamber and the edges of the stage are well diffused which avoids the feeling of being boxed in.
This set does a complete flip when playing tracks recorded in large, cavernous venues (Theatre, Dome etc.) wherein the set's tendency to diffuse the edge of its soundstage makes such recordings sound quite holographic. That's a term I will only associate with sets like the Andromeda 2020 and something that Harman tuned sets cannot recreate at lower listening volumes (or so I've experienced).
The imaging is inverted front to back. While conventional Harman tuned sets have treble and vocals upfront with bass and drums pushed back, this does just the reverse. This leaves us with a strange sound stage where vocals are pushed back, drums and bass are distinctly further behind the vocals but the thumps and visceral qualities that they possess are very forward ahead of them, all without muddying the most forward elements of the treble (voices, percussions etc.). It can be described a 'colored' since this emphasizes specific elements of music more than reference.
This set doesn't have the largest stage but is noticeably strong in one aspect, the ease of imaging. It images instruments rather strongly, helped along by its good dynamics and thus macrodynamic contrast, and does so at lower volumes as well. Each track requires careful volume balancing to get the most out of its imaging and staging. Due to how our ears' sensitivity to various sound frequencies varies relative to volume (equal loudness curve), this set's bass shelf will completely drown out details and compress the sense of staging at higher volumes. As an oversimplification, this is because for every unit increase in volume (dB), we become more sensitive to bass than treble so a set will sound more and more bassy as we crank the volume up.
What this leaves us with is quite a queer set indeed, very track dependent, very volume dependent. keep a DAC with good linear volume control or a mobile EQ app around to help make quick fine adjustments.
Music pairings & Technicalities:
This depends on what you define technicalities as. It is technical in that it separates individual instruments well. Every element of sound sounds distinct and contrasting. These macro details are well resolved but lack the 'edge' which gives that sense of clarity. This set is analogue sounding and relaxing, I would liken it to the audio equivalent of applying a mild bokeh effect to your music. Everything is there, distinct but blurry with only the key parts (vocals, main instruments) are in focus, the rest (synth etc.) dances around.
This set does not fit libraries with lots of high frequency details (cymbals etc.) as they don't have the airy resonance of BA sets. They also tend to perform poorly with bass heavy tracks (metal etc.), the sheer amount of double peddling and how the bass is usually mixed in this and similar genres usually ends up drowning the already recessed treble.
What this sets does well is jazz, indie music, post rock, funk, classical, EDM and Disco. I find that these genres generally tend to have the right instruments, mixing levels and acoustics that play into this set's strengths.
That is the gist of this set, it sounds great when played with tracks that synergize with its quirks and sort of falls apart and very quickly regresses into Je ne sais quoi when used otherwise. Though whatever that may be, it will certainly be a far cry from what its asking price commands as well as its full potential.
Conclusion:
This set may or may not be for you so it is highly recommended to try and get a demo for it before committing to a purchase, especially with the aforementioned issue regarding fit comfort.
The HS1750cu gives you a unique experience in a market saturated with Harman and other similarly tuned sets. While it may often be caught out on the wrong foot by competitors from the increasingly competitive chi-fi space, it is a niche set that offer something...different, in a good way.
Now, that's something which makes this an interesting one to check out.
Acoustune HS1750CU Review: Tastefully Flavored
Prelude:
Even in an age where many are striving for high driver counts and experimenting with various different combinations of driver types, few companies stay true to the “original” single dynamic driver design. Three such include DITA, Sennheiser (IE lineup), and Acoustune.
Acoustune, an IEM company founded in 2013 in Japan, also subsidiary of NDICS, parent company of Pentaconn. Not only do they adopt some of their sister company’s products, such as the 4.4mm plug and the Ear connector, they also showcase their own Myrinx diaphragm material and unique two-piece metal shell design. Many of their products are highly recognized and popular in East and Southeast Asia, such as their old mid-tier IEM HS1551CU, previous flagship HS1697TI, entry-level HS1300SS, current flagship HS2000MX (MkII), and their newest mid-level, and the star of the show, the HS1750CU.
I don’t know any Acoustune dealers in North America, or Europe (if you do, please tell me in the comments), so if you are in these regions and want to get one, you might have to get it from some dealer in Asia (Zepp & Co., DMA Audio, e-earphone etc.). The MSRP is ¥67,320 JPY, around $475 USD, but given that this price is for Japan (original country of manufacture), you are probably looking at a single-DD earphone worth between $550 - $600 USD on the international market.
Unboxing:
Acoustune’s unboxing experiences have a throughline: a paper sleeve that wraps around a black rectangular cardboard box. Inside that box we have a black metal storage case, and the IEMs, with another carrying case, cables and eartips inside. The only exceptions to this are the 1300SS (no metal case), the RS series, and the HS2000MX (uses a fancy wooden box instead of the metal case). The presentation and layout are really nothing special, in fact, I think there can be more work done here (more organized layout, special box texture etc.).
Accessories:
But the accessories themselves are actually good/great. The HS1750CU comes with a square fabric/leather carrying case with a magnetic flap, 6 eartips, their 8-braid OFC+SPOFC ARC51 cable, and the aforementioned metal case.
The metal case does remind me a bit of Noble’s flagships, of how they all come with a large case and a small case inside. However, I do think that the metal box Acoustune ships is much more premium than the plastic Nanuk 903 case Noble provides, and much more usable (that Nanuk case is fit more for an over-ear headphone than an IEM). I can fit up to 6 IEMs (with cables) into Acoustune’s metal case, or 4 IEMs plus a DAP, and can easily slide this into any backpack, making it the perfect box to bring to an audio shop or expo. The Nanuk 903 that Noble uses is far too thick to be backpack-able, leaving me with a question: is this much protection actually necessary? While Acoustune’s case may not be practical for people who have very few or have a lot of IEMs, it is a fantastic addition to my collection as a travel case for my favorite earphones (just 5).
The square carrying case is not the largest, yet not the smallest I’ve used. Most of it is constructed out of fabric, with some leather lining and a metal, branded plaque on top. Even though this isn’t the most premium case I’ve touched, it is sturdy enough and provides adequate protection for the IEMs themselves and the stock cable which it fits almost perfectly.
Speaking of the cable, it is quite chonky. It is an 8-wire OFC + Silver Plated OFC cable (each wire has a blend of both). Although no specifications list it, my guess for its wire gauge is around 26AWG. It is soft and pliable, with little memory retention. Very little complaints on the usability front, except for how the chin slider takes quite some force to move up and down, and that the cable itself is a bit heavy. The pins are Pentaconn Ear, making your aftermarket cable choices limited to manufacturers who take such orders, or ones that use swappable connector systems (i.e. EA ConX), or simply buy an adapter. The stock cable, the ARC51, is terminated in 3.5mm, and its aftermarket counterparts, the ARC52 and 53 are terminated in 2.5mm and 4.4mm respectively. Do note that the ARC51 doesn’t have earhooks, while the 52 and 53 do. Overall, the ARC51 scores passing marks for a stock cable.
Other accessories include a full set of 5 AEX07 eartips, 1 pair of foam tips (both stored in a matte black plastic case), a (faux) leather cable clip, and Velcro cable ties. The AEX07 eartips, unfortunately get hot inside my ears after some time. This characteristic is usually attributed to eartips using middling- to low-quality materials. Acoustune’s AEX70 (sold separately) has much better long-term comfort, as it has the same material as the JVC FX-10++ (my all-time favorite eartip). However, the eartip case and the cable clip are accessories that are very practical, yet often not provided. The SoftEars Twilight and the EA Gaea, IEMs I’ve reviewed in the past that are much more expensive than the HS1750CU, don’t have either of these.
Acoustune does provide a modest number of accessories, with most being useful or necessary. At this price point, I don’t think there is much more to ask for.
Build Quality:
No sugarcoating here, the HS1750CU is built excellently. The shiny copper parts have all been very well-polished, same with the aluminum shell, showing net zero surface imperfections when I unboxed it. The aluminum parts are also sandblasted, so fine to a point where my finger glides on it. There are very few aluminum parts I’ve touched that come close to this level of surface texturing (the L&P W2 might be the closest). The HS1750CU is what I call a benchmark for build quality, regardless of price. My HS1300SS also shares the same level of build quality, showing that Acoustune pays attention to every detail in all of their products. I can see why Acoustune’s “HS” earphones are all part of the “Master Series” as they are indeed masterfully crafted.
While the earpieces themselves are built excellently, the rest of the accessories are no slouch either. The y-split, pin and plug shells are finished with brushed aluminum shells, providing extra grip when you hold on to them. Per what my distributor told me, it also seems like the cable is machine-braided, as each braid is extremely tight and uniform to level I haven’t seen before in any hand-braided cable. The leather lining on the carrying case are ruler-straight, so are the stitches that hold it down. The large metal case also has no signs of surface imperfections, although I believe that the plaque is off-center (by a millimeter or so).
I’ll say that the HS1750CU’s build quality can be an independent reason to buy it. It has comparable, if not even better build quality than many kilobuck IEMs (damn your resin shells).
Fit:
The HS1750CU fits fairly well in my medium-sized ears, with no parts causing direct discomfort. However, it may not fit you because: 1. It takes up quite a lot of concha area and 2. It may push against your tragus as it has an edge sticking out at the bottom. And it’s 9.1 gram raw earpiece weight is definitely not making it easier to wear for smaller ears.
Another potential point of concern is the screws. The screw at the top, right next to the Ear connector, protrudes outwards significantly. It causes minor discomfort when you hold on to the earpieces themselves. The other two screws on the body also protrude outwards, however not to the same extent. This design flaw is not present on any Acoustune IEMs prior to the HS2000MX.
I’m quite a fan of Acoustune’s “Cyberpunk”/”Iron Man”-style design, but am not sure if eargonomics were a priority in the design process.
Equipment:
DAC/Amps: L&P W2, ddHiFi TC44C (Blue), iBasso DX170, Shanling H5
OTG Cables: ddHiFi TC05 (Type C), MFi06s (Lightning)
Sources: MacBook Pro 16”, iPhone 11 (Apple Music Hi-Res Lossless)
IEM Cable: Acoustune ARC53 (P-Ear to 4.4mm)
Eartips: JVC Spiral Dot FX-10++ (Size M)
Shown above is the frequency response and channel matching of the HS1750CU measured off an IEC-60318-4 clone coupler. The Bold Green line is my personal target, while Blue and Red stand for Left and Right channels respectively. The closer the Blue and Red lines are, the better the channel matching; the closer both lines are to the Green target line, the more “neutral” these IEMs sound (theoretically).
Tonality:
The 1750 can be described as a neutral-warm IEM, as while I don’t feel like the treble is lacking anyhow, the focus of this IEM is primarily on the mid-low frequencies, especially vocals.
The bass on the 1750 is very solid. It sounds much bassier than the 4dB it graphs with. There is adequate thump, slam and rumble. Yet the most impressive part of the 1750’s bass is its articulation. Notes are exceptionally well-defined thanks to its fast attack and decay. Yet its transient speed isn’t too fast to a point where sheer meat behind the bass is erased (unlike most BA bass I’ve heard). While this bass response won’t satisfy the most ardent bassheads, it is for sure one I can live with. 8 out of 10.
The mids on the 1750 is definitely not as bad as the graph shows. The mids do have an early pinna gain at ~2.5kHz of around 8.5dB, surely makes male vocals sound a bit thin. Yet its 4dB dip at 3.8kHz also reduces shoutiness for female vocals. On first listen, the 1750’s midrange does sound a bit wonky, relative to the scientifically-tuned MoonDrops. However, the 1750’s midrange texture is commendable. It has fantastic transient control, thus microdetails are resolved adequately without sounding too sharpened and unnatural. I also hear a slight hint of sweetness for female vocals, similar to that of the Tanchjim Oxygen’s. This might be due to dynamic drivers’ higher second-order harmonic distortion (the same reason why tubes sound sweet). The midrange on the 1750 is simply very well-done. 9 out of 10.
Treble is where the 1750 retains the “Acoustune” flavor: a big peak around 5.5k, with relatively good extension afterwards. Some say that this peak is tuned intentionally to emphasize instruments. Indeed it does that, however, at times I think it’s too much. The massive gain also boosts plastickiness, making this region sound thin and splashy. That aside, the 1750 has good extension upwards. I hear adequate amounts of air and enough crispiness to notes. The 1750’s treble is good, but I think if Acoustune reduced the Q-values of the 5.5k peak, it can sound even better. 7-8 out of 10
Timbre on the 1750 is generally good, even though it does sound somewhat thin and plasticky in the mids and treble. Where I think the 1750 does superb is in its coherency. Transients across the entire frequency range are basically the same: fast, but not too fast to a point where texture starts fading. 8 out of 10, I’ve heard better, but have heard a lot worse.
To sum it all up, the 1750 sports a very solid v-shaped tonality. It has adequate extension on both ends, and a generally good midrange to complement it. While it is definitely not perfect, I think some small tonal quirks at 600 bucks is tolerable.
Technicalities:
Technicalities on the 1750 are excellent. Dynamics, imaging, resolution, it has it all, in spades.
For dynamics, the 1750 does superb in both macro and micro. While many people may associate dynamics (primarily macrodynamics) with the amount of bass or slam an earphone has, upperdynamics harmonics also have macrodynamics. An earphone’s ability to accurately resolve sudden changes in volume is its explosiveness, is its macrodynamic ability, and I think that the 1750 is outstanding in this aspect, even in absence of a large bass shelf. Microdynamics are basically the opposite of macro. It is more about the minute shifts in loudness of microdetails. Often I use vocal inflections to measure microdynamics, as it is amongst the most apparent things I hear. And again, the 1750 does pretty well. All in all, the 1750 scores a 9 for dynamics, as I still think there are IEMs out there that are even more explosive and well-textured, such as the Gaea.
Even though the 1750’s stage width isn’t the largest I’ve heard thus far, it has excellent layering and positional accuracy, while also being capable of rendering height and diffusal. That is quite a lot of terms for imaging, so here’s a breakdown: width is basically how far instruments are away from the ear laterally. Layering is pretty self-explanatory. Positional accuracy involves both precise localization of individual instruments often in the background, and continuity between left and right channels (able to hear left-right pans correctly). Height is the vertical space an earphone can create. And finally diffusal is how the farthest instruments slightly blend into the background, making the stage sound like it doesn’t have a restricted border, thus creating that feeling of spaciousness. Initially the 1750 didn’t impress me, because it didn’t have a particular imaging aspect that struck me. Yet closer listening suggests that it is simply an all-rounder; there’s nothing much to fault about its imaging performance. 8-9 out of 10.
Resolution is probably where the 1750 truly shines. All notes are cleanly presented with adequate microdetails following thanks to its fast transients. Paired along with its excellent layering abilities, this lands the 1750 at around a high-9 out of 10, with that final point taken away simply because I’ve heard a few monitors that do have slightly more internal detail (Gaea, Fourte, Skyline, Phönix etc.).
Suffice to say, the 1750 comfortably seats itself amongst the “most technical sub-kilobuck monitors”.
Comparisons:
Note: the frequency responses shown below are the averages of 5 takes with varying insertion depths. The bold green line is the frequency response of the 1750, while the bold blue line is the frequency response of the compared earphone. Earphones that have only been demoed do not feature frequency responses, as I might not be in the right conditions to test them.
Sennheiser IE 600: In some ways the IE 600 and the HS1750CU are very similar. Both are highly resolving (the IE 600 out resolves the 1750 by being just a bit cleaner and brighter) and both are very dynamic (I might give the 600 an edge on macrodynamics). However, I’d say the 1750 has a better soundstage in terms of both width and layering. Tonality wise, the 600 is V-shaped with excellent extension on both ends, while the 1750 is flatter across the board, aiming for a slightly more neutral/warmer signature. On the non-sound front, the 1750 does provide a good set of accessories, while I basically didn’t use the 600’s tips, cable and case (they were all kind of bad). However, the 1750 is a medium-large IEM, while the 600 fits in literally all of my friends’ ears and many of them have very small ears.
SoftEars Twilight: If we say the 1750 is a warmer IE 600, then the Twilight is a warmer 1750. The Twilight has setbacks in extension and resolution, but is notably better in soundstage width, height, diffusal, timbre, and general ease of listening. Objectively speaking, the 1750 is a direct competitor to the Twilight, even though there is a 300-dollar price difference between them. In terms of the non-sound aspects, the Twilight takes up less concha area, but might push against your Inferior Crus. I believe that the 1750 is built just slightly better (the metal parts are extremely clean, unlike the Twilight’s Y-split, where two large machining marks were present). The 1750 also has better accessories. The Twilight is a good option for those who want to listen to music for hours on end, while the 1750 is better for those who want some more excitement.
Acoustune HS1300SS: When I first looked up the FRs on crinacle’s website, I thought that the 1300 and the 1750 would sound similar to one other. However, A/B testing shows that the 1750 is simply cleaner than the 1300, literally everywhere. Less mid-bass, lower Q-values in the high-mid and treble regions, less timbral grain, snappier in terms of transients, generally more resolving with more microdetails, and better positional incisiveness. Thus it is adequate to say that the 1750 is a direct refinement to the 1300. Do put in your mind that the prices of two 1300s roughly matches the price of one 1750, so it is up to you which one is worth more.
Acoustune HS1790TI: To be honest, I didn’t quite like both of the 1790TIs I demoed. The 1790 reduces both bass quantity and ear gain. However, the 1790 is not exactly a relaxing earphone to listen to, as the treble is basically identical to the 1750. Thus there is this weird mixture of flatness and aggressiveness, ruining the 1750’s good balance between each frequency. I didn’t find the 1790 to be anyhow more technical than the 1750 either. Unless if the 1790’s sound is exactly what you are looking for, I don’t think the 400-dollar price hike is justifiable.
Acoustune HS2000MX MkII (ACT05): The 2000 MkII’s tonality sits just in between the 1790 and the 1750, having the same midrange recession as the 1790, while retaining the bass performance of the 1750. Yet, I’d still prefer the 1750’s tonal balance. Tonal balance isn’t only about the amount of each frequency band, but also about how they harmonize with each other. The 1750 does this well in that the whole earphone sounds slightly aggressive, and that sensation is only created when there is adequate gain in all frequency bands. Both the 1790 and the 2000 MkII sound awkward because the mids are recessed, thus having parts that are aggressive, but also parts that are relaxing. Technicalities-wise, the 2000 MkII sounds ever so slightly cleaner than both the 1790 and the 1750. But beyond that, there is hardly any difference. Acoustune’s high-end products don’t seem to really surpass their low-end/mid-tier ones. They simply offer a slightly different flavor. Now the one thing the HS2000MX has that is totally unique is the ACT system. Unlike traditional systems which either change the damping values of filters or impedance of certain crossover routes, the ACT system allows the users to change the entire acoustic chamber, transducer included. This allows the earphone’s sound to change drastically. However, you do have to pay extra for each ACT capsule, and they cost about the same price as a brand-new 1750, some of which are even more expensive. Not to mention that the 2000 Mk II (ACT05) itself costs around 1.8k. I haven’t heard any of the other ACT capsules (01-04, 06 & 07), but given the 1790 and the ACT 05’s performance, I don’t think they’ll be significantly better than the 1750. Unless if you have say 3000 dollars’ worth of spare money, then maybe you can consider getting the full HS2000MX experience, all the capsules and the earphone, thus giving you the ability to freely change sound the way you want it. Otherwise save your money and get a 1750 and thank me later.
MoonDrop Variations: How does the 1750 stack up against probably my favorite 500-dollar IEM? To be honest, I think the Variations is just a small step ahead. It has better texture, more amount and control in its bass. And has a more natural midrange and treble tuning. While technical performance is mostly around the same level between the two. But as I’ve repeated a few times now, I still think that the 1750 has better accessories. The Variations’ stock case is too small unless if you used the stock cable, which had this uncomfortable plastic smell and came without a chin slider (booo). The 1750 came with a good case, another good case and a cable that is at least usable. I don’t have an outright recommendation for which to buy, so choose based on your preference.
SoftEars RSV: The RSV still remains as the best-tuned IEM out of the 185 IEMs I’ve listened thus far (haven’t heard the lauded Supernova yet). Thus tonality-wise, it indeed is just more natural and pleasing than the 1750. However, in terms of technicalities, I think the RSV is quite a big step behind the 1750. Be it dynamics, where the RSV exhibits macro and microdynamic compression, be it soundstage where the RSV has average layering and stage width, be it resolution, where the RSV simply doesn’t have a lot of internal detail to speak of. The RSV’s technical performance competes with 300-buck IEMs, not 600-buck ones. It’s an IEM held up totally by its impeccable tuning. For the non-audio aspects, the RSV does have a CIEM-ish fit (a.k.a deep fit), while the 1750 has a medium-shallow insertion depth. Both come with a modest set of accessories, but the 1750’s metal case is a bonus point for the 1750 (it was actually one of the reasons why I bought it). I’d go for the 1750 unless if having a dead-neutral reference tuning is a must.
DUNU SA6 MkII: Let me be frank, I don’t particularly like the qdc/64Audio sound, where there’s a 3kHz dip to prevent the upper midrange from being too strident. However, this takes away energy and sweetness from vocals, and in some cases, adds a layer of veil, making the upper harmonics sound somewhat wispy and soft. While I do think the SA6 MkII and the U4s are amongst the best implementations of this type of sound in the sub-kilo and kilobuck markets respectively, I still prefer the 1750’s tuning. Mids aside, I found the upper-treble on the SA6 MkII to be a bit spicy, and the bass generally lacking slam and articulation. Technicalities-wise, the DUNU SA6 MkII might be the most resolving IEM under 1000 dollars now, but I think it lacks the 1750’s great macro and microdynamics. I think these two IEMs land around the same level of performance. In terms of the non-sonic aspects, the SA6 MkII has a very large resin shell, its lighter, but takes up more concha area than the 1750. The SA6 MkII also has interchangeable plugs, allowing the user to select their preferred plug and replace one in case its worn out. The 1750 comes with the 3.5mm plug only.
FAudio Minor: I have not A/Bed the Minor with the 1750. But I did with the 1300. On FR, the Minor seems very similar to both Acoustunes, however, I don’t think I heard lots of resolution nor dynamics, which are aspects the Acoustunes perform commendably-well in. My impressions on FAudio’s Dark Sky is also similar, just an Acoustune without the technical chops that made Acoustunes good. Also, the design on the FAudios are simply boring (when compared to the Acoustunes). It is quite obvious which one I’d go for at this price point.
Conclusion:
When it comes to IEMs with colored tonalities, I always ask this one question: do these colorations make sense? And in the case of the 1750, it does. I understand why it is tuned this way, even though it is not neutral nevertheless perfect. The 1750 also has the technicalities to back it up, making it a strong contender for the best IEM under 1000 dollars.
Edit (2023/10/17):
After playing around with some filters, I came across this:
One of the filters, Tanchjim's (used on the Oxygen, Darling & Tanya), generated these frequency responses (one of the left is against the 1750 without a filter, the one on the right is against my target, blue for new frequency response with filter, green for compared response).
Filter completely kills the 5k and 2.5k peak (-5.6dB @ 5kHz, -3dB @ 2.5kHz), and adds slightly more bass (+1.7 dB @ 20Hz), generating a much smoother sound than before while retaining most of the technicalities (minor reduction in microdynamics though). The 1750 is now a whole lot more neutral and palatable, while still retaining a dash of spice up top to push out details as intended. Highly recommended to try this mod (if you don't have Tanchjim filters, either ask your distributor for some, or buy a Tanya, which supplies some spare filters). Take the filter and stick it to the nozzle (on top of the steel mesh), it’s that simple.
Prelude:
Even in an age where many are striving for high driver counts and experimenting with various different combinations of driver types, few companies stay true to the “original” single dynamic driver design. Three such include DITA, Sennheiser (IE lineup), and Acoustune.
Acoustune, an IEM company founded in 2013 in Japan, also subsidiary of NDICS, parent company of Pentaconn. Not only do they adopt some of their sister company’s products, such as the 4.4mm plug and the Ear connector, they also showcase their own Myrinx diaphragm material and unique two-piece metal shell design. Many of their products are highly recognized and popular in East and Southeast Asia, such as their old mid-tier IEM HS1551CU, previous flagship HS1697TI, entry-level HS1300SS, current flagship HS2000MX (MkII), and their newest mid-level, and the star of the show, the HS1750CU.
I don’t know any Acoustune dealers in North America, or Europe (if you do, please tell me in the comments), so if you are in these regions and want to get one, you might have to get it from some dealer in Asia (Zepp & Co., DMA Audio, e-earphone etc.). The MSRP is ¥67,320 JPY, around $475 USD, but given that this price is for Japan (original country of manufacture), you are probably looking at a single-DD earphone worth between $550 - $600 USD on the international market.
Unboxing:
Acoustune’s unboxing experiences have a throughline: a paper sleeve that wraps around a black rectangular cardboard box. Inside that box we have a black metal storage case, and the IEMs, with another carrying case, cables and eartips inside. The only exceptions to this are the 1300SS (no metal case), the RS series, and the HS2000MX (uses a fancy wooden box instead of the metal case). The presentation and layout are really nothing special, in fact, I think there can be more work done here (more organized layout, special box texture etc.).
Accessories:
But the accessories themselves are actually good/great. The HS1750CU comes with a square fabric/leather carrying case with a magnetic flap, 6 eartips, their 8-braid OFC+SPOFC ARC51 cable, and the aforementioned metal case.
The metal case does remind me a bit of Noble’s flagships, of how they all come with a large case and a small case inside. However, I do think that the metal box Acoustune ships is much more premium than the plastic Nanuk 903 case Noble provides, and much more usable (that Nanuk case is fit more for an over-ear headphone than an IEM). I can fit up to 6 IEMs (with cables) into Acoustune’s metal case, or 4 IEMs plus a DAP, and can easily slide this into any backpack, making it the perfect box to bring to an audio shop or expo. The Nanuk 903 that Noble uses is far too thick to be backpack-able, leaving me with a question: is this much protection actually necessary? While Acoustune’s case may not be practical for people who have very few or have a lot of IEMs, it is a fantastic addition to my collection as a travel case for my favorite earphones (just 5).
The square carrying case is not the largest, yet not the smallest I’ve used. Most of it is constructed out of fabric, with some leather lining and a metal, branded plaque on top. Even though this isn’t the most premium case I’ve touched, it is sturdy enough and provides adequate protection for the IEMs themselves and the stock cable which it fits almost perfectly.
Speaking of the cable, it is quite chonky. It is an 8-wire OFC + Silver Plated OFC cable (each wire has a blend of both). Although no specifications list it, my guess for its wire gauge is around 26AWG. It is soft and pliable, with little memory retention. Very little complaints on the usability front, except for how the chin slider takes quite some force to move up and down, and that the cable itself is a bit heavy. The pins are Pentaconn Ear, making your aftermarket cable choices limited to manufacturers who take such orders, or ones that use swappable connector systems (i.e. EA ConX), or simply buy an adapter. The stock cable, the ARC51, is terminated in 3.5mm, and its aftermarket counterparts, the ARC52 and 53 are terminated in 2.5mm and 4.4mm respectively. Do note that the ARC51 doesn’t have earhooks, while the 52 and 53 do. Overall, the ARC51 scores passing marks for a stock cable.
Other accessories include a full set of 5 AEX07 eartips, 1 pair of foam tips (both stored in a matte black plastic case), a (faux) leather cable clip, and Velcro cable ties. The AEX07 eartips, unfortunately get hot inside my ears after some time. This characteristic is usually attributed to eartips using middling- to low-quality materials. Acoustune’s AEX70 (sold separately) has much better long-term comfort, as it has the same material as the JVC FX-10++ (my all-time favorite eartip). However, the eartip case and the cable clip are accessories that are very practical, yet often not provided. The SoftEars Twilight and the EA Gaea, IEMs I’ve reviewed in the past that are much more expensive than the HS1750CU, don’t have either of these.
Acoustune does provide a modest number of accessories, with most being useful or necessary. At this price point, I don’t think there is much more to ask for.
Build Quality:
No sugarcoating here, the HS1750CU is built excellently. The shiny copper parts have all been very well-polished, same with the aluminum shell, showing net zero surface imperfections when I unboxed it. The aluminum parts are also sandblasted, so fine to a point where my finger glides on it. There are very few aluminum parts I’ve touched that come close to this level of surface texturing (the L&P W2 might be the closest). The HS1750CU is what I call a benchmark for build quality, regardless of price. My HS1300SS also shares the same level of build quality, showing that Acoustune pays attention to every detail in all of their products. I can see why Acoustune’s “HS” earphones are all part of the “Master Series” as they are indeed masterfully crafted.
While the earpieces themselves are built excellently, the rest of the accessories are no slouch either. The y-split, pin and plug shells are finished with brushed aluminum shells, providing extra grip when you hold on to them. Per what my distributor told me, it also seems like the cable is machine-braided, as each braid is extremely tight and uniform to level I haven’t seen before in any hand-braided cable. The leather lining on the carrying case are ruler-straight, so are the stitches that hold it down. The large metal case also has no signs of surface imperfections, although I believe that the plaque is off-center (by a millimeter or so).
I’ll say that the HS1750CU’s build quality can be an independent reason to buy it. It has comparable, if not even better build quality than many kilobuck IEMs (damn your resin shells).
Fit:
The HS1750CU fits fairly well in my medium-sized ears, with no parts causing direct discomfort. However, it may not fit you because: 1. It takes up quite a lot of concha area and 2. It may push against your tragus as it has an edge sticking out at the bottom. And it’s 9.1 gram raw earpiece weight is definitely not making it easier to wear for smaller ears.
Another potential point of concern is the screws. The screw at the top, right next to the Ear connector, protrudes outwards significantly. It causes minor discomfort when you hold on to the earpieces themselves. The other two screws on the body also protrude outwards, however not to the same extent. This design flaw is not present on any Acoustune IEMs prior to the HS2000MX.
I’m quite a fan of Acoustune’s “Cyberpunk”/”Iron Man”-style design, but am not sure if eargonomics were a priority in the design process.
Equipment:
DAC/Amps: L&P W2, ddHiFi TC44C (Blue), iBasso DX170, Shanling H5
OTG Cables: ddHiFi TC05 (Type C), MFi06s (Lightning)
Sources: MacBook Pro 16”, iPhone 11 (Apple Music Hi-Res Lossless)
IEM Cable: Acoustune ARC53 (P-Ear to 4.4mm)
Eartips: JVC Spiral Dot FX-10++ (Size M)
Shown above is the frequency response and channel matching of the HS1750CU measured off an IEC-60318-4 clone coupler. The Bold Green line is my personal target, while Blue and Red stand for Left and Right channels respectively. The closer the Blue and Red lines are, the better the channel matching; the closer both lines are to the Green target line, the more “neutral” these IEMs sound (theoretically).
Tonality:
The 1750 can be described as a neutral-warm IEM, as while I don’t feel like the treble is lacking anyhow, the focus of this IEM is primarily on the mid-low frequencies, especially vocals.
The bass on the 1750 is very solid. It sounds much bassier than the 4dB it graphs with. There is adequate thump, slam and rumble. Yet the most impressive part of the 1750’s bass is its articulation. Notes are exceptionally well-defined thanks to its fast attack and decay. Yet its transient speed isn’t too fast to a point where sheer meat behind the bass is erased (unlike most BA bass I’ve heard). While this bass response won’t satisfy the most ardent bassheads, it is for sure one I can live with. 8 out of 10.
The mids on the 1750 is definitely not as bad as the graph shows. The mids do have an early pinna gain at ~2.5kHz of around 8.5dB, surely makes male vocals sound a bit thin. Yet its 4dB dip at 3.8kHz also reduces shoutiness for female vocals. On first listen, the 1750’s midrange does sound a bit wonky, relative to the scientifically-tuned MoonDrops. However, the 1750’s midrange texture is commendable. It has fantastic transient control, thus microdetails are resolved adequately without sounding too sharpened and unnatural. I also hear a slight hint of sweetness for female vocals, similar to that of the Tanchjim Oxygen’s. This might be due to dynamic drivers’ higher second-order harmonic distortion (the same reason why tubes sound sweet). The midrange on the 1750 is simply very well-done. 9 out of 10.
Treble is where the 1750 retains the “Acoustune” flavor: a big peak around 5.5k, with relatively good extension afterwards. Some say that this peak is tuned intentionally to emphasize instruments. Indeed it does that, however, at times I think it’s too much. The massive gain also boosts plastickiness, making this region sound thin and splashy. That aside, the 1750 has good extension upwards. I hear adequate amounts of air and enough crispiness to notes. The 1750’s treble is good, but I think if Acoustune reduced the Q-values of the 5.5k peak, it can sound even better. 7-8 out of 10
Timbre on the 1750 is generally good, even though it does sound somewhat thin and plasticky in the mids and treble. Where I think the 1750 does superb is in its coherency. Transients across the entire frequency range are basically the same: fast, but not too fast to a point where texture starts fading. 8 out of 10, I’ve heard better, but have heard a lot worse.
To sum it all up, the 1750 sports a very solid v-shaped tonality. It has adequate extension on both ends, and a generally good midrange to complement it. While it is definitely not perfect, I think some small tonal quirks at 600 bucks is tolerable.
Technicalities:
Technicalities on the 1750 are excellent. Dynamics, imaging, resolution, it has it all, in spades.
For dynamics, the 1750 does superb in both macro and micro. While many people may associate dynamics (primarily macrodynamics) with the amount of bass or slam an earphone has, upper
Even though the 1750’s stage width isn’t the largest I’ve heard thus far, it has excellent layering and positional accuracy, while also being capable of rendering height and diffusal. That is quite a lot of terms for imaging, so here’s a breakdown: width is basically how far instruments are away from the ear laterally. Layering is pretty self-explanatory. Positional accuracy involves both precise localization of individual instruments often in the background, and continuity between left and right channels (able to hear left-right pans correctly). Height is the vertical space an earphone can create. And finally diffusal is how the farthest instruments slightly blend into the background, making the stage sound like it doesn’t have a restricted border, thus creating that feeling of spaciousness. Initially the 1750 didn’t impress me, because it didn’t have a particular imaging aspect that struck me. Yet closer listening suggests that it is simply an all-rounder; there’s nothing much to fault about its imaging performance. 8-9 out of 10.
Resolution is probably where the 1750 truly shines. All notes are cleanly presented with adequate microdetails following thanks to its fast transients. Paired along with its excellent layering abilities, this lands the 1750 at around a high-9 out of 10, with that final point taken away simply because I’ve heard a few monitors that do have slightly more internal detail (Gaea, Fourte, Skyline, Phönix etc.).
Suffice to say, the 1750 comfortably seats itself amongst the “most technical sub-kilobuck monitors”.
Comparisons:
Note: the frequency responses shown below are the averages of 5 takes with varying insertion depths. The bold green line is the frequency response of the 1750, while the bold blue line is the frequency response of the compared earphone. Earphones that have only been demoed do not feature frequency responses, as I might not be in the right conditions to test them.
Sennheiser IE 600: In some ways the IE 600 and the HS1750CU are very similar. Both are highly resolving (the IE 600 out resolves the 1750 by being just a bit cleaner and brighter) and both are very dynamic (I might give the 600 an edge on macrodynamics). However, I’d say the 1750 has a better soundstage in terms of both width and layering. Tonality wise, the 600 is V-shaped with excellent extension on both ends, while the 1750 is flatter across the board, aiming for a slightly more neutral/warmer signature. On the non-sound front, the 1750 does provide a good set of accessories, while I basically didn’t use the 600’s tips, cable and case (they were all kind of bad). However, the 1750 is a medium-large IEM, while the 600 fits in literally all of my friends’ ears and many of them have very small ears.
SoftEars Twilight: If we say the 1750 is a warmer IE 600, then the Twilight is a warmer 1750. The Twilight has setbacks in extension and resolution, but is notably better in soundstage width, height, diffusal, timbre, and general ease of listening. Objectively speaking, the 1750 is a direct competitor to the Twilight, even though there is a 300-dollar price difference between them. In terms of the non-sound aspects, the Twilight takes up less concha area, but might push against your Inferior Crus. I believe that the 1750 is built just slightly better (the metal parts are extremely clean, unlike the Twilight’s Y-split, where two large machining marks were present). The 1750 also has better accessories. The Twilight is a good option for those who want to listen to music for hours on end, while the 1750 is better for those who want some more excitement.
Acoustune HS1300SS: When I first looked up the FRs on crinacle’s website, I thought that the 1300 and the 1750 would sound similar to one other. However, A/B testing shows that the 1750 is simply cleaner than the 1300, literally everywhere. Less mid-bass, lower Q-values in the high-mid and treble regions, less timbral grain, snappier in terms of transients, generally more resolving with more microdetails, and better positional incisiveness. Thus it is adequate to say that the 1750 is a direct refinement to the 1300. Do put in your mind that the prices of two 1300s roughly matches the price of one 1750, so it is up to you which one is worth more.
Acoustune HS1790TI: To be honest, I didn’t quite like both of the 1790TIs I demoed. The 1790 reduces both bass quantity and ear gain. However, the 1790 is not exactly a relaxing earphone to listen to, as the treble is basically identical to the 1750. Thus there is this weird mixture of flatness and aggressiveness, ruining the 1750’s good balance between each frequency. I didn’t find the 1790 to be anyhow more technical than the 1750 either. Unless if the 1790’s sound is exactly what you are looking for, I don’t think the 400-dollar price hike is justifiable.
Acoustune HS2000MX MkII (ACT05): The 2000 MkII’s tonality sits just in between the 1790 and the 1750, having the same midrange recession as the 1790, while retaining the bass performance of the 1750. Yet, I’d still prefer the 1750’s tonal balance. Tonal balance isn’t only about the amount of each frequency band, but also about how they harmonize with each other. The 1750 does this well in that the whole earphone sounds slightly aggressive, and that sensation is only created when there is adequate gain in all frequency bands. Both the 1790 and the 2000 MkII sound awkward because the mids are recessed, thus having parts that are aggressive, but also parts that are relaxing. Technicalities-wise, the 2000 MkII sounds ever so slightly cleaner than both the 1790 and the 1750. But beyond that, there is hardly any difference. Acoustune’s high-end products don’t seem to really surpass their low-end/mid-tier ones. They simply offer a slightly different flavor. Now the one thing the HS2000MX has that is totally unique is the ACT system. Unlike traditional systems which either change the damping values of filters or impedance of certain crossover routes, the ACT system allows the users to change the entire acoustic chamber, transducer included. This allows the earphone’s sound to change drastically. However, you do have to pay extra for each ACT capsule, and they cost about the same price as a brand-new 1750, some of which are even more expensive. Not to mention that the 2000 Mk II (ACT05) itself costs around 1.8k. I haven’t heard any of the other ACT capsules (01-04, 06 & 07), but given the 1790 and the ACT 05’s performance, I don’t think they’ll be significantly better than the 1750. Unless if you have say 3000 dollars’ worth of spare money, then maybe you can consider getting the full HS2000MX experience, all the capsules and the earphone, thus giving you the ability to freely change sound the way you want it. Otherwise save your money and get a 1750 and thank me later.
MoonDrop Variations: How does the 1750 stack up against probably my favorite 500-dollar IEM? To be honest, I think the Variations is just a small step ahead. It has better texture, more amount and control in its bass. And has a more natural midrange and treble tuning. While technical performance is mostly around the same level between the two. But as I’ve repeated a few times now, I still think that the 1750 has better accessories. The Variations’ stock case is too small unless if you used the stock cable, which had this uncomfortable plastic smell and came without a chin slider (booo). The 1750 came with a good case, another good case and a cable that is at least usable. I don’t have an outright recommendation for which to buy, so choose based on your preference.
SoftEars RSV: The RSV still remains as the best-tuned IEM out of the 185 IEMs I’ve listened thus far (haven’t heard the lauded Supernova yet). Thus tonality-wise, it indeed is just more natural and pleasing than the 1750. However, in terms of technicalities, I think the RSV is quite a big step behind the 1750. Be it dynamics, where the RSV exhibits macro and microdynamic compression, be it soundstage where the RSV has average layering and stage width, be it resolution, where the RSV simply doesn’t have a lot of internal detail to speak of. The RSV’s technical performance competes with 300-buck IEMs, not 600-buck ones. It’s an IEM held up totally by its impeccable tuning. For the non-audio aspects, the RSV does have a CIEM-ish fit (a.k.a deep fit), while the 1750 has a medium-shallow insertion depth. Both come with a modest set of accessories, but the 1750’s metal case is a bonus point for the 1750 (it was actually one of the reasons why I bought it). I’d go for the 1750 unless if having a dead-neutral reference tuning is a must.
DUNU SA6 MkII: Let me be frank, I don’t particularly like the qdc/64Audio sound, where there’s a 3kHz dip to prevent the upper midrange from being too strident. However, this takes away energy and sweetness from vocals, and in some cases, adds a layer of veil, making the upper harmonics sound somewhat wispy and soft. While I do think the SA6 MkII and the U4s are amongst the best implementations of this type of sound in the sub-kilo and kilobuck markets respectively, I still prefer the 1750’s tuning. Mids aside, I found the upper-treble on the SA6 MkII to be a bit spicy, and the bass generally lacking slam and articulation. Technicalities-wise, the DUNU SA6 MkII might be the most resolving IEM under 1000 dollars now, but I think it lacks the 1750’s great macro and microdynamics. I think these two IEMs land around the same level of performance. In terms of the non-sonic aspects, the SA6 MkII has a very large resin shell, its lighter, but takes up more concha area than the 1750. The SA6 MkII also has interchangeable plugs, allowing the user to select their preferred plug and replace one in case its worn out. The 1750 comes with the 3.5mm plug only.
FAudio Minor: I have not A/Bed the Minor with the 1750. But I did with the 1300. On FR, the Minor seems very similar to both Acoustunes, however, I don’t think I heard lots of resolution nor dynamics, which are aspects the Acoustunes perform commendably-well in. My impressions on FAudio’s Dark Sky is also similar, just an Acoustune without the technical chops that made Acoustunes good. Also, the design on the FAudios are simply boring (when compared to the Acoustunes). It is quite obvious which one I’d go for at this price point.
Conclusion:
When it comes to IEMs with colored tonalities, I always ask this one question: do these colorations make sense? And in the case of the 1750, it does. I understand why it is tuned this way, even though it is not neutral nevertheless perfect. The 1750 also has the technicalities to back it up, making it a strong contender for the best IEM under 1000 dollars.
Edit (2023/10/17):
After playing around with some filters, I came across this:
Filter completely kills the 5k and 2.5k peak (-5.6dB @ 5kHz, -3dB @ 2.5kHz), and adds slightly more bass (+1.7 dB @ 20Hz), generating a much smoother sound than before while retaining most of the technicalities (minor reduction in microdynamics though). The 1750 is now a whole lot more neutral and palatable, while still retaining a dash of spice up top to push out details as intended. Highly recommended to try this mod (if you don't have Tanchjim filters, either ask your distributor for some, or buy a Tanya, which supplies some spare filters). Take the filter and stick it to the nozzle (on top of the steel mesh), it’s that simple.
