Review written by Andrew Park (@Resolve)
This review unit was sent on loan for evaluation by Dunu as part of a loaner tour.
IntroductionI first got a chance to hear the Dunu Luna for a few minutes at CanJam NYC 2020 back in February. It was near the end of the show so it was actually the last product I happened to try there, but the Luna left a distinct impression on me for the few minutes I did hear it. Ever since then I've wanted to hear it in my home environment for a longer period of time. The big question on my mind has been whether or not the technical performance of its beryllium driver can compete with other premium IEMs.
- Driver: 10 mm Acoustic-Grade Pure Beryllium Rolled Foil with Polyurethane Suspension
- Total Harmonic Distortion: 0.2% at 1 kHz
- Sensitivity: 110 dB at 1 kHz
- Impedance: 16 ohm@ 1KHz
- Plug: Patented DUNU Quick-Switch Modular Plug System
- Connector: Patented Catch-Hold MMCX Connector
- Cable Length: 1.2 m
- Cable Material: Mixed Strands of Furukawa Electric Ohno Continuous Cast (OCC) Copper & DHC Silver, with Silver-Plated OCC Copper Shield Surround
- Net Weight: 10.3 g
- Price: $1699
Build, Design & Comfort
The Dunu Luna has a small form factor with a shallow fit, meaning it doesn’t insert particularly far into the ear. This is likely welcome news to many who find deep insertion style IEMs to be a challenge. The outside of the shell has a kind of circular button-style look to it that can be used to press the tips in, almost like an indicator for where to press to get the fit right. But with that said, I do find that because of the shallow fit, it can sometimes feel like the Luna isn’t fully inserted - at least if you’re used to more conventional IEM styles.
I do find the Luna to be quite comfortable, regardless of the tips being used, and the fact that it’s small means that it’s easy to wear for a long period of time. The small and lightweight design also makes it so that the shell doesn’t protrude out of the ear either, so it’s possible to wear while resting on a cushion or pillow (this will make some people very happy).
Speaking of tips, however, this is one area where I find the Luna’s sonic performance to vary far more significantly than other IEMs. Normally changes to the tips influence the treble response to a certain degree, but it’s usually only by a few dB. With the Luna, by contrast, I find that switching tips makes a much more significant difference for a wider range of the frequency response. Part of this has to do with the shallow fit, and also the tip interactions with the ear canal. If you think about it, a smaller tip would allow you to insert the IEM deeper into the ear canal, while a larger tip creates a seal farther out. So to a certain degree the Luna’s tonality can be adjusted based on insertion depth and fit.
The Dunu Luna’s other defining feature is that it uses a single beryllium dynamic driver. While this isn’t something all that new for over-ear headphones, Focal has been doing it with their Utopia and Stellia, and ZMF has a beryllium coated PEN driver in their Verite, at the moment I’m only aware of one other IEM that uses this type of driver, namely the Final Audio A8000. My understanding is that while there are tangible benefits to using this material, it also introduces additional challenges to get the balance and tuning right.
For detail retrieval, the Luna’s use of Beryllium is immediately recognizable. For textural nuance, image clarity and structural definition, the Dunu Luna is one of the best I’ve heard at the $1699 price point. Needless to say this is one of the most technically capable IEMs at any price, and in many ways I’m reminded of the detail ability of the Focal Utopia and Stellia. As far as where I hear the best detail, that’s in the mids down to the upper bass, but there’s also a frequency response related reason for this.
Speed & Dynamics
I find the Luna to sound tight and well-controlled, and easily one of the best for dynamic driver IEMs, even if it’s not quite on the level of some planar magnetic IEMs from Audeze in this regard. But in my opinion one of the Luna’s shining characteristic is its dynamic punch and slam, or what some have traditionally called ‘macrodynamics’. In other words, the Luna hits like a truck. I don’t want to make this seem like there’s an extra bass boost or boomy kind of sound because it’s not. Merely that the kind of punchy quality I typically associate with high excursion dynamic driver over-ear headphones is readily available for the Luna as well. In fact, for this quality I’m once again reminded of some of the Focal over-ear headphones like the Utopia and Stellia.
Soundstage & Imaging
I find the Luna’s soundstage to be middle of the road for an IEM. It’s not the most spacious sounding but it also doesn’t have a claustrophobic or overly tight presentation. I think it’s important to remember that IEMs in general don’t have much for space and stage. But because the Luna is so detailed, it has an excellent sense of depth and layering. This isn’t the kind of flat presentation I’ve come to fear with IEMs. To put it into perspective, I find the Luna’s stage to be better than that of the 64 Audio tia Trio, but not as spacious as the Campfire Solaris. For depth and layering I find the Luna to be at least as good as the Solaris.
For high performance IEMs, one of the biggest concerns has traditionally been having to deal with the dreaded ‘balanced armature timbre’. Naturally, because the Luna uses a single dynamic driver, this isn’t something we have to worry about. People often talk about how dynamic drivers impart a more natural decay tone, and I find this to be evident for the Luna as well. I think any timbre shortcomings for the Luna are more the result of frequency response and tonality than anything else.
Frequency Response & Tonality
"The Standard IEC 60318-4 (711) Ear Simulator (GRAS RA0045) has a step half-wave resonance at 13.5 kHz which effectively limits its usefulness to below at least 10 kHz and it uses a ½" microphone. However, the RA0401/02 has a damping system that attenuates the half-wave resonance at 13.5 kHz and thus extends the useful frequency range to 20 kHz. It uses the same ½” microphone as the original version and fully complies with the standard. This is why we recommend it as the first choice when you are looking for a “standard” 60318-4 ear simulator - but without its shortcomings at high frequencies. We think of it as “the new normal”."
When looking at the Luna’s frequency response, it’s important to recognize there’s a very well-considered reason for it to be the way that it is. Now with that said, I do find it to sound a bit strange in the mids and treble.
For the bass, the Luna is excellent. I find it to have just a slight bass emphasis, never sounding boomy or bloated, and it transitions into the mids without overpowering anything. In my opinion this is an appropriate level for a dynamic driver - especially one with the kind of punch and slam that the Luna has. If I’m nitpicking, it’s that more of the bass emphasis exists for the mid and upper bass rather than the sub-bass, but I think that’s perfectly acceptable. It sounds clean, well-defined, and a lot of fun at the same time.
For the mids, that’s where things start to get strange, specifically around 2khz and into the upper midrange around 3-4khz. I mentioned earlier in this review that the sound changes a lot depending on the tips and the insertion depth, but the general trend I’ve found is that the Luna has a substantial upper midrange emphasis with most of them. I’m told this is intentional, and is even a preference with certain audiences. In particular, I'm told that this tuning was developed according to preferences that exist in the Chinese IEM market. This may be due to certain musical style preferences that prioritize forward vocal characteristics that may make the upper midrange elevation more agreeable.
To my ear, however, is undoubtedly too strong of an elevation. But to be clear, it’s not exactly the level of energy it has that’s the problem, it’s more that the balance isn’t quite right with the treble, at least the way I hear it and given my preferences.
The Luna’s treble is quite a bit subdued by contrast to the upper midrange elevation, meaning at first listen it almost sounds like a warm tuning. I think if the treble energy had been a bit higher, the 2-4khz emphasis wouldn’t sound quite as intense as it does. Once again this may be a preference for certain audiences, but to my ear, it causes the mids to sound a bit shouty and there’s some glare for certain instrument tones like electric guitars. But the plus side is that I don’t hear any fatiguing qualities in the treble.
Now let’s think about the upper midrange emphasis and overall tonal balance issue. Apart from the fact that this type of emphasis may be a preference in the Chinese market, this may also be a ‘lesser of two evils’ type of tuning choice that’s related to the treble peak consideration - and I think we can see an alternate philosophy at work with the other Beryllium driver IEM from Final Audio, the A8000. The A8000 has the extra treble energy, but this results in a more fatiguing sound signature.
So with the Luna, Dunu may have taken the safer and more ‘non-fatiguing’ approach for treble presentation, at the cost of tonal balance in the upper midrange. I still find it to be over-emphasized and I think 3-5khz could have been taken down a bit to more coherently achieve a warm yet detailed kind of sound, but many of Dunu’s design choices with the Luna are understandable. For me, the Luna is an IEM that I would EQ, even just slightly to get the balance closer to what I like. Thankfully, it’s not all that difficult to do with this one, it just requires dropping the 3-5khz range by a few dB, or by boosting the treble above that.
For those that don't want to EQ anything, it's worth experimenting with different tips. While for the most part I found the upper midrange emphasis to be there, tip rolling did change the sound quite a bit for the treble. I'm also told that for anyone wanting to tame the upper midrange balance a bit, using the SpinFit CP240 double flange tips may help. You can read more about this here.
The A8000 is probably the most sought after comparison for the Luna since they’re both using single beryllium dynamic drivers. As mentioned, I find it fascinating to see the different approach each of these companies has taken when it comes to tuning a beryllium dynamic driver. The Final Audio A8000 sounds more balanced for its overall tonality, but at the same time it’s treble peak is far more noticeable. With the Luna, Dunu has instead subdued the treble response overall, so as not to have the peak be as noticeable, but at the cost over tonal balance for the upper midrange.
Both IEMs have similar technical performance, with incredible detail retrieval and excellent slam. To my ear, the Luna is initially more agreeable because you don’t hear the same treble shimmer from the A8000, meaning any problem areas that are immediately noticeable don’t show up as obviously. At the same time, eventually the Luna’s upper midrange shoutiness does start to become an issue for me - and this is something that I don’t have any problems with on the A8000. So while I’d EQ both of them, I find the Luna easier to EQ, especially with portable players and DAPS. Oftentimes multi-band EQ applications don’t allow for the kind of fine-grained adjustment that’d be beneficial for the A8000, while the Luna’s adjustment is doable with much wider frequency ranges.
The Campfire Audio Solaris is the opposite of the Dunu Luna in many ways. Instead of a more mid-forward kind of sound signature, the Solaris is much more on the 'fun' side of things with a more relaxed upper midrange.
The important thing to note here is that the Campfire Audio Solaris is less upper mid forward and has a bit more treble presence than the Luna. Overall I find the Solaris' tonality to be more to my taste, however it's important to also recognize that the Luna does sound more detailed to me, especially in the bass and lower mids. Additionally, I do find the Luna's bass response to be more well-defined and cleaner than that of the Solaris.
To my ear the Dunu Luna has some of the best technical performance I've ever heard, at any price. In particular, the detail retrieval, speed and dynamics are exceptional. At the same time, I find its upper midrange emphasis over the treble to become a bit fatiguing, especially for certain instrument tones. So while some may enjoy the Luna's warmer tuning, I prefer their more balanced sounding IEMs like Dunu's excellent DK3001 Pro. At the same time, if you're looking for one of the most detailed IEM experiences, the Luna is worth consideration, even if its tonal balance doesn't line up with my preference.
-Andrew Park (@Resolve)