Editor’s Note: This is our first piece of the year, and our first piece in a long time — an extensive interview with the folks behind DUNU.
2019 is here. As we bid 2018 adieu, we have to ask: where has the portable audio world gone this past year? Certainly, when it wades alongside the swift currents of the smartphone world, portable audio moves and progresses at an almost equally breakneck speed. From two grand flagship IEMs to three grand ones, and from massive 18-driver balanced armature grids to electrostatic and planar magnetic drivers, the tides are constantly changing for the topmost tier of earphones. But when new flagship models are being introduced every year, it can be a struggle for companies to keep up. One can imagine, then, the kind of drastic change that occurs across the span of almost four years — which is how long DUNU has taken to formally release the company’s 5-driver flagship hybrid.
When the flagship DK-4001 was announced way back in 2015, I had just managed to do an extensive review of DUNU’s then-flagship, the DN-2000J. At the time, I was highly impressed with DUNU’s plucky, can-do attitude, as well as its humble responsiveness to constructive criticism. Over the years, this kind of company work ethic doesn’t seem to have changed. The company’s subsequent models, the budget-minded Titan series, the Falcon-C, and the DK-3001, have all earned praise online and off for the value they bring to high-fidelity in-ear audio. Expectations were reasonably high for the absentee DK-4001.
Even with each release, however, details for the flagship always remained quiet. Twice over, in late 2016 and early 2018, I’d bump into their representatives and ask about the DK-4001. Each time their answer was, “it’s almost there, but we’re still putting it through some adjustments.” It wasn’t until late this summer when I found out DUNU quietly began holding listening sessions for the DK-4001 in China that I set out to find out why exactly it had taken so long and whether time would pass this company by in the innovation department. In this day and age, when hybrid IEMs are a dime a dozen, known quantities like DUNU are no longer darlings of IEM users’ technophile spirits.
When the DK-4001 was first announced, it was to have been the first non-CIEM derived universal fit IEM with four balanced armature drivers and a dynamic driver. There are now several earphones with the same kind of design; AKG’s N5005, Fidue’s A91 Sirius, and Meze’s soon-to-be released RAI Penta are a few models that come to mind. But despite the temptation to go in a completely different direction, DUNU kept with it, refining their promised flagship with multiple redesigns and remaining mum about a release date. However, now that the DK-4001 is finally ready for its global debut, DUNU promises it is as flagship-worthy an earphone as any.
Thus, on a chilly December afternoon in Northern Taiwan, I sat down with DUNU TopSound’s CEO, Mike Sun, and held a conference call with DUNU’s senior acoustic engineer and China factory lead, Andy Zhao. Our conversation included everything from the technical details of the DK-4001, why it took so long to develop, and where where the company is headed in the future.
The original conversation was held in Mandarin Chinese, so the following content has been translated, re-interpreted, and edited for optimal flow and ease of comprehension.
CYMBACAVUM: Thanks to both of you for taking the time to meet with me this afternoon. I’ve been listening to the DK-4001 for the past day or so, and while my thoughts on it are currently a little raw, I’m nevertheless highly impressed. It sounds very even from end to end.
Andy Zhao: Oh, no problem at all — in mainland China, we’re constantly holding meetings with local audiophiles, and this is one big area where we learn to get better, through feedback from guys like you.
CEO Mike: Absolutely. We want to be a company that does this for the long haul, and in order to do so, we have to really understand our customers — what they want in a hi-fi sound, and how they think. This is a meeting that is immensely helpful for us.
CYMBACAVUM: Then I’m glad we finally put this meeting together! Let’s cut to the chase, then. It has taken three, almost four, years to release the DK-4001. People are wondering — what took so long?
CEO Mike: Well, let me frame what the original plan was — after the success of our DN series of products, we announced the DK-3001 and DK-4001 with the intent to release the two products simultaneously. The original design of the DK-4001 was pretty close to finished by the time we released the DK-3001, but we decided to go back to the drawing board because we felt the DK-4001, at the time, wasn’t that much of an obvious upgrade over the DK-3001. Relatively speaking, across all our markets, the 3001 has sold well for us, and customer satisfaction has been good, so we can’t reasonably expect buyers to choose the DK-4001 over the DK-3001 when there’s not that large a performance difference between the two models. So, for the past year or so, Andy spent most of his time — probably over 60%, almost 70% of it — in reworking the DK-4001. It was a huge redesign in incorporating the Beryllium driver, so aside from the driver count and general shape, the current iteration of the DK-4001 is different from its original form in almost every way.
CYMBACAVUM: It certainly seems so. The shape of the housings is also quite different, with the same kind of Zirconium liquid alloy used in the Falcon-C. I notice quite a few companies using this material for housings, like Campfire Audio and even Sony. What was the biggest change — the housings or the acoustic design?
Andy Zhao: Well, the housings are what is making the 4001 so difficult to manufacture right now, and let me get to that later, but acoustically, the biggest change was definitely the Beryllium driver. It opened up a lot of possibilities for us and allowed us to finally get that leap forward in sound quality. However, it was also really unpredictable to work with.
CEO Mike: Developing the Beryllium-coated driver was really a pivotal moment for us in the evolution of the DK-4001, because it enabled us to use something really unique. No one else is doing a dual-sided Beryllium coating, and we actually wanted to patent the driver, but the patent office rejected it, since they regard any Beryllium-coated driver as the same thing, regardless of whether it’s single-sided or dual-sided. Nevertheless, we really wanted to take advantage of this technology. And as you know, manufacturing this driver requires using physical vapor deposition, and we had to devote considerable resources to make it work.
Andy Zhao: Our goal from the very beginning was to convincingly recreate the visceral feeling of bass in a live setting, and the dual-sided Beryllium coating allows us to get the kind of sound density and extension that is convincing and befitting a flagship product.
CYMBACAVUM: And that’s where I assume this Air Charging Loop System (ACIS) comes into play? From the conversations we’ve had over e-mail, I remember that it was designed specifically to respond to frequencies under 80 Hz. How does it work? It seems like it’s some kind of bass reflex port. I know that, for speakers, the length and diameter of reflex ports have to be calculated, but I don’t know how exactly it’d work with IEMs.
Andy Zhao: Yes, it’s very similar to a bass reflex port. But as with most things when it comes to earphone development, calculations are not enough. We found that using conventional calculations to determine the length and diameter of the bass reflex port just didn’t work for our Beryllium driver, and we ended up just trying an endless number of variations on length and diameter before we settled on the final design that was able to bolster our sub-100 Hz frequencies. There’s just a lot of trial and error involved. So just as a side note, I actually bought a pair of Focal Utopia headphones and had it by my work bench so that I could always refer to it for how a good Beryllium driver sounds. We also attended a good number of live performances and made recordings to make sure the 4001 was reproducing sound as faithfully as possible.
There’s just a lot of trial and error involved.
CYMBACAVUM: And I assume switching to the Beryllium driver also affected the way the balanced armatures interfaced with the dynamic driver?
Andy Zhao: Absolutely. The balanced armatures and crossover are now completely different. Originally, the DK-4001’s acoustic design was to have been a more traditional design, with the dynamic driver only handing the lows, with a pair of Knowles TWFK-30017 for the midrange, and the SWFK-31736 for the highs. But we were quite pleased with the way the Beryllium driver sounded, so I opted to simplify the design and use two SWFK-31736 instead for the highs and ultra-highs. The SWFK is Knowles’ highest performance supertweeter, and doubling up on it gives us a lot of flexibility to tune the treble.
CYMBACAVUM: Oh — so this means the DK-4001 is now a 2-way hybrid system? That actually makes a ton of sense, considering how much you’ve been emphasizing this Beryllium driver. And looking at the frequency response, it seems like there’s a vocal boost in the 1 kHz region. It seems like it’s almost done on purpose, to better show off the native sound quality of the Beryllium driver in the midrange.
Andy Zhao: Yes, that’s exactly right. Boosting vocal presence was done purposely. A lot of people prefer the more natural midrange presentation of a dynamic driver, so we’re pretty much using the balanced armature drivers to add that little bit of extra sparkle and presence, to make sure we’re getting the right kind of high frequency extension that is both natural sounding and still retains HI-RES certification. The other thing is that we wanted to make sure vocals sounded true to form. This is probably a question of differences in personal and cultural tastes, but some people, like the Japanese, enjoy hearing really sweet-sounding vocals. Boosting the upper midrange and lower treble will give us really sweet, almost girly sounding vocals. But sometimes, doing so also turns someone like Tsai Chin [legendary Mandarin Pop singer], with that smooth, rich voice of hers, into more of a girly-sounding singer. So we really wanted to avoid mischaracterizing vocals with coloration.
CYMBACAVUM: The DK-4001 is definitely the least sibilant IEM I’ve heard from DUNU, with far better control of sibilance and harshness than the DN-2000J.
Andy Zhao: Yeah; the other big thing we spent a lot of time on was controlling the resonances to minimize sibilance and harshness. After the decision to go with a redesign, I spent two months alone adjusting the tubing diameters and lengths, changing materials, and the crossover for the tweeters. As you probably know, it has to be a combination of different techniques. If we use damper filtering too much, we lose some detailing, while we have to make sure we control the phase structure and timing with electronic crossover and tube filtering.
CEO Mike: With so many tweaks, I actually became a little worried about whether we were ever going to get to release the DK-4001! Over the past year, we only had the Falcon-C and DK-3001 for sales, and both the distributors and our loyal customers were getting antsy. *laughs* But as an engineer, Andy has certain things he insists on getting right, and over the years, I’ve learned to let him do his thing, because it usually works out really well in the end.
CYMBACAVUM: Well, as they say, slow and steady wins the race…
CEO Mike: Admittedly, we’re not the fastest moving company out there, but we do believe in going a steady path forward. When we first got started in this business, we were strictly OEM makers, making mostly telecommunications devices for companies like Sony Ericsson and Nokia. So we had the factory capacity and capability to manufacture earphones but no idea of what headphone enthusiasts really wanted. But while we didn’t start out with audiophile pedigree, we built up our knowledge incrementally over these past few years, beginning with the DN-1000. These days, I have a ton of confidence in Andy to design great products for our customers and getting the sound tuning right. If there’s one thing I’ve learned in my years in this industry, it’s to let naturally motivated people do their thing. Mr. Zhao has been with our company from almost the very beginning, and he’s been loyal, persistent, and incredibly hardworking, running a lot of our factory and R&D operations at our Dongguan location. He spent a lot of time talking to people just like you, and these days, we feel very fortunate to have gained the trust and enthusiasm of audiophiles from around the globe. I know that both Andy and I are very happy about the DK-4001 and we certainly hope others feel the same way.
CYMBACAVUM: Definitely — the DK-4001 is the first IEM from DUNU that feels truly complete and thoroughly thought out from head to toe. It has a mature, even-keeled sound signature that might not wow people at first, but performs at a very high technical level. You should be very proud of this flagship.
Andy Zhao: Thank you.
CEO Mike: Thank you. We’re very honored.
CYMBACAVUM: So in terms of the delay in getting sufficient quantities in stock; you mentioned the Zirconium alloy casing was the big delay. But doesn’t the Falcon-C use the exact same manufacturing process? As I can recall, Campfire Audio used the alloy for a number of their previous models as well, and the new Sony IER-Z1R flagship, outside of its Magnesium alloy inner structure, uses it for the exterior housings as well.
Andy Zhao: Yes, the Falcon-C also uses Zirconium alloy, but the DK-4001 has a smaller size and is more complex in shape. The sheer stiffness and hardness of the Zirconium alloy makes it very difficult to work with and process, so while larger shapes like smartphone cases are easy to produce, the revised 4001 housings are way more difficult to deal with. We actually made things easier by giving the 4001 a sand-blasted matte finish. If we tried to do mirror finish polishing like one of the other models you mentioned, it would be even more difficult to produce.
CYMBACAVUM: You mean the Sony? I think Campfire has stopped making models using Zirconium alloy shells.
Andy Zhao: Well, let’s just say that when I go visit the shell factory, which is just a few blocks away from us, I get to see the production progress of shells for other brands as well, and it definitely seems like everyone, regardless of brand, has a difficult time with this alloy.
CEO Mike: Material-wise, the Zirconium alloy is really great, but it is just so difficult to work with. We’re not sure we’ll continue to work with this material in the future, and we’re going to hold internal discussions on whether to transition to something else in the future.
CYMBACAVUM: Speaking of shell revisions, the general shape and design of the DK-4001 has changed. It still looks similar to the original design, but it’s definitely different as well. The original design is very similar to that of the DK-3001; while I never had too much of an issue with the fit of the DK-3001, I know many have said the sharp edges of the inner facets of the housings, as well as the short nozzles, make it not that comfortable to wear. What went into the revisions?
Andy Zhao: The shells of the DK-4001 are vastly improved over those of the DK-3001. Because of the improved structural rigidity of the Zirconium alloy, we were able to shave off millimeters of the shell thickness and create something that is much more conformal to the shape of the concha of the ear. So even though the size of the new housings doesn’t appear smaller from the naked eye, the shape is definitely much more comfortable to wear. We also adjusted the length and angle of the nozzles, and I believe everyone I’ve spoken to at audio shows in China have told me the DK-4001 is much more comfortable.
CEO Mike: Yes, we’re also going to carry over a lot of these revisions into a DK-3001 ‘Mark II’ version some time later next year, as well as a DK-2001 model, which is a dual-BA, single dynamic hybrid that effectively replaces all of our DN series models.
CYMBACAVUM: I take it they won’t be housed in ZIrconium alloy shells then, considering the difficulty in getting adequate volumes with the DK-4001?
CEO Mike: Yeah, maybe, maybe not. We’re still not sure yet. The possibility is certainly there that we switch to some other kind of material entirely. Obviously, these models are coming along later down the pipeline, so the decisions haven’t yet been made. Looking ahead to our portfolio, aside from the DK-4001, we’re concentrating on getting out the Titan 6, which will replace our Titan 3 and Titan 5 models. These were popular models for us, but I think that, with the single-sided Beryllium driver, the Titan 6 will allow the Titan series to continue being a value leader for us. We’re still making some small, final tweaks, but hopefully we’ll be able to release it worldwide by March 2019. We’re also looking forward to the release of our limited edition 15th anniversary model, the ‘Zen’.
CYMBACAVUM: Oh, the one that looks exactly like the DK-4001?
CEO Mike: Yes, it’ll use the shells of the DK-4001 and use a Beryllium driver as well, but the shells will have a polished metallic finish instead. As a limited edition model designed to commemorate the brand’s 15th anniversary, we’re going to limit its production to either 150 or 200 worldwide — I forget exactly how much.
Andy Zhao: We’re also working on a model that uses a fully Beryllium driver like what Focal uses, and it’ll be our dynamic flagship in the future, but I’m still waiting on the shells and need to do more sound tuning for it. We’ll probably have engineering samples for people to listen to at headphone shows in the latter half of next year.
CEO Mike: The DK-4001, for now, is our hybrid flagship. We might end up developing a 5 balanced armature, single dynamic hybrid later on, but there are no definite plans for now. It would probably involve using one of those lid-less balanced armature modules at the very tip of the nozzles to give it that extra bit of high-end extension, as well as improve vocal dispersion.
CYMBACAVUM: It all sounds very exciting! But back to the DK-4001 — this new cable with the modular plugs, it’s going to interest a lot of people. I find the quick release system to be really convenient. I take it you’re going to sell it as a standalone product in the future?
CEO Mike: Absolutely. We regard the cable alone as being over $200 USD in retail value, so we feel we’re giving the consumer a lot of value with the DK-4001. The OCC cable material is sourced from Furukawa. They don’t actually make OCC cabling anymore, so we have to process it additionally. It also consists of individual strands of silver and copper, so it’s a very special cable.
CYMBACAVUM: This new modular plug is definitely one of the fastest, but still secure solutions for hot-swapping plugs. My only concern is durability. How many pulls and insertions is the latch mechanism rated for?
Andy Zhao: I don’t remember the exact figures, but from our tests I know that there are absolutely zero problems with 3000 pulls and insertion cycles, slight loosening of the friction between the two sides — but zero signal issues — with 4000+ cycles, and even with 7000 to 8000+ cycles, there are essentially no issues with signal loss. I feel it’s a really robust connection point. For example, I’m pretty sure MMCX connectors have a durability rating of less than 1000 cycles, so I’m not worried about the plug system’s durability at all.
CYMBACAVUM: That’s certainly reassuring to hear. Certainly, with the cable eventually being sold standalone, I feel that this cable may possibly be some peoples’ first experience DUNU as a brand. It seems like it’d be a good idea to add even more options, like an Apple MFI Lightning plug, or Android-compatible USB Type-C audio plug — would that be a possible option.
CEO Mike: Yeah, it’s something we’re looking into either as a combo package, or as an optional add-on.
Andy Zhao: Maybe as an optional add-on. Usually, people use either an Android-based smartphone or an Apple iPhone, not both. It might not be practical to include both.
CYMBACAVUM: Well, with the cable, I think DUNU continues its tradition of giving the consumer a lot of value by way of accessories. I like the idea of a modular cable a lot. It saves people the hassle of having to keep multiple cables around for different output devices. It seems like, between the new cable and the completely new acoustic design, the DK-4001 can sell for at least $1000. Sony, in their latest press conference for the IER-Z1R, mentioned that their market research indicates huge demand for $1000+ IEMs in the Asia-Pacific region, consisting of over a 20% proportion of market share in the $100+ IEM category. This points to a huge 6% total market share of $1000+ models out of all IEMs sold in Asia, regardless of price. I did another sub-group analysis of the information they presented, and out of all $500+ IEMs sold in the Asia-Pacific, over half are over $1000 in price. So $880 is an interesting price point. It’s priced closer to $1000 than $500. Some potential buyers might even scoff at the price tag and not even consider the DK-4001, even though it clearly delivers top level performance. What went into this pricing decision?
CEO Mike: What I can say is that pricing is the result of long conversations we have with our distributors. It’s always a balance of allowing them to be flexible financially, while simultaneously making sure we’re giving the customers as much value as we can. Do I think we can conceivably raise the price of the 4001 to something much, much higher? Indeed, over 70% of our sales revenue is within mainland China, with another large chunk in Japan. So the vast majority of our sales happens within Asia. The numbers you just told me are very interesting and revealing, I think. But while giving the DK-4001 a price hike for higher profit margins certainly can be tempting, sure, I think people eventually figure it out — and I don’t like the idea of pulling wool over peoples’ eyes. It doesn’t build trust. Like I mentioned before, we want to be in this industry for the long haul, and we want to be a brand that can be relied on, year after year, with products that stand the test of time. This is a lesson I learned while we were going through the somewhat painful transition from our OEM business to DUNU as we know it now during the wake of the global economic recession. There were times when our orders were discontinued overnight, and we had to figure how to deal with all the extra workers we hired, along with all of the parts that were no longer going to be used. So it wasn’t just that we lost a lot of money, we realized that the OEM business was just too fleeting to sustain reliably. We set our sights toward building a brand that gives us full control over our fate, and my philosophy is that if I build trust between my suppliers, my distributors, and most importantly our customers, we can keep growing in this industry.
CYMBACAVUM: Well, I think you’ve put it very aptly. I wish DUNU the best in this coming year — I’m quite sure many audio enthusiasts will love the DK-4001. Thank you so much for taking this huge chunk of time out for us — I’m sure everyone is looking forward to reading about this!