The DUNU DK-4001 is the company’s new flagship hybrid universal monitor consisting of a single 13mm beryllium dynamic driver and a quad-BA design. The DK-4001 is priced at $899 including the stock Noble detachable cable system which has a separate retail price of $389.99.
Disclaimer: The DUNU DK-4001 sent to us is a sample in exchange for our honest opinion. We thank the team at DUNU for giving us this opportunity.
To read more about DUNU products we reviewed on Headfonics, click here.
So, we are back with the full review of the DK-4001 from DUNU. For those who want to read our initial thoughts on the DK-4001 from our June First Contact feature, you can click here. There is a degree of overlap in our main review for page 1 so feel free to skip to page 2 to read our in-depth sound impressions, source pairing, and comparisons.
For this review, we will also go in-depth a little more on the Noble cable which comes as stock with the DK-4001. What I did not know from the original feature is that this is now priced as a fairly premium cable. If you wish to buy it on its own it will cost you $389.99. It still has that awesome cable connection system of the HULK which, honestly, is just the ‘bee’s knees’ for those who own DAPs with multiple connection options.
The DK-4001 is the company’s universal hybrid flagship monitor priced and from what I can tell, had one heck of a journey from the original 2015 release schedule to actually making it to the retail shelf in 2019.
I am told that the DK-4001 was originally supposed to be launched alongside the DK-3001, (2015). However, DUNU felt the DK-4001 tuning and design needed to be substantially higher in quality compared to the DK-3001.
Now I have not heard the DK-3001, you can chime in and tell me all about it though we will be shortly reviewing the Pro version which recently launched. In fact, we are just waiting for it to land on our desk in the coming weeks.
The DK-4001 consists of a single 13mm beryllium coated dynamic driver and 2 x dual-tweeter Knowles SWFK-31736 for the highs and ultra-highs using a 2-way crossover. The DK-4001 is rated at 32Ω with an SPL of 112dB so it should be fairly easy to drive but at the same time just about avoid the hissing pitfalls more sensitive armature driver designs can often succumb to.
Beryllium Driver Enhancements
Beryllium coated drivers are generally known to have an excellent bass performance, however, the DK-4001 version is coated on both sides of the diaphragm and not just one side. Ideally, the enhanced extension and physicality of the performance should be much improved on standard single-coated variants.
Not to mention the two-way design of the crossover means that not just the lows, but the mids also are going to be colored by the beryllium driver’s tonal qualities leaving the dual-tweeter BA’s to focus on the highs and super-highs. Quite a few designs using similar driver counts will pull a hard stop 3-way for the mids and highs and introduce balanced armatures which can significantly change the timbre from around 1k onwards.
Air Charging Loop System (ACIS)
However, the technical design of the low-end and mids response inside the DK-4001 is more than just a dual-coated beryllium driver build. The dual coated 13mm beryllium driver is also enhanced by DUNU’s own ACIS or air charging loop system which is being pitched as a considerable step up on the standard bass venting port used with most hybrid designs.
The ACIS consists of a refined internal spiral structure right to the backplate behind the dynamic driver position in order to maximize the bass response right down into the sub-bass presence region.
I was told by DUNU that it more or less kicks in around 80Hz downwards to prevent possible roll-off or a softish response. Indeed, our own measurements confirm a significant but not overcooked lift in the DK-4001 bass response starting around the same 100Hz to 80Hz marker.
The DK-4001 doesn’t use a custom universal acrylic build. Instead, this is a sandblasted matte-black zirconium liquid alloy shaped into somewhat of a more traditional form factor. The is a much higher quality and more durable material than regular CNC Aluminum and from what I am told costs a bit more to create due to the complexity of the DK-4001 shape and the tiny dimensions.
That additional rigidity does have its advantages allowing DUNU to keep the housing walls thin enough to create a shape that is fairly comfy in the ear. I am told this is one of the clear differences from the older aluminum housing of the DK-3001. Side by side, the DK-4001 will have a smaller form factor.
The net result visually is a 3-part design with an MMCX stem to the rear that is almost a separate unit entirely, the diminutive main housing and a medium length angular nozzle with a metal gauze on the tip.
You will see another silver metal gauze just to the rear of the faceplate which is where the ACIS venting system terminates. The rest of the design is a mix of clean seam lines and some very elegant curving with the branding front and center.
This is a styling I have seen before when looking from afar but up close the finishing is quite excellent with zero imperfections and a very smooth surface to the touch.
So, the stock cable has a name now, called the Noble. On its own and as an aftermarket cable this will cost you $389.99. That is a bit more than the HULK aftermarket cable at $299 and the reasoning behind this difference we will get into more in the forthcoming HULK review.
This 1.2m cable consists of alternating strands of Furukawa sourced OCC Copper and DHC pure silver wire in a 4-wire build. Like the HULK the Noble is jacketed with a soft PVC jacket, short memory wire, and terminated with 0.78mm connectors (you can buy MMCX also).
This is not a braided technique for the external binding though. The Noble uses a twisting process that keeps the dimensions quite tight so the net effect is a fairly flexible cable with little chance of the twisting every unwinding over a period of time.
The handling is a little on the bouncy side though there is next to no chance of tangles creeping in and definitely no memory retention. The slightly flyaway feel to the handling is more to do with the more rigid twisting technique which does not have the same “deadening’ effect as the HULK braiding. It does also retain some microphonics on the thinner 2-wire twists above the splitter.
This is the beauty of the Noble cable, (and the HULK for that matter). The jacks are swappable with an excellent interchangeable connector plug system which I rate as a bit easier to use than DITA’s threaded variant.
This kills that annoying requirement for adaptors/pig-tail extensions that may have different internal soldering or wiring standards as well as reducing the need to have alternative cables with different soldered jacks. It is clear a lot of work has been put into the design and application of the locking system.
Instead of threading, you have small flexible guides that rise and fall to latch the female 4-socket jacks in place into a 4-pin recessed male socket. To take the different jacks off you simply pull back on a small slider in the middle of the cable side termination and pull on the jack side and it slides off. DUNU has supplied a small manual to guide you on how to do that but honestly, once you do it once you need never look at the guide again.
DUNU has supplied 4 dedicated interconnecting jacks for the Noble cable including a 4.4mm, 3.5mm TRS, 3.5mm TRRS, and 2.5mm TRRS. Honestly, unless you are using RSA-style plugs for your cables you do not need anything else to use the Noble with just about any DAP out there today.
Comfort & Fit
In terms of comfort, there are no real issues with the DK-4001. They are quite light and small so you won’t feel any awkward pressure pains on your outer ear ridges and they do sit flush to the ear also. However, the level of isolation and secure fit is a lot more tip dependent and I did get variable results with the supplied tips.
You get plenty of tip choices with the DK-4001 but from my own personal experience finding the right fit and also the right tonal response was a studied process. Some of this is purely down to my ear canal size so your mileage may vary. Inside you get 2 pairs each of s/m/l translucent single bore silicone, 4 pairs of SpinFit single bore silicone in s/m/m and l as well as a single set of medium Comply T-500 foam tips.
The largest translucent single bore silicone tips did well in terms of comfort but the isolation is just average with them. Still, they are the most secure of the supplied silicone tips for my ears.
Initially, I thought the SpinFits were a dead loss as the size was too small but in what seems to be packing error by me after the photo session I missed the fact two medium blue-stem SpinFits are in the box. I ended up assuming the blue was large when in fact the yellow stem tips are the largest. With the yellow stem SpinFits, I felt the isolation was on par with the translucent silicone tips but not quite as steady and secure as the Comply tips.
The medium size Comply T-500 offer a slightly better seal and isolation and feel secure. However, due to the large venting port, the DK-4001 isolation is just average overall. I presume that the bass vent breaks the level of isolation you can get with the DK-4001.
Packaging & Accessories
The DK-4001 comes in a charcoal colored and fairly sizeable retail box using DUNU branding to the fore and the name of the product in multiple languages as well as a decent pic of it on the front. It looks pretty professional on the outside with a similar route take on the very impressive internal layout.
The box comes absolutely loaded with accessories with a top-quality presentation split into two layers so you pretty much see everything you are getting right away.
The top-level of the internal shelf holds the Noble cable, the DK-4001 drivers and 4 interconnection plugs that lock onto the cable. The included terminations are 2.5mm, 3.5mm (balanced and unbalanced) and 4.4mm gold-plated TRS and TRRS jacks.
The second layer of the box contains a nicely finished dark brown leather carry case and the remaining accessories. This includes tips, the tips tray for the SpinFit variants, a cleaning brush, quarter jack, and an airline converter. I think that makes about 5 different connections for one cable alone, pretty handy stuff.
My only critique is the case which I noted in our First Contact feature previously. This is a good quality lambskin leather material with a magnetic latch which holds its seal well so there are no issues on the quality.
Rather the critique is on the size. It is a little too small to pack all those accessories inside. Open up that top lid and pretty much everything will fall out. Slide in the tip tray and you just have enough room for the cable and drivers and not much else. You will need to store most things in another container when on the move.
Click on Page 2 for Sound Impressions & Comparisons