Today, we review the HIFIMAN Sundara Closed Back which is a full-sized closed planar headphone with Stealth Magnet technology. It is priced at $399.
Disclaimer: This is a sample sent to us in exchange for our honest opinion. Headfonics is an independent website with no affiliate links or status. We thank the team at HIFIMAN for this opportunity.
To read more about the HIFIMAN products we have previously covered on Headfonics click here.
Note, that this article follows our latest scoring guidelines which you can read up on here.
In one of our previous writeups, particularly the Edition XS review, we casually mentioned within the comparison section the thought-provoking possibility of a Sundara Stealth Edition.
Perhaps it was said to stir up some thought within the HIFIMAN design team and open up the possibility of an improved version of the iconic headphones down the road.
Conceptually I never would have considered it a small task either since the Sundara has been one of HIFIMAN’s top sellers, perhaps it’s even on the top spot, and improving on them would not be easy.
I do live the “if it isn’t broke don’t fix it“ rule, but I always give thanks to all the pioneers for pushing the envelope on our behalf.
Well, the envelope was pushed and, I must say that daringly and surprisingly HIFIMAN not only released another version of the Sundara with the incorporation of stealth magnets fulfilling the previously mentioned vision but they made them a closed back. I honestly didn’t see that coming.
Tech Highlights
I have no idea why HIFIMAN called this headphone the Sundara Closed Back and if I had the chance, to be honest here, I must say that I don’t see the resemblance or similarity conceptually except within the headband and the given name. Practically every part of the cup itself has been redesigned. I mean everything except their connectivity.
For example, the driver itself looks to be a never-before-seen driver design, different from all the other drivers within the HIFIMAN lineup. The driver is not a round type and it seems to be oval and around 80mm x 60mm in diameter or at least the frame does. Also, instead of the driver being installed vertically, it’s mounted horizontally.
There’s a visible perforated plate or phase plug in front of the driver diaphragm so it’s not a completely open driver that outputs directly to the ear, it’s closer in appearance to a T50rp driver. It seems to be the only driver within the HIFIMAN lineup that employs some sort of phase plate or that I can recall.
The Sundara Closed Back driver does have some familiar HIFIMAN tech besides the stealth magnets and that’s the NEO super nano diaphragm. If you look at the exploded view you also can see two sets of magnets. So the driver is a dual-sided magnet planar.
Design
The Sundara Closed Back uses the same headband carried over from the original Sundara. However, the cup design is way different in that the cup itself instead of being made of metal is made from Beechwood with an almost Luminarc yellow tint plus the back is completely closed off with no apparent visible vents.
Okay, I’ll probably get laughed at here but the Sundara Closed Back cups remind me of burger buns. If you put the two cups together and squeeze, the pads become the patties, a double beef patty of course, and the two cups are the buns. But hey, who doesn’t like a good burger right?
Connectivity to the Sundara Closed Back cups was kept traditional and employed the common set of 3.5mm connections that use the standard HIFIMAN configuration in which the tip of the plug is the positive and the sleeve is the negative end.
Cable rolling ability is high and there are plenty of cables out there that will work with the Sundara Closed Back.
I took a peek inside the cups and there is little damping material inside the cup and there’s a minimum amount of tuning inside the cup but the driver itself seems to have some visible tuning tweaks.
For example, the driver has a foam front ring and some additional damping on the backside, stuff like that.
Comfort
Right around the second iteration of the Sundara, something changed with the headband manufacturing and I think it was particularly with the steel spring section of the headband assembly. I had the first Sundara version plus the second version and the clamping force was increased on the second version.
On the second version, you could see a stamped ROHS logo under the steel spring which was not there on the first version so I’m guessing that’s a way of telling which one you have. Ever since this version was released I noticed a slight increase in clamping force plus the headband could not stretch as wide.
The Sundara Closed Back does have some decent clamping force and I would put it slightly above medium in pressure comparatively but it doesn’t seem to affect comfort much.
I think comfort is more attributed to the new pad design which has the same sized 100mm round shape but it seems much softer and moldable.
Pads
HIFIMAN has redesigned the pad mounting system so the older Sundara trim ring mounting system pads will not work on the Sundara Closed Back. But I do like the new system more so than the old system which was somewhat challenging, as far as removal and particularly reinstalling.
The new mounting system still uses a six-slot system that clips onto the driver’s mounting base instead of onto a metal mounting trim ring.
The Sundara Closed Back pad itself is a hybrid type, around the same round 100mm size as mentioned but some of the materials used are way different compared to the Pali pads for example which are the stock Sundara open-back pads.
The inner portion is perforated protein leather, the upper portion that touches your face is the same cloth used on the Pali pads and the outer portion is a very soft protein leather. The foam seems to be a quick-reacting memory foam that is softer, and much more moldable that requires less pressure to sink in.
These pads are quite comfortable. I could wear the Sundara Closed Back for hours with no discomfort even though the clamping force is a touch on the high side. The softness of the pads which mold well to facial contours counterbalances the clamping force well.
Stock Cable
The Sundara Closed Back stock cable seems to use the same cable the 4xx came with and other models. The stock cable used has a black rubber outer shell that has plenty of bounce which is the major problem with it in general.
The hardware seems to have received a slight downgrade since none of the hardware is metal as with the one that comes with the original Sundara. This cable assembly will get you through the day as they say but the headphone itself is deserving of a better cable so I predict you will probably source a better cable after purchase.
The stock cable connectivity uses the common HIFIMAN 3.5mm single-ended tip that connects to each ear cup and the other end is equipped with a right angle 3.5mm plug.
To be fair and sincere, most will see the lack of balanced connectivity as a negative but most single-ended equipped gear can power up the Sundara Closed Back so there might not even be a need for balanced connectivity here.
Packaging & Accessories
The included stock cable as stated will get you by and you also get a 3.5mm to 6.35mm gold-plated converter in the box but not much else, not even literature.
HIFIMAN seems to have gone green and that’s fine by me. I do see wastefulness in producing fancy boxes that will sit in a closet forever and this packaging seems more eco-friendly. Here, you get an organic brown box with a laminate upfront.
However, HIFIMAN came up with a brilliant idea with their packaging and that was to convert the foam packaging inside the box into a headphone stand. This was an excellent idea to take all that stuffing within the box and turn it into something useful. It’s also a cool-looking stand and it most certainly adds value and novelty to the overall package.
The HIFIMAN Sundara Closed Back stand is made of a dense foam that is fairly sturdy and it has a polymer flat sheet at the bottom that keeps the stand, well, standing. I mean it’s not the most elaborate headphone stand around but it’s still beneficial and innovative, to say the least.
Sound Impressions
Summary
One of the first things I did was break in the Sundara Closed Back for a very long period probably beyond what HIFIMAN recommends which is usually around 150 hours. The Sundara Closed Back does improve with time and it seems that pattern will continue for a while to come.
Even though the break-in period has expired weeks ago I still hear some peaks and dips. For example, when I ran a tone generator sweep I noticed a significant dip in bass response below 50Hz. The dip is gradual but below 40Hz there’s very little energy. This produces a timid bass response impression.
Above that 50Hz point, the Sundara Closed Back bass response and the transition into the midrange is ruler flat until you reach 2kHz where you’ll run into a peak. I ran into a few other peaks at 5k, 7k, and a smaller one at 9k. However, the most prominent peak seems to be the 2kHz peak.
The Sundara Closed Back treble seems flat in response and there seems to be a good representation in the upper portion of the frequency response region but the very top is slightly shy. Where this headphone does best is within the midrange frequency bands regardless of the various peaks.
Timbre
To get the ruff out first, the lower bass response needs some assistance to be up to my taste since it seems almost absent until you use some equalization and turn those frequencies below 50Hz up at least by 5 decibels.
Then the soul and some of the warm characteristics of the recordings come through. In stock form, the bass seems cool, cogent, and too slim for my taste, particularly below 50Hz.
The Sundara Closed Back midbass section up to the midrange transition is rather neutral and flat in color and body with a hint of pep within the 80Hz range and up to 120Hz. This area becomes the prominent representation of the bass.
Above all else, the midbass in those frequencies excels in note clarity and distinction just don’t expect any low-end rumble.
The midrange section is the highlight here and coherently presents itself although there are some peaky areas.
The stealth magnet design seems to cater to a true tone characteristic and it seems to lift a thin layer of a veil and in turn, lets many details come through. There’s a good sense of roominess, a lack of clutter, good separation, and nuanced forwardness.
The Sundara Closed Back treble response is all there and what I noticed right away is the ability to quell a bright recording without blurring or veiling any of the high-frequency characteristics.
They’re rather sharp and well-defined, but sometimes seem underwhelmed or unstressed. At the same time, they remain present in a propulsive sense.
Staging & Dynamics
HIFIMAN headphones are not known as ghetto blasters that will rattle your brain with massive amounts of ultra-low bass but the Sundara Closed Back has less slam compared to previous models.
It might just be the nature of the closed-back cups that don’t allow the new style driver to reach higher amounts of lower-frequency energy and excursion within its completely enclosed environment.
It seems to affect staging as well since I find the Sundara Closed Back staging to be medium in size and not large in the general sense. The staging seems evenly dispersed but introverted nonetheless and forward in character. I guess you could consider it wide compared to most similar closed-back cans.
The Sundara Closed Back staging does have a good three-dimensional aspect and a well-defined one with a small amount of rear projection. Height, width, and depth even in size. Within the projected space, there’s good, precise placement capability. Elements can seem small or large and there’s a good reflection and interpretation of the size each element occupies.
Some good technical abilities can be harnessed here. Placement definition and detailed nuances make the HIFIMAN Sundara Closed Back interesting to listen to.
So the only true impediment here is the lack of impactfulness and low-end rumble which can be remedied up to a point with equalization, to summarize.
Click on page 2 below for pairings and our select comparisons.
