ZMF Closed-Backs Initial Comparison: Atrium Closed - Caldera Closed - Bokeh

I recently had the great opportunity to test out the latest headphones from popular wood-artisan audio brand ZMF. Zach Mehrbach, the founder and owner of the company, sent the latest three closed-back headphones for me to check out, along with a box full of accessories including bads, dampening systems, cables, etc. I'm overwhelmed to say the least.

The three headphones include the Caldera closed-back, the Atrium closed-back and the newest Bokeh, a lighter-weight and easier to drive (power) closed-back. Since this is such a great challenge to test every single combination, I decided to start with a three-way comparison of my first initial impressions of the three headphones using their default specific pads they come with. Then I'll write specific in-depth reviews of each independently of each other, so you can think of this as a 4-part review of ZMF's newest line-up of closed-back headphones.

All listening impressions were done with the following setup:

Home Listening:
  • Holo Audio Spring 3 KTE
  • Holo Audio Bliss KTE
  • Roon + HQPlayer
With the ZMF Bokeh, I also used my Fiio M15S digital audio player to listen to music with it, since it's the "semi-portable" headphone of the bunch.

Initial Impressions of the ZMF Bokeh & Default Pads

The new ZMF Bokeh is their lightweight and easier to drive semi-portable solution to something a lot of users have asked for -- a smaller ZMF headphone. It's not small. It's still just as large other ZMF products, and contains a 50mm dynamic driver that is typically used on non-portable headphones. But, it does feel lighter than some of their other products (still heavier than a typical headphone), and much easier to drive off any source available to you.

Another big change is the change from the mini-XLR connectors to the smaller and lighter-weight 3.5mm connectors that are more standard across the headphones industry. This makes cable replacement and transportation easier. 

The standard Bokeh at the time of this is the Black Limba wood, and its fairly lightweight and a nice natural looker. The demo unit I have has a wood-tan color with dark streaks and kind of a mahogany-like wood appearance but with much more variation. It's a cool looking wood. The demo unit weighs about 490 grams without cables.

The Bokeh is a warm and balanced headphone that is perhaps a tad dark. It's very much ZMF-House sounding but not quite as resolving as some of their flagship products. At first, it reminded me some what of the ZMF Verite, where the upper-mids have a slight suck-out when I first listened to Maeta's Cool Cat, and like my time owning the Verite, I grew to enjoy the laid back presentation.

What the Bokeh has over the Verite is more bass levels, albeit, no where near as fast and resolving as the Beryllium drivers that made that headphone special. I'll discuss it a little more in the next section, but the Bokeh is the Atrium, but less exciting, and less resolving, but also a lot more forgiving. 

My first impressions are that I do dig the Bokeh. While I am not sure it's any major sonic improvement over the Emu Teak or Fostex TH-610 series. The Bokeh has a similar tonality and resolution to these, but with improved soundstage openness. But, while these Foster-based headphones are a similarly semi-open closed-back, but even lighter-weight and half the cost, the Bokeh has a much, much more premium design and quality to it. It has all the hardware of the other ZMF headphones for the most part, so you know it'll last and be durable.

Initial Impressions of the ZMF Atrium Closed-Back & Default Pads

The Atrium was one of my favorite headphones when it launched a while back. It still remains one of the most natural and balanced sounding open-back headphones I think out there. My impressions here and comparison to the original open-back are mainly from memory, reading back at my old review and notes, and graph comparison.

The Atrium Closed is a heavy headphone for me, weighing 500 grams without cable. With ZMF's suspension system and padded straps, it is still quite comfortable to wear though, as the weight is balanced well enough, and its soft. The 10 gram difference between this Atrium Closed set and the Bokeh is quite noticeable though, even if it should be fairly negligible. This could just be due to how the weight is distributed.

The closed-back version retains much of the same magic I liked about the original with a generally smooth tuning. The Atrium Closed does have a little bit of a v-shaped sound that I do not remember the Atrium Open having. The bass range is elevated, tastefully, and its definite weighty. The upper-mids are fairly well-controlled with a small peak in the low treble that I actually don't find bothersome in my hearing. You can hear it in some tracks, like Nanna's Disaster Master, where the trailing edges of her vocals are a little etchy-sounding, but nothing too bothersome.

Like the other ZMF headphones mentioned here, the closed-back nature of the headphones do not seem to really detriment the sound like some other closed-backs would. I don't hear any resonance or echo effects when listening to music. The soundstage of the Atrium has always been more intimate and it still is here in closed-back form, relative to some other ZMF headphones I've heard. 

Initial Impressions of the ZMF Caldera Closed-Back & Default Pads

The ZMF Caldera Closed-Back is the closed-back version of the planar magnetic open-back headphone that came out a 1.5 years ago. The open-back Caldera is one of my favorite headphones because it has all the ZMF warm-gooey goodness but with a more neutral sound signature that really appeals to me. It's a warmer interpretation of the Hifiman Susvara sound-signature.

The closed-back version comes standard with the striped ash wood cups and it's a stunner. The dark grain lines over the tan wood body is easily recognizable, but so is the triangular raised bevels in the center of each cup. This bump-out design , called the Caldera Volcano, acts as an acoustic chamber of sorts to help reduce sound deflection that is a typical problem with closed-back headphones. It also makes the headphone easier to hold! 

The demo Caldera Closed weighs 545 grams without cable. It's pretty heavy for my tastes, and despite really enjoying the sound signature, looks, and everything else about it, the heavier weight does potentially kill it for me. It's 150 grams heavier than my Hifiman Susvara, and 250 grams heavier than my other closed-backs (albeit that they're portable headphones).

The Caldera Closed is very much similar in sound as the original Caldera Open, with a warm/neutral sound signature that has a good amount of low-end weight, slightly muted upper-mids, and airy highs. It's very well-balanced, and doesn't have any major flaws.

Some may like its laid-back upper-midrange and some may dislike it. That's a bit of taste. While coming from the Susvara, it does sound quite a bit tamed down here, it does add more low end weight balance for thicker, meatier, and heavier body to male vocals, at the expense of female vocals and a bit of dynamic excitement. That said, it's still great sounding for all music and all genres.

The Caldera Closed has good resolution, impact and slam, and a surprisingly large soundstage, despite being physically closed. If I were to listen to it without knowing it was closed-back, I wouldn't have known and thought it could very well be open-back since there was very little resonance and did not feel encapsulated.

Comparison Thoughts

My initial thoughts between the three:

Caldera Closed is my favorite of the bunch. It's also the hardest for me to wear because it's heavier than I would like! 

The Bokeh is like Atrium Closed, Jr. They share a lot of similarities with the Atrium having a slightly more dynamic sound with its bigger bass heft and treble zing. The Bokeh is perhaps the most laid-back and pleasant tuning here, but with the least amount of excitement.

And finally, the Bokeh is the lightest and easiest to wear. It feels much lighter on the head than what the sticker weight would lead you to believe, thanks to the headband design from ZMF.

What's Next

Now that I have some initial thoughts on these three closed-backs, I am going to do some individual articles and measurements on each specific product and the different pad and tuning options available that Zach sent me to test out. These will come out in the coming weeks as I have time to try out all the various combinations. I can't wait to see what incremental changes these will lead to!

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