ZMF Caldera - The Review

I've had the pleasure of an extended review loaner of the $3499+ ZMF Caldera that's been at times on my head and off-times off my head over the course of several months now. It is no fault of the Caldera at all, it just happened to be a rather busy period of holidays, being stricken with illness, recovering, traveling, and just a busy work schedule. But, every time I do reach out for the Caldera, it's been a nice, pleasurable listen that I am going to discuss more in this full review.

First off, I did provide my first few days of listening impressions way back in November prior to the headphone's launch. I was lucky to have been able to get my hands on the headphone to try out from Zach of ZMF himself, and have been holding on to it for quite some time, though sharing it with several members of the Seattle audio community in the months I've had this in my possession.

Each local audiophile auditioner loved what they heard, and I can go more on that later, as I did collect some notes to discuss. 

The Headphone

The ZMF Caldera is Zach's first foray into a custom-designed planar-magnetic driver. Previously, he started the ZMF company on the backs of modifications and improvements to the Fostex T50RP series of planar magnetic headphones. He introduced new internal mods, and his famous and unique wood-cup designs to the headphone and went through a few different iterations, before switching over to custom biodynamic driver-based headphones, and then the beryllium-based drivers of the Verite series. 

The Caldera brings him full-circle back to his roots from 2011, when he made his first modded T50RP. The new design here is an 80mm planar driver that has an impedance of 60 ohms and headphone sensitivity of 95 dB/mW. It's not a hard to drive headphone, but it may push your portable gears to the other end of its volume limits than the beginning.

The unit that was sent to me is the standard Oak wood cups with black grills, rods, and chassis. This is the basic model, but as with all ZMF headphones, there are upgraded color and metal options, and limited edition wood runs that are very popular and always look stunning. As I am writing this now, there is a limited run of Bocote and Redheart woods available. 

Each Caldera order comes with 2 sets of pads of your choice, and a cable with the termination of your choice. Every order is customized for you, and because each wood piece is unique, you'll get a surprise of how it looks when you open the box. Each one I've seen, in real-life or online, have been spectacular looking, and owning ZMF headphones previously, I've never been disappointed in quality of the build, or appearances of the wood pieces. The Caldera is no different. 

The new headband design is more padded than ever and is designed in a way that makes the weight of the headphones feel much lighter than the scale will tell you. For most headphones over 450 grams, I typically feel the weight of them pretty quickly. This one scales at well over 500 grams, but it still feels comfortable for long listening sessions.

The pad options included in this set were the Caldera leather pads and the Suede pads, as well as a cowhide pad that was a bit thinner than the other two. The Caldera leather and suedes were on the thicker side, but are both very comfortable to wear. Each of these have their own unique sound characteristics that I will describe in the sound section later.

The cable included is the new ZMF standard headphone, which is a black-cloth sheathed copper cable comes terminated in the connector of your choice, and meets the headphones with the standard mini-XLR jacks that are normal on every ZMF headphone.

Sources

I primarily used the 1/4 inch cable with my listening sessions, although there was a balanced XLR cable available in this kit. I did try using that for quite a bit of time early on with my iBasso DX240 DAP, but for the most part, I used the standard unbalanced 1/4 inch cable with my Bakoon AMP-13R and Holo Spring 3 KTE set-up I use for headphones.

Sound Impressions

Some of the following will be a bit of a re-hash of my prior impressions, but I'll try to add more detail and some sample impressions as I write this, along with some feedback from community members who have also had an opportunity to demo this specific set over the past few months.

The Caldera is a warm-tilted, and slightly-dark sounding headphone, but doesn't stray too far away from what I consider a neutral sound target, at least for a typical ZMF. It's easily the most traditional reference sounding headphone that I've tried in ZMF's lineup, but it also continues to feature a heavy dosage of the ZMF House Sound that has a warm and rich mid-range that is quite engaging and enjoyable, and a sweet treble range that is extended and smooth. The bass extends into the sub-bass fairly well, and is generally linear throughout with a little dip as you go further down to the sub-regions.

If someone took the tonal balance of an Audeze planar (e.g. LCD-4) and a Hifiman planar (e.g. Susvara), and split it down the middle, I'd say you'd land pretty close to what the ZMF Caldera sounds like. It takes the best parts of both, and gives a very well-balanced headphone in its tonality.

I enjoyed using the Caldera a lot with rock music. It's the stuff I grew up on and I always love listening to 90s alternative and this headphone does it quite well, and better than my "end-game" Hifiman Susvara. When I listen to Alice in Chains or Smashing Pumpkins, or even Radiohead or The Ataris, there's just more meat on the bones on a Caldera than a leaner, but more elegant Susvara. The Caldera has more body in the mids and a slightly darker treble range that eases off on the wailing guitars and crashing drums, and gives more thickness to vocals, bass guitars, and kick drums, that help give more raw power to these anthem tracks. 

When I put on some Nickel Creek, and their brand of bluegrass music, I still found the Caldera to be quite enjoyable, with a good soundstage, imaging and instrument separation. The band's trio of string instruments sound defined, but don't necessarily have the crispness that they would sound on the Susvara, and trails just behind it on resolution for these very minute details such as the faint strings fading away in the background. But, the Caldera still does a commendable job on resolution and soundstage -- it's just not as open and resolving as the Hifiman flagship that also cost over 50% more.

In terms of planar magnetic headphones, the Caldera is one of the closest to a dynamic driver sound that I have heard. It's still "fast", but the weight of the notes, and the richness in its presentation, along with the longer decay give it a more natural sound than the typical Hifiman planar headphone that have stocked my collection through the years. 

Pads

The pad material options do play a role and a fairly significant one here. 

The standard leather Caldera pads have the most neutral sound of the three I had, and provides the most dynamics and punch. The transient speed felt the fastest here, and most intricate.

The suede Caldera pads offered a smoother sound, with a little less emphasis in the upper-midrange and low treble, and more rounded edges and slowing down the overall transient speed.

The cowhide pads are quite a bit thinner than the other two in size, and with this, made a very different sound presentation. I found this one darker in the upper-mids with a treble lift that is similar to the Verite series. I thought this still kept the snappiness of the leather pads, but also gave a more holographic soundstage, but with a much more wonky tonal balance that I liked the least.

More Listening Impressions

I took these out to a couple audio meets in the Seattle-area over the winter months, post-pandemic, and had a few people I met in the community try them out. For the most part, I think everyone enjoyed what they heard, with some seriously contemplating buying them. Some compared these to the Atrium, another ZMF headphone with a similar tonal balance, but in a dynamic driver configuration.

The Atrium is one of my favorite headphones, and I absolutely loved using them for rock music when I had them on loan from ZMF when they first came out. They were my favorite ZMF at the time, and now the Caldera has surpassed them for me, because the Caldera improves the resolution and its tonality fits my preferences more.

But that said, there were folks who preferred the dynamic driver sound on the Atrium over the planar sound on the Caldera. The Atrium is a little bit richer with a stronger note presentation and longer decay. It's ever slightly darker, and so there were people who preferred this thicker and more relaxing presentation over the Caldera.

There was another listener who really loved the Caldera and has been contemplating buying one for a while now, as an upgrade to the Hifiman HE-6. When this person first listened to it, he thought it was good with the Caldera leather pads, and was already thrilled with it. Then we swapped out the pads with the Suede pads and I quickly observed his smile grow as he listened to them. It seemed like a serious "A-Ha!" moment had occurred! At the time of writing this, he was still deciding whether to buy this headphone or not, but hopefully he'll get to demo this set again in a couple weeks and go from there.

Like I said, of the dozen or so people who tried it, I didn't see or hear any dislikes or even "so-sos". Everyone seemed to enjoy the Caldera. Some still preferred the sound of a dynamic headphone and leaned toward the Atrium or Verite, but all of them really enjoyed that ZMF sound, despite other top end headphones around. 

For me, I don't necessarily care one way other the other if it's a dynamic or if its a planar. There's some characteristics that help kind of define the sound of the two, but I find that that is changing as we evolve headphone technology anyway. The Caldera has a lot of carry-over sound that reminds me of a ZMF dynamic headphone, more-so than most other planars. It is a great in-between, and does so with a good all-arounder sound.

Final Thoughts

The Caldera is a great headphone. It has the ZMF DNA in it -- wonderful wood aesthetics, solid build quality, top notch customer service, and the typical warm and lush, engaging mid-range I've come to expect from their products. For folks that had hesitation on ZMF's tonality in the past, this one, along with the previous release, Atrium, should help provide a different outlook -- it sure did for me, despite being owners of other ZMF gears in the past. 

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