ZMF Caldera Discussion

Discussion thread for the ZMF Caldera planar magnetic over-ear headphone.

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I was lucky enough to borrow the new ZMF Caldera planar yesterday, with a full complement of pads, and have had multiple hours using it over 2 days.

My chain was a Mojo Mystique X SE DAC, driving a Pass HPA-1, Burson Soloist 3XP or ampsandsound Nautilus. I stuck with the Pass for the most part to reduce the variables when I pad and cable rolled.

I’ll list the cables I used, only to give context to my findings:
Silver DHC Molecule Elite - very detailed and textured, neutral signature with no warmth (but not bright).
Copper DHC Complement-C - less detailed than Molecule Elite, warm signature, where mids and upper bass are accentuated, treble is slightly rolled off.
Copper Danacables Lazuli OG - least detailed, nice warm mids, more even in tone than Complement-C.

Music was a mixture of rock, punk/indie, 80s synth pop, jazz.

I’ll start by warning any ZMF fans that you may feel disappointed when you first hear these, if you have the expectation that it has that warm ZMF house sound. I fully expected it to sound like the RAD-0 (which I’ve previously described as “If ZMF ever designed a planar, it would sound like this”), but it is much more neutral, and more detailed. But please give it some time, and allow your brain to adjust to the new sound, and let some of your biases drain away.

TLDR: My first reaction was “I don’t like this, I’m going to buy an Atrium instead”. My conclusion was “I love this, I’m going to buy one”.

Maybe the best way to describe my journey between 2 extremes is to describe my reaction to the different pads.

I first tried the stock “Caldera” lambskin pads, which are very neutral. However the uber-detailed combo of Pass HPA-1/stock pads/Molecule Elite was too much of a good thing for me, as it gave cymbals more sizzle than I can take. Complement-C brought the treble down, but pushed the mids too much, so the winner for me was the Lazuli, which added the warmth I was craving. There was still plenty of detail and texture, but less so than the Molecule Elite. If I were to keep these pads, I’d consider going up the Danacable range to keep the warmth but expose more of the detail that I know the Caldera has.

I then tried the cow hide pads, which are warmer than the stock lambskin. They paired very well with the silver Molecule Elite cable. This was my favorite combination by far, as I got a combination of huge stage, lots of detail but slightly warm of neutral tone. It is still more neutral than than a RAD-0 or typical ZMF dynamic, but it was a magical feeling to be enveloped in a big bubble of sound. Vocals are holographic. Bass is lean but tight and well defined. Both stringed and brass instruments have a 3D texture, whether it’s rock or jazz. I think the RAD-0 gives synths a bit more body, but the Caldera is not lacking.

When I tried the suede pads, I couldn’t find a pad/cable combo that hit the spot for me. They had a nice tone, less sizzle in the treble than the stock, but vocals sounded either distant or muffled, depending on which cable I used.

The Caldera has a different signature than my other headphones, much more neutral and detailed, but that’s a good reason to buy it as a complement to my existing collection (RAD-0, Verite, Stellia) rather than an Atrium, which is more of a variation of what I already have.

After my initial negative reaction to the stock pads and silver cable, I wasn’t sure if I wanted to spend any more time with the Caldera, but I’m so glad I persevered. And the great thing about the subjective side of our hobby is that you may dislike the sound I love and love the sound I dislike, yet there’s probably a pad that will suit your tastes.

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Thanks for sharing. The 3d like effect staging seems like a recurring trait for all zmf tuning. Can’t imagine anything more resolving than the Verite though as it is right up there with some of the best to my ears. Wonder how it stacks up to other resolving headphones like the Utopia and Susvara.

It seems like a greater departure to the Atrium and Verite. Would you say this is the most neutral of all ZMF’s offering?

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I haven’t heard an Auteur yet, which I believe is the most neutral of ZMF’s dynamics, but yes, it’s the most neutral headphone I’ve heard, not just ZMF.

IMO, I would say Caldera with stock lambskin pads with stock cable is the most neutral, with a slight treble edge that I haven’t got used to (probably due to my preferences, given my past history with headphones slightly on the warm side so YMMV).

If I want a darker Caldera, then the cowhide pads smooth out that treble edge and bring me closer to the ZMF house sound that I’m used to.

But as a caveat, bear in mind that most of my listening has been done on a Pass HPA-1 amp, which is also neutral and ruthlessly revealing too. I wanted to use that as a baseline, to try to get as close as possible to the sound of the headphone without worrying about the sound of the amp.

I also want to point out that neutrality is not a bad thing. Having always bought headphones that provide just a little warmth in the past, it took me that first 24 hours to realize what a good thing it is to have a neutral headphone in your chain. Not only as a different flavor, but it also provides a blank canvas to push the sound one way or another using pads and/or cables if you’re in the mood for a bit more flavor, a little like having a tube amp.

And if you happen to have a tube amp, the sound will also change depending on which tap you use. For instance, I found that if use the 100 ohm tap on my Nautilus, it thickens up the mids, which is great for guitar music.

The only other planar I have is a RAD-0, which is not only warmer, but also has a tiny stage compared to the Caldera. I had an Atrium on loan for a while and the Caldera is on par with my memory of that Atrium’s stage. It’s not something I cared about in the past until I experienced the Atrium and Caldera, that both excel in stage, and now I realize why some people are obsessed with that.

BTW I absolutely loved the Atrium that I had on loan, especially as I was able to experiment with the different meshes, in addition to pad and cable rolling. I know Zach didn’t do this on purpose, but the meshes allow you to customize the Atrium according to your treble preferences. If you like a darker headphone, use the solid mesh. If you want a brighter headphone, use the Titan mesh. And the stock Atrium mesh falls in between.

I can’t afford to buy both the Atrium and Caldera, so it’s very difficult decision.

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Short answer is it doesn’t. Utopia/Susvara/LCD5/RAAL all extract even more detail than Verite. It isn’t the ZMF aim though, wooden cups and fair bit of dampening, he goes after timbre and tonality.

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Exactly right. And I posit that “resolution” can/should include timbre and tonality–as much, if not more than detail.

A photographic analogy: some photographs convey detail in a hyper-realistic style. Others convey the appearance of light and shadow on that day, at that hour. The camera resolves both things; and both are valid creative choices.

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That is a conundrum. I’ve bought the Atrium on day 1 and has been absolutely thrilled with it. There is more than enough technicalities on that headphone and just the overall sound makes it is one of the biggest wow moment I’ve heard on a headphone since the hearing the Utopia and Verite all those years back. That and some of the source gear I purchased the past 2 years made me lost a ton of interest in trying out any new audio gear. That still ring true for the most part but the Caldera and Auteur classic does spark a bit of interest. Namely the more neutral tonality and the driver type. Biocell can have the potential to make a very addictive sound and I’m not one for planar but can acknowledge the things that a good planar driver can do but I always find them very uninspiring in terms of an overall package in sound so one that is made by ZMF sounds very intriguing.

I am well aware that those will out resolve the Verite just slightly interested in hearing about how the Caldera stacks up against those aforementioned hyper detail headphones. The Verite and Atrium for example doesn’t out resolve some of the best planar and dynamic headphones I’ve heard but I do think it can convey textural information and decay characteristics as good as the best of them. As an overall package there really isn’t much out there I prefer which is why I got them over the Utopia.

That I very much agree. The Atrium is the most natural sounding headphone and renders some of the most natural and true to live sounding drums I’ve heard on a headphone. The Verite is also no slouch in that department.

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I couldn’t agree more.

Again same. I ordered mine on launch, and when it came I was floored. Never heard anything like it in terms of staging, and such a liquid, lush, and beautiful midrange. The bass slam and impact was astonshing. I still feel the same.

I am also very interested in the Caldera, but just can’t do it. I now have 3 top tier headphones in Atrium, RAD-0, and Verite, the first 2 of which I bought in the last year. I’ve been very bad! :laughing:

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I havent posted much here for a while and that’s mostly because I’ve been taking a bit of a break from audio reviews for the past few months with some occasional commitments. This week I was sent the Caldera to check out and I love it.

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This is just going to be “a couple days of use” set of impressions and some measurements. Don’t consider this a full review. :)

First, off I received this demo from Zach the other day and I had posted my first impressions after just an hour of play. I will say that the “spiciness” that I was hearing seems to have waned off a little bit with the default Caldera leather pads that came attached with the unit. The Suede pads smooth it out even more, though with those pads, there is a small bit loss of some of the intricacies and agile-transient response I hear with the normal pads. I also tried the thin cowhide pads, but I did not like them much for my own tastes/music, and basically put them away after I measured them afterward.

For those who are interested in pad measurements, I’ll post those at the end here, along with a comparison to the Susvara, which is my favorite, and normal headphone I use when I want to listen to music on headphones at home.

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I spent a good chunk of my first day and half listening to the Caldera on my iBasso DX240 DAP with Amp 8 MK2. I used a 4.4mm to XLR adapter and listened to it on that, as well as just listening to it on the single-ended output. I found the Caldera to have no issues with this portable source. I then took the Caldera for most of last night and today and plugged it into my normal listening setup of the Holo Spring 3 KTE and Bakoon AMP-13R through my Roon Core dedicated server PC. This opened up the quality quite a bit, with more depth, and improved resolution, and just opening up the overall sound in general. In my photo, I also have the new SMSL DO200 MK2 DAC, which was also sent to me for a review, and I’ve listened to it briefly with the Caldera, but I prefer the more engaging Holo Spring 3 in general.

I also compared it to the Hifiman Susvara on both source setups, and same general opinions on the source synergy. Susvara, as you know, needs quite a bit of current to get it to drive correctly, and just to get it loud. For reference, I had to double the volume output on high gain on my DAP to get it to the same listening levels.

Caldera General Impressions

I had a nice email exchange with Zach the other night sharing some music suggestions back and forth as we found out we share some common fondness for progressive bluegrass and indie folk music. For those who are interested in what type of music this is, I recommend checking out the Country Coffeehouse playlist on Spotify (I ported this playlist over to Qobuz/Roon for my listening here), and check out bands like Crooked Still or Andrew Bird, or stuff like that. I also listened to a bit of piano jazz music from artists like Bill Laurence, GoGo Penguin, and Tingvall Trio.

For this type of music, I really like the tuning that the Caldera brings with the more forward upper mid-range and treble, that I think sometimes is missing some prior ZMFs. The Atrium is another one that I think does this really well. Of course, making this go too forward can make it nasally sounding and I think the Caldera can hover that line on the default pads, with the Suede pads smoothing this out a little more as I mentioned before. The cowhide thin pads that I briefly tried remind me of of how Verite sounded when I owned it, but it’s been a long time now since I parted ways with it, so take that with grain of salt.

The Caldera, to me, is fairly neutral sounding, with an elevated bass region that provides more body and meat to the bones than, say, my Susvara and other Hifiman planars. In this comparison, Hifiman-house sound is thinner and more focused on speed and attack, where I find the Caldera is more focused on being powerful and thicker, with a sound that has that traditional ZMF sound on the dynamics, but with the added agility and attack that the planar drivers typically bring. For the most part, this headphone reminds me of a Hifiman with a warmer and more bass emphasized sound. I prefer it over typical Audeze sound, and to me, it brings together the best of both worlds – an Audeze-like low end mixed with the mid-range and treble of a typical upper-tier Hifiman (i.e. not too bright, but smooth sound of the Susvara, HE6-series, etc.)

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In a direct comparison to the Susvara:

The Susvara is still beating the Caldera in resolution and speed. While the Caldera is meatier and thicker with a more balanced sound, I do find the Susvara to be overall smoother, with a more ethereal sound that is little more refined. The Caldera has more “dynamic driver” qualities to me than the Susvara does, if that makes sense. Both of these have quite similar general sound balance outside the slightly more elevated bass response of the Caldera.

I think the Caldera has a good soundstage and also good layering and depth. The Susvara is stretches a little wider and deeper. It has a more grand sound than the Caldera. I enjoy both for different needs. For orchestral and jazz music, I like the Susvara a lot. For rock and this progressive country music I talked about earlier, I like the Caldera quite a bit too. Both do all these genres well in my listening experiences so far.

I haven’t compared the Caldera directly to my Sennheiser HD580 and HD600 yet, but I can see some similarities here too, in terms of tonality, but with a better soundstage and resolution. The Caldera kind of fits somewhere between the Susvara and those two for me in overall qualities (though leaning closer to the Susvara for some of the very critical listening things like detail retrieval).

Anyway, I don’t know where I am going with this anymore. I don’t think the Susvara and Caldera are necessary competitors, though it’s hard not to compare them. For my personal tastes and enjoyment, I can see both being very good compliments to each other.

More to come.

Measurements

Now for the measurements I took. I use an IEC-60318-4 coupler with a flatplate and ear pinna that somewhat simulates the GRAS 43AG, however it is still a clone. I have a compensation file that I use to make it as close to that as possible and I’ve been very happy with how my FR graphs have turned out over the past couple years that I’ve used this over-ear system.

This first graph is of the three pads that came with this unit. The blue line is the default Caldera pads, while the red is the Suede (thick), and the green line is the Cowhide.

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This second graph is a comparison to the Hifiman Susvara, in yellow. I removed the cowhide pad from this comparison as it measures a bit differently. I don’t want to go too deep in the squiggle interpretations, but I hope you take a read through my audio listening experience above before really going over the graphs. Remember the lines are normalized to a specific frequency (in this case, 800Hz), and you need to look at the lines relative to themselves too as a whole response (i.e. Caldera bass may not show that its more elevated in this graph, but in my listening experience, it definitely has a warmer and thicker sound – which maybe attributed to the less elevated treble range, when compared to the Susvara)

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Matched at 1KHz – (you’ll see the bass levels are show it higher on the Caldera than the Susvara with similar treble levels)

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Feel free to ask me any questions you have on either my impressions, squiggles or both. I’ll post something more formal later when I have more time on these headphones, but this is probably going straight towards the top or near the top of my ranking list at this point. I really like what I am hearing here.

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Thank you so much for the early impressions - the best and most detailed review available anywhere as far as I can tell. I’m not completely sold yet, but I am intrigued. There may very well be a Caldera in my future.

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I wanted to add some more experiences to what I wrote above.

Zach has said in the past that that he tunes his headphones using the stock cables, so that he knows exactly what his customers will hear when they first plug in. So I put my after-market cables to one side and tried the regular ZMF stock cable.

Lo and behold, the combination of stock pads and stock cable sounds great to me. The only issue I previously had with the stock pads was that there was a bit too much sizzle on songs with prominent cymbals (e.g. Fleetwood Mac’s “Dreams”, Tubeway Army’s “Are Friends Electric”) and the stock cable tones that down a little compared to my silver cable, but still provides a full range of frequencies. My reaction to the cymbals is obviously related to my preferences, and YMMV.

Listening to the funky “Say It Loud - I’m Black And I’m Proud, Part 1” by James Brown, the texture of the brass is fantastic, and my foot is tapping away to the rhythm. Switching to “Superstition” by Stevie Wonder highlights the funky guitar line and again has my foot tapping.

Moving to female vocals, “Down To River To Pray” from the “O Brother Where Art Thou” soundtrack puts me on the stage with Alison Krauss, with the chorus surrounding me. The Sundays’s “Here Where The Story Ends” floats Harriet Wheeler’s vocals over strummed acoustic guitar, where I can focus on the detail or just let it all hang together.

More compressed electronic music like “Kill V. Main” by Grimes somehow sounds less compressed, maybe because of the stage. It’s a pretty bright track, but with the stock cable, it’s within my limits.

Everyone’s favorite Tool test track, “Pneuma” sounds phenomenal, as the Caldera separates out all the instruments and the richness of the guitars and bass sound fantastic, either when they are playing different notes or those times when they are layered on top of each other.

As I said before, I was also using the Pass HPA-1 as my baseline amp, to provide a baseline. The HPA-1 is very neutral and ruthlessly revealing. The Burson Soloist 3XP is a little richer in the mids and softer in the treble than the Pass, so the cymbals were more subdued on this amp.

I then moved to the LTA MZ3. I wasn’t sure if the MZ3 would have enough power, but I was very pleasantly surprised that I only had to turn the volume up from my normal 25 to about 35. If you don’t have a powerhouse amp, I wouldn’t worry too much. In fact, if I have time, I might try this off a iFi Go Blu and Gryphon later.

The combination of MZ3 and Caldera was probably my favorite combination for long-term listening because the mids were even richer, and the highs are there, but soft enough to meet my preferences.

Switching to the more neutral ampsandsound Nautilus was another glorious experience and showed me that the Caldera loves tubes, and really does provide a window into the sound of the amp that’s feeding it.

I did briefly try the cowhide pads with the stock cables but it was a little too dark for me. This might suit those of you that want a darker sounding headphone. Or in my case, when I switched to my silver cables, it evened out the frequency response, so if you have some upmarket cables, this might be an option for you.

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Do you happen to know the construction of the different cables - ie coax, twisted pair or something proprietary?

I’m curious as to separating out the difference due to materials vs construction technique.

Might be foolish of me to try but thought I’d ask.

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All good questions but I’m afraid I don’t know, although Double Helix does seem to provide some transparency into their construction. I wish I understood more about this, because then I would stop experimenting with (i.e. buying new) cables to see if I like them.

In addition to construction, the material seems to matter too. It’s not as simple as silver = bright and copper = warm.

From my experience, OCC silver tends to be less bright than ‘regular’ silver. I’d describe it as lean (i.e. lacking warmth) and detailed, but not bright. Adding more OCC silver (e.g. going from DHC Molecule Elite to DHC Prion 4) appears to add some richness to the sound, so it’s not as lean.

OCC copper is a little smoother and more detailed (IMO) than ‘regular’ OFC copper. Still trying to determine what adding even more copper wire will give you.

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Ok, thanks for the info.

The reason I ask is because the electrical field doesn’t travel through the wire - it travels in the space around the wire. This means the construction of the cable affects the field.

It was a hard lesson when they tried to run the first long underwater cables for morse code messages. They included an iron layer around the wires in order to give the cable strength.

Turned out the signal was so distorted by the time it got to the other end it was nearly useless. I don’t know if the relatively short length of audio cables makes this effect irrelevant.

As if we needed audio to get any more mysterious.

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Quick update on whether you can use the Caldera on the go.

I plugged it into an iFi GO Blu using a Hart cable with a 3.5mm connector and connected the device to my iPhone using blue tooth, using Amazon HD as my source. It sounded pleasant, with volume at around 50%, so it’s definitely not hard to drive. On the other hand, it did benefit from the extra power from switching to a 4.4mm balanced connector, which improved separation and clarity (e.g. I could hear the texture of guitar strings better) and music just sounded a little tighter and under control, so I would recommend the balanced output of whatever mobile device you’re using.

I then tried my iFi Gryphon, and that was a sublime combination. Playing the ubiquitous “Chameleon” by Trentmoller showed that this mobile combo doesn’t compromise down low. I then moved through my Amazon HD test track playlist, playing every genre I could think of. Special mention goes to “Creeping Death” by Metallica, which just sounds huge, a wall of guitars around my head, with Lars’ drum beats bouncing around “below” the guitars in the soundscape. I’m currently listening to “Banquet” by Bloc Party as I type, tapping my foot to the post-punk dance rhythms. If I was going to be staying in an Airbnb, I would strongly consider taking a Gryphon, Hart cables and a Caldera as my vacation setup.

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Much respect for mentioning this. I also like to test with Vamp from that album. Brilliant bass on both tracks.

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These are brilliant test tracks, added to the list!

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