ZMF Caldera Review and Impressions

After 48h of continuous burn-in, Oor>Caldera gained coherence and refinement, with strings and wind instruments gaining definition and heft, while maintaining separation & layering. Listening to a very busy track with acoustic and electric instruments by Gordon Grdina's "Haram" ensemble, I could easily attend to each instrument very distinctively within the sound image.

 

I have Hypsos as well, as I want to explore orthos a bit, starting with Caldera for now.

 

Further impressions: listening to Mance Lipscomb's "You Got to Reap What You Sow" after watching a wonderful documentary on him "A Well Spent Life." Oor>Caldera renders all the fine details and roughness in Lipscomb's voice and his guitar playing, while keeping a clear separation between voice and guitar. He could be sitting just across me. This combo sits at an interesting sweet spot: neither wet nor bone dry, excels in separation and depth, not analytical but full of detail, engaging.

I guess I'll pass on that Zähl HM1 <ducks rotten fruit and eggs>

 

HQPlayer>May>Oor>Caldera assessment continuing, after some 100h of burn-in: this chain is the first one I've owned that gives HQPlayer>May>Stellaris (with fancy tubes)>Atrium serious competition. It's different as I noted earlier: more open, more space like being in SFJAZZ's Miner auditorium in seat row D or so, while the other setup is more intimate, like one of the front-side tables at the Village Vanguard. Stellaris>Atrium is more relaxing, Oor>Caldera more "wow, this music is intense!."

Caldera has come together across the frequency range now, coherent energy across the spectrum for small-ensemble jazz. Listening to Art Hirahara on "Peonia" ("Open Sky" album), and the setup makes me almost "see" his hands, with the high and low notes so well separated and yet forming a coherent sound picture.

Jazz vibraphone and xylophone are really intense and yet delicate with this setup, all the overtones are there but with zero "aura" around them, while with Stellaris>May there's a subtle aura that makes them more romantic but less driving.

TL; DR Two great setups for two different moods, so much music to explore again, so lucky that I can enjoy the outstanding craft of the outstanding designers and engineers at Signalyst, Holo Audio, DNA, Ferrum, and ZMF. You all make recorded music come live again!

 

One more Oor>Caldera comment: listening to Wadada Leo Smith's "Pacifica Koral Reef" with Henry Kayser and Alex Varty on guitars, those guitar string attacks are *fast* and the decays trail into silence without truncation, overtones all present, as if the Caldera drivers were "impersonating" the strings. This setup achieves a level of physical immediacy for some material/instruments/recording conditions beyond what I was used to, which the as always superbly recorded WLS work takes full advantage of. Speaking of which, his trumpet seems right here a few feet away, all breaths and roughnesses, like last time I heard WLS from the front row at SFJAZZ.

 

I also seem to get a better synergy with the Caldera with a neutral-tilted amp. Initially the Cayin HA-300 MK2 (SET 300B, warm leaning sound but very suitable for planars) didn't impress because it introduced too much bloom into the headphone but my own HeadAmp GS-X MK2 (with custom Kevin Gilmore's golden reference dual mono power supply) seems to fare much better. It's just a bit strange because that Cayin does amazingly well with the Verite and Atrium. I still think that Susvara remains the most natural, refined and delicate when it comes to resolution and timbre but now with proper amp pairing the Caldera is not too far behind while maintaining the ZMF house sound and can be a good alternatively if you desire a more traditional dynamic driver sound.

Hmm... I think the next order of business is to test the Caldera with neutral-tilted tube amps that do well with planars like Woo WA33, Ultrasonic Telemachus and Riviera AIC-10 (this one is a hybrid SS/tube but it's extremely well tuned).

 

ZMF Caldera Loaner Impressions

Once again, big thanks to @zach915m for loaning us his latest creation and @ChaChaRealSmooth for putting the loaner together!

Preamble

You can read the Preamble and Preferences sections from my Atrium loaner impressions here.

The loaner only came with the stock lambskin perforated pads. I used my own Forza Noir Hybrid HPC at first, but then switched to the stock 4-pin cable.

Setup

My setup changed quite a bit since my Atrium review. Utopia and LCD-R went bye-bye and in came the Susvara to replace them both. The Atrium stayed, because I'm still deeply in love with it

• Media: Qobuz, FLAC files (Roon)
• Source: iFi NEO Stream powered by 15V iPower Elite (+ optibox)
• Headphones: Susvara, Atrium, Caldera
• DAC: Rockna Wavedream XLR Edition (I2S)
• Amps: ECP T4 (Atrium), Bakoon HPA-21 (Atrium & Caldera), Ferrum Oor + Hyspos (Susvara & Caldera)

TL;DR

Caldera are great headphones overall, but either the tuning or the timbre didn't really work for me and I didn't really connect with them the same way I connected with the Atrium (or the Verité loaner a few years ago). For someone who was never bothered by the 'Focal timbre' (in particular the Be drivers), I found the 'zingy' timbre of the Caldera quite distracting. I'm not sure if it is a driver timbre thing, or if the FR is elevated in a region of the treble I'm particularly sensitive to?

Nevertheless, I could recognize the great all-around technical performance, which I found to be a small step above Atrium overall, but not quite to Susvara level. YMMV. The one technical area where I found Caldera didn't quite match Atrium was in staging (especially depth). Mind you, they're still very good in that respect, but the Atrium and Susvara are both excellent at this. I think they are slightly more detailed than Atrium, but it's not an easy comparison because detail is not emphasized on the Atrium but it's still there (especially evident on the Bakoon HPA-21 in current mode). I found the Susvara were quite easily more detailed, though. In fact, save for impact (mostly bass), I found the Susvara to be superior all around, technically.

Bass quality combined the best parts of both the Atrium (impact / quantity) and Susvara (clarity / extension) and was a standout. I wouldn't change anything about it, to be honest.

Mids were less present than Atrium, but still more "ZMF-like" than not. I don't personally mind the upper-mid depression in the Susvara, but I know some people do and should like the Caldera better as a result.

Highs - as mentioned above - is where I had issues. As far as technical qualities (extension, speed, detail), Caldera was great overall. It wasn't painfully sharp or glarey either. "What's wrong then?", you may ask? I just felt it was trying to be "its own thing" and stood out from the rest of the FR in a way that was distracting.
Note that switching from the Noir Hybrid HPC to the stock cable (which I hated with Atrium because it muddied up everything) actually helped here. I'm now wondering if different pads could fix my issue with the treble and allow me to fully connect with the headphones and finally enjoy its superb performance...

Amp pairing

I tried all 3 amps I own with Caldera:

• ECP T4: I wasn't expecting it to work at all, but it wasn't bad at all. It's not what I would call an optimal amp for Caldera, but it's worth noting that a tube amp designed for dynamic headphones (80R and 300R headphones) didn't fall apart completely.
• Ferrum Oor (+ Hypsos): this is the amp driving my Susvara, so I knew power would not be an issue. The only thing is that I find the Oor has a slightly annoying emphasis in the mid bass with every headphones but Susvara. It offers great technical abilities and projects the largest soundstage I've heard, but clarity takes a small step back (compared to the next amp) as a result of the mid bass bump. Still, if you already own the Oor, you don't need to go out and buy another one to drive the Caldera.
• Bakoon HPA-21: in current mode, this is my favorite pairing with Caldera. The clarity is just outstanding (same as with the Atrium) and the "inner illumination" and immediacy the amp is known for is intoxicating. You'd think its tendency to shine light on all the small details would make the issue I had with treble worse, but it didn't. The only aspect of sound I liked better with the Oor was staging: the latter pushes things further out in front of you, while the Bakoon has more of a "wrap around the head" effect.

To be continued...

 

"I'm now wondering if different pads could fix my issue with the treble and allow me to fully connect with the headphones and finally enjoy its superb performance..."

We don't offer it publicly because out of the Caldera we've sold or loaned it hasn't been a complaint we've heard from more than two people, but none the less we developed a special laser cut titan mesh configuration the smooths out the peaks, which worked for the owner who requested it.

If that ends up being the case for anyone that reads this we would happily sell the same configuration for to anyone who needs it for a few bucks plus shipping. You would just want to email me. I tend to find the Titan mesh does more for the Caldera in the treble than any pad swap.

The greater majority of owners seem to find it either neutral or slightly smooth in the treble, I think it's just where the mileage varies the most in audio because of listening volume, genre choices, and age.

 

The Titan Radial mess has fixed the treble fatigue with my Grado RS1i, which speaks to the possibility that the mess may work with multiple headphones and be more effective than pad swap..

 

NOTE: For those not aware, Zach replaced the specific, early pair of Calderas from this loaner tour with a final version, which to my ear benefited from some very strong improvements. I provided an addendum mini-review of the final model a post or two below, and also revised this review to reflect the final product.

As always, thank you SBAF and Zach for the loaner tour.

The Caldera is not at all what I expected from ZMF's first in-house planar. I've gone on record numerous times saying that the ZMF Ori (with oval pads) is probably my favorite headphone of all time -- it's neutral, impactful, timbre is pretty much perfect. If there are flaws to be found with it: it's not the final word on resolution, it could stand to be a little smoother in its delivery, and it can lean maybe just a bit dark. ZMF's most recent headphones (that I'm familiar with) tackle some of these defecits with aplomb: the Verite Closed are bassy, slap like a mother, with oodles of smooth resolution, and addictive timbral oomph; but to me it's a romantic, dramatic approach -- not particularly neutral; the Atriums are spacious, honeyed in the mid-range, gracefully detailed up high, and nicely bassy for open-backs; but it is similarly a departure from the standard, rather than an attempt to achieve a new one. The Caldera, it turns out, is to my ear probably the most-neutral of ZMFs recent stable.

The first impressions upon listening was that it was the most un-ZMF ZMFs yet -- their sound profile is actually quite effervescent, almost 'citrusy'. (In case that's too conniseur-y: the Calderas are 'bright' but not quite sibilant or piercing, it's just got some textural fizziness up top.) This results in what I think are the Calderas' strongest and most apparent trait: they are absolute monsters in detail & imaging. Songscapes are utterly holographic, layered yet beautifully parseable. Textures are vivid and rendered with ultrafine clarity and precision. 'Clarity' would be maybe the one noun I'd attribute to the Calderas -- even Youtube videos, like reviews or interviews, seem somehow extra-crisp via Calderas. They are airier than the VCs or Atriums, as well -- but without becoming diffuse or overly breezy.

They are not as 'refined' and 'smooth' as either the VCs or Atriums, and have slightly more serration in treble presentation than the Ori's. But I imagine this to be a bit of give-and-take, where with the extra effervescence up-top comes an amazing sense of airy decay/reverb, and oodles of effortless detail, without any discernable veil a la the 600s/650s/800S. Timbre is also excellent, very organic and with great 'knock' -- though they sound overall 'flatter' than the VCs or Atriums, where transients have more of a thick rounded chocolatey thwack. Partially for this reason, I feel the Calderas thrive most on tracks with rich, intricate production and arrangements -- more simplistic songs can come off as a relatively flat or lacking in dynamics.

*Revised section regarding bass impressions*: The early version of the Calderas I'd heard had what to my ear was a bit of a recess in the midbass, which seemed to me the only real deviation from what I'd call a neutral sound signature. This seems to have been adjusted in the production process; in fact now the midbass attack and bass-to-subbass resonance are probably my favorite component of the Caldera's presentation. With the Caldera's airy high-end presentation, the bass creates a kind of peanut-butter-jelly, sweet-and-salty effect where the Calderas present an intoxicating blend of sugary highs and impactful, savory low end, and it makes for a really captivating listen. I found the early pair to be an essentially treble-oriented headphone that brought production nuances and the like into stark relief: that's not lost in the production set, but the highs are modestly brought into balance by the final, vivacious low end, and so those aforementioned details are present in a slightly more realistic fashion. After a fashion, the final Calderas stick more closely to the ZMF modus operandi of engagement over clinical, surgical appreciation of music.

I really, really, really like the Calderas. I think they're immensely impressive. If you're a detail-nut, or love to really pick apart nuances in production and recording, these are a sure bet. I don't think you can do better. For my part I will probably be eagerly anticipating a Caldera Closed, mostly just because open-backs don't seem to work well for my situation at home most of the year (wall-mounted air conditioners, yay). But if I had 3.6k laying around I'd nab one in a heartbeat. For now I’ll twiddle my thumbs holding out for a closed version.

 

I was finally able to spend some time listening to Caldera driven by ecp DSHA-3F nickel in contrast to Ferrum Oor. All in all, the Oor gets out more of Caldera's almost fizzy character. With 3F, it's a more sedate story, still full of detail and depth but not as driving. For the music I listen to (lots of modern jazz, some modern classical and this and that from around the world), I think the ZMF matches are Atrium with Stellaris, Caldera with Oor, and Verité with 3F. Different moods and highlights, of course.

 

Just sent off the loaner of the production set of Calderas and damn. I really didn't expect there to be too much of a difference but the production set

1) Didn't have that recess in the midbass that I mentioned -- these hit. And

2) Also came with the various Caldera pads, all of which felt and sounded great. My favorite ended up being the Thin Cowhide pads, they are just addictive in their mix of clarity and engagement.

The (to my ear) more-present midbass that the production set means the Caldera actually is much more engaging and impactful and straight-up enjoyable than how I felt about the early set. I also couldn't tell if highs were simply tempered a bit or if that extra bassiness took some of the edge off, but the highs were more pleasant as well -- very airy, elegant, nimble, without verging into the too-fizzy the way that the early model sometimes did. To that effect, these did come with the titan mesh, but I didn't add them as actually at no point did I feel I wanted to. I think the extra balance in the soundscape also helped nicely flesh out more pared-down songs, as well.

I think the Calderas are unique as a headphone on the market in that they have excellent impact and detail retrieval and timbre (albeit, as I mentioned, a 'flatter' presentation compared to VC or Atrium, which isn't inherently bad, just different) -- all while never getting veiled or dark or oppressive with the presentation of their bass; indeed, they have a great sense of clarity. They are very very enjoyable, and bring to mind the good traits of better electrostatics that I've heard, while maintaining the ZMF house sound of amazing timbre and bass. I really liked the early model Caldera we heard; I really really really like the finished product. I didn't have too much of a hard time sending off the earlier model of the Calderas; I was really sad to see these ones go.

For those interested, I've also revised my original review to reflect my feelings about the final set, and that includes more impressions, particularly regarding the bass and how they synergize with the highs.

 

My Caldera arrived yesterday. God damned beautiful set of cans. Sounds wonderfully euphoric and lush coming out of my iFi Pro iCan Signature-- My girl was having a hard time handing them back after I let her spend 30 minutes trying them out. I am yearning for a little bit more crispiness in the treble. Part of that is undoubtedly due to my amplifier, but it's also likely a symptom of transitioning from my beloved HD800. I plan to purchase a reference amplifier in the near future, likely an ahb2 with a preamp. After that, I'm graduating to the Holo May DAC from my Pontus II. Despite the room for improvement in my chain, I found that I still prefer the Caldera without EQ.

All in all, the Caldera is a massive upgrade I wouldn't dream turning back from. I prefer it to the Susvara, Diana TC, and DCA Stealth that I auditioned earlier this year. I listen to a wide array of genres from rock, hip hop, electronic, jazz, vaporwave to classical, and the Caldera easily performs with all of those genres.

On a scale of 1 to making Linus cry, I feel closer than ever to the TOTL listening experience I've been searching for.

 

Chain: Musicbee (WASAPI) (FLAC) > BF2 (OG) > LG (Tung-Sol 6C8G's BG RP) or LAu

I want to thank SBAF and Zach for putting this loaner tour together.

Despite my work schedule being quite hectic over the past few weeks, I grew fond of these cans despite my limited time with them. The only negatives that I could find included the stock 4-pin XLR cable (a bit stiff and retains some memory) and lack of finishing touches with the headband (leather ends of the cover are left open). I don't wish to belabor this point much longer, but IMO the leather cover/wrap in its current state gives the Caldera an unfinished look. Thankfully, the quality of the wood cups is superlative, as usual from ZMF, and the overall build of the headphone felt very sturdy. Zach was very generous in providing a number of pad options for loan participants to try. I wish I had more time to try them all, but I ended up sticking with the cowhide perforated (regular) after switching from the stock suedes. This being the first time that I tried out any ZMF headphone at length, I was happy to find that pad swapping was a fairly straightforward affair, which simply entailed slipping the edge-flap of the pad into the lip/groove of the earcup. Now on to the sound.

At the office, my work setup includes a Modi 3 and a SW51+ (stock tubes) driving my HD6XX. One of the biggest compliments that I can give the Caldera is that it doesn't give me that "ah, there's that planar timbre" when I listen to it during my evenings after listening to my office setup for most of the day, especially when compared to my HE-6 and the Arya v2 (the latter being among the worst offenders). Granted, my sources for the Caldera are on the warmer side of things. My preferred pads were the cow hides (regular perforated). Initially, the stock suedes were on them and the dip in the upper-mids/lower-treble reminded me of the forward mids/withdrawn treble of Audeze's LCD-5 but less exaggerated in view of Audeze's flagship planar. I switched to the cowhides and, to my ears, found the mids-to-treble transition to be more even than the suedes, so my impressions will be with the cowhides from here. I would also like to note that most of the pads (except for the suedes) looked a little flat compared what I've seen online, which may be due to tight shipping conditions.



With respect to its bass, the Caldera extended just fine to the lowest registers. It was readily apparent that the Caldera's bass is not only textured (expected for planars at this price point) but also presented a physicality that I haven't heard in many other other planars. IMO, the Caldera comes very, very close to my speaker amp driven HE-6 in the physicality department. Mids were neutral and a bit more present than most other planars but slightly less romantic than the HD6XX. The treble was fine but lacked a little bit of air, which was readily apparent when listening to a few classical tracks towards the end of my time with them (the first movement from Mozart's 41st symphony in particular). I would of liked to do another pad roll, but alas I ran out of time.

The soundstage of the Caldera wasn't as wide as an HD800S or HEKv1, but it was far larger than the Utopia pictured above. The Caldera's imaging was not only highly accurate but also nicely holographic. Detail retrieval was on par with the Utopia on my setup. With the wider soundstage, the Caldera does a better job than the Utopia at sound separation, although I admit that I'm not sure that my setup gets the best out of the Utopia. For example, for the House of Love's track "On the Hill" (see below), the strumming background guitar on the right channel (towards the rear) is presented by the Utopia as being mixed in part with other instruments. On the Caldera, the background guitar is presented as being slightly separated from the other instruments in the mix where its reverberant strings are more fully resolved/realized compared to what I heard on the Utopia; while I hear the strumming in the Utopia, the final portion of the background strumming is obscured by other instruments.

With the right pads, these are probably one of, if not the most, natural sounding planars that I've heard. I wish that I had time to find the right pad combo that gave the Caldera a little bit more air for classical tracks (again, I only tried two out of the five pads provided), which could make them the one can to rule them all for me.

I'm looking forward to read what @rhythmdevils has to say about these cans.

 

Caldera Loaner Impressions
Due to MOT status, I will be brief and compare the Caldera to the Atrium.

Chains
Pi2AES->Modi Multibit (V1 modded)->Vali2+
Ambre->SFD-2 MK 2 (Mazda tubes)->Stellaris (loaner from RD)

Brief Thoughts
Wow the Caldera with the Redheart wood is BEAUTIFUL! The matching strap and other pieces makes for a really nice look.

Comparison against the Atrium:

• I used to consider the Atrium to be the "ZMF neutral" headphones, I think Caldera has taken that title now. Both in tuning and tone
• Caldera has more of a crisp sound, the type of crispness I'd expect from ortho drivers
• Atrium has a bit more of a cozy sound, not warm like the Atticus, the Atrium is subtle in this area
  
• Caldera is more resolving but not by a wide margin
• Atrium is a bit warmer, a smidge boomy in comparison (I wouldn't call the Atrium boomy nor the Caldera thin it's something I only noticed in direct comparison)
• I'm hearing a bit of "heat" in the top end, worth noting I'm super sensitive to this
• Atrium mids are a little more pronounced

Thank you ZMF and SBAF for the loaner! I've been a fan of ZMF for a long time, great headphones and fantastic people.

 

Oh yeah someone asked about this at Munich as well. We don't "tuck" in the leather in an effort to make the headphone completely modular. If we did tuck it in every time you wanted to change steel or the leather you'd have to switch out more parts and it would be more costly. So I like the modular nature more than I like the tucked in look, but I know there's no right or wrong there.

I am learning more and more through the Caldera because it's a little snappier past 10K than our dynamics how much people differ in this area. I think I heard it's up to 10-20 dB per person or something insane. Anyways - the mantle mesh has helped for those who have sensitivity to this area, everyone who has tried it really loves it (but it seems like 90-95% of people prefer without), I have a video to release showing how much it damps the high highs which I'll try to release shortly.

https://shop.zmfheadphones.com/collections/diy/products/acoustic-titan-mesh

 

Hm, I think that might possibly be part of why I liked the Caldera so much when I listened to it in Munich. The Focal Clear Mg, which I own a like a lot, are rather recessed in the 8k region, but go up strongly above 10k. I hear that as “air”, and I love it.

If people hear so differently in that region, that might also be a reason why the opinions about the Clear Mg differ so strongly?

 

Yeah for sure. Some of the final prototype drivers (like your set) had it to a slightly greater extent which is why I wanted to change out the tour unit, we negated most of it with new jigs to make the driver tension as uniform as possible. But the titan mesh really kills it, too much for me and most people I think, but it really dulls that area out. But I really think it's lessened greatly on production drivers, before titan mesh.