I’ve been living with the Caldera for a little over a week now, thought I’d share some early impressions and some brief comparisons to the Atrium, which has been my daily driver headphone since launch. I thought that might be more helpful than reiterating what others have already said so eloquently. Worth noting that my Atrium has the full mesh in front of the driver. DAC in my headphone chain is the Audial S5. I’ve listened on a mix of my 6528 OTL and my transformer-coupled 6A5G SET amplifier.
Caldera with 6528 OTL.
Atrium with 6A5G SET.
Starting off with some general Caldera observations, what immediately struck me when I put on the Caldera for the first time was its clarity and resolution. Of the ZMFs that I have in my stable, it is the most technically impressive. It has a huge head-enveloping soundstage, precise imaging, airiness, all without sounding sterile, dry, or “revealing”. It presents details in the mix in the most enjoyable and musical way, it’s a celebration of the nuances of the music, not a dissection.
In terms of bass performance, the Caldera has that thick, weighty, bass that surrounds and shakes your skull. It isn’t overly prominent, it is there when called for and supplied with ease. It’s punchy and dynamic, it has a physicality to it that makes the music lifelike and convincing.
The midrange of the Caldera isn’t forward to my ears, it is well-balanced with the rest of the frequency spectrum, but again, very detailed and natural. I think the best descriptor for it is liquid, it has a smooth, flowing quality to it, very easy on the ears while being simultaneously textured and transparent, aided by the Caldera’s technical prowess.
The treble of the Caldera is perhaps very slightly relaxed, but more prominent I would say than other ZMFs I have owned. It has shimmer and sizzle, but never strident or piercing. It has presence in the mix and aids in the airiness and space the Caldera presents.
So overall, I find the Caldera to be highly resolving, detailed, but without compromising on body, heft, or dynamism, while providing a liquid smooth midrange and maintaining the musicality ZMFs have become known for. Oh, and they look pretty good too
Now, as for how it compares to the Atrium...in terms of technical performance, I find the Caldera more resolving than the Atrium, which is no slouch itself when it comes to detail retrieval. I think the stage of the Caldera is a bit larger than the Atrium’s. Perhaps the Caldera's stage is a little bit wider than it is high, but the Atrium’s soundstage is very large on its own and well-rounded in terms of its dimensions.
As far as frequency response, as you might expect, the Atrium doesn’t have the sub-bass detail and extension of the Caldera, but provides very satisfying mid-bass body and slam. Something notable in my chain, I find the Atrium to be significantly more mid-forward than the Caldera, which really makes vocals / strings / guitar / piano pop in a mix. Full mesh notwithstanding, Atrium is a warmer headphone overall with a more relaxed upper register. It really is a nice, wooly, comforting listen, warm and inviting.
The place where the two headphones differ most significantly is their timbre. The bio cellulose driver of the Atrium gives it that lush, organic, “analog” quality that is extremely addictive. Doing the listening for this write up, one thing that jumped out to me is how the Atrium makes the attack and reverberations of percussion sound so lifelike and satisfying. I also find the decay and more forward midrange is also a boon to those genres that emphasize vocal performance and stringed instruments.
On the other hand, the driver of the Caldera gives the music that buttery smoothness and liquidity in its timbre, well-balanced and easy on the ears, I could listen to this headphone for hours and hours on end. Pair that with its impressive technicalities and full-bodied, physicality and dynamics, it makes for a compelling package. Just imagine liquid butter being shot into your ear with a firehose, and you’ll have a good understanding of where the Caldera stands (joking, sorta).
I think these headphones can definitely coexist in one’s headphone collection, they are clearly both TOTL offerings. If either one of these headphones existed without the other, I would tell you “I could live with just this headphone the rest of my life.” But of course, Zach has blessed us with two amazing headphones, so if you can only own one, which one is right for you?
I think if you crave resolution, clarity, a liquid midrange and bass extension, and you have the proper amplification, then the Caldera will definitely please. If you have heard other ZMF biocellulose headphones and are drawn to their lush, organic, analog-esque sound and place a premium on midrange presence, you will get all of that in the Atrium, paired with a huge soundstage and excellent technical performance in its own right.
