Closer Examination

Every retail purchase of a ZMF Caldera will come with at least two headphone cables. You get a choice of 6.35 mm (1/4) single-ended and 4-pin XLR balanced connectors to work with and the decision to make is which one will be on the stock braided cable which sells for $60 as-is and which the more expensive OFC (oxygen-free copper) cable will have. You choose from a drop-down menu on the Caldera product page so logically you'd go for the more expensive cable to have the connector you will be using most. The cables you see in the photos above are all the four ZMF stock cables on offer, which ZMF decided to throw in the box with the demo headphones but also tell you the four terminations the various other cables come in. I am quite satisfied with the stock cable as it is given it's non-microphonic and doesn't retain memory while still being easy enough to shape and re-shape. Given the OFC cable claims to use 24 AWG copper strands with aluminium and copper shielding, presumably these stock ones use less thick copper and perhaps not as much shielding—it still does the job well enough for me. The branded splitter is placed ~15" from the source connector and the all-black fabric braid is a safe choice. It terminates in two mini-XLR connectors that come wired to match the likes of Audeze headphones too with heatshrink to work as strain relief and L/R markings on the metal housings to help indicate the left and right channels, respectively.


All right, I've teased you enough. Here's what the stock version of the ZMF Caldera looks like with its black and natural oak finish. The components that undergo wear and tear are meant to be easily replaceable in this modular design, thus allowing longevity as well as allowing customers to play around with them to get the comfort and tonality to their desire. The headband assembly, for example, is called the ZMF crescent strap and I do get some Audeze vibes with the yoke rods and the headband style. The difference is the six foam "moons" on the underside of the headband help distribute the weight better across the top of your head while still having room for airflow. The lower strap then smoothens it out further and has the ZMF lettering embossed on it as well as on the outside on either side. There's a steel band in the curved section by default and you can choose to get this in leather, as seen above, or vegan suede.


The headband installs with screws into the frame which is made of aluminium or lighter magnesium at a $200 premium if you so choose; this demo unit has the default black anodized aluminium. On the inner side we also find L/R markings to help indicate the left and right sides of the headphones, respectively. The yoke rods are black by default and coffee gold as seen in the other version in the thumbnail. These have several discrete notches allowing for not only easy vertical sizing but also matching the two sides. The tension of these rods can be adjusted using the tiny screw on the side, in case you find them somewhat loose over time. As seen above, there is plenty of sizing to allow the Caldera to fit over heads small or large alike.


Those yoke rods also act as pivot points allowing the ear cups to swivel freely. Add to this the rotation upwards and downwards as usual and there is so much freedom of movement in all three axes to guarantee you get a great fit around your ears.


The ZMF Caldera is an open-back set, so it's not surprising to see a metal grill given a geometric pattern to look neat while still allowing open access. The stock version goes for a black metal grill which turns into the same coffee gold color as the yoke rods if you go for the more expensive version. The stock wood is American white oak in a natural finish that comes off more a pale yellow in color after the hard wax oil applied, whereas the coffee gold metal version has darker, aged oak ear cups which look great from what I remember seeing in person too. There are multiple vents along the side placed carefully to be part of the patent pending damping system behind the grill, with the ear cups having grooves to accommodate the ear pads that stretch over and into said grooves for installation as seen above. Removing the stock ear pads shows a carbon fiber baffle used for weight reduction with screws securing it to the cups and the driver assembly to the baffle itself. Here we get a closer look at the planar magnetic drivers used in the Caldera, including the traces on the diaphragm and the magnets pointing down.


Remember when I said the demo unit had been used at a trade show before? ZMF was kind enough to send a new set of the stock lambskin pads for photos, measurements, and tests. That's why you see "stock" written on the back in a silver sharpie which won't be the case on the pre-installed ear pads. In fact, as seen in the previous set of photos, there will be a red dot on the right-side ear pad to help identify it. You can also choose to have vegan suede pads instead of lambskin leather and we will talk more about the various Caldera ear pads soon enough. The Caldera pad design is new and proprietary to ZMF despite it working for many other open- and closed-back sets on the market. The stock lambskin is of medium thickness and goes for an asymmetric design such that it is sculpted to be thinner on the front than the back for a better fit around the ears. These are perforated on the contact surface and outside but solid on the inside to have a balance of airflow through the pads but with controlled diffusion as from a solid pad. The inside has stiffer-than-average gel infused slow rebound foam, the pads are 110 mm in diameter with a 72 mm ear cavity and thickness going from 20 to 25 mm from the thinner side to the thicker one. The stitching mark can be lined up at the bottom of the ear cups so that these are installed correctly, although feel free to adjust via pad rotation to get the best fit and comfort for yourself.


On the bottom of the ear cups, towards the middle where the pad stitching also lines up, is where we find the mini-XLR cable connectors jutting out slightly from the surface of the cups. Connecting the cable follows the procedure described in the quick start guide, whereby you simply align the locking pin in the cable-side connectors to the opening in the headphone-side connectors and push until they lock in place. Removing them is as simple as pushing the locking pin inward while pulling out the cable—thankfully no issues here as with some early production Audeze LCD-5 units. Depending on the cable you have and the connector type chosen, you can get different lengths and your choice of single-ended or balanced connectors on the source side—these then head over to your headphone amplifier as usual. The nature of the Caldera headband means you will have some pressure on it when using a headphones stand but here too I recommend against going with one of those omega-style stands that may add unnecessary wear to the ear pads.