ZMF Headphones Caldera Closed

Caldera Closed's biggest strength at the drawing board was that it was designed from scratch. While it walked the same path as Caldera Open, Caldera Closed breaks the mould with a cup shape inspired by the rugged, geometric form of a volcanic caldera.

Its unique, asymmetrical curves not only look striking, but also allow the exceptional sound of our drivers to truly come alive. With a new asymmetrical magnet array working for – not against or apart from – earcup acoustics, ZMF's original work merged their two biggest technical accomplishments into one headphone.

Certainly, CADS birthed Caldera Closed together with the Atrium Damping System (ADS). CADS starts with trapezoidal N52 magnets that shape and optimise airflow either side of Caldera's 80mm planar driver minimising turbulence and phase issues. 

It's a volcano-like magnet structure that allows air to naturally spread out, and maintains a slightly asymmetric force making the membrane more nodal, pushing a massive amount of air towards the ear while diffusing it at the same time.

Macro dynamics are a given but it's micro-dynamic reproduction that distinguishes Caldera Closed. The traces in proprietary ZMF planar driver film are gold-plated copper, and the diaphragm is coated with silver to maximise excursion along the traces.

It's not just sheer driver size producing authority and slam – actual pistonic excursion akin to dynamic drivers reproduces tiny gradations in SPL. This sees Caldera Closed's timbral resolution on par with the likes of its Open, Atrium and Vérité counterparts. 

Atrium Damping minimised back-wave cancellation from the rear of the driver, for more pressure to be exerted in a controlled manner towards the ear, carefully away from the back volume at determined frequencies.

The smallest details made all the difference to a driver with as much resolution as Caldera Closed produced, and ZMF extended their research to earpads with three depth variances released for a complete ecosystem of accessories.

All Caldera pads bear fluting – the tapering of rim thickness and circumference back to front – officially sealing the integral role oft underestimated items play on the ZMF tuning process.

Already, Caldera Closed's combination of Atrium Damping plus the horn-like acoustic amplifier its sculpted earpads take the form of ensure substantially better SPL loading of the driver ear-side.

With sensitivity at a high 95dB ensured by these added implements, the driver and motor are then freed to focus on mustering as much deep bass extension as possible from the air volume within limited cup enclosures.

This is a closed headphone, so naturally it works as meant to from portable sources. Caldera is a call to experiment with amplifiers, so big-small devices such as Cayin Audio's C9ii, HiBy Music's FD5, R8II and RS8 and Enleum's HPA-23RM throw their hat into the ring to work very satisfactorily.

At the desk and in a public office, compact voltage sources like that fit the desk only enhance the performance. The solid-state route is straightforward with Questyle Audio's current-mode desktop flagship CMA18. The Cayin iHA-8 and HIFIMAN EF500 are absolutely capable.

That's exactly the kind of attention Caldera Closed deserves, the planar-magnetic cherry on the ZMF cake that completes the circle from the very first days Zach Mehrbach spent modding venerable Fostex T50RPs. Caldera is a headphone unlike any other, entering a world of planar magnetics yet not being entirely of it.

Switch to Caldera Open here when you step back into the home environment, check out ZMF's dynamic driver headphones when looking for the perfect OTL tube amplifier match here, or view all our other headphones here.