Hardware Reviews

Jern 12XF


Denmark is famous for many things, apart from Vikings, and not least some discerning high-end hi-fi, including Jern loudspeakers. Their latest model is the 12XF and, as Trevor Butler discovers [in this worldwide scoop review], good things do indeed come in small packages. To save you dashing to the conclusion first, which is what I always do when reading reviews, let me start by saying that these revolutionary loudspeakers are unbelievable and represent excellent value for money. Ideal for those without much space to devote to speakers, the Jern 12XF is the latest in a growing line of models from this newish Danish marque.

Once you realise that Jern is the Danish word for iron, all becomes clear. Certainly it explains how such a compact 30cm high enclosure can be so darn heavy at over 12 kilos (27lbs). No wonder they are packed and shipped in separate boxes; as a pair they would be any courier’s nightmare. So, this iron business… cast iron to be precise for the Vibrakill cabinets, a one-piece casting fabrication creates an elegant as well as sonically adept solution. Graphite is included in the mix for better results. The metalwork is by Jern’s sister company, Dansk Skalform who are well-known for precision casting complex parts for prestigious brands such as Rolls Royce and Daimler. The metal used here is recycled, earning ‘green’ credentials and has a projected lifespan of around 100 years. In the accompanying literature, the listener is advised that cast iron is over fifty times better at reducing cabinet vibration than conventional wood; be that MDF or birch-ply. The immediate sensation of a shape somewhat reminiscent of a Russian doll in silhouette, is of a very pleasing aesthetic quality.


Ole Lund Christensen, the CEO and technical director of the company, has more than 50 years’ experience in the hi-fi business. He is an engineer by profession and has a recognised pedigree in acoustics, designing some of the world’s top studio’s he built the famed PUK studio in Denmark. He is also the father of the Gamut company, creating some very reputable amplifiers there before he sold that brand many years ago now. Ole met Soren Dissing, the owner of Dansk Skalform, one of the world’s top precision casting companies and heavily involved in making cast parts for much of the automotive sector as well as aerospace and defence. Soren is an audiophile and wanted to build speakers in his second-generation owned family business, and so Jern  was born. The company has been building speakers for four years now and this year’s [cancelled] high-end event in Munich would have seen a fourth anniversary party and the launch of new models including the 12XF.

The speakers are a two-way with Mundorf crossover components in a sealed (infinite baffle) cabinet of extreme rigidity. For some of the other Jern models a subwoofer is suggested (nay recommended) but with the 12XF it will only really be necessary to satisfy true bass junkies by creating a 2.1 system. That rounded enclosure is key to a design that aims for a smooth frequency response and low diffraction, the absence of sharp edges should ensure the latter. Jern’s  literature refers to what some acousticians still refer to as the ‘sound bible’, Dr Harry F. Olson’s book Elements of Acoustical Engineering published back in 1957.

Think of the cabinet as two metal spheres, welded together. It stands 30cm high, is 19.5cm deep and 21cm wide at its maximum width. Boasting a nominal impedance of four ohms the intention is to be an ‘uncomplicated’ load and therefore suitable for a wide range of amplifiers. Sensitivity is quoted at 86dB although I found them to be ‘deafer’ than my usual BBC-style monitors which claim 85dB. That said, it was no problem to drive them with a range of modern-day integrated and Monoblock designs, simply a case of advancing the volume control slightly. A 19mm SEAS tweeter, with a quoted upper limit of 32kHz, is coupled with a new 146mm Wavecor midrange/bass driver which can play up to 9kHz. Jern has employed a phase-linear 6dB/octave (first order) crossover utilising a Mundorf coil and capacitor.

Without a bass reflex port, a position really close to the rear wall is possible without undue issues. Such a design also leads to a faster impulse response and better definition in the lower registers. The closed cabinet having only 12dB per octave reduction below 65Hz. A bass response down to 40Hz is claimed and, certainly, I noticed frequencies around that of mains hum at 50Hz being audible. A range of powder coated colour finishes is available as well as cast iron grey, but these are such minimal units that they are hardly noticeable in most domestic settings.

Sound quality
I tried these little marvels in various positions and ended up with the 12XFs sited about a foot away from the rear wall on some Hi-Fi Racks wooden stands. After a week I removed the stands and placed the speakers either side of my 40-inch TV monitor where they remained for the conclusion of the review. In both settings I used the large rubber rings provided for precise placement and almost infinite adjustment. The performance remained adept and with amplifiers including a Hegel H120 and a pair of Trigon Monoblock’s.


The immediate sensations is ‘wow’ – how can such a small speaker create such a huge sound. And I mean big. Every speaker has a USP: for some (including my usual BBC-style monitors) it’s the mid-range, for others the earth-shattering bass, but with the 12XF it is clearly imaging and soundstage. The height, width and depth created is just staggering. And the imaging across this enormous stage is not only precise but also rock solid. On more than one occasion I was taken out into my garden to investigate a sound which was, in fact, being created by the speakers some six feet from where the noise appeared to emanate.

Soundstage and imaging ranks high on my list of sonic priorities (second only to an accurate midrange), so it is little wonder that I fell in love with the sounds created by Jern’s 12XF from the off. Just a few bars into Alison Moyet’s ‘Love Resurrection’ and my feet began tapping involuntarily. Always a good sign. I was at Hi-Fi News & Record Review when the PRAT term was invented. Pace, Rhythm and Timing was something I found hard to grasp at first. Coming from a BBC background, surely a speaker’s function is to reproduce the sound faithfully, I thought. It was a while before I grasped the concept of musicality; a term derided by some loudspeaker designers then as now. Well, the 12XF PRATted away merrily and with abundance as those tapping feet verify. Another indicator that I am listening to a winner is the protracted listening session; settling down for an hour’s critical analysis only to find that several hours have passed by and, rather than a page full of notes, I have simply wallowed in the sound produced. Thus it was here.

Across a wide range of material, as well, the 12XF was clearly very competent. On larger works I was  delighted by a 3D soundstage as orchestras were brought into the intimacy of my listening room. With Beethoven’s Missa solemnis (Chamber Orchestra of Europe/Harnoncourt on Teldec from 1992) the mass was created with as much spatial dynamism as I can recall, bringing home (literally) the spirituality and a glorious rendition from the stunning team of talented soloists to capture the work’s intense excitement and drama alongside an inspirational sense of devotion.

Bass extension also seemed to defy physics. How could so much low-frequency energy be created by such a modest enclosure with a meagre drive unit? The result is quite staggering as well as enormously satisfying. Track after track, from Yello (‘The Race’), ‘The Chain’ from Fleetwood Mac as well as Red Hot Chili Peppers’ ‘Around the World’ and ‘Give it Away’ showed just what can be achieved with speakers of this scale. Those feet were tapping away again from a bass extension of precision and depth while driving the room in a lively and dynamic presentation.

The only area where I had a modest reservation was on human voice. Here, on some occasions, I sensed a slightly recessed presence region, making it necessary to increase the volume for some male voices to be intelligible over background noises on radio and TV dramas. That said, I would prefer this to the all-too-common balance in modern speakers of having such a forward projection that performers are placed in the listener’s lap in a most disconcerting and certainly highly unnatural way.


Just before packing the cartons to return some speakers I could happily live with, I immersed myself in Gregorio Allegri’s masterful Miserere (Tallis Scholars/Peter Phillips) in a stunning performance, beautifully recorded by Bob Auger for Gimell Records. This award-winning disc is something of a test piece for me, and a kind gift from some audiophile friends down in the Allgäu. The haunting setting of ‘Psalm 51’ is beautifully reproduced by the Jern’S with the acoustic setting brought to the listener in a most convincing and natural way with the trademark soundstage of enormous width, depth and height as well as superlative imaging featuring pinpoint accuracy. Magical, just magical, and without any hint of confusion between performers or instruments thanks to a pleasingly uncluttered presentation.

The Danes have created something rather special here; the Jern 12XF is a highly competent design, and shows just what can be achieved from a small enclosure if it’s stiff enough. The speaker provides great value-for-money, superb build and high-quality resolution which is reminiscent of speakers as several times the size and price. A real winner from a brand which deserves greater recognition.


Type: Infinite baffle two-way loudspeaker with cast iron cabinet
Crossover Frequency: not specified
Drive Units:
Mid/bass – 146mm Wavecor
Tweeter – 20mm SEAS
Typical frequency response: 45Hz – 32kHz (-6dB) in room
Nominal impedance: 4 Ohms
Connectors: single wire 4mm binding posts
Sensitivity: 86dB 1w/1m
Dimensions HxWxD: 300 x 210 x 195mm
Weight: 12.2kg
Finishes: Polar white, Fine red, cast iron grey, Nordic black
Warranty: 5 years against manufacturers defects

Price when tested:
Manufacturer Details:

Jern Aps
T (+45) 96 98 17 75


standmount loudspeaker


Trevor Butler

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