If you look at the world of loudspeaker design it is very crowded and the diversity of materials used in cabinet construction is wider than it has ever been, yet up until recently no one has had the temerity to make one out of cast iron. It’s not hard to see why but when Ole Christensen met Søren Dissing the CEO of a Danish casting company and saw his idea for the speaker he realised that it just might work.
Christensen founded Gamut Audio and designed a range of electronics that garnered a great reputation among those who heard them, myself included. He sold that company in 2003 and has been consulting on various projects including speakers from Roksan, Avantgarde and Amphion and electronics from Parasound. He had also been doing a lot of work on studio design when he came across the idea to use cast iron. It appealed because of its great strength and stiffness as well as the ability to cast an entire speaker cabinet at a relatively affordable price, but another benefit is that this material has great self damping. Ole is keen to demonstrate this at shows where he hits pieces of aluminium and cast iron with a hammer to show how little ringing the latter exhibits, an effective demonstration and one that challenges the use of aluminium in loudspeaker cabinets quite neatly.
In a way, think of the Jern as a ‘swords into ploughshares’ design, as a lot of that cast iron once upon a time was being fired out of a cannon and at (sometimes ‘through’) some unsuspecting foot-soldier. Recycling old cannonballs into a loudspeaker shape that looks a little like a small cannonball sitting atop a larger one seems right.
The Jern cabinet is not large, it stands just 30cm (12 inches) tall, but it is as you might imagine quite heavy at over 12kg. The shape of the casting was chosen to minimise diffraction; there are no sharp edges to diffuse the sound, and this provides a degree of time alignment by putting the magnetic centres of tweeter and woofer in the same plane. The cabinet is an infinite baffle (there is no port) and in Jern11 guise has a low 86dB sensitivity allied to a four Ohm impedance, so will require a bit of power to get it jumping. The casting has a flat base but the speaker is supplied with a thick rubber ring that sits on the stand and allows the speaker to be angled almost any which way you fancy. In practise this means that it’s a little tricky to get both speakers upright in both planes, alternatively they can be tilted to project the sound upward. Jern makes a single pole stand for its speakers but this is also cast iron and costs nearly as much as this speaker, a more affordable alternative is apparently on the drawing board.
A natural by-product of using cast iron is what happens in extremis. At one point or another, any reviewer worth his or her salt has dropped a bit of audio equipment on their foot. It hurts. Dropping a bookshelf speaker on your foot wrecks the speaker, damages your shoe, and likely breaks your toes. It’s painful, but you survive. Drop the Jern11 on your foot and you will need to get used to the nickname ‘stumpy.’ Fortunately, despite the rounded enclosure, the flat bass means it doesn’t roll around. More importantly, if you are using these speakers as bookshelf speakers (their ability to work close to a wall makes that a distinct possibility) make sure the shelves can take the loading and use Jern’s supplied rubber O-rings to make sure you don’t ruin the veneer on your bookshelf as you position the speaker.