In a hi-fi world largely populated by loudspeakers that stick pretty close to the marketplace stereotype, it's always interesting and challenging to come across something that is very different and which quite deliberately flouts normal loudspeaker design conventions, such as these Zu Essence loudspeaker.

Founded in Utah around the beginning of the century, Zu Audio is a young company with a radical – one could even say iconoclastic – attitude to hi-fi sound reproduction.

Its main activity is concerned with loudspeakers, but it also has a comprehensive collection of cables and a handful of other bits and pieces, including modified versions.

Zu's principals reckon things have gone wrong with hi-fi today; that it has become "clinical and dead" and "unmoored from its pioneering past and the music and physics that had set it off".

Zu is by no means alone in questioning whether hi-fi has lost its way as components have become more complex with the passage of time and in proselytising a return to simplicity.

A whole subculture is devoted to revived and restored historic hi-fi, including idler-wheel drive turntables, single-ended and push-pull valve amplifiers and speakers with solitary 'full-range' drive units.

Zu's £3,750 Essence doesn't quite fit into the latter category, but it gets pretty close and the combination of an easy load with high(ish) sensitivity means it's well suited to driving valve amplifiers with limited power outputs.

The main driver in this case is that rare beast, a dual-cone 10-incher – 250mm in modern parlance, though few have been around since our masters instructed us to go decimal.

Essence 1

The need to position such a large driver so that its centre is roughly at seated-ear height means that the essence is both taller and wider than is currently fashionable. indeed, some might describe this speaker as a bit of a throwback stylistically speaking and the situation wasn't helped by the rather anonymous dull brown veneer that dressed our samples.

Happily, there are many much prettier options available, including (at a £500 premium) high gloss any-colour-you-like and even (to special order) any custom finish you care to specify.

The essence is effectively the successor to Zu's Druid IV, but although the two models look somewhat similar, the measured differences between them are, in fact, surprisingly large.

The two enclosures look much the same from the front, though the essence has a much deeper – roughly square in plan – enclosure and a different (and much more satisfactory) plinth treatment. The essence also has a ribbon, rather than a horn tweeter and its 250mm main driver now has a large cylindrical central polepiece extension.

This is actually a 'one-and-a-half-way' design, as no attempt is made to roll off the upper end of the main driver. Its large 195mm paper cone, terminated in a double-S doped fabric surround, will naturally have restricted and very directional high frequencies, but the smaller 95mm 'wizzer' cone should help extend things a little.

Ultimately, however, the relatively large diameter (50mm) voice coil will have a relatively high inductance and this will introduce its own natural first-order rolloff (while also conferring generous power handling).

It's logical, therefore, to add a tweeter to extend the top end and Zu has gone for a powerful ribbon device, roughly 60x 5mm, transformer-coupled to its crossover and mounted little below seatedear level.

The bass is loaded by a 'slot' port created by spacers between two identical plinths, providing what the measurements suggest is some species of reflex-loading. however, Zu attributes the actual loading system to the motorcycle exhaust tuning technique of one Ron Griewe, based on 'alternating velocity theories'.