Zu Cable Druid mk. IV

By Marc Phillips

June 2006

Zu Cable Druid mk. IV loudspeaker. $5580

The Zu Druid stands 1270mm high

The full range driver includes a "whizzer" cone to increase high-frequency extention. A super-tweeter adds sparkle over 12kHz

The back of the Druid features Cardas binding posts, with an oversize single screw-down system. The pure copper terminals suit spades, and can accommodate banana plugs.

It’s easy to think of the Zu Cable Druids as the Swiss Army knife of loudspeakers. They’re 101dB sensitive (with a 12-ohm impedance), so my two watt-per-channel Yamamoto Sound Craft A-08S amplifier can easily drive them. And yet, unlike the Lowthers and Rethms of the world, they will still mate well with a high-powered solid state amp.

They also measure flat down to 35Hz, despite a slim, well-proportioned cabinet (again, unlike those aforementioned single-driver behemoths). The Druids are also ruthlessly revealing, dynamic, and incredibly musical, and they look very cool to boot.

New thinking

Zu Cable is a Utah-based company headed by Sean Casey and Adam Decaria, two guys who are, much as I hate to say it, much younger than me. They combine, however, a lot of new thinking and enthusiasm with a real old-school approach to loudspeaker design, such as a rigidly coupled short-throw 10.3" (260mm) woofer that sports a good old-fashioned whizzer cone.

The similarities to the Lowthers and Tannoys of yore end there, however, because the guys at Zu add a beautifully-machined aluminum super-tweeter that takes over for the main driver above 12KHz, making it more of a 1.5-way design. Sean Casey describes this driver as adding a little more “splash” to the sound, and he suggested to me that for fun I could always try sticking some duct-tape across them to see what the Druids sound like as a pure single-driver design. I actually did this and found that the Druids did sound like a bit like classic Lowthers – very smooth, with a gorgeous, expressive midrange, but just a tad rolled off at the top. The super-tweeters definitely give the Druids a more modern, satisfying sound.

I’ve stressed the versatility of the Druids, but in my listening room, they were perhaps the most difficult speakers I’ve used in terms of extracting their ultimate potential. My first challenge came when I tried to properly couple the Druids to my carpeted floor. The spikes used with the Druids are thicker than most, and it was almost impossible to get them to pierce through to the wood beneath. You really have to stomp down on them (it’s a good thing that they are very rugged and can withstand such abuse) or else they remain a bit wobbly, which makes the bass quality suffer. In fact, getting down to 35Hz is impossible unless the interface with the floor is absolutely perfect.

Motorcycle design

This is because the bottom of the Druids are open, with a large, precisely-engineered channel running through the cabinet. If you’re thinking of a transmission line or horn-loaded design, don’t – the guys at Zu describe this as a proprietary feature which they call a Griewe driver-loading design, based upon Ron Griewe’s “alternating velocity” work in motorcycle design (new thinking indeed!). It is therefore very important to ensure that the spikes raise the bottom plinth of the speaker so that there is a slight separation from the floor. Sean Casey recommends that this gap be about the width of a single CD jewel case. That’s how I eventually achieved a satisfying balance in the lower frequencies.

The next obstacle was a result of room interaction. The Druids simply need a large room. They don’t need to be placed far away from the rear walls necessarily. In fact, they are very similar to Audio Note AN/Es in that placing them against the rear wall definitely brings out the deep bass. But the Druids require breathing room in front of them so that the drivers integrate properly. This is definitely not a speaker for near-field listening. The height of the driver is higher than I’m used to, with the speaker standing 1270mm (50") high, and in a smaller room, the sound seemed to almost fly over my head. It also sounded a bit too peaky and aggressive. Moving my system into a larger room (something I wanted to do anyway during the course of a recent remodel) resulted in a drastically improved sound, one that I found hard to fault in any way.

Mated with the extraordinary Yamamoto amp and preamp combination, the Naim CDX2, and my Michell/SME/ Koetsu analog rig, the Zu Cable Druids are now producing some of the most exquisite sounds I’ve experienced. The final icing on the cake is Zu’s own Libtec speaker cables, which improve the bass even further, and make the entire system more compelling at low volume levels, something I didn’t think cables could do.

All in all, the Druids are fantastic loudspeakers. Needless to say, I’m keeping them.