Predator: A Future Classic

The Making of HT/1508 Predator

Follow along as our design team details the process whereby a simple idea—the need for a true flagship for the HT range—takes on a life of its own.

When the decision was taken to build a pure home theatre line of subs, we knew we needed a legitimate flagship to solidify HT’s position in the REL firmament.  As soon as we’d finished the design phase of the volume models (HT/1003 and HT/1205) we set to work on what quickly came to be known internally as Predator™. Predator had to be effortless, have massive output and yet still manage to retain a REL hallmark; quickness which, in home theatre applications, results in slam and conveys suddenness to scenes.

Since we had learned a wealth of lessons developing the awesome No. 25 15” driver just a couple years back, the decision to use a 15” was an easy one. These large drivers deliver the effortless quality we were looking for, yet, as the No.25 proved, can be astonishingly light on their feet. But we still had our work cut out for us because a core feature of the HT range is high value, lots of performance for relatively low cost and a No.25 driver isn’t cheap to build.

As it happened, the 15” Predator driver came together fairly easily; some projects struggle and fight you at every step along the way but turn out great in the end. Fortunately, this was one of those rare and happy instances where we built off our No.25 experience and it saved us huge amounts of time and money. From start to finish, the Predator 15” engine came together in just 5 months. We selected glass fibre for its lightweight and cost effectiveness for main cone body. It’s tough, resilient and decent at self-damping, which is a critical characteristic in cones. A quiet cone means more musical information can get through and detail isn’t obscured by resonance. And being light, it requires less wattage to get moving. Think of it as the affordable version of carbon fibre (minus some strength, quietness and lightness) and you wouldn’t be far off.

One area we have focused on in recent years is using combinations of cone materials to generate stiffness on one hand, and to produce quietness on the other. Nothing beats carbon fibre for cones but when molded into complex shapes, it gets quite expensive. The simple solution was to select carbon fibre but use a simply inverted bowl shape that required no complex bends, or terminated edges, thus keeping the cost relatively low. This overlaid on top of the center of the glass fibre cone produced exactly the results we were hoping for. The challenge was assembly, a high precision event because if this crucial component is off center by even a little, it can throw the driver off concentricity. But we’re used to such nuanced precision and we had the core of our driver working almost from the start.

A couple months of fettling the balance, the glues and the surrounds and we had the basis of a successful project. What resulted was a 15” driver with extended stroke; we offer 3” of stroke fore-and-aft but still remain lighter than an old R Series 10” paper driver of a few years back. Sonically, it’s a beast, with tremendous dynamics and attack, yet due to its large size the sound is huge and effortless

The amplifier is an all-new design for us—quite different from the one used in No.25 or 212/SE. It is extremely powerful and capable of 1,000 watts continuous and will easily deliver at 1,200 watts. We limit it in this application to 800 watts as it clearly plays extremely loud and controls the driver beautifully. By using a conservative limit, it guarantees long life for the amplifier as it is relatively unstressed, important for REL amps. It is extremely efficient and sips just 20 watts at idle (standby not engaged where it draws just .5 watt). Our guidance would be to set it to always on and unplug it when going on holiday. Where the No. 25 amp is like unto a scalpel, the 1508’s is more of a broadsword, which is fine for this application as it has this big, swaggering quality to it. Just what you want when staring into the mouth of a T-rex or dodging photon torpedoes!

Finally, all this is clothed in a classic HT cabinet, meaning it struts the same line-grained aluminum-look of the smaller models and looks deadly serious. Happily, the cabinet is quite compact for such a powerful unit, those who have seen it in person were somewhat surprised by this, but we wanted it to fit into the majority of living rooms without being overbearing in scale. At just 17” in depth (430mm), it will fit into some cabinets and can easily be built into scrim walls for dedicated theatre builds.

Internally, we used the same window-pane brace with a broad centre circle lined with felt that cups and cushions the rear of the magnet, both to prevent shipping damage as well as to quiet the motor in use. It’s yet another example of using cost effective methods to produce superb results. The cabinet has one last feature that may surprise some; instead of 4 individual feet, Predator has full depth rails running underneath the cabinet from front to rear. The rails, along with included black powder coated couplers that bolt to the rear panels and lock units together, allow for stackability of multiple 1508s.These are machined to flow around the beautiful, high gloss black lacquer top plate that dresses up the most visible surface and performs double duty damping the crucial top panel from vibrating. We recommend limiting stacking to 3 units high per side but concede that there will be some (Hello, Texas?) who feel the need to stack 5 high. Sigh…Ah well, if a little’s good, far too much is almost enough.

Predator is designed to be an extremely high performance flagship using a 15” longstroke, composite driver with 3” of stroke powered by an 800 watt hybrid amplifier intended principally for large-scale theatre applications. However, and listen up you 2-channel mavens; after final development and sign off using it strictly for theatre we strapped it into our high end 2-channel reference system and lo and behold, when crossed over appropriately, it blends remarkably well with the mains and its speed and tactility allow it to perform incredibly well as a musical sub—quite amazing. But then, it has fast filters and really good bones with a great driver and powerful amp so we shouldn’t be too surprised. In the end, it is a proper REL first and a theatre beast next, at a price that everyone will find pleasingly affordable. We would however suggest keeping small children away from it; as its name suggests, it might well devour them.

February 20, 2019 - Posted in: News, Principles of Sound