Mark Evans: Back in November 2017, we published an exclusive first test on the lightweight travel-friendly Apeks XL4, which is also cold-water rated, and to give it a proper review, we took it to the chilly waters of Iceland.
The XL4 was the travel regulator the Apeks design team always intended the Flight to be. When the Flight was initially being made, the team wanted it to be cold-water rated as well, but it just never came to pass, so the XL4 from the outset was going to be a cold-water-rated, lightweight travel regulator, and after diving it in the cold waters of Silfra in Iceland, I can say that they well and truly achieved their goal.
It never missed a beat, even when I breathed rapidly through it and also extensively purged it in 3-4 degrees C water. In fact, it was so good, I forgot I was diving a new regulator and not my usual MTX-R or Black Sapphire.
So, what’s different about the XL4+? As with the XL4, the compact, machined first stage of the XL4+ is based on the expedition-tested Apeks DS4 platform, and features a break-through, innovative over-moulded first-stage endcap and environmental diaphragm that helps prevent ice build-up that can cause first stage freeflow in extreme circumstances, as well as protecting the first stage from impact damage.
The large surface-area heat exchanger diaphragm clamp helps increase the gas temperature inside the first stage, resulting in improved cold-water performance, while the unique over-balanced diaphragm design – as the diver descends, the over-balancing feature allows the medium pressure gas in the hose to increase at a faster rate than ambient – which results in superior performance at depth.
One thing that some divers pulled up was that the XL4 first stage only had one high-pressure port, but that has now been rectified with the XL4+, which is equipped with two high-pressure ports for those that want them. The hose-routing is perfect, with everything falling where it should. Thanks to its high performance and cold-water rating, Apeks are also promoting the XL4+ as an ideal stage regulator.
Apart from the nifty new white colour option, the XL4+ features the same second stage as the standard XL4. It is compact and lightweight, to improve comfort and reduce jaw fatigue on long dives, and features a high-performance, pneumatically balanced, lever-operated poppet valve, over-moulded self-flushing and controllable purge button, and ergonomic venturi lever that is easy to use and locate.
As we noted when we tested the XL4, in looks, the second stage is reminiscent of the Flight, with a wide exhaust tee to direct the exhaled bubbles either side of your face, but the cover is very different, emblazoned with a large ‘A’ on the big purge button. It is a simple aesthetic, but it works, especially in this bright-white colour scheme.
We took the XL4+ with us when we completed exploratory dives at the new St Andrews Lakes inland site in Kent, and the water temperature, while not quite Icelandic, was still a rather brisk 5 degrees C at depth, and as with the XL4, it never faltered, delivering a nice, smooth breathe regardless of depth, temperature or orientation.
NB: The XL4 octopus is available separately priced.