Head-to-Head Testing
HOW WE TEST
Objective testing was conducted on an ANSTI wet breathing simulator that measures effort (work of breathing) required to move air through a reg as it is subjected to a series of depths and breathing rates. The testing was done at Dive Lab, a commercial testing facility in Panama City Beach, Florida.
Tests are performed at an HP supply pressure of 750 psi (+/25 psi). Regs are tested in the face-forward position, and those with breathing adjustments are set at the wide-open/no-free-flow point.
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The simulator pressurizes the chamber to simulate depths of 132 feet of seawater, 165 fsw and 198 fsw. Each “breath” of the machine moves a specified amount of air, called the tidal volume, through the reg. We do this at 2 liters/20 breaths per minute, 2.5 L/25 bpm and 3 L/25 bpm. Multiplying the tidal volume by the breathing rate gives you the respiratory minute volume (RMV).
WHY DO WE TEST AT THESE DEPTHS AND BREATHING VOLUMES?
40 RMV at 132 fsw:
This represents 20 breaths per minute times a 2-liter volume. This is pretty much the maximum recreational depth at a somewhat aggressive breathing rate.
62.5 RMV at 165 fsw:
This rate represents the European conformance standard EN250. This is the depth and breathing rate commonly used by manufacturers when determining a reg’s performance. This is the U.S. Navy’s Class A test depth and breathing rate.
75 RMV at 132 fsw or deeper:
This simulates the potential demand at maximum recreational depth for a diver at an extremely heavy work rate.
The breathing simulator monitors how much effort is required to “breathe” in and out, measuring the work of breathing in joules per liter (j/L). As depth and breathing rate increase (and with them, the density of the air being moved), the work gets harder. Many modern regs are able to perform at 40 RMV at 132 fsw with less than 1 j/L of work.
If a reg doesn’t exceed the test parameters in our standard tests—the toughest of which a human diver would be hard-pressed to keep up for more than a couple of minutes—we push it to more extreme conditions. Regs aren’t tested for a pass/ fail grade but to objectively gauge their performance in carefully controlled conditions. You can see how each reg performed on the simulator in the charts that accompany each review.
Ergonomic testing was conducted at Blue Grotto Dive Resort in Williston, Florida, by a team of divers who evaluated each reg in the following categories, assigning a score from 5 (excellent) to 1 (poor), and recording observations about performance.
Courtesy Keone Drew PhotographyTest divers (clockwise from top left): Jerry Henkins, David Woods, Ignacio Avellaneda, Jenn Kunis, Reg Thomas, Roger Roy, Robbie Gomez, Kalina Maynor, John Conley, Mary Frances Emmons, Darcy Rios, Jeff Borod and Robby Myers.
» Ease of breathing: How well does the reg deliver air in a standard swimming position? Face-up? Head-down?
» Wetness: During normal swimming, how dry does the reg breathe? Face-up? Head-down?
» Bubble interference: How well does the reg deflect bubbles from your field of view?
» Ease of clearing: How difficult is it to clear the reg by exhalation or via the purge?
» Purge stiffness: Is it soft and progressive or forceful and abrupt?
» Resistance to free-flow: Is the Venturi control easy to use and effective at blocking free-flows?
» Breathing adjustment: Is the adjustment easy to find and use? Is it effective?
» Comfort of second stage: Taking into account its size, shape and weight.
» Noise: Does the reg operate with excessive noise?
NEX
STEALTH WITH 2.5-INCH BALANCED SECOND STAGE
MSRP $1,021.99 (as tested)
CONTACT nexdive.com
The new N1 Stealth overbalanced first stage lives up to its covert moniker with a blacked-out military grade DLC body and matching PVD ports and inlets. It includes five low-pressure ports on a swiveling turret and two high-pressure ports. It was paired with Nex’s 2.5-inch balanced second stage during testing, which includes a breathing adjustment and Venturi control. It took excellent scores on the breathing simulator and had the lowest work of breathing of the test at low and moderate work rates. Testers scored it excellent for ease of breathing in swim position and ease of clearing, and very good for everything else. Multiple divers described the reg as a “smooth, easy breather” and picked it as a favorite. The N1 Stealth is our Testers Choice for regs.
Love how smoothly it delivers air with minimal inhalation effort.
CRESSI
AC5/ZEN
MSRP $389.95
CONTACT cressiusa.com
The new balanced diaphragm Zen second stage impressed with lightweight, compact comfort and very dry, easy breathing. It earned good and very good scores overall, though some testers felt the purge was too stiff and the mouthpiece was uncomfortable. The unbalanced piston AC5 first stage has one high-pressure and four low-pressure ports in a spoke-like arrangement. The reg earned very good scores on the simulator, with high marks at low and moderate breathing rates regardless of depth. This budget-friendly reg is simple, capable and comfortable.
Simple and effective.
DIVE RITE
FT1/XT2
MSRP $459, $739 (basic open water package)
CONTACT diverite.com
This breathing system—also available as a complete set with octo, SPG and carry case—pairs the balanced, environmentally sealed FT1 first stage with the dependable, feature-rich XT2 second. It earned excellent and very good simulator scores, with consistent breathing effort between depths. Testers scored the second stage very good for comfort and for its ergonomic breathing adjustment and Venturi lever. The purge scored excellent. The reg offers reliable low-effort inhalation with plenty of control.
Really pleasant experience overall.
DIVE RITE
XT1/XT2
MSRP $475, $755 (basic open water package)
CONTACT diverite.com
This tec-inspired system uses a balanced, environmentally sealed XT1 first stage with five low-pressure ports on a rotating turret and a durable diamond-like coating paired with an XT2 second stage. Testers scored it very good across the board. On the simulator, average work of breathing was slightly higher than the FT1/XT2 but showed a similar consistency across depths. The reg offers solid performance and an array of features suitable for divers interested in pursuing more advanced diving.
Pulls air smoothly and evenly; makes for very low effort breathing.
IST SPORTS
R-1000
MSRP $ 998
CONTACT istdivingsystem.com
Composed of small, lightweight first and second stages, the R-1000 is travel-ready with dive-all-day comfort. Testers loved the strain-relieving ball-socket connection on the featherweight second stage and scored it very good for comfort. “It can just rest in your mouth,” one tester said. It showed excellent and very good work of breathing on the simulator at low and moderate work rates, but performance began to struggle at extreme work rates. Offering very good performance overall, this compact reg is a solid option for travelers and new divers alike.
Easy to use; breathes nicely.
SCUBAPRO
MK11 EVO/C370
MSRP $719
CONTACT scubapro.com
The updated MK 11 Evo first stage uses a double spring layout to increase performance while maintaining a compact size. Paired with the C370 second stage, it took excellent simulator scores across the board with remarkable consistency. Divers scored it very good for ease and dryness of breathing and described it as “soft, smooth and quiet.” The reg has a powerful purge and a tendency to free-flow without the inhalation adjustment and Venturi dialed in. Offering impressive performance at a below average price, the MK11 EVO/C370 is our Best Buy for regulators.
Breathing is effortless.
SCUBAPRO
MK 17 EVO 2/C370
MSRP $789
CONTACT scubapro.com
This breathing system combines the C370 second with the next-gen MK 17 EVO air-balanced, environmentally sealed first stage. It earned excellent scores on the simulator and delivered a consistent work of breathing at each work rate. Although work of breathing was impressively low, we felt it was worth noting that the reg does require slightly more effort than the other two Scubapro models in our test. Divers scored the reg very highly across the board and praised its low-effort breathing and quiet operation. “Almost like its breathing for you,” is how one test diver described it.
Smooth operation— almost effortless.
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SCUBAPRO
MK 17 EVO 2/S620 TI
MSRP $989
CONTACT scubapro.com
This reg pairs the new MK 17 Evo with the S260 Ti second. It earned the best simulator scores among the three Scubapro models and had the lowest work of breathing of any reg at extreme work rates. This ready flow of gas resulted in very good scores from testers for ease of breathing and a powerful purge that should be handled with care. The reg is primed to free-flow with the breathing adjustment wide open, but a slight adjustment combined with the Venturi keeps things in check. The reg offers refined ergos, light-weight comfort and outstanding performance.
Wow! Super comfortable and dry in all positions.
