Mares or Apeks

[Amphibious]

Stay away from the Apeks first stages with the electronic "Status" feature. It's the equivalent of an idiot light for divers. Ridiculous technology if you ask me. Spend a few bucks on a good quality IP gauge instead.

agreed. an IP gauge is something every diver should have in his tool kit. I picked up one from dive rite for $15.

 

[scubafanatic]

I believe that Mares has a special second stage design (Vortex Assisted Design -- VAD) that makes an inhalation adjustment knob less important (but I could be wrong about that). Sounds suspiciously like marketing BS to me, though.

umm, nope, it's not marketing hype, if you look at a Mares 2nd-stage, on the side of the 2nd-stage where the LP hose attaches, you will see a small metal tube OUTSIDE the 2nd-stage main body, it's a little 90 degree tube, that's the famous VAD.

 

[Bubbletrubble]

umm, nope, it's not marketing hype, if you look at a Mares 2nd-stage, on the side of the 2nd-stage where the LP hose attaches, you will see a small metal tube OUTSIDE the 2nd-stage main body, it's a little 90 degree tube, that's the famous VAD.

@scubafanatic: Interesting. And this design helps the breathing feel more "natural"? The Mares YouTube video describes a low pressure vacuum that "sucks" the diaphragm in during inhalation. It sounds like this might create more dynamic instability in flow rates, but maybe it reduces breathing resistance just enough to make it feel natural. I'll have to check it out some time.

 

[LeadTurn_SD]

@scubafanatic: Interesting. And this design helps the breathing feel more "natural"? The Mares YouTube video describes a low pressure vacuum that "sucks" the diaphragm in during inhalation. It sounds like this might create more dynamic instability in flow rates, but maybe it reduces breathing resistance just enough to make it feel natural. I'll have to check it out some time.

Hi Bubbletrubble,

I believe your statement that I highlighted is what is occuring, at least that is how it feels to me.

I believe the VAD increases venturi effect during inhalation, but does not "force-feed" the airflow like some regs; the result is a "natural" feeling breath while keeping the regulator "stable" (not prone to freeflow during the dive).

The downside I've seen is like all non-adjustable regs that are well-tuned: The Mares will tend to freeflow easily at the surface when out of your mouth if not handled carefully... the same thing you'd expect from an adjustable reg set to it's easiest breathing position. My guess is that this tendancy may be why the 2nd stages are somewhat "conservatively" tuned from the factory, so that novice divers do not bring them back to the dealer. If I'm right about this, it is a shame because the diver never sees the real potential of the regulator... :depressed:

Best wishes.

 

[Bubbletrubble]

I believe the VAD increases venturi effect during inhalation, but does not "force-feed" the airflow like some regs; the result is a "natural" feeling breath while keeping the regulator "stable" (not prone to freeflow during the dive).

The downside I've seen is like all non-adjustable regs that are well-tuned: The Mares will tend to freeflow easily at the surface when out of your mouth if not handled carefully... the same thing you'd expect from an adjustable reg set to it's easiest breathing position. My guess is that this tendancy may be why the 2nd stages are somewhat "conservatively" tuned from the factory, so that novice divers do not bring them back to the dealer. If I'm right about this, it is a shame because the diver never sees the real potential of the regulator... :depressed:

Thanks for your input, LeadTurn_SD. Your explanation seems to make sense (with my limited understanding of the Mares design). Now I'm really interested in trying out a Mares reg with the VAD.

I tune my second stages at a fairly low cracking pressure (my personal preference), so I don't think the increased tendency to freeflow would bother me that much. I'll give Mares a harder look next time.

 

[hg frogman]

According to MARES, the bypass (main feature of the VAD) on the Abyss second stage aims also at reducing the "dead space effect" (less CO2 when you breathe).
It gives also an enormous air flow at any depth. When I breathe from it I feel it's more akin a Scubapro Mk25 than a Mk17 if you know what I mean.
There is no knob to make it harder and prevent free-flow. On my Mk17-G250 I don't usually use this knob. I only turn this knob slightly after, say, every 50 dives to eliminate a little starting free-flow. That comes from the engraving of the second stage's seat.
With the Abyss it's about the same, especially for the octopus : nothing to do for 40 (seat new) to 80 dives (seat old) (provided I take care of how I place my regs when I jump in the water) and then I have to tune my second stage slightly to compensate the engraving of the second stage's seat.
Very easy to do (with a wrench and an allen key) but still a little bit more complicated than turning a knob. The counterpart of it being the extreme simplicity of this reg : servicing it is a dream and you need almost no special tool (only an Allen hollow screwdriver 5.5 mm). Easier even than to service an unbalanced piston reg. Very convenient when you're in isolated places.
Last thing : when I don't use my Abyss regs for a while I unscrew a little bit the body of the second stage from the seat's connector (to prevent engraving the seat) and I store them in a dry, clean place to avoid any growth of nasty stuff in the hose.
At least that's my experience with it.