Mares Proton Metal vs. Mares Abyss Nitrox

[awakefie]

I am looking at buying either a Mares Proton Metal or a Mares Abyss Nitrox as a replacement second stage for my Abyss 22 first stage. I am debating which replacement is the better option. The Proton is the cheaper option, but the Abyss Hero second stages seem to be popular.

Any input would be appreciated....

Thanks,

awakefie

[scuba_punk]

I dive the MR22 Abyss when I'm not diving my OTS Guardian FFM and haven't had any issues. The coldest that I have taken it was around 56 and the deepest was 60ft with no trouble. The majority of my diving is done in warmer water (70) and I don't get the extreme dry-mouth feeling that comes from breathing compressed air. It might help others give you advice if you list the conditions you will be diving in.

[LeadTurn_SD]

I prefer the Abyss 2nd to the Proton 2nd... but this purely subjective however, nothing at all to do with any performance difference I've noticed. I own both, but just like the Abyss better... just "because".... but both are very good "classic downstream" 2nd stages.

Best wishes.

[awakefie]

I dive the MR22 Abyss when I'm not diving my OTS Guardian FFM and haven't had any issues. The coldest that I have taken it was around 56 and the deepest was 60ft with no trouble. The majority of my diving is done in warmer water (70) and I don't get the extreme dry-mouth feeling that comes from breathing compressed air. It might help others give you advice if you list the conditions you will be diving in.

75% of my dives are cold water with air (around 50 degrees). The other 25% are warm water. (Coz and such) I am usually diving no deeper than 100 feet and at average right around 60 feet. I do get dry mouth while diving from time to time.

Also if someone could explain or point me to a good resource regarding the different types of second stages and assorted pros and cons I would be very appreciative.

awakefie

[LeadTurn_SD]

..... Also if someone could explain or point me to a good resource regarding the different types of second stages and assorted pros and cons I would be very appreciative.

awakefie

I'm not sure about a good online resource. Here are two broad categories that you'll see today (but there are a few exceptions):

1.) "Classic Downstream": The Mares 2nd's are examples of classic downstream. They are unbalanced, and do not have an external adjutment knob. They are simple, reliable, extremely easy to service, but my opinion need a little more "art" to adjust/tune well. Despite their simplicity, they perform very well. Some people feel that the lack of external adjustment somehow makes this type of 2nd inferior in performance, but this is not necessarily true. It all comes down to good design & tuning. I've taken "Classic Downstream" 2nd's well beyond recreational depths without issue.... they performed great. The major con (for me) with the classic downstream is that to adjust it at all you need tools... no "on-the-fly" adjusting / fine tuning.

2.) "Barrel poppet" (unblanced or balanced, with or without external adjuster): I'm just guessing, but I'd say the majority of barrel poppet regs today are balanced since it is easy to accomplish with this design. Many (most?) also have venturi assist & external adjusters. The advantage with the external adjuster is that the diver can adjust the spring tension to increase/decrease breathing difficulty "on the fly". This can also help make up for a slightly "sloppy" tuning job by the tech, and can compensate (a little) for decreasing performance between services. The ability to adjust the 2nd stage spring pressure "on the fly" can help prevent freeeflow in a strong current, or in high stress situations will allow you "max out" ease of breathing....

I've been able to test a classic downstream and balanced adjustable barrel poppet reg side-by-side at depth (one on a stage bottle, one on my main tank). My (very limited) experience between the two types at "recreational" depths? Only a VERY slight difference in ease of breathing. You can tune a barrel poppet a little closer to the edge of free flow than a classic downstream.... which I've found means that if I crank my barrel poppet reg (Zeagle Flathead VI, ZX 2nd) to it's easiest position (just a hair away from freeflow is the way I tune mine to breath at it's easiest), it will breath just slightly easier than my well-tuned, well-mannered, less-aggressively tuned classic downstream (Mares MR22, Abyss 2nd). But only slightly, and only if I crank the Zeagle's adjuster knob out to just the happy side of a freeflow.

Not sure if this helps in the least, hopefully other more knowledgeable folks will chime in.

Best wishes.

[Stu S.]

Proton metal is OK with me. I've had it 3 years. My dealer wants me to "trade up" to the Abyss. I see no reason to do so at this time.

[awakefie]

Thanks Guys, This advice is very helpful!

[hg frogman]

Mares Abyss 2nd stage is mechanically much simpler than the Proton Metal. Look at the schematics, the Abyss 2nd has only two O-rings ! It's also a bit bigger than the Proton Metal, which allows for better performance of the diaphragm/lever.

The Abyss (and the Proton) is not a typical "classic downstream" 2nd, because it has a patented Mares "bypass" which allows for bigger flow than the classic downstream design.

IMHO the only advantage of the Proton Metal is that you can open it underwater more easily, albeit it's still not so easy ! (To open a Abyss underwater you would need a small screwdriver). It's a feature I don't need.

For robustness and proven design & record, my choice would be the Abyss.

BTW when I use an Abyss instead of a G250 I do notice less dry mouth effect.

[awakefie]

Thanks frogman. I think the reason I have been swaying towards the Proton is because it is the cheaper option to buy as an octo and adjust. I also dive cold water and like the idea of a metal second stage. Its really still a toss up at this point.