ScubaPro MK17/S600 vs. AquaLung Titan LX Supreme

[Doc.Caliban]

Hi there,

I figured I'd ask this in an old, semi-related thread instead of starting another "Which <whatever> should I get?" thread.

I've been diving with the same old and abused MKII/R90 Scubapro combo for years as an instructor / guide. Clearly there are fancier things to stick in one's mouth, but I'm so used to the thing that I've never really cared to explore the options.

Now I'm no longer working as a DI, so I can afford to buy something else. Did I mention that I never cared to explore the options because I was working as an instructor? The old 'What do an Instructor and a small pizza have in common?' bit.

I really am completely comfortable with it because I've never used anything else but other instructor's clapped-out workhorses and that 40-year-old Mistral in the avatar pic. But I want to treat myself to something new. All I care about is that it breaths differently enough to justify the cash and it's no less reliable than what I have now. Scubapro is what I will most likely go with due to a line on a good discount, and I was looking at the MK25/S600 until I read this thread and saw the comments about the G250V. I dive in warm water 98% of the time, but a cold water dive is not out of the question down the road.

Is the G250V my reg, or should I just stick with the "if you don't know what you're missing, then carry on" approach?

Thanks for any feedback,

-Doc

EDIT: Actually, I'd be happy to get feedback on the first stage as well. I'm not set on anything.

 

[halocline]

Given your long experience with the MK2, and the fact that you seem to be more interested in performance than hype, I would start by getting a used metal case SP 2nd, and having it converted to balanced/adjustable status. You can probably get one in near mint, paying top dollar, and get it rebuilt and converted for around $100 easy. Put that on your MK2 and try it out, you might just stop there. If you like that, you could find a SP balanced piston 1st to go with it, MK5,10,15,20, or 25, depending on what you can find that's in good shape. Personally I like the older stuff.

The G250V is a re-issue of the old G250; to me it's no surprise that the current SP reg getting the best reviews is, in fact, an older design. The original G250 was based on the metal case balanced adjustable. It would not surprise me to see SP re-introduce the metal 2nd stage, probably updated with some fancy materials and an extravagant price tag. I'd want one.

As far as reliability goes, you can't beat the MK2, but the balanced piston regs are still pretty bulletproof.

If you're determined to buy new, the MK25/G250V would be my choice, and you really would notice a difference from the MK2/R190. You might not like it better, though. I have introduced 4 diving friends to the metal case regs, 3 of them instructors, and they all ended up tightening down the adjustment because they were not used to such low breathing resistance. Go figure.

 

[pescador775]

It may be that Scubapro should have stopped with the MK II. They went on to produce piston designs that had more internal parts than many diaphragm type regs. That is remarkable because the MK V and MK II were originally promoted for simplicity and quick service turnaround. In addition, the MK V was touted for large air flows associated with a piston with a huge 3/16 bore. Unfortunately, the valve to which it was attached had only a 1/8 bore, or less. Heh.

Go with a diaphragm operated reg, for example something from the Mares line or a SP MK17 based system. The Mares has no control knob but some of the Mares second stages are service adjustable from outside. Pop a cork, insert tool and adjust poppet valve. You might like that feature combined with a bullet proof, leave it alone, first stage on top of a simple second stage. On the other hand, the G250V and especially the G250HP are smooth breathers. They don't depend solely on Venturi effects for large flows. They use a pneumatic spring which "lets off" slightly when inhaling. You get the air without the blast which one expects from the Mares or the old 109 model Scubapro. That's why the old timers crank down the knob on those things. The G250V is simpler internally (for service) without the adjustable balance valve of the HP. That's a good thing. Now, you really didn't think that we could solve attitudinal issues without the couch did you? We're all techies to the core and that means I'd better stop here.

 

[halocline]

Actually, in my experience the metal case balanced adjustable has less venturi effect than the G250. It's one of the things I like about the old metal case regs.

I agree that the flow rates on the SP balanced pistons, especially the MK20/25, are way beyond what a tank valve is capable of supplying, and of no practical value in diving. But I don't agree that they're overly complex. The only added parts for the later balanced piston design are the bushings (2 of them) and the retaining device for those bushings, a circlip for the MK15 and a spring for the MK20/25. There is some value in those parts; they tighten the tolerances around the HP o-ring. The MK25 does have the adjustable seat retainer which I suppose adds a little unnecessary complexity.

 

[pescador775]

The MK25 is a pretty piece of craft but so was the Spanish galleon. I mean, did they really need a poop deck and a flying nun on the masthead? Does SP need a number of plastic pieces to scrub the piston? A couple years ago, I posted the actual number of parts in that SP piston reg and the total number was higher than that of a typical diaphragm reg ( I guess you missed it). What happened to the "one moving part" advertisement? Gone, along with the Viking long boat? If the regulator is subject to annual service anyway why not just keep the piston design simple and use diaphragm designs for the heavy lifting in harsh conditions like silt and ice? I guess they are catching on, finally.

 

[Doc.Caliban]

Hey guys,

Sorry for the long delay, but I'm ready to buy something now. (Been too busy these last couple months to even think about it.)

I'm pretty much decided on the G250V, so now it's down between the MK17 and MK25. All good arguments above, any final input?

I'm going with new SP stuff because I can get it at a ridiculous discount thorough a shop I used to work at.

Thanks again!

-Doc


EDIT:

Nevermind, I found a few piston/diaphragm threads.