mixing 1st and 2nd stages

[cat fish]

If you can freely mix and match 1st and 2nd stages, what would be the best 1st and 2nd stage combinations out there? I was thinking of Scubapro S600 2nd stage and Aqualung Cousteau Cryo 1st stage.

The criteria that I consider important are high air flow, low breathing resistance, durability and cost. Environmental sealing is also a plus given that it affects service intervals.

A lot of people on the message board speak well of Apeks, but I cannot find a shop that I would trust to service Apeks regs in my place. Scubapro 2nd stages seem to be among, if not the best, but I prefer a dry sealed diaphragm 1st stage because of the silty conditions I sometimes dive in. Scubapro diaphragm 1st stages do not seem to be held in high regard although I may be wrong.

Locally serviced brands are Mares, ScubaPro, Dacor, Oceanic, Aqualung, and Beuchat.

Thanks in advance for any response to my query.

 

[Stone]

Originally posted by cat fish
If you can freely mix and match 1st and 2nd stages, what would be the best 1st and 2nd stage combinations out there?

I can't answer the question, but I can comment that "match" is the operative word since (in many/most? cases) the 2nd stage should be tuned to match the intermediate pressure supplied by the 1st stage.

<Edit> . . . And welcome to the Board.

 

[canuckton]

No problem "mixing and matching," but for best performance, have a certified tech go over the reg. The intermediate pressure on the 1st stage should be tuned for optimum performance in the second stage.

Beware of putting cheapie cheap octos on high performance 1st/2nd combos. Tuning the octo can be tricky, and it's an important piece of kit.

 

[Stone]

Originally posted by canuckton
No problem "mixing and matching," but for best performance, have a certified tech go over the reg. The intermediate pressure on the 1st stage should be tuned for optimum performance in the second stage.

Canuckton,

I may be misreading your post, but as long as the 1st stage has a solid IP within the manufacturer's allowable range, I would tune the 2nd stage to match the 1st.

<edit> And welcome to the Board.

 

[canuckton]

Stone,

thanx for the welcome.

The idea with the mix and match is the different specs for different manufacturers. For instance, if I tried a sherwood 2nd (recommended 125-135 psi for most of the range) with an apeks first (which everyone here loves) then I'd have to detune the apeks to the lower sherwood range.

But if I threw, say, a SEA4 2nd on said apeks, I'd probably dial the IP into the 140-150 psi range...the SEA4 can handle it, and will perform much better than at 125 psi

Goes without saying that you'd tune the 2nd. But dialling in the 1st is essential to prevent IP creep problems on lower end regs or single pivot arc arms.

Personally, I try to keep all my regs in a common range, then if one fails at the site, or I need a spare, I can put my chosen primary 2nd on whatever 1st happens to be in my kit.

Anyhoo, I suspect we'd do just about the same thing. Order of ops is in the eye of the beholder

 

[Stone]

Originally posted by canuckton
Goes without saying that you'd tune the 2nd. But dialling in the 1st is essential to prevent IP creep problems on lower end regs or single pivot arc arms.

I see what you're saying.

All of my regs are balanced pistons that use shims. I don't "dial in" the IP, I add a shim to increase the IP, or remove a shim to decrease it, and hope I hit 135 to 150 psig on the first try.

 

[canuckton]

Aha!

And that's the drawback of shims...But I like the performance of a piston better.

My shop does mostly USD and Mares...so dialling the IP in is easy and good. Also good for detuning ips for extremely cold water

happy bubbling!

 

[cat fish]

Thank you to everyone for your informative replies. I would like to restate the question though: could you equal, or surpass the performance and reliability of Apeks regs by mixing different brand 1st and second stages?

 

[canuckton]

No....the vaunted reliability of apeks is due largely to their overboosted first stage design

Any decent 2nd with heatsinks and tunability would perform as well in most cases.

The best reason to mix and match is to get that great 1st stage, and then a 2nd with superior comfort , exhaust, etc etc.

For instance, when I do mapping dives, or underwater photography, I plug an Odin 2nd into my DS4. Bubbles miss my face that way. But I find the Odin fatiguing on long dives. So I use a D400 or tx50 or whatever, for those 1 hr plus dives.

So for comfort or preference, yes, but performance wise, probably not worth the trouble.