Atomic users

[El Diablo]

I've played around with a lot of regulators. Based on what I have seen, with regard to performance (when the tank has more than 300 psi), there is no difference between first stages.

The tuning and attributes of the second stage account for 99.9% of any performance advantage/disadvantage that the first and second stage combo provide - at recreational depths. For example, I used an MK-2 as a primary first stage for a while, worked perfectly- no difference compared to a more expensive first stage.

I do kinda think a swivel can make a difference in comfort, but not performance.

BTW, my cheap dishwasher takes forever to run and it does not do a very good job.

Hi John,

I stated multiple times that the differences will show at depth and demanding breathing conditions.
Of course when the tank pressure is dropping, balanced 1st & 2nd stages will work much better.

 

[johndiver999]

Yeah when the tank is at 200 psi and you are deep, it is really important that the regulator gives you a ton of air with zero effort - otherwise..... you might run out of air later? Only half kidding..

 

[Centrals]

If you can't tell the difference between breathing from a Mk2 and a Mk25 well... can't help you.

I was asking Mk 25 and Mk17.

 

[El Diablo]

I was asking Mk 25 and Mk17.

Same applies. There's not a huge difference but there's a difference nevertheless. I own both systems, tried it several times.

On my own Mk17 the 2nd stage is inferior to the S600 I have with the Mk25. My dive buddy has the newer Mk17 EVO with also the newer S620Ti and my Mk25 is still breathing slightly better. We service both regs in the same store (DCP - Dive Center Paradise) and they give us printed the ANSTI results.

 

[Centrals]

Same applies. There's not a huge difference but there's a difference nevertheless. I own both systems, tried it several times.

On my own Mk17 the 2nd stage is inferior to the S600 I have with the Mk25. My dive buddy has the newer Mk17 EVO with also the newer S620Ti and my Mk25 is still breathing slightly better. We service both regs in the same store (DCP - Dive Center Paradise) and they give us printed the ANSTI results.

If you want to compare two 1st stages, the 2nd stage should be the same one.
Blind test.

 

[El Diablo]

If you want to compare two 1st stages, the 2nd stage should be the same one.
Blind test.

Yes, I said it myself previously.

Here you can see my ANSTI machine tests.

The Mk25 breathes so slightly better and perhaps the biggest difference and the one I 'feel' is the effort to inhale that is considerably less than the Mk17.

 

[Centrals]

Yes, I said it myself previously.

Blind test under water and with the same 2nd stage!

Good read:

Regulator Performance With Increasing Depth

first off i don't know anything about regulators i am just reading all the post and trying to learn!! so would this be the BOTTOM LINE ?? a balanced diaphragm 1st stage only makes breathing easier when the tank pressure drops below 400 psi..(true or false).. most modern day 2nd stages are...

scubaboard.com

 

[El Diablo]

Blind test under water and with the same 2nd stage!

Good read:

Regulator Performance With Increasing Depth

first off i don't know anything about regulators i am just reading all the post and trying to learn!! so would this be the BOTTOM LINE ?? a balanced diaphragm 1st stage only makes breathing easier when the tank pressure drops below 400 psi..(true or false).. most modern day 2nd stages are...

scubaboard.com

I summited above the test for the regs. I am talking about my personal actual experience with both, you are talking based on... other people's comments, mostly theoretical.
I also posted a video from SCUBAPRO stating exactly the same.

The second stage on the Mk17 will influence the results only at great depth as it is not balanced.
In addition, the test on the Mk17 was done with the bottle fuller by 25 Bars or 17% (170 vs 150) that also should give a slight advantage to the Mk17 vs the Mk25 but the venerable piston reg still wins. As I wrote, it 'feels' slightly better.

I love both my regs. Diaphragm regulators are (usually) environmentally sealed and therefore require less maintenance. Piston regulators have less moving parts, therefore are lighter and breathe ever so slightly better as the piston orifice allows more air to pass through. Both systems have pros and cons.
Depending on your needs and preferences you can chose one or the other (or both like me).

Mind that they are both high-end regs, on entry level models differences might be more substantial.
This is in regards to your comments on 'regs having no differences as you cannot breathe so many L/min'.
Use any rental Calypso and compare it with a Legend, then tell me if there's a difference or not. Blind test, no blind test or drunk test...

Also technology changes, the newer Mk11 has a better flow rate than the (much) older Mk2 (1963) so in this case, the membrane reg is better than the very old piston reg. Let's see what happens

 

[scrane]

At what depth does the performance of the Mk17 degrade as to be not usable under heavy load as compared with the Mk25? You keep on throwing in so many variables with piston/diaphragm, balanced/unbalanced, test rig/depth, different second stages that it is difficult to follow your logic. I am not doubting that the piston regulator has a theoretical advantage due to it's having a larger orifice, but outside vague declarations of "feels ever so slightly better" what are the real world results?
I dive both piston and diaphragm first stages in recreational settings and as far as I'm concerned there are no differences in performance. They are interchangeable. Any difference in breathing characteristics is due to the second stage in my rigs.

PS: The MK17 is a balanced regulator. The Mk11 is also balanced. The Mk2 is not. The Mk2 may be old, but it is still in the catalog. The cash cow of first stages.

 

[wetb4igetinthewater]

2,600L/min!
Can your lung take that amount of gas in one minute?

I'd really like to know how that is measured, as I wish there was some industry standard to compare performance between regs. There is too much nonsense of "this breathes better" that is really personal bias.

Yes, I said it myself previously.

Here you can see my ANSTI machine tests.

The Mk25 breathes so slightly better and perhaps the biggest difference and the one I 'feel' is the effort to inhale that is considerably less than the Mk17.

I'd like to learn more about these tests, as I just stated I'd love to have an objective means for performing comparisons.

Maybe we start a separate thread? This is a topic that interests me greatly.