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Difference of Second Stages?
SummerCharpentier - 4/26/2014 10:26 AM
Category: Equipment
Replies: 12

Greetings everyone,

Does anyone happen to know IF or WHAT the difference is between second stages (that are the same) sold with different first stages?

IE: Oceanic NEO comes with CDX5 or FDX10. The second stages look identical. Do they have different internal components or are they the same? From what I get the first stage is the most "operational" part of the reg
diver69420 - 4/26/2014 2:04 PM
The second stage should have a list of features. And usually two are not the same. For example one may have a dial for breathing control. One might a better purge. I’m gonna check on that for you.
Eric_R - 4/26/2014 2:10 PM
Some first stages have environmental kits already installed.
diver69420 - 4/26/2014 2:14 PM
If the second stages are the same than if u put it on a better first stage than you would get better performance. But they are identical. Your breathing and experience is gonna depend on the choice of first stage.
RAWalker - 4/27/2014 1:34 AM
Some are Piston others are diaphragm design each can type can be environmentally sealed which is to keep the internals clean and helps performance in cold water by reducing icing.
The first stage is to reduce the pressure in the tank to a level that the second stage can handle.
It has to deal with the tank pressure reducing from consumption during the course of the dive and maintain consistent pressure regardless of this fact and the external pressure changes from different depths.
The second stage reduces the pressure further to a level we like to breath and some are adjustable for effort of breathing. They are demand valves and shouldn’t flow without being sucked on. Some have means of avoiding free flow at the surface with a sort of switch that can partially obstruct the venturi
Greg - 4/27/2014 6:18 AM
Regarding the Oceanic NEO Second Stages...they both have the same list of "features":

- Pneumatically balanced second stage with virtually no breathing effort
- Advanced composite construction for rugged durability and light weight - our lightest second stage at only 5.7 ounces (without hose)
- Ergonomic Adjustable Venturi Switch (A.V.S.) for simple Dive/Pre-Dive Adjustment
- Patented Orthodontic Mouthpiece with high-density bite tabs for increased comfort and reduced jaw fatigue

The FDX-10 and CDX-5 First Stage say the same thing:

- Effortless pneumatically balanced breathing paired with a compact overbalanced diaphragm first stage
- Nitrox compatible to 40%
- Oceanic’s DVT (Dry Valve Technology) eliminates corrosion of critical internal components
- Designed for extreme depths and cold water

The FDX-10 seems like the newer model and physically looks they changed up the design some...but kept the same features.
OUBobcat - 4/27/2014 6:33 AM
I have the Oceanic Neo with the FDX-10 first stage. The difference between the FDX-10 and CDX-5 when I bought mine 4 years ago was the DVT. Only the FDX-10 came with it.

Now looking at the specs like Greg said, it appears the CDX-5 comes with the DVT now. Also, from doing some research, you can get the CDX-5 with and without an Environmental kit.

P.S I have never had any issues with my reg setup- NEO with the FDX-10.
SummerCharpentier - 4/27/2014 7:35 AM
Thanks for the info guys. Using the NEO as an example, second stage is identical on both first stages.... What I’m asking:

Is it safe to assume that they are the exact same internally and obviously work on both first stages?

There’s nothing that makes them work differently for each stage?
OUBobcat - 4/27/2014 12:35 PM
They should be the same unless they are the octo (yellow) version and the primary second stage. It’s my understanding the octo might not be fine tuned as the primary. Other than that regardless of the first stage they are the same.
TColJeep - 4/27/2014 5:37 PM
Yes. The second stages with the same names, the Neo in your example, are exactly the same. The differences would be in the design of the first stage. They will perform the same on either unit.
DiveBuddyChgo - 4/28/2014 1:43 PM
They are the same.
RichKeller - 4/28/2014 3:42 PM
Most manufactures change the names if they make an upgrade of some sort but very little really changes. Many will make the upgrade available on older models once the newer models have been on the market for a while. Some manufactures will use the same parts in many of their regs but they will have different part numbers for each different model. There is no correlation between 1st and 2nd stages within the same manufacture or other manufactures for that matter. Did you have a specific question about two regs?
SummerCharpentier - 5/02/2014 7:07 AM
Nope, it got answered...

I just wondered if they were the same second stage for different first stages.

Thanks guys!