Does your first stage and second stage have to match or be the same brand?

[00wabbit]

I have a cressi Ellipse MC-9 Balanced 1st and 2nd stage with a yoke valve.

I would like to get a din first stage so that I can rent the steel tanks at the shop. Do I have to buy a cressi first stage or can I use a different brand? If yes are there certain requirements I should look for to make sure it works with my reg?

 

[tracydr]

No, mine are different and work fine together. I have an Oceanic first stage and secondary, a new HOG for my primary.

 

[chrpai]

Do the rental tanks have pro/convertible valves that you can insert yoke plugs?

Amazon.com: XS Scuba DIN Valve to Yoke Valve Insert For Scuba Tanks: Sports & Outdoors

Another option is to convert your 1st to DIN:

Cressi Din Conversion Kit MC7 @ Divers-Supply.com

Otherwise, they don't generally have to be the same brand. As long as the IP range is the same and the seconds are adjusted to the IP of the 1st.

Personally, I love my Hogs. The prices are so good that you might want to see what you could sell your whole reg for and replace it with a Hog D1 single tank package complete with 7' long hose and 2" brass and glass SPG.

 

[00wabbit]

Cool I didn't even know that was a thing. I might look into getting that. I see they also make one for my MC9 1st stage.

Do the rental tanks have pro/convertible valves that you can insert yoke plugs?

Amazon.com: XS Scuba DIN Valve to Yoke Valve Insert For Scuba Tanks: Sports & Outdoors

Another option is to convert your 1st to DIN:

Cressi Din Conversion Kit MC7 @ Divers-Supply.com

Otherwise, they don't generally have to be the same brand. As long as the IP range is the same and the seconds are adjusted to the IP of the 1st.

Personally, I love my Hogs. The prices are so good that you might want to see what you could sell your whole reg for and replace it with a Hog D1 single tank package complete with 7' long hose and 2" brass and glass SPG.

 

[Wolfie]

90% of first and second stages run with the same IP I think that's 125 +-10psi. As long as those specs are kept your fine for brands. I hear your pain for the din conversion than a din to yoke adaptor. It make you reg less than optimal for yoke and it cost 100 to 150 to do this. I too considered buying a hog d1 1st for this same reason. (and still may do so). Also to be considered is the increased annual cost of having multiple regs. The good thing about hog is their 2 year service recommendation and the DIY option. Yet it is still another reg to service. Currently I have 2 sp and 1 oceanic firsts and 2 sp 2 oceanic seconds. I swap all universally when trying new configurations. No problems yet. (except for a flooded SPG but I swear that was a spool issue I can blame on my LDS.)

---------- Post Merged at 11:41 PM ---------- Previous Post was at 11:30 PM ----------

Opps you posted while I was typing. I thought you had dismissed the conversion. What I mentioned about less than optimal for yoke refers to the fact that converting it to din will give it a much more compact design. Then you put the din to yoke adaptor on for your common rental tanks. This pushes the regulator out about an inch which tends to bother some people with banging there head against the first. The other complaint I've heard is that it's another potential failure point. I don't think that is a really valid point.
IMHO if you are ok with the head banging you're fine. I think I will make sure I keep one yoke anyway for cruising the warm waters with yoke rental tanks.

 

[idive2]

I recently switched a second stage to a different first stage and had a noticeable difference
in breathing effort. Pretty sure the second stages are tuned with the first stages they are set
up with. I think you could tune the second stage to match the first stage but maybe
a 10 psi or so difference on the IP pressure from one first stage to another could effect the
performance of the second stage.

 

[chrpai]

I recently switched a second stage to a different first stage and had a noticeable difference
in breathing effort. Pretty sure the second stages are tuned with the first stages they are set
up with. I think you could tune the second stage to match the first stage but maybe
a 10 psi or so difference on the IP pressure from one first stage to another could effect the
performance of the second stage.

2nd stages have adjustable orifices valves that have to be tweaked to the upstream IP. You want to get it to the sweet spot where it won't free flow but the cracking pressure is as little as possible. This is typically measured in inches of water using a magnehelic gauge. While different regulators are adjusted in different ways ( for a Hog regulator you turn the orifice adjustment by taking the regulator off the hose and sticking a hex key inside the inlet ) the basic practice is outlined in a thread somewhere around here. Basically you submerge the regulator face down into water until it begins to free flow. Measure that depth with a ruler. You then adjust the orifice until the depth is to the spot you want. That spot depends on the capabilities of the regulator and how "hot" you want it adjusted. My primary is set for .75" and my alternate is set for 1.25" for reasons explained elsewhere.

 

[Wolfie]

I recently switched a second stage to a different first stage and had a noticeable difference
in breathing effort. Pretty sure the second stages are tuned with the first stages they are set
up with. I think you could tune the second stage to match the first stage but maybe
a 10 psi or so difference on the IP pressure from one first stage to another could effect the
performance of the second stage.

As I had mentioned there are couple of brands that use a higher pressure for first and second stages. The effects mentioned here sound like either there was a mismatch in the brands or the first stage was out of adjustment. You need to have the first adjusted to proper specs before you can adjust the second as charpi had explained.

Also the first specs are to plus minus 10 lbs. so if two firsts are within specs (one up one down) and you swapped seconds, the seconds would breath off because they weren't tuned to "that" first. Thus the need to retune.

 

[coldwatercanada]

Most second stages will work on any first stage, you just might not be getting the full performance out of either if the specs dont match up. Id recomond the din conversion kit personally if you like your current set up

 

[ams511]

I recently switched a second stage to a different first stage and had a noticeable difference
in breathing effort. Pretty sure the second stages are tuned with the first stages they are set
up with. I think you could tune the second stage to match the first stage but maybe
a 10 psi or so difference on the IP pressure from one first stage to another could effect the
performance of the second stage.

You are basically right. If you are using a balanced second stage you should not notice a difference unless there is a huge difference in IPs. Remember is one is high by 10 and one is low by 10, the difference could be up to 20 assuming both are within spec.