Combining Un-Balanced 1st-stage with Balanced 2nd stage regulator ?

[scubafanatic]

Picked up a cheap $ 40 Aqualung Calypso unbalanced 1st-stage, will combine it with an Aqualung Titan LX 2nd stage. Building a 'cheapo' back-up reg set that will still be fine for any conceivable level of recreational lever warm-water vacation diving. (max depths 150'). Looking for reliability/simplisity WITH sufficient performance.

Will I really be missing anything by not going with a balanced 2nd-stage ? Will I experience any wierd characteristics/regulator behavior with this 'combo' ?

Thanks in advance!

 

[runsongas]

the balanced 2nd will let it tolerate the ip variation better. i would probably have picked up a conshelf/titan or mk5/10 instead though as they are fairly ubiquitous and cheap. not much need for unbalanced pistons except for maybe dedicated deco use.

 

[scubafanatic]

the balanced 2nd will let it tolerate the ip variation better. i would probably have picked up a conshelf/titan or mk5/10 instead though as they are fairly ubiquitous and cheap. not much need for unbalanced pistons except for maybe dedicated deco use.

Hi, was looking for very simple 1st-stage, and I hear the unbalanced 1st's are as simple as exists. Was hoping to build a super simple but still very usable 'reserve' set with it, hopefully it's not a paperweight.

 

[tbone1004]

shouldn't be a paperweight, but with the unbalanced regs you need to make sure you tune the second stage when the first is giving its highest IP. That may be at really low or really high tank pressure, not sure with that reg in particular, but with my Poseidons the IP is inversely proportional to tank pressure so they have to be tuned at ~300psi or so

 

[scubafanatic]

shouldn't be a paperweight, but with the unbalanced regs you need to make sure you tune the second stage when the first is giving its highest IP. That may be at really low or really high tank pressure, not sure with that reg in particular, but with my Poseidons the IP is inversely proportional to tank pressure so they have to be tuned at ~300psi or so

Thanks for the recommendation, I'm not sure on that either 'high' vs 'low'....more investigation to do. Unless some kind poster answers the question here.

 

[tbone1004]

Thanks for the recommendation, I'm not sure on that either 'high' vs 'low'....more investigation to do. Unless some kind poster answers the question here.

unbalanced regulators exhibit different IP at different tank pressures, well all regulators do but balanced ones are closer. So the IP at a tank pressure of 3600psi may be 125psi, but at 300psi it may be 150psi. Since you have a downstream second stage, you have to find out where the IP is going to be the highest throughout the tank pressure range and tune the second stage there. If you tune it at 125psi, then it will freeflow at 150psi, so you need to tune it at 150.

 

[scubafanatic]

I was roaming old SB threads and found this one with much good info:

1st stage recommendations (Aqualung Calypso Series ???)

per 'Herman' : All are solid regs but as long as the first stage is connected to a balalanced or for that matter a user controlled second stage (ie SP-109) they will do as good a job as the best first stage sold. 99% of the preformance of a reg is in the second stage, the first stage has little to no effect on WOB when paired with a good second stage. These regs are usually paired with low end seconds which is the reason they do not have as good a WOB as their more expensive counterparts, pair it with a good second and you can't tell the difference.

...so if that really is true, I should be in great shape once I get the 2nd stage 'tuned' with the 1st stage, right ?

 

[rsingler]

The Calypso is a great old reg. Aqualung's version of the Scubapro Mk2.
As @tbone1004 suggested, your 2nd should be tested at the reg's highest IP to prevent unexpected freeflow, although a balanced second should tolerate a wide swing in IP, because as IP goes up, the pressure in the balance chamber goes up too, augmenting the spring.
As the Calypso is an unbalanced piston like the Mk2, highest IP will be at highest tank pressure. IP will fall with tank pressure, perhaps as much as 20 psi.

 

[scubafanatic]

My 'new' 1st stage arrived today, it appears 'mint' condition, really is barely used, so happy so far.

 

[buddhasummer]

I was roaming old SB threads and found this one with much good info:

1st stage recommendations (Aqualung Calypso Series ???)

per 'Herman' : All are solid regs but as long as the first stage is connected to a balalanced or for that matter a user controlled second stage (ie SP-109) they will do as good a job as the best first stage sold. 99% of the preformance of a reg is in the second stage, the first stage has little to no effect on WOB when paired with a good second stage. These regs are usually paired with low end seconds which is the reason they do not have as good a WOB as their more expensive counterparts, pair it with a good second and you can't tell the difference.

...so if that really is true, I should be in great shape once I get the 2nd stage 'tuned' with the 1st stage, right ?

If Herman said it, it's true.