Are Converted Scubapro 109's a weak link?

[Aloha Joe]

Thank you Nemrod. I updated my previous post as I had just assumed the 250 had a larger diaphragm due to the larger diameter case and "more natural" inhalation. Its kind of crazy that‘s all case geometry and Venturi then?!

The sound is not the bubbles, it just seems the flowing air is louder - maybe it’s something to do with the case‘s resonance? It’s considerably louder than a 109 with the same internals (less Venturi). I unfortunately only have side-by-side experience with the 109 and 250 so can’t compare against other regs.

The 109 seems more connected I guess, it just gives me the sense it’s always right where it’s supposed to be, while the 250 seems more floaty. I was attributing that to the extra weight of the 10i, but I guess it could also be because the 109 is less draggy.

It’s hard to communicate how noticeable things like this are. Maybe I’m particularly sensitive (likely) or my environment or the way I dive. But I feel like the fact that the 250 never stays as my primary reg for more than 2 dives, despite being basically brand new and more enjoyable to breathe, says something.

 

[Angelo Farina]

Thank you Nemrod. I updated my previous post as I had just assumed the 250 had a larger diaphragm due to the larger diameter case and "more natural" inhalation. Its kind of crazy that‘s all case geometry and Venturi then?!

The sound is not the bubbles, it just seems the flowing air is louder - maybe it’s something to do with the case‘s resonance? It’s considerably louder than a 109 with the same internals (less Venturi). I unfortunately only have side-by-side experience with the 109 and 250 so can’t compare against other regs.

The 109 seems more connected I guess, it just gives me the sense it’s always right where it’s supposed to be, while the 250 seems more floaty. I was attributing that to the extra weight of the 10i, but I guess it could also be because the 109 is less draggy.

It’s hard to communicate how noticeable things like this are. Maybe I’m particularly sensitive (likely) or my environment or the way I dive. But I feel like the fact that the 250 never stays as my primary reg for more than 2 dives, despite being basically brand new and more enjoyable to breathe, says something.

I did not measure the noise of these two regs, albeit in my lab we have calibrated hydrophones and I used to make this kind of measurements for checking compliance to NATO specs.
Subjectively I perceived the G250 producing more high frequency, some sort of white noise, while the noise of the 109 is less hissy, it is more similar to pink noise.
I think that the total linear SPL is not much different, but due to the different spectrum, the A-weighted SPL of the G250 can be 2 or 3 dB larger than the 109.
Then the question is: why is the spectrum different?
There are 3 possible explanations:
1) different noise source (Venturi van causing turbulence)
2) the heavier case of the 109 is more effective attenuating high frequencies (mass law).
3) the more regular cavity of the G250 goes into resonance.

A couple of tests should be made for understanding which cause is it.
First test is removing the Venturi vane from the G250.
If the high frequency noise goes away, that was the cause.
If this is not working, then you should encase your G250 with a thin layer (1mm) of self-adhesive lead.
If also this way the high frequency noise does not disappear, then the resonance hypothesis remains.
And for checking if this is the cause you should place a piece of sound absorbing foam inside the case of the G250.

 

[halocline]

It’s funny to read the same old tired nonsense from the shop about obsolescence and liability and the great improvement off the latest models. It’s been going on for years. It’s like these guys get a script or something. When the guy said something like “Don’t expect a shop to work on them” my reaction was “Good, thankfully you won’t be screwing up my gear and feeding me BS while you’re doing it!”

Anyhooo, I’ve used many SP 2nd stages and I’ve pretty well settled on B/A (156) and 109s for my diving which is primarily in caves. I think they’re ideal for that, because they’re very tough and can get dragged around on rocks (an unfortunate result of all those sidmounte entries/exits in limestone grottos) and they help reduce dry mouth in my dives, which are typically 2-3 hrs. The metal case encourages a little condensation from exhaling and the venturi effect is less pronounced than in smaller plastic case 2nd stages. I.E. they are very reliable and comfortable to use. I don’t really care about the breathing machine numbers.

 

[Nemrod]

Thank you Nemrod. I updated my previous post as I had just assumed the 250 had a larger diaphragm due to the larger diameter case and "more natural" inhalation. Its kind of crazy that‘s all case geometry and Venturi then?!

The sound is not the bubbles, it just seems the flowing air is louder - maybe it’s something to do with the case‘s resonance? It’s considerably louder than a 109 with the same internals (less Venturi). I unfortunately only have side-by-side experience with the 109 and 250 so can’t compare against other regs.

The 109 seems more connected I guess, it just gives me the sense it’s always right where it’s supposed to be, while the 250 seems more floaty. I was attributing that to the extra weight of the 10i, but I guess it could also be because the 109 is less draggy.

It’s hard to communicate how noticeable things like this are. Maybe I’m particularly sensitive (likely) or my environment or the way I dive. But I feel like the fact that the 250 never stays as my primary reg for more than 2 dives, despite being basically brand new and more enjoyable to breathe, says something.

The G250/G260 have a more powerful Venturi than the 109 and you say (the G250 has) a "more natural inhalation" and I would agree from my experiences. Maybe that (the stronger Venturi) is why you perceive the G250 to be louder as well as the difference in case materials are acoustically different, @Angelo Farina is an acoustics expert. Apparently I have found out I have a hearing deficit, in both low and high frequencies, maybe not being able to hear has certain advantages, especially selectively . I do not notice any sound difference between the G250 and G260. All of them are noisy compare to a double hose Kraken.

 

[ZzzKing]

It’s funny to read the same old tired nonsense from the shop about obsolescence and liability and the great improvement off the latest models. It’s been going on for years.

I can’t believe you would question the shop expert. I mean, it’s life support equipment you are talking about here! I throw my entire kit away after every dive and don all new gear. How else could I be certain that it is safe?

I have a half dozen or so 109’s a couple of BA’s and some 1085’s. I converted the fleet over to G250V’s a couple of years back and like them marginally better although I don’t have the scientific basis for my opinion like some of you do. I haven’t been on SB in quite a while. It’s good to drop by and hear the gospel from some of the usual suspects. Hope everyone is doing well.

 

[race890]

You are right OG 109 still available with the duro poppet.

I saw in another topic that you can supply Scubapro service kits for Mk25 & S600; I need 2 - maybe 4 of each; do you have these & a price?
Thanks

 

[buddhasummer]

I saw in another topic that you can supply Scubapro service kits for Mk25 & S600; I need 2 - maybe 4 of each; do you have these & a price?
Thanks

DM sent