old scubapro vs new (G250 vs. G250HP)

[DA Aquamaster]

The 109 brass seconds were good regs by 70's stds. However, the 250HP is a much better breather and, most important, the mouthpiece is light. The 109 causes jaw fatigue. There was a tendency for the adjustment knob of the brass second to bind with salt corrosion and the unbalanced poppet needed frequent adjustment. However, with yearly maintenance, the 109 was extremely simple and reliable, very rugged. The 250HP is quite complex and plastics are always questionable in severe environments like diving. Give a little, get a little.

Light mouthpiece - Personally in my experience a well designed mouth piece (the rubber part that actually goes in your mouth) and a properly sized and routed LP hose both have a lot more to do with eliminating jaw fatigue than the weight of the second stage itself.

I have never personally had a problem with jaw fatigue on a 109 second stage but light weight is a big selling point for phenolic resin/graphite resin cases, so it is obviously a good thing from a marketing perspective, even if it is not a major concern in the water.

One other thing about the light weight resin cases, a graphite resin case with 100 dives on it is normally extremely scratched and not at all attractive. In contrast my 20 year old chrome plated Balanced Adjustable second stages all have an even patina of very faint scatches but the chrome is still intact and they still look very attractive and not nearly as old and worn as the average 3 to 5 year old G250 which normally look like they have been mauled by a very big and angry wire brush.

Corroded knobs - I agree the metal adjustment knobs could get sticky in the metal cased regs, but they had the same problem in the older G250s with the the plastic case and the metal air barrels. The same argument was used to move away from metal orifices. We do seem to agree that with good maintence it was not a problem though.

G250 HP =much better beather and unbalanced poppet (?) - The Adjustable had an unbalanced poppet but the Balanced Adjustable had a balanced flow through poppet design.

In fact the Balanced Adjustable's poppet assembly was used in the original G250 and the only performance advantage offerred by the G250 was the adjustable VIVA flow vane. For most divers who set it in the middle at a moderate viva setting and seldom touch it, it is not really an advantage at all. The newer poppet assemblies used in progressively more advanced versions of the G250 are also available for use in the Balanced Adjustable, so the performance advantage of the current G250 HP over the original balanced adjustable still bascially comes down to the viva adjustment. Give a lot, get a little.

 

[ddown]

I have a new Mk25AF S600 purchased at my LDS took in a Balanced adustable I picked up for 20.00. Tech Put in new poppet/seat assembly and new orifice small nick in old one it now breathes better than my S600. He noticed that and he said next time in he would adjust S600 (Which by the way is drier than a popcorn fart) 1 hr dives in Puerto Rico were almost (note Quite unbearable)

ddown

 

[Genesis]

I have a new Mk25AF S600 purchased at my LDS took in a Balanced adustable I picked up for 20.00. Tech Put in new poppet/seat assembly and new orifice small nick in old one it now breathes better than my S600. He noticed that and he said next time in he would adjust S600 (Which by the way is drier than a popcorn fart) 1 hr dives in Puerto Rico were almost (note Quite unbearable)

ddown

I can't deal with 30-45 minute dives on the S600. I find myself getting SEVERE dry throat to the point that I get concerned about things back there sticking together, so I end up doing a "mouthwash" deal with the water. That's YUCKY, especially in the ocean

The G250 doesn't cause this problem for me.

 

[ddown]

I agree Completly with the Dry I am Trying to find a new Moustache for my Balanced Adjustable dont care if it's orange or Black. Mines going soft after that they start popping off.

ddown

I can't deal with 30-45 minute dives on the S600. I find myself getting SEVERE dry throat to the point that I get concerned about things back there sticking together, so I end up doing a "mouthwash" deal with the water. That's YUCKY, especially in the ocean

The G250 doesn't cause this problem for me.

 

[DolphinDiver]

What I really don't like about my old G250 is that it breaths very hard when in any position other than looking straight ahead. Is the G250HP any better at that? Can I upgrade my older G250 to fix the problem?

 

[redacted]

I agree Completly with the Dry I am Trying to find a new Moustache for my Balanced Adjustable dont care if it's orange or Black. Mines going soft after that they start popping off.

ddown

I bought 2 of them in the last month. Any SP dealer should be able to get them. One shop had it in stock, another took a couple weeks to get one. I've heard that orange is no longer available.

 

[DA Aquamaster]

What I really don't like about my old G250 is that it breaths very hard when in any position other than looking straight ahead. Is the G250HP any better at that? Can I upgrade my older G250 to fix the problem?

Well not really. The newer G250 will have the same problem. It has nothing to do with the air barrel or the poppet but rather with the location of the exhaust valve in relation to the diaphragm.

For example with the S-wing poppet you get get an out of the water cracking effort of .5 pretty easily if the orifice is in good shape. However it will dribble air out the exhaust valve ina face down position and if the vacuum developed is enough to open the valve, then you get a steady freeflow. The result is you need to increase the cracking effort to around 1.0 to 1.2 to get the reg to be completely stable in the water in all positions.

1.0 is still very good performance, it just feels heavier if you started the dive at .5 and had to increase things to stop the freeflow.

The D400 does not have the same case fault gemoetry problem as the exhaust valve is mounted in the center of the diaphragm. If properly tuned will be stable at a cracking effort of .6 to .8.

The new X650 is reported to be stable down to around .8 as the exhaust valve is closer to the center of the diaphragm.

 

[ddown]

I bought 2 of them in the last month. Any SP dealer should be able to get them. One shop had it in stock, another took a couple weeks to get one. I've heard that orange is no longer available.

Thanks for the tip appreciate it

ddown

 

[DolphinDiver]

DA,

Yes, I remember your earlier post on thread on the x650. Makes sense. Thanks.

 

[ElectricZombie]

SP is ditching the seat saver feature and along with it is changing the balance chamber design to eliminate the need for a special adjustment tool to seal off the end of the balance chamber. The new design will allow an air on adjustment with only a screwdriver - much easier for the tech to adjust properly.

Sounds like a great idea. When are they going to start doing this?


I have an old G250 and a new G250HP. The breath pretty much the same. I overall prefer the old style G250 because it is a simpler design.