Differences in ScubaPro Second Stages

[certainmisuse]

In looking at schematics of the s600 vs. the g250, the two ScubaPro regulators look pretty darn similar to my untrained eye (e.g, the poppet is the same). I know the more modern g260 is certainly heavier than the s600. I'm assuming the additional metal is the culprit, intended more for cold water, deeper diving. I could not find the schematic for the g260, but I'm assuming the g250 is close enough. A few questions:

1. Is the g600 much different in functionality than the g250?
2. Same question for the ScubaPro c-series (e.g, the c350 or c370) vs these other two?

I know the c370 is very light, but I can't find any schematics to compare internal parts against the other two here.

Thanks for any insight.

--
David

 

[Divectionist]

I would decide between the S600 and G260 based on
- whether you worry about the additional heat transfer from the air barrel and resulting cold water reliability
- whether you care about the smaller vs larger housing size out of the water, the weight won't be too different in your mouth while diving

Functionality wise they both have dive/predive (venturi) and sensitivity adjustment.

I went for the S620Ti which breathes as good as anything out there, and I don't really encounter sub 18 degree water at depth where I dive. I'd only consider the G for technical/cold water/deep/rugged diving, but would opt for the S series for rec diving.

Also, I thought the G260 is like a G250 with a housing allowing for the hose to be mounted on the left? Don't quote me on it but that may be all there is to it.

 

[PfcAJ]

G250, S600, G260, G250v are all very similar. Case size and air barrel material seem to be the only real differences. G250HP is different despite the similar name. IMO, G250 is the gold standard.

C-series is different. I don’t own any nor have I had any experience with them.

 

[stuartv]

I went to ScubaPro school last year and got trained to work on the G260, S600/S620Ti, the A700, and the C350.

I have never actually breathed on an A700 or a C350. But, the C350 was designed from scratch by a totally different engineer than where the G or S came from. It is pretty different on the inside.

After the training, I bought a pair of G260s and a pair of S620Tis. And Mk 25 EVOs for all of them.

The big difference between the G and the S is the size of the body. The G is noticeably bigger. It's also a little heavier. I don't think the G is heavier because of more metal. I think it's heavier just because it's bigger.

I bought the G and S because ScubaPro was claiming that the S620Ti had the lowest Work Of Breathing of any of their 2nds. It's supposed to be something like a 20 or 30% improvement in WOB over the S600. Nobody at the shop I was working for had ever tried one. But, everyone at the shop said that the G260 was the best-breathing setup. So, I wanted to compare them for myself.

I put one of each, on identical hoses, connected to the same Mk 25 EVO 1st stage and dived them. I switched back and forth at depth to compare them.

My feeling is that the S620Ti breathes pretty much the same as all my other regs (Dive Rite XTs and Hollis DC3/212). The G260 breathes just a tiny (but noticeable) bit nicer. I don't know how else to put it but "nicer". There's just a little bit of extra feeling of air being jammed into my mouth when I inhale. It's a small difference, but I can feel it.

I let a friend borrow the same reg set to try. She dived it and said the same thing. The G260 breathed just a little bit more nicely than the S620Ti.

Now, my single tank, travel reg set is a Mk 25 EVO with both of the S620TI 2nds on it. It is lighter and more compact than if I put G260s on it. The G260s are on their own Mk 25 EVOs as my doubles reg set. I'd rather have the sweeter breathers on the regs I use for OC technical dives.

 

[certainmisuse]

I went to ScubaPro school last year and got trained to work on the G260, S600/S620Ti, the A700, and the C350.

I have never actually breathed on an A700 or a C350. But, the C350 was designed from scratch by a totally different engineer than where the G or S came from. It is pretty different on the inside.

After the training, I bought a pair of G260s and a pair of S620Tis. And Mk 25 EVOs for all of them.

The big difference between the G and the S is the size of the body. The G is noticeably bigger. It's also a little heavier. I don't think the G is heavier because of more metal. I think it's heavier just because it's bigger.

I bought the G and S because ScubaPro was claiming that the S620Ti had the lowest Work Of Breathing of any of their 2nds. It's supposed to be something like a 20 or 30% improvement in WOB over the S600. Nobody at the shop I was working for had ever tried one. But, everyone at the shop said that the G260 was the best-breathing setup. So, I wanted to compare them for myself.

I put one of each, on identical hoses, connected to the same Mk 25 EVO 1st stage and dived them. I switched back and forth at depth to compare them.

My feeling is that the S620Ti breathes pretty much the same as all my other regs (Dive Rite XTs and Hollis DC3/212). The G260 breathes just a tiny (but noticeable) bit nicer. I don't know how else to put it but "nicer". There's just a little bit of extra feeling of air being jammed into my mouth when I inhale. It's a small difference, but I can feel it.

I let a friend borrow the same reg set to try. She dived it and said the same thing. The G260 breathed just a little bit more nicely than the S620Ti.

Now, my single tank, travel reg set is a Mk 25 EVO with both of the S620TI 2nds on it. It is lighter and more compact than if I put G260s on it. The G260s are on their own Mk 25 EVOs as my doubles reg set. I'd rather have the sweeter breathers on the regs I use for OC technical dives.

Excellent post, and thank you. A few hours ago I placed an order with my LDS for an MK17/G260 setup.

Thanks everyone!

--
David

 

[shurite7]

1. Is the g600 much different in functionality than the g250?
2. Same question for the ScubaPro c-series (e.g, the c350 or c370) vs these other two?

I know the c370 is very light, but I can't find any schematics to compare internal parts against the other two here.

1. Functionally - not really. The internal design is a little different. A tech can finely tune the S600 / S620Ti series via the crown and adjustment screw. Same with the G250HP, G260, and C370. The G250 is only tuned via the crown. All of them have the ventura and inhalation adjustment knob. The big difference is the hose can be set on either side of the G260, but not the S600.

2. The C350/SG50 is an under appreciated second stage. Internally it is slightly different, but nothing major. It does use a different poppet from that of the G and S series. The C370 is the pneumatically "balanced" version of the C300/C350/SG50 series. The second stage is compact and light. The only thing I haven't like about it is the purge button. The purge on the S and G series is easier to use when diving. Otherwise, it is a nice little second stage.

- whether you worry about the additional heat transfer from the air barrel and resulting cold water reliability
.

You can use the S600 in cold water if it has the metal housing / barrel. The polymer plastic housing / barrel is more suitable for warm water tropical diving.

 

[Dan_P]

The S600 and A700 are pretty comparable to eachother with the material being the main difference - metal vs. plastic (heat transfer vs. weight).
If you hold up a G260 against those, they are different but spec out pretty evenly in terms of flow.

The G250 stands out.

It’s an older version, but easy to deal with and the large diametre on the diaphragm reduces the cracking pressure really well.
It’s an older model, but an exceptionally nice regulator, which is why H picked it up in OEM for the Halo.

The only reason I dive A700s and not G250s is because I want metal for an increased heat transfer.

I’m not interested in regulators made from silly materials like titanium.
You can get an extra bag for all your dive travels for the rest of your life for probably less than the cost difference, and on top of that, they corrode when exposed to O2.

The C-series are pretty nice actually, but don’t perform like G250/G260/S600/A700.

For 1st-stages, I like the Mk2 for school use as they’re the AK47 of gas, and they’re fine for the 6m-stop, so I keep one in my kit.
Other than that, the Mk25, all the way.
I think they’re still the best ranked reg on the market for performance, and they just keep going.
They’re a bit more tricky to service, but once they’re sorted out, you’ve got a great, great regulator going for you.

I’d say it’d probably be pretty fair to call the industry benchmark a mk25/G250.
Again, I opt for the mk25/A700 instead because icewater.

 

[buddhasummer]

The S600 and A700 are pretty comparable to eachother with the material being the main difference - metal vs. plastic (heat transfer vs. weight).
If you hold up a G260 against those, they are different but spec out pretty evenly in terms of flow.

The G250 stands out.

It’s an older version, but easy to deal with and the large diametre on the diaphragm reduces the cracking pressure really well.
It’s an older model, but an exceptionally nice regulator, which is why H picked it up in OEM for the Halo.

The only reason I dive A700s and not G250s is because I want metal for an increased heat transfer.

I’m not interested in regulators made from silly materials like titanium.
You can get an extra bag for all your dive travels for the rest of your life for probably less than the cost difference, and on top of that, they corrode when exposed to O2.

The C-series are pretty nice actually, but don’t perform like G250/G260/S600/A700.

For 1st-stages, I like the Mk2 for school use as they’re the AK47 of gas, and they’re fine for the 6m-stop, so I keep one in my kit.
Other than that, the Mk25, all the way.
I think they’re still the best ranked reg on the market for performance, and they just keep going.
They’re a bit more tricky to service, but once they’re sorted out, you’ve got a great, great regulator going for you.

I’d say it’d probably be pretty fair to call the industry benchmark a mk25/G250.
Again, I opt for the mk25/A700 instead because icewater.

Old thread but I beg to differ. I have extensive experience with G250/G250V/G260/C370 and a little experience with the S620Ti and A700. I'd rate the C370 and G260 as top equals out of the bunch. Both "slightly" nicer than a G250/G250V. Don't rate the S620Ti or A700 at all. Of course all subjective and YMMV.

 

[BoltSnap]

When I use the S600, I think that it is better than the G260 but when I use the G260, I think it is better than the S600. Of course, when I use Atomic SS, it is better than the rest but then I switch again back to SP and it is the same cycle. I am waiting for the S620Ti and D420 to try in the next few weeks. There is very little and subtle difference between the S600 and G260 and it is a matter of taste. The S600 is like an S600 Mercedes compared to a fast muscle car, the G260. The Atomic SS is in a different class. The AFC makes the Atomic SS different and special, I found no other SS like it.

The C370 for its price, an awesome value high performance SS but it isn't an S600/G260 or Atomic but the difference is very subtle.

I have spent a very long time comparing all of these SS's in the pool (when I couldn't go diving because of bad sea state) and diving in OW down to 30 meters.


NOTE: When comparing these high end performer second stages, a lot of the commentary and preferences are personal and subjective; just like chocolate vs. Vanilla ice cream preferences (to some extent).

 

[stuartv]

When I use the S600, I think that it is better than the G260 but when I use the G260, I think it is better than the S600. Of course, when I use Atomic SS, it is better than the rest but then I switch again back to SP and it is the same cycle. I am waiting for the S620Ti and D420 to try in the next few weeks. There is very little and subtle difference between the S600 and G260 and it is a matter of taste. The S600 is like an S600 Mercedes compared to a fast muscle car, the G260. The Atomic SS is in a different class. The AFC makes the Atomic SS different and special, I found no other SS like it.

The C370 for its price, an awesome value high performance SS but it isn't an S600/G260 or Atomic but the difference is very subtle.

I have spent a very long time comparing all of these SS's in the pool (when I couldn't go diving because of bad sea state) and diving in OW down to 30 meters.


NOTE: When comparing these high end performer second stages, a lot of the commentary and preferences are personal and subjective; just like chocolate vs. Vanilla ice cream preferences (to some extent).

Why are you comparing an Atomic SafeSecond to those other regs?

To add to what I said upthread, not only do I think the G260 is just a little bit nicer breathing than the S620Ti, I also experienced the S620Ti to be a lot louder in the water. The noise of inhaling and exhaling was noticeably louder (to me) when using the S versus the G260.

Since my post upthread, I have acquired Atomic M1 regs (for doubles), Atomic Z2 for single tank, and Halcyon Halo/H75P for single tank. I still have my G260/Mk 25 EVO setup as well.

I rate the Atomics (M1 and Z2) as pretty much equal to the SP G260 setup, for "niceness" of breathing.

I have had some trouble with my Halcyon regs. They did not breathe well out of the box. I got them adjusted at EE when I was down in cave country last year. They were still funky. We rebuilt the 2nd stages at the shop. Then they were good for a little while and went back to funky. We talked to a H guy at DEMA and he said he thinks mine have bad levers in them and we should install the diaphragm levers they had sent us (that we didn't use), which he said have an updated design. Haven't done that yet, so jury is still out on them.