My Scubapro A700 and my wifes Scubapro S600

[halocline]

I added a G250 to my D400 / m25 thinking the G250 since newer , would be my primary. Boy was I wrong. They breathe so differently. Still miss my Pilot, but the D400 still reigns. Will Scubapro rework the case symmetry and valve to the older models or did the X650 kill any chance ?

It's a good question but I'm afraid the answer is almost certainly no. The X650 looked sort of like the D series but internally was completely different, as you probably already know. SP is apparently dropping support for the D series and parts (other than service kits) are getting more difficult to find. It's too bad, that center balanced poppet and coaxial exhaust valve may have been one of the only true innovations in 2nd stage design in the last 25 years or so.

 

[halocline]

Is the from experience or what people say? I have an a700 and want another reg and the 156 looks like a great choice.

It is a great choice, maybe you can compare them directly and then let us know what you think. I don't think awap has ever used an A700, I know I have not. I did look for a service manual and stumbled on a video that showed the internal design. It does look like the same poppet and lever as the S600, but it's very small and low volume. This usually means lots of venturi assist, faster moving air in the body of the reg, less mechanical advantage for the lever, all things that IMO are downsides.

The volume of air in the case is important, because a larger volume of air at ambient pressure means better heat transfer and warmer, moister air entering your lungs. This is a major advantage of the old 109/156. But it runs counter to the sales trends of selling smaller "lighter" 2nd stages that look good in a shop.

 

[Shotmaster]

I have X650 and S600 on MK25s, I dive both, but I like the X650 better. Both are tuned hot, and crack easy. I miss my 109s. Almost never had dry mouth with those.

 

[rhwestfall]

I have X650 and S600 on MK25s, I dive both, but I like the X650 better. Both are tuned hot, and crack easy. I miss my 109s. Almost never had dry mouth with those.

So get one.... With Vintage Double Hose making soft parts, as well as having both 109 & 156 kits plus the 156 upgrade, and the orifice, it becomes very simple to get this great reg running, and for pennies compared to the new stuff....

Sourcing a lever (if necessary) is the only "obstacle",and there are options for that.

I garage sale picked my first one 25+ years ago for about $10.00 when i got my first gear. Had no idea how good these were as I dove them exclusively with nothing to compare them to. Guess I was "spoiled". There is a reason I have stockpiled some gems as I come across them over the years.

 

[redacted]

I have never used an A700, but based on experience with most other Scubapro 2nds and an examination of the various designs, there is not a lot of difference between any of the hgher performance 2nds when they are well tuned.

If spending $500+ for a great breathing 2nd stage doesn't bother you, go for it. There are lots of good options with the biggest differences being the price.

 

[shurite7]

I've worked on both the A700 and S600. There shouldn't be a significant noticeble difference between the two in terms of breathing effort. We have both regs in rental and they breathe very similar to each other.

 

[wgmontgomery]

I've read several posts about metal regs "moistening" the air; I understand how heat exchange can warm the air, but (I'm NOT being sarcastic) how can it add moisture to it? I can see how warmer air may seem...more moist (?), but I don't see how metal can add any moisture.
Plenty of SB members know A LOT more about how regs work than I do, so I thought that I'd ask.

 

[Shotmaster]

It's simple, you exhale warm moist air which condenses against the cold metal housing, then when you breathe in, the dry incoming air picks up some of the condensation and the air is not as dry. Plastic body regulators don't do this.

 

[rockinrebel]

Thanks everybody. I still haven't found anything that breathes as good as my old Scubapro AIR 1. That thing was awesome.

 

[redacted]

It would not be hard to find one and restore it. Or you could go for the somewhat better performing Pilot.