Collectors list of notably easy breathing second stages?

[Kupu]

I have Pilots, Air 1's and all the D-Series SP regulators, as well as 109's, 156's and a G250. The Pilot is incomparable in my experience, though I have never used Sea Hornet or Kirby Morgan regulators. A properly set up Pilot is nearly effortless on inhalation. The Air 1 is a fabulous easy breather, but there is a noticeable difference between it and the Pilot on inhalation. It uses the same exhaust "valve" (diaphragm) as the Pilot, so exhalation is the same. The performance gap between the Air 1 and the D-Series regulators is closer, in my opinion, but the Air 1 is noticeably better. YMMV.

Thanks for your comparison on the early Scubapro regulators. One day, hopefully soon, I will get the chance to dive a Pilot. I have a couple that need to be rebuilt, just need to find a full day that I can sit down and focus on the project.

I put new lever, poppet, balance chamber, and spring in the trusty Balanced/Adjustable today. It had been sitting unused for a few years and was breathing a little stiff, it is now smoother than ever and will be back in the water tomorrow.

 

[halocline]

I think the numbers, both cracking effort and work of breathing, do a generally lousy job of representing what a 2nd stage feels like to dive with. It's much more subjective. The D series don't have great WOB numbers compared to some modern 2nd stages because exhaust effort is a little higher and they lack the amount of venturi 'punch' that newer 2nd stages often have. But, at least to me, I don't like the feeling of dry cold air being pushed down my throat just so the reg scores a lower overall WOB on a test machine. And I don't care about slightly higher exhaust effort; I don't even notice it, in fact almost nobody does. We don't have the same sensitivity to exhalation effort as we do inhalation effort.

The only way to evaluate these regs is to dive with them, and compare them over several dives. I seem to be moving more and more to my balanced/adjustables and converted 109s, especially for cave diving where the dives are all 2 hrs+. The D300s that I've used for years in caves are definitely easier breathing, but a little dryer and colder on the inhalation. I like the moisture and warmth provided by a metal case with a bit of volume. The original pilot I have is amazing for effortless REALLY high flow, but it's finicky and the converted pilot is probably 95% as easy and more consistent from dive to dive. Both of them (and the AIR1) breathe wet when inverted because the diaphragm-as-exhaust valve is notoriously leaky. Even ones that hold great vacuum let water in during the exhaust cycle. The D series mostly fixed that with the smaller, concentric exhaust valve.

It's fun working on these older 2nd stages, and to me they are all WAY better for diving than any of the new, small, plastic 2nd stages.

 

[Kupu]

Agree completely, there is nothing like diving a regulator to decide what feels best.

Being able to switch back and forth between two second stages tuned to best performance during a dive really allows a person to notice the little differences. From that standpoint, I do feel a clear difference between certain regulators with regards to exhalation effort during the dive. Not that I would chose one over the other for that reason alone, and its not something I would be aware of unless switching during the dive.

I have been excited to try and dive the D-series (I may prefer the AIR1), but the inhalation noise from the D-350 had me preferring to use the B/A during two dives yesterday, which is what I had been using for many years. It will take quite a few more dives doing side by side comparisons to settle on one or two favorites, I still have adjustments to make and several regulators yet to get in the water. Dives are 60-90 mins, currently in water temps ranging from low 60s to low 80s.

There are many here who are years ahead of me in knowledge and experience with the various regulators, some of my statements surely seem elementary or even incorrect to some. But I am learning, and enjoying the process of finding/fixing/diving various regulators. The feedback and contributions to this thread and others is very much appreciated.