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G260 vs d420?

Discussion in 'Regulators' started by Ryan Wininger, Feb 9, 2021.

  1. Ryan Wininger

    Ryan Wininger Registered

    I've searched here and other sites to compare/contrast the two without much luck.

    I've got one getting certified this spring and one next summer. We currently have a full aqualung legend and Mk21/s560 reg set. Will need to add another set sometime in the next year.

    Pretty sure I want to get a mk19 evo 1st stage, just not sure on which 2nd stage to pair with it. It will see salt water, silty zero viz water, as well as ice diving. Unless I've read wrong, both appear to fit the bill. Does one have an advantage over the other? Thanks!
  2. Angelo Farina

    Angelo Farina Marine Scientist

    # of Dives: 1,000 - 2,499
    Location: Parma, ITALY
    For me, G260 (or G250V, even better).
    Simple and proven design, easy to service and tune yourself.
    The D series could be advantageous only if breathing air below 50m, a practice which I would certainly avoid to do anymore...
    buddhasummer likes this.
  3. Raphus

    Raphus Assistant Instructor

    # of Dives: 200 - 499
    Location: Germany
    Can you explain, why the D series is better at breathing air below 50m? What about other mixes? Helium?

    The G260 is a good 2. Stage. I dive cold and dirty with 2x G260 and had no problems yet.
  4. Angelo Farina

    Angelo Farina Marine Scientist

    # of Dives: 1,000 - 2,499
    Location: Parma, ITALY
    Below 50m the air becomes very dense, increasing the WOB. The design of the D series (and, even more, of the original Pilot, of which the D series is a subpar, low cost, simplified emulation) reduces the WOB in case of high density gas.
    If nitrogen is replaced with helium the density is much smaller, so the G250/G260 still breaths smoothly even below 50m when using a trimix properly formulated for the depth.
    Diving deep air down to 90m was common practice in the seventies, so the Pilot was a real big advantage at the time over the 109 (the precursor of the G250, using the same design and actually the very same internal parts).
    Nowadays no one uses air below 50m...
    Raphus likes this.
  5. rsingler

    rsingler Scuba Instructor, Tinkerer in Brass Staff Member ScubaBoard Sponsor

    # of Dives: 500 - 999
    Location: Napa, California
    Here's a side by side comparison between the G260 & D420
    D420! How about that?
    Either second stage would be a superb choice.
    The G260 will be more familiar to younger LDS technicians come service time. IMO, the D420 performs slightly better, and is lighter in your mouth in the water.
    Andrew Dawson and gqllc007 like this.
  6. Angelo Farina

    Angelo Farina Marine Scientist

    # of Dives: 1,000 - 2,499
    Location: Parma, ITALY
    It must also be said that, whilst in 1978 the Pilot was WAY better than the 109, the difference in performances is nowadays much smaller, almost not detectable.
    In fact the G250, in its long evolution, and more recently the G260, albeit maintaining exactly the same working principle of the 109/156, were progressively improved working on two components: the poppet, which became balanced with the 156 and further refined until the current S-wing design, and the Viva vane for controlling the Venturi effect. Finally also the exhaust valve was improved.
    On the other side the D series never reached the top performance of the original Pilot. Here the evolution was not done for improving the performances, it was going in the opposite direction: leaving back some of Pilot's performances in change of a simpler design, with less parts, easier to service and to tune.
    In this sense the D420 is the final step, being much simpler and easy to tune than its predecessors, albeit not as simple as the G250V, which was the best.
    The G260 instead is the easiest to tune, albeit not as simple as the G250V.
    In conclusion nowadays both the G260 and the D420 are great regs with substantially the same excellent performances.
    For me the theoretically slightly better performances of the D420 are irrelevant, as you should dive to 60m in air for perceiving the advantage.
    Instead I give more weight to the reliability and facility of service of the G260.
    The D420 is lighter in your mouth out of the water. But in water the G260 gets some more buoyancy, so I think that actually it is the lighter one.
    It was the 109/156 which was quite heavy, being all chromed brass.
    Still I am very happy of my old 109s (converted to balanced and using the S-wing poppet of the G260)...
    Open Ocean Diver and Fishyhead like this.
  7. gqllc007

    gqllc007 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 100 - 199
    Location: Albany NY
    Hmmmm I will chime in as a non professional who has a little bit of personal knowledge of some different regs and take my information as a grain of salt. I will start off with the different regs I have now. I have an Atomics M1, An Atomics ST1, A Deep6 Signature, and a Mk19/D420. I looked at the G260 and there is NO question whatsoever that it will work great for you. So would the Atomics M1, the Atomics ST1, the Mk19/D420 and the Deep6 signature.
    The ICE diving you stated is what made me think of the M1 for you or the Deep6 signature. Dollar for dollar the Deep6 signature reg is a steal...It is just awesome at that price point. My Mk19/D420 is with rsingler as I type. He will be going through it thoroughly for me as I don't trust the local dive shop to understand the nuances of the D420. The great thing here is you have access to these guys that are true masters for service. If finances are an issue then get the Deep6signature with a Deep6signature Octo and their diaphragm first stage. If not any of the ones mentioned will work. I am guilty of liking the newest latest and greatest cool thing and that is how I ended up with the D420. It will be my warm water reg with a Scubapro S620 as the Octo and a spare D400 second stage as backup...why? Because I am fortunate to be in a position to do so at this later stage in my life. When you use an Atomic you have to rinse it while it is pressurized. While I am home it is not a big deal and most likely while I travel it won't be a big deal but I was just looking for something that I don't have to do that when I travel. I am hoping with the D420 you don't have to rinse it while it is pressurized and rsingler has confirmed that....he also said with the Atomics just make sure the first stage is higher than the second stage and the don't have to be pressurized either...I haven't read that yet..I think Atomic M1 would be great for all your different intended purposes...Otherwise I would go with the Mk19/260 or 420 as long as you don't mind shipping off the 420 to rsingler for service....the 260 would be far more serviceable when traveling...
    Doctor Rig likes this.
  8. jakehbk

    jakehbk Contributor

    # of Dives: 1,000 - 2,499
    Location: California
    As someone who dove a G250 and an S600 for many years before nabbing a D420 late last year I would recommend the G260. It's a conventional reg that's been improved upon over the years and is pretty much at its peak.

    I haven't been impressed by my D420 so far although to be fair it may need to be retuned. I find that it doesn't "feel" like it breathes any better than my other 2nd stages.

    It also has developed intermittent leak which can't be fixed without an allen key. Whereas on an adjustable reg like the G260 can be temporarily solved with a twist of a knob.

    You mention silty water and ice diving. The G260 has more metal for better heat transfer. And is also easier disassembled for cleaning.

    I don't think the D420 is a bad reg by any means, I just prefer a conventional adjustable reg i.e. G260, S600, S620
  9. lexvil

    lexvil Contributor

    # of Dives: 1,000 - 2,499
    Location: jamestown, ca.
    I like the D 420 but I’ve tinkered with it extensively and I find it to have exceptional performance (potential) the G260 is perhaps the best standard design SP has made, it’s very tunable, much more so than the 250 series (also great Regs) and the 260 can be reversed if you have such a need, so can the D420 and it’s much easier.

    I like the smaller size of the s600 and haven’t yet had the chance to try the 620ti, but the G260 is a great reg that can be tuned easily, one can never go “wrong” choosing a G260.
  10. jakehbk

    jakehbk Contributor

    # of Dives: 1,000 - 2,499
    Location: California
    Scubapro simplified the S620 tuning so that it's identical to the G260. Supposedly they created some improvements on the exhaust side as well, but that's something I seriously doubt you could feel while using it.

    Forgot to mention, both the G260 and D420 have better purge buttons than any S series reg. Nice and snappy and solid feeling rather than the mushy rubber purge cover style.
    Geo7 and buddhasummer like this.

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