Why no adjustment knobs on Mares regs?

[Ski_Lounge]

So I just bought a new set of regs for doubles, a small upgrade from my Mares Prestige regs. I'm still getting used to the adjustment knobs on the new second stages, something that didn't exist on my Mares. I took a look at the Mares line up, and see that almost none of the second stages have adjustment knobs, with the exception of the Ultra. Why is that? Is that a feature or bug? And how much use do you find for the knob during routine diving, outside of servicing?

 

[Zef]

Why do you think a 2nd stage needs an adjustment knob?

Mares 2nd stages, at least the Abyss and its derivatives, are uncomplicated workhorses that when properly adjusted don't need any unnecesary accoutrements like adjustment knobs. They are like the Timex watch of the regulator genre...they just work.

The adjustable capability of the Ultra is akin to Mares "trying to keep up with the Joneses"...they are trying to attract those divers whose purchase decisions are swayed by extra (and in some opinions, unnecessary) bells and whistles.

-Z

 

[lowwall]

Mares classic seconds didn't have adjustments for two reasons. The first was that there was less need for them. The VAD bypass tube results in s more consistent airflow path than you get with second stages that require the gas to flow through springs, around plastic bits, take a 90 degree turn out a square hole and then get redirected by vortex vanes. Also, since you can separately set the lever height and orifice intrusion, you can tune them closer to where you want them compared to classic barrel seconds. This means that once a Mares second is tuned properly, there is minimal need to fiddle with it to keep it from free flowing or breathing hard.

That design brings us to the second reason. There is no easy way for Mares to add an adjustment to their regs. There are no vanes to rotate out of or into the airflow path or ways to divert that path. And the interior of the case needs to be kept free of any adjusting widgets that would interfere with the low pressure area that forms adjacent to the diaphragm when gas is flowing. [Edit - see @L13's post below, there's also no balance chamber to adjust]

Still, for marketing reasons they felt they had to try to add some sort of controls. A few years ago they introduced the Twin Power System which uses the hose cover as a switch to slightly shift the orifice depth, basically creating a dive/pre-dive switch. I don't see much of a point to this and it adds a few plastic parts which I believe are detrimental to the ultimate reliability of the stage. I suspect this is the reason that Mares does not include this "feature" in the second stages it offers in its XR tech line.

There is one clear marketing drawback to unbalanced downstream second stages like the classic Mares and that is, all else being equal, the initial cracking effort is slightly higher than for balanced seconds. This means that Mares lost out in Work of Breathing comparison graphics so something had to be done. The result are the regs that have "ADJ" in their names. These are true balanced adjustable seconds. I haven't tried them so I can't say how they compare to the classic downstream seconds like your Prestige, Zef's Abyss or my metal Protons.

 

[L13]

Mares second stage regulators are unbalanced. The vast majority of adjustable second stages are adjusted by moving the balance chamber. The unbalanced second stages of other brands are also generally not adjustable.

 

[Searcaigh]

Mares 2nd stages, at least the Abyss and its derivatives, are uncomplicated workhorses that when properly adjusted don't need any unnecesary accoutrements like adjustment knobs. They are like the Timex watch of the regulator genre...they just work.

Mares classic seconds didn't have adjustments for two reasons. The first was that there was less need for them. The VAD bypass tube results in s more consistent airflow path than you get with second stages that require the gas to flow through springs, around plastic bits, take a 90 degree turn out a square hole and then get redirected by vortex vanes. Also, since you can separately set the lever height and orifice intrusion, you can tune them closer to where you want them compared to classic barrel seconds. This means that once a Mares second is tuned properly, there is minimal need to fiddle with it to keep it from free flowing or breathing hard.

In other words they don't need them

I've been using Mares regs for over 30 years and they are perfect.

My tech regs are ScubaPro Mk25 with S600 second stages and the difference in breathing is noticeable especially when I switch to a deco gas where I use a Mares MR22 and Abyss second stage.

 

[lowwall]

In other words they don't need them

I've been using Mares regs for over 30 years and they are perfect.

My tech regs are ScubaPro Mk25 with S600 second stages and the difference in breathing is noticeable especially when I switch to a deco gas where I use a Mares MR22 and Abyss second stage.

So why not use a 22 Abyss for tech? Lack of a turret on the first stage and hand removable faceplate on the second?

 

[lexvil]

Because some people refuse to buy a hammer when they are surrounded by rocks.

 

[Ski_Lounge]

Thank you, fellas, for the detailed and informative posts.

Why do you think a 2nd stage needs an adjustment knob?

TBH, I'm not entirely sure From my barebones knowledge, I thought it allows one to change the cracking effort? But you bring up a good point; why exactly is it needed in other regs, like most of the ScubaPro lineup?

This means that once a Mares second is tuned properly, there is minimal need to fiddle with it to keep it from free flowing or breathing hard.

Your reasoning about airflow around the internal components is very helpful to visualize. What I didn't grasp, once any reg (with additional components), is correctly tuned, isn't that reg "done & tuned"? Why would it need to later be adjusted?

(Please excuse my limited understanding, genuinely curious to learn more.)

 

[James79]

What I didn't grasp, once any reg (with additional components), is correctly tuned, isn't that reg "done & tuned"? Why would it need to later be adjusted?

With an unbalanced 2nd on an unbalanced 1st, you can tune the second to have to be cranked down on a full tank and turn out the adjuster as you use up the tank, offsetting the change in cracking effort from the reduction in IP. If either stage is balanced, the only remaining benefits are to tighten it a bit as the seat breaks in (only needed if you tune it hot) or to tighten it down on a reg used as an octo or stage to minimize risk of freeflow when not in use (open it back up when in use).

Respectfully,

James

 

[lexvil]

Like a knife, you can go years and years without needing it but when you do it’s nice to have.

it’s there to increase the spring pressure.