balanced second stage that important?

[squidster]

I have never had a balanced second stage, I have a scuba pro 295 .
Does it really make a notible difference how they breathe or just a mild difference?

 

[cerich]

Depend on the design and first stage performance. In your particular case providing that you don't have a Mk2 first stage you would notice a distinct improvement with any of SP's balanced seconds, or any of our unbalanced or mechanical balanced or any AL/Apeks balanced, any Mares unbalanced, any Zeagle second stage but see no improvement with a Sherwood second stage.

Did that help?

 

[DA Aquamaster]

I have used balanced regs almost exclusively for the last 2 decades. Occasionally I test dive an unbalanced second and I definitely notice the difference even when they are tuned for optimum performance.

The balanced design potentially allows large orifices and lighter springs whihc both equate to better response, flow rate and inhalation effort.

On the other hand, some divers like their balanced regs set up to breathe a little harder for personal reasons that have always eluded me and/or made no sense. For those divers a balanced second stage is in most cases a waste of money.

I would also argue that an unbalanced second stage will breathe better on a balanced first stage than on an unbalanced first stage due to the stable IP delivered by the balanced design. It is able to be tuned to a lighter inhalation effort and can then deliver peak performance as the IP does not change.

Similarly, a balanced second stage will deliver noteably superior performance compared to an unbalanced second stage when used with an unbalanced first stage as the balanced second stage design levels out much (but not all) of the effects of the change in IP on inhalation effort that you would normally experience with an unbalanced second stage.

So in effect, if you add a balanced second stage to a unbalanced Mk 2, you'll notice a big improvement in inhalation effort. If you add a balanced second stage to a balanced frst stage like the Mk 17 or Mk 25, you will note a lot less improvement (and perhaps very little improvement) IF the orignal unbalanced second stage had been tuned to deliver optimum performance and minimum cracking effort.

 

[cerich]

I have used balanced regs almost exclusively for the last 2 decades. Occasionally I test dive an unbalanced second and I definitely notice the difference even when they are tuned for optimum performance.

The balanced design potentially allows large orifices and lighter springs whihc both equate to better response, flow rate and inhalation effort.

On the other hand, some divers like their balanced regs set up to breathe a little harder for personal reasons that have always eluded me and/or made no sense. For those divers a balanced second stage is in most cases a waste of money.

I would also argue that an unbalanced second stage will breathe better on a balanced first stage than on an unbalanced first stage due to the stable IP delivered by the balanced design. It is able to be tuned to a lighter inhalation effort and can then deliver peak performance as the IP does not change.

Similarly, a balanced second stage will deliver noteably superior performance compared to an unbalanced second stage when used with an unbalanced first stage as the balanced second stage design levels out much (but not all) of the effects of the change in IP on inhalation effort that you would normally experience with an unbalanced second stage.

So in effect, if you add a balanced second stage to a unbalanced Mk 2, you'll notice a big improvement in inhalation effort. If you add a balanced second stage to a balanced frst stage like the Mk 17 or Mk 25, you will note a lot less improvement (and perhaps very little improvement) IF the orignal unbalanced second stage had been tuned to deliver optimum performance and minimum cracking effort.

All true, my post above with the MK2 comment was more directed at using some of the unbalanced seconds I mentioned.The 295 isn't among the smoothest in WOB seconds out. A balanced second will make work of breathing easier on a unbalanced first stage, however it won't improve RAW performance because the first stage will only flow what it will flow(the MK2 is a solid unbalanced first, we and Zeagle has passed by in performance in the last couple years in our unbalanced first stages by a little however). Think of Work of Breathing as being a transmission in a car, some can be smoother than others which while very nice to use isn't as important from a performance standpoint as the transmissions ability to effectivly use all the horsepower the engine produces(think Posedin Jetstrean, Oceanic Omega, WOB loop looks funny but man can they flow!). However no matter how smooth a transmission it falls short when unable to use all the power the engine produces.(a balanced second on a unbalanced first).

 

[pescador775]

I doubt that most users could notice a difference in a 30 year old SP MK5 balanced/unbalanced regulator and a full balanced setup like the MK20/G250. Even if they did, initially, the differences would be minor and mainly involve the weight of the mouthpiece as older seconds were brass vs plastic. Divers don't focus on tiny differences in regulator performance unless they are gear heads. Mainly, divers are otherwise occupied in the course of a dive. Single hose regulators use small diaphragms to activate the demand lever. To compensate for the loss of force, the components of the single hose second have to made with lighter, softer components. For example, the poppets use soft materials and are seated with rather small force. This in spite of the fact that they have to deal with fairly high intermediate pressures. Nevertheless, the second stage mechanism is in a rather delicate balance and something as small as slight wear or indentation in the poppet valve can change regulator performance. To the extent that some balance valve designs can allow a compensated closing force on the poppet then one could expect less indentation wear and more consistent performance. This appears to be a point in favor of some types of balanced second stages. However, whenever the extra parts required are taken into account, then at least some theoretical disadvantage to the balanced second must be factored in. It is just more difficult to do field adjustments not to mention repairs. The most common complaint seems to be instability or "bubbles" (free flow). Fortunately, many of these problems can be tolerated until the diver is able to get his balanced regulator to an authorized repair station.

 

[Diver0001]

I have never had a balanced second stage, I have a scuba pro 295 .
Does it really make a notible difference how they breathe or just a mild difference?

You'll get a whole bunch of opinions about this that all conflict. The only relevant advice is to rent/borrow a variety of different regs and dive them yourself at different depths and see for yourself what you think.

Personally, I think balanced regs breathe easier but if you're smart you won't listen to me.

R..

 

[drew52]

I used the MK16 (balanced) with the R390 (unbalanced) and the MK16 (balanced) with the S550 (balanced) and the difference was huge. But then again I may have been imagining things.

I would go for balanced unless it's not in your budget.

Good Luck

 

[pescador775]

The balanced diaphragm MK16 first stage is well-suited for harsh environments. Coupled to either the unbalanced R380 or the balanced S550, the reg dives dry and purges efficiently. Both combinations breathe easy in the water and produce excellent simulator performance. MK16/R380,

Scubalab 2003

 

[halocline]

I doubt that most users could notice a difference in a 30 year old SP MK5 balanced/unbalanced regulator and a full balanced setup like the MK20/G250. Even if they did, initially, the differences would be minor and mainly involve the weight of the mouthpiece as older seconds were brass vs plastic. Divers don't focus on tiny differences in regulator performance unless they are gear heads. Mainly, divers are otherwise occupied in the course of a dive.

I completely agree with this. Someone like DA aquamaster who works with regs all the time, and is a real expert on subtle differences in design will have a very sharp perception of reg performance, but for most of us, they all work well as long as they're tuned. Not that there's no difference; I became interested in older SP regs, bought one (MK15/G250/BA), and it does breathe noticably better than my MK2, but I'm certain if I had never tried the higher performing reg I'd be perfectly satisfied diving with the MK2. Someday I'll borrow the worst reg I can find just to get an idea of what "bad" performance is. Any suggestions?

 

[John C. Ratliff]

Here's the thing that goes unmentioned above. There are balanced first stages (where the interstage pressure does not fluxuate as tank pressure drops) and balanced second stages (where the second stage can be fine-tuned to the exact interstage pressure). With the advent of octopus regulators, where you want to balance two different second stages against one balanced first stage, you now have that option.

Originally, with unbalanced downstream second stages, the manufacturer set the pressures and you just dove them. Problems developed with two regulator second stages when they both were fine-tuned for optimal performance, but one was an octopus--it tended to free-flow. So with a balanced second stage, that second regulator can be "detuned" to not free flow when on a first stage delivering the same interstage pressure to each regulator.

In the old days, with unbalanced first stages (many of mine currently are of that vintage), you varied the interstage pressure to fine-tune the regulator. This was fine, until the octopus was put onto the system.

Now, I understand that some will say that the balanced second stage allows the manufacturer to gain in orifice size, etc. I don't think that is correct, but there is an outside chance that there is some things done with this design that couldn't be done otherwise. But I think the main reason is the "detuning" feature for the octopus, rather than breathing performance.

SeaRat