:) Scubapro MK11 with balanced S600 or S500 or G250

[SCU5]

Any modern scubapro second will work with any scubapro first. I use an S600 with a MK11 and have around 80-100 dives on that setup, works like a charm, breathes great.

 

[nomro]

Thanks cbrich and jimmytaroh , that is very comforting news

 

[buddhasummer]

The non adjustable C200 and the adjustable C300 are not balanced but the design is exceptionally well executed and offers excellent performance.

If used on a balanced first like the Mk 11, Mk 17 or Mk 25, where the IP is stable throughout the dive, balancing the second makes no real difference provided the second stage is otherwise high performing. The R series seconds were not all that great in terms of quality, consistency or performance, but the C series second stages have so far impressed me.

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The only difference between the Mk 11 and Mk 17 is sadly not restricted to just the sealed ambient chamber - the differences in diaphragm and washers restricts the working range and flow rate on the Mk 11. Still a good reg, but it has the potential to be better if SP would let it be better.

Looking at schematics it appears as all parts from diaphragm back are different with different part numbers, 6 in total: All parts after the diaphragm through to the end of the HP end are identical. I've read numerous posts stating they are identical save enviro sealing, that appears not to be the case as DA touched on.

Diaphragm
Diiaphragm ring/s (MK17 has 2)
Diaphragm Disc
Spring TIS
Washer
Spring screw

Now what parts account for the difference in performance I'd have no idea. I wonder if all parts would need to be changed or just some. I'd guess, the diaphragm, diaphragm rings (x2) would need to be changed for sure. The spring screw I'm guessing is different on the MK17 due to its enviro sealing. All other parts I have no idea.

I have both a MK17 and MK11 so will pull both apart, diapghram side and measure and try to see what's compatible and what actual differences are in parts, size etc. If anyone knows what parts would need to be changed, (axxel, DA?) in order to get MK17 performance out of a MK11 that would be great.

And why am I'm bothering to do this? Boredom, curiosity and I have easy access to parts. Cheers.

 

[buddhasummer]

Should probably have started a new thread...

 

[halocline]

My guess is that the difference is in part due to the need to fit the piston in place. Other than depth compensation, the only thing I can think of that might affect the regulator's performance would be the flexibility and motion range of the diaphragm. I would have low expectations that switching the MK11 diaphragm/spring/pad to MK17 would yield any real-world improvement. Maybe a higher flow rate under maximum demand and unlimited supply, but probably not any improvement in IP drop/recovery.

But it's worth a try.

 

[buddhasummer]

Thanks Matt. I already have the MK11 apart, what a simple reg it is. I'll pull the LP end off one of my MK17s and do a side by side. I blame DA, his post got me started. I have a MK17 diaphragm and the two washers on hand so might just try those for s%#*s and giggles.

Side note: I'm placing order tomorrow, you're good?

 

[DA Aquamaster]

You have to change the spring pad as the Mk 11's pad is bigger and won't fit in the Mk 17 ambient chamber.

Scubapro used a thinner diaphragm on the Mk 17, and then added an extra plastic washer on top of it to take up the extra space. This theoretically increases the working range of the valve and allows the seat to be lifted a bit higher off the orifice. Practically, I doubt it makes much difference at all in real world diving.

 

[PfcAJ]

I just posted on Scubapro package strategy - it has nothing to do with what works. Any SP first will work fine with any SP second and the Mk 11 with a G250 or S600 makes a good combination for a warm water diver wanting great inhalation effort in a smaller and lighter first stage than the MK 25.

I am waiting on the C300 I ordered in March - I have played with them a bit but want one for thorough testing in silty/sandy caves, etc. But it promises to be an excellent performing second stage with low parts count, easy maintenance and extremely good reliability at a very good price point.

If that holds true, it would work very well on a Mk 11 for a lot less money than an S600.

How'd the c300 shake out? Seems like it never gained a lot of popularity.

 

[buddhasummer]

Thanks DA, your post quoted above just got me thinking so wondered what I'd need to put into the MK11 (sans dry chamber) to "increase" its performance to that of the MK17. If it will make no real difference then I'll not bother.

 

[buddhasummer]

Update for anyone who's interested. I pulled one of my MK17 Evos apart to compare. Bottom line, unless you're doing a full MK11 to MK17 Evo conversion including dry chamber, the only parts that can be swapped are the diaphragm and it's two washers (MK17 Evo). All other parts are completely different sizes and are not interchangeable. I'll swap to a MK17 Evo diaphragm and it's two washers just for s%#€# and giggles. From what's been said by the experts I'm very unlikely to notice any difference. I'll do an ip check/recovery before installing the MK17 Evo parts just to see if it behaves any differently. If I see or notice anything I'll report back.