Question Any issues with swapping my Hollis DCX First stage with a DC7 or MK 11 - DIN?

[Matt Stallman]

HI guys and gals— WE are heading to RAJA in March next year. I have been diving a HOLLIS 200LX /DCX first stage and it is really heavy. It is fantastic but I’m trying to trim weight. I bought a ScubaPro MK11 First STage to swap and now I’m looking at the DC7 DIN because it is 1.1 pounds. The lightest I have found for what I’m willing to spend. I’m a rescue diver by certification— lol. Any advice on the pros and cons of interchanging the firsts and the wight would be very appreciated!

 

[rsingler]

Mk11 is pretty unbeatable as a small form-factor diaphragm. That said, it's unsealed, for whatever marginal cost that imposes for rinsing. It's perfectly suitable to pair with your 200LX, though that would hardly be my preference for a second (as a service technician).

On the other hand, since Hollis redesigned the HP seat and volcano mechanism, the lockup is much crisper and the drift I used to have in my DC7 is gone. More important, the seat (that used to be the volcano) gets changed every time, and the moving volcano/valve piston (that used to be the seat) is loose and easy to polish. Much better design. And finally, it's sealed.

I'd stay with a DC7 DIN, if ounces are important.

But if you're changing to a whole new reg set, a Mk11/C370 is a great value, and a better second stage.

 

[Matt Stallman]

Wow thank you. So are you saying the 370 is better than my 200 LX second? The whole setup is light than what I have , but from a cost perspective and having only 80 dives on my 200, was thinking just changing the first . And if I do that the DC7 sounds like a better choice, esp. being sealed? Is that right?

 

[rsingler]

The C370 is head and shoulders above the 200LX! Zero doubt in my mind about that. This balance chamber mechanism is overly complex, reverse threaded, and a PITA to service properly.

A little hard to find a loose C370 second stage for a reasonable price. Scubapro doesn't make that part easy. But if you could find one, pairing with your DIN DC7 (if the valve components have been upgraded) is a fantastic sealed lightweight travel set with excellent performance.
But if you can't find a separate C370 at a reasonable price, the Mk11/C370 set is reasonably priced. You could recoup your costs by reBaying the new Mk11, or have a spare first. You won't get what the DC7 is worth on the use market, because it didn't have a great rep. But after the valve upgrade, I think it's a solid regulator.