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I'm trying to get WOB and cracking specs.
D420! How about that?
- Thread starter axxel57
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sbijou
Contributor
Could it be that much easier breathing than the D400 I currently use? But at least they'll be service kits out there for the 420.
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I was completely anti diaphragm for decades, piston only but I admit that was filed by the past materials, hardened stiff diaphragms and crappy seat materials just caused to many problems and all the little parts were a pain yet new materials have made a big difference, still a lot of little parts compared to a piston but great performance overall, lately the only piston reg I use is a MK 25 on a pony, my other pony has a Poseidon.DH in Curacao.
I use MK2 for for pony/deco, a collection of SP MK-3,5,10 and 15 pistons I rarely use (collected over the years, either gifted, or with seconds I was after), and wife & daughter use M20/G250 for warm water travel. With the exception of my Poseidon rig, all my other stuff is diaphragm (MK-17, HOG & Deep6). Not a piston fan, and wouldn't buy any more..
YMMV
halocline
Contributor
It would be great if it's the same poppet and diaphragm/exhuast valve assembly as the D400. That would make maintaining my D300s easier, although I probably have 8-10 poppets left and a spare diaphragm. It's about time SP got smart and brought this design back.
On the other hand, I just finished a week of cave diving, and after the 2nd day I swapped out my D300 for a balanced/adjustable primary 2nd stage. It's nice to have the moister air from the condensation in the metal case on those long dives. The B/A does not breathe quite as effortlessly but I don't really care. For stable, smooth, easy breathing in any position, the D series is really hard to beat. I just am more comfortable these days with a metal 2nd stage.
On the other hand, I just finished a week of cave diving, and after the 2nd day I swapped out my D300 for a balanced/adjustable primary 2nd stage. It's nice to have the moister air from the condensation in the metal case on those long dives. The B/A does not breathe quite as effortlessly but I don't really care. For stable, smooth, easy breathing in any position, the D series is really hard to beat. I just am more comfortable these days with a metal 2nd stage.
HOW DID I MISS THIS THREAD!!???
OMG, I'm about to have a heart attack.
Thank you for the specs!
From the schematic, I think WOB might be better in standard diving position: exhalation valve looks to be about 3/4" higher than diaphragm. Unfortunately, losing a coaxial diaphragm/exhaust means that cracking effort can't go down to 0.6" like the D400, and effort will be noticeably harder (just a little) on your back.
But that poppet looks to be a throwback to the original (great news!) aaaannnnnd...I can't find a stupid Delrin orifice!!! It looks like an all-metal assembly, though I can't really tell from schematic. In any case, there's no separate removable orifice component.
Adding in diver-controlled Venturi is just icing on the cake.
The lever looks like the low-friction method in the C360, so that's fantastic news.
This is better than porn.
And I haven't even watched the video yet...
I'll be back later.
@buddhasummer , I think we'll be talking.
OMG, I'm about to have a heart attack.
Thank you for the specs!
From the schematic, I think WOB might be better in standard diving position: exhalation valve looks to be about 3/4" higher than diaphragm. Unfortunately, losing a coaxial diaphragm/exhaust means that cracking effort can't go down to 0.6" like the D400, and effort will be noticeably harder (just a little) on your back.
But that poppet looks to be a throwback to the original (great news!) aaaannnnnd...I can't find a stupid Delrin orifice!!! It looks like an all-metal assembly, though I can't really tell from schematic. In any case, there's no separate removable orifice component.
Adding in diver-controlled Venturi is just icing on the cake.
The lever looks like the low-friction method in the C360, so that's fantastic news.
This is better than porn.
And I haven't even watched the video yet...
I'll be back later.
@buddhasummer , I think we'll be talking.
coldwaterlloyd
Contributor
I was wondering what took so long
Nice video!
The video cross-section seems to confirm metal orifice.
The WOB curve is fantastic - note how it shifts slightly into positive mid-inhale. That is classic for D-series. Crossover was an issue for the old ones. I'm thinking that the stutter issue with your last set, Simon, might have been a Venturi gate too open? Being able to close it a little on the fly might be key at higher air density (deep). And the big exhaust valve should eliminate the ONLY deficiency the D ever had.
But @rhwestfall had it right - too funny in the video where they refer to the NEW balanced valve. Bwaahaha! Having a centrally balanced valve was the one thing that set the D's apart from everybody else, THIRTY YEARS AGO! So of course they let it slide because it was too complicated for the techs to service. And now it's "new"!
I don't care.
I want two.
Yesterday.
Oh, wait! Christmas is coming!
My wife's not allowed to complain (because I'm not allowed to complain, just so we're clear).
What's an extra $800 for two useless Mk25 EVO's? I'll have my D420's!
The video cross-section seems to confirm metal orifice.
The WOB curve is fantastic - note how it shifts slightly into positive mid-inhale. That is classic for D-series. Crossover was an issue for the old ones. I'm thinking that the stutter issue with your last set, Simon, might have been a Venturi gate too open? Being able to close it a little on the fly might be key at higher air density (deep). And the big exhaust valve should eliminate the ONLY deficiency the D ever had.
But @rhwestfall had it right - too funny in the video where they refer to the NEW balanced valve. Bwaahaha! Having a centrally balanced valve was the one thing that set the D's apart from everybody else, THIRTY YEARS AGO! So of course they let it slide because it was too complicated for the techs to service. And now it's "new"!
I don't care.
I want two.
Yesterday.
Oh, wait! Christmas is coming!
My wife's not allowed to complain (because I'm not allowed to complain, just so we're clear).
What's an extra $800 for two useless Mk25 EVO's? I'll have my D420's!
Oh, sh!t. 
What am I gonna do with a thousand dollars worth of D350/D400 spare parts?
What am I gonna do with a thousand dollars worth of D350/D400 spare parts?
More candy...
It ain't great - the guy clearly never saw a D400 before in his short life. But at least it's in somebody's hands.
It ain't great - the guy clearly never saw a D400 before in his short life. But at least it's in somebody's hands.
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