Noisy M1 seconds- too hot?

[StefinSB]

Never had the issue you are describing with atomics 2nds. I just checked and I have serviced 21 Atomic 2nd stages so far. I have had a honker here or there when breathing dry but that always got solved re- seating the diaphragm.

When you adjust the orifice you want a small movement of 0.5mm or so of the lever before it activates. Then set the cracking with spring pad (1/8” hex).

 

[Wookie]

I think the issue here is the Atomic 2nds combined with diaphragm firsts. An Atomic is a pretty highly engineered reg set. I would have no issues using a T2 with a B1 or a Z1 with an M2, but using a M2 with a completely different brand of first stage, and diaphragm vs piston and expecting excellence is a bit of a stretch IMO.

I’m trying really hard not to sound like an Atomic Fanboy, although I certainly am, I think you’re asking for something the equipment wasn’t designed for and you aren’t modifying it to make up for its shortfalls.

 

[Rusty Shackleford]

I think stutter in a reg is the diaphragm bouncing off a lightly-loaded demand lever.

 

[Rusty Shackleford]

I think the issue here is the Atomic 2nds combined with diaphragm firsts. An Atomic is a pretty highly engineered reg set. I would have no issues using a T2 with a B1 or a Z1 with an M2, but using a M2 with a completely different brand of first stage, and diaphragm vs piston and expecting excellence is a bit of a stretch IMO.

I’m trying really hard not to sound like an Atomic Fanboy, although I certainly am, I think you’re asking for something the equipment wasn’t designed for and you aren’t modifying it to make up for its shortfalls.

I have used ST-1s on MK-20 and MK-25s without issue.

 

[Wookie]

I have used ST-1s on MK-20 and MK-25s without issue.

An Atomic and a Mk20 are brother and sister, and a mk25 is a kissing cousin, all designed by the same guy.

 

[Rusty Shackleford]

An Atomic and a Mk20 are brother and sister, and a mk25 is a kissing cousin, all designed by the same guy.

I know.

 

[lexvil]

Well the diaphragm vs piston seemed unlikely but since I have the gear went out to do a test, hooked my M1 second to a Zeagle FH 6 first and..........smooth as silk, exactly the same as expected, IP 140.

 

[buddhasummer]

I think the issue here is the Atomic 2nds combined with diaphragm firsts. An Atomic is a pretty highly engineered reg set. I would have no issues using a T2 with a B1 or a Z1 with an M2, but using a M2 with a completely different brand of first stage, and diaphragm vs piston and expecting excellence is a bit of a stretch IMO.

I’m trying really hard not to sound like an Atomic Fanboy, although I certainly am, I think you’re asking for something the equipment wasn’t designed for and you aren’t modifying it to make up for its shortfalls.

They were on an M1 first stage, issue was the same. I would have thought the second stage didn't care as long as it was being provided with a within spec steady ip? I'm not saying you're wrong but have I've mixed and matched for years and have never encountered an issue. Scubapro offer most if not all of their seconds with either piston or diaphragm firsts, I can't see that the design of an Atomic is so different that my use of a diaphragm first, especially given behavior was the same on an M1 first, is the culprit, of course could be wrong, often am. Cheers.

 

[buddhasummer]

Never had the issue you are describing with atomics 2nds. I just checked and I have serviced 21 Atomic 2nd stages so far. I have had a honker here or there when breathing dry but that always got solved re- seating the diaphragm.

When you adjust the orifice you want a small movement of 0.5mm or so of the lever before it activates. Then set the cracking with spring pad (1/8” hex).

I'm having trouble ascertaining lever play, I assume one removes cover and presses lightly on diaphragm to see how much travel before activation? That's what I was trying to do. Cheers.

 

[buddhasummer]

A bad Workman always blames his tools. Sorry Atomic.

Took them out this morning, not perfect but waaaay better. At depth a minor stutter on initial inhalation and a minor high pitch whistle, could tune out both screwing in adjuster. At shallower depths, silky smooth and quiet. Head down leaks a little.

I'm going with I had, perhaps still do a little, the lever too high ???

I'll drop it a little more up cracking to 1.2" and I think I might be a happy Atomic owner.

Thanks for all the input, suggestions and advice guys, you rock.