ScubaPro MK20/S550 vs Hog D1

[chrpai]

This came up in my mind because I think I recall reading on a DIR page somewhere that 2nd's and stages should be adjustable so that you could tune them down. I thought I read a reference to because the bungeed second is hanging upside down that you should do this.

But what I'm hearing is don't worry about it. Sounds fine to me.

I wouldn't throw rocks at the S555 or the D1 anyways.... damn plastic body.

 

[50Fathom]

The standard doctrine is that the primary 2nd is balanced and high-performance, for ease of breathing, but the bungeed backup should be an unbalanced, lower-performance 2nd. This is for simplicity of design, ruggedness and reliability. IF you are on your backup, you want it to WORK first, and be finely-tuned second. You also want it slightly detuned compared to your primary, so it's less likely to freeflow, and if it does, it doesn't blow tons of gas into the water.

I am considering going to an unbalanced second as my backup, but most philosophy-compliant divers I see dive matched sets, IE: G250/G250, S600/S600, XTX50/XTX50, etc.

 

[redacted]

The standard doctrine is that the primary 2nd is balanced and high-performance, for ease of breathing, but the bungeed backup should be an unbalanced, lower-performance 2nd. This is for simplicity of design, ruggedness and reliability. IF you are on your backup, you want it to WORK first, and be finely-tuned second. You also want it slightly detuned compared to your primary, so it's less likely to freeflow, and if it does, it doesn't blow tons of gas into the water.

I am considering going to an unbalanced second as my backup, but most philosophy-compliant divers I see dive matched sets, IE: G250/G250, S600/S600, XTX50/XTX50, etc.

I like a balanced 2nd as a primary and an unbalanced adjustable 2nd as an alternate. An adjustable primary is usually unnecessary. An adjustable alt allows easy user detuning of the alternate and can be retuned when the reg goes in your mouth. All of my alternates are 109's. It would be quite easy to convert a G250 to unbalanced.

 

[halocline]

The standard doctrine is that the primary 2nd is balanced and high-performance, for ease of breathing, but the bungeed backup should be an unbalanced, lower-performance 2nd. This is for simplicity of design, ruggedness and reliability. IF you are on your backup, you want it to WORK first, and be finely-tuned second.

I think that's mostly an old-school tech diving idea so that in the event of an IP spike the alternate will free flow before the primary. In practice, there is no real-world difference in reliability between most high quality balanced and unbalanced 2nd stages of similar design. Good examples of would be G200 and G200B or the 109 and balanced/adjustable. The only difference is in the poppet. In fact, even though the parts count is slightly higher with the balanced poppet, it's also more tolerant of IP creep, so my guess is that they're just about the same in terms of reliability, which is to say very very reliable.

There's no sense in deliberately choosing a lower-performing 2nd stage as an alternate on the assumption that lower-performing means more reliable.

 

[ams511]

The standard doctrine is that the primary 2nd is balanced and high-performance, for ease of breathing, but the bungeed backup should be an unbalanced, lower-performance 2nd. This is for simplicity of design, ruggedness and reliability. IF you are on your backup, you want it to WORK first, and be finely-tuned second. You also want it slightly detuned compared to your primary, so it's less likely to freeflow, and if it does, it doesn't blow tons of gas into the water.

I am considering going to an unbalanced second as my backup, but most philosophy-compliant divers I see dive matched sets, IE: G250/G250, S600/S600, XTX50/XTX50, etc.

I think the doctrine has evolved over time, so that the secondary does not need to be an unbalanced second. I agree with the others that prefer an adjustable secondary that can be tuned down when not needed and tuned up when needed.

 

[chrpai]

I ended up selling the s550 to cbrich. With Black Friday prices and loyalty points its pretty much a wash to me.

I offered the mk20 up but I guess the price wasn't right.

So I get standardization on my 2nd stage. I probably don't really need adjustable but I do plan on using it as more then just a pony.

So if any 1 of my first or seconds break or need servicing I can keep diving. It's nice to be slowly growing my gear collection.

---------- Post added November 26th, 2012 at 10:52 AM ----------

Oh, and I ordered a few masks too.

 

[ams511]

You gotta love Black Friday.