Work of Breathing (WOB) MTX-RC (0.9 J/l) vs MK25 A700 (0.51 J/l)

[Ian Fatzinger]

Awesome, did you find that the second stage of MTX-RC is heavier than S600/S620ti in the water?

Yeah its kinda heavy comparatively bc its made for cold water

 

[scubadada]

Latest ScubaLabs reg test - huh?

Is "DACOR" back in business? This is news to me. News to me too. It said the company was West Marine which runs retail stores selling boating items here in the US. They must have bought the name from Mares. From what I remember Dacor was supposed to be Mares budget brand but they really didn't...

scubaboard.com

 

[Endler's]

Numerous times, 'have forgotten to change venturi on MTX to dive position; while diving, was unaware because it breaths so easily.

Two additional considerations/differences to ponder:
1. Apeks is environmentally sealed, Scubapro is not.
2. Scubapro turret rotates 360 degrees. Apeks turret won't.

 

[AISM]

Yeah its kinda heavy comparatively bc its made for cold water

Why cold water reg is supposed to be bigger?

 

[AISM]

Numerous times, 'have forgotten to change venturi on MTX to dive position; while diving, was unaware because it breaths so easily. View attachment 717848

Two additional considerations/differences to ponder:
1. Apeks is environmentally sealed, Scubapro is not.
2. Scubapro turret rotates 360 degrees. Apeks turret won't.

You mainly do cold water with MTX-RC? What is the max depth you dived with it?

 

[tbone1004]

Why cold water reg is supposed to be bigger?

More metal mass to act as a heat sink to mitigate risk of freeflow

 

[Endler's]

You mainly do cold water with MTX-RC? What is the max depth you dived with it?

I dive them mostly in Tahoe in summer. Have taken them to 80 ft., at 53 degrees in August, in 7mm wetsuit.

Only when 'go to rinse, do I notice that I forgot to change venturi to dive position

The First stage is large:

I have a DST for Pony, and prefer its smaller form.

 

[Brad_Horn]

Hey Guys,
Now I am in market for a regulator and I'm torn between Apeks MTX-RC and Scubapro MK25 A700/S600.
I dive mostly in the Red Sea and warm water, but I want the easiest regulator with the least WOB and high reliability, money isn't a big issue here.

I emailed Apeks to ask for the WOB of MTX-RC and they relied with the total WOB is 0.9 j/l, without specifying the depth, RMV nor temps.
On the other hand, I found a graph showing the WOB for Scubapro MK25 A700 (0.51 J/l) and MK25 with S600 (0.65 j/l).

Apeks MTX-RC (0.9 J/l) V.S MK25 with S600 (0.65 j/l)

Does a human capable of feeling a difference of (0.25 j/l)?
How would (0.25 j/l) impact comfort or anything?

Should the WOB be part of the process of choosing a regulator at all?
I really don't know which one to go with, I like the look of both (tried none of them) and I can get them both serviced locally.

Thanks for looking at the comparison of these Regs. Interesting.

FYSA that Apeks 2nd will probably be 0.9J/L at 62.5lpm at 50m on Air. See independent WOB testing of one of their older TX100s here https://www.opensafetyglobal.com/Safety_files/DV_DL_ALVBOV_Breathing_Params_A3_100318.pdf

What's interesting is the ScubaPro reg is seemingly only tested at 25bpm at 50m. And completely fails to articulate the tidal volume. So its actual WOB at 62.5lpm may be - and very likely is - considerably higher than the Apeks reg....

Comparing WOB between different components requires them tested to the same standard. You might want to ask ScubaPro for their EN250 test results as that is a defined standard required to get CE marking. See above link for example of its test criteria.

 

[Endler's]

Wond'ring Aloud...
'Had LDS change Pony bottle MTX second stage to Left hand side (white body). Now, gas outlet in air barrel, faces towards exhaust valve.
Is this normal?

 

[Shabaday]

I think the top line regulators are all pretty similar. The tuning to me is the most important part. I have the Apeks XTX 200 first and second. Tuned by Rsingler. Breathes amazing. I have a SP Mk19/G260 tuned by Rsingler...Breathes amazing. My wife has an Atomic ST1 that breathes incredible. So good I bought another one for myself. Did I tell you that was also tuned by Rsingler? I could also mention the D420 that was tuned by Rsingler. So I am sure you can see the trend here. If you will be in the Red Sea no need for that model Apeks. I would think you have greater support for SP than Apeks especially if you are traveling and in warm water. The Mk25 and the G260 would be a great set up for you. I had the S600 and the S620ti and was unimpressed by the S620ti. I MUCH prefer a sealed first stage but as long as you take good care the Mk25 will last a LONG time. Out of all my regs if I had to buy just one I think I would be doomed but most likely the Atomic ST1 or the Mk19/G260 would be my choice. For cold I use my XTX 200 and it just breathes amazing cause of course Rsingler tuned it. I do have a Mk17/C370 that Buddhasummer tuned which I can't wait to try out