The way I understood it, the ATX series second stage regs are smaller and lighter than the TX series... And we have no question that this is in fact, the case.
However, the new ATX200 is, I've heard, the smallest of the bunch thus far. I understood that it's even smaller than the ATX100, the previous "flagship" of the line. It's reputed that the newest ATX200 is by far the most simple and straightforward design, with the best breathing of the bunch, which is supposed to be the strongpoint of Apeks regs anyway.
I also understand that the new ATX200 gets a cool looking "black chrome" treatment.
I haven't seen any of these in person, much less used them. However, this is the information that I've gathered. I believe it to be correct, but if I'm not, someone please let me know!
Here's a breakdown of what I believe to be the case:
1. Apeks makes two distinct lines of regs (I'm talking about "second stages" of the regs)... The TX and the ATX. The TX is their original design, and the ATX is made of different materials and thus is both lighter and smaller.
2. A "20" series reg is designed for warm water environments only, because it has no heat sink built in that's designed to warm the air rushing past the second stage and into your mouth. All other Apeks regs have heat sinks, which warm the air for your comfort and also help to prevent freezing of vital parts in the regs in really cold water. Keep in mind, however, that Apeks is saying that "warm water" means "50 degrees F" or higher. Most people diving in subtropical environments or higher will rarely see temps lower, unless you're talking at the bottom of a murky lake or something. There are no adjustments on the 20 series to speak of.
3. A "40" series reg gets you a heat sink for cooler waters, both to warm the air slightly for your comfort and also to keep things functioning properly in the second stage (helping to prevent freeflow.) A "40" series reg also gives you a diver-adjustable venturi which allows you to adjust for either freeflowing breathability or create a little turbulence inside the reg so that it doesn't freeflow easily when you drop the reg in the water at the surface or something. Both adjustments have their advantages. It seems that most divers dive with the reg as freeflowing as possible, but turn the "sensitivity" of the reg back a little when they surface so that it doesn't freeflow as easily.
4. A "50" series reg is like a "40," with an additional adjustment... The "cracking" adjustment. This is an "on the fly" adjustment that will allow a diver to tune the reg's sensitivity to go from closed to open and flowing... In other words, how hard a diver has to "suck" on the reg to get it to open and deliver air. The question is, how sensitive do you want your reg to be to opening up and delivering air in the first place? I can only imagine that with both a venturi adjustment and a "cracking" adjustment, a diver would be able to fine tune his reg quite to his satisfaction. The "50" series also has a technician-only adjustment inside which helps the reg to maintain "like new" performance as the parts inside wear or age with time. Apparently, if the tech who services your reg knows what he's doing, he can basically fine-tune the reg to feel "like new" every time it's serviced.
5. I do not know the difference between the "50" series regs and the "100" series regs, but I believe there's no funtional difference, only a difference in the quality and expected lifespan of the materials. I do, however, believe that there is a difference in the first stages of the "50" and "100" series. The pictures at the site of the first stages from each of these units show that the "20," "40," and "50" series regs all get a swiveling "turret" style first stage, whereas the "100" series gets a one-piece, better angled first stage which supposedly breathes better and provides less potential problems over time. However, I've heard that you could, for example, mix a "50" series second stage with a "100" series first stage, so apparently you can purchase them seperately, negating the point of going with a "100" series reg. Perhaps someone can elaborate on the differences.
6. The new ATX200 is a whole new animal... This new reg is apparently even smaller and lighter than the rest of the ATX series, has a heat sink, both diver adjustments and the technician adjustment, and the top of the line, non-turreting, natural-hose routing first stage. The reg also apparently gets this cool looking "black chrome" treatment.
That's what I believe to be the case... Someone please tell me if I'm wrong.
Personally, I like the "20" series regs, and am attracted to the smaller sized regs even though I'm a big guy with a big face. I'd have to see them in person in order to go with the right one. I like the lack of adjustments... I feel that's a simpler design, and I've found that manufacturers tend to tune the venturis of their nonadjustable models at a happy medium between flowability and resistance to freeflowing, and I've enjoyed nonadjustable models over having an adjustable model which never seems to be tuned right. I will tell you, however, that I intend on doing deep dives in the next few years, and in many cases it'll be in low vis or darkwater... So the unit may operate below temps of 50*F regularly, so I might move up to the ATX40 just for the heat sink and the extra assurance that my reg's gonna work. I will also tell you that I'm very much attracted to the new ATX200 because it's supposedly even smaller than the ATX40, and the hose routing is a bit more natural. There's also a difference in the quality of the materials, which I like. The new color is cool, but that really doesn't make much difference to me. Lastly, the extra reassurance that I've got the best available for my dives is nice... That might be some extra peace of mind at 220 feet, and that's worth something to me too.
So I personally need to see both the ATX40 and the ATX200 and probably use them to see if I can justify the price difference. I'd also like to see the size difference between the ATX and TX series and see if I really do want a smaller reg. I understand that deeper divers like larger regs.
Either way, I very much like their 5000ST secondary and will probably be purchasing one of those as well. Or maybe the Sentinel... Again, I'd have to see them in person
