Wow, you're planning on four L22's??? That's gonna be a mighty lot of bass! How big is your room? FWIW, my actual AV room is approximately 16' by 25'... but it opens into another room that adds an additional 13' by 21' space (plus a couple of alcoves). While I'm sure that the REL team would prefer that I built a pair of their stacks, they ultimately recommended that I go with a pair of their 212/SX, as they felt it would be needed to adequately 'pressurize' my room.
It's kind of interesting that while both of us seem to be headed in the same direction, that REL and Rythmic came to the same conclusion and pointed us both toward their 2 X 12" subs. Of course I'm choosing the integrated approach while you are going with the RDL converter, but we will likely end up at the same place.
Wait just a second! What happened with the car?
Two stacks is what I'd like to end up with, but by the time I get the second sub it might be evident that only two are enough. But I really want to feel like I'm at a 1970's Deep Purple concert with lots of Marshall stacks all over the place!
The info on Rythmik's web site is not organized well enough to know which amp is being used on some models. So there was some confusion which was cleared up today, at which point they told me there's a new model, E22, which has upgraded drivers, the amp is 800 watts rms instead of 600, couple more features on the amp, and comes in a nicer finish if desired (yes it is), and costs 2/3 more. I asked how to order the new model since it's not on the web site yet, but that was late in the afternoon, so hoping to hear tomorrow.
The thing to keep in mind with Rythmik is there are reasons the price is reasonable. Most of the cabinets are covered in vinyl, with some being upgradeable to piano black or white. The E22 can be ordered in piano black. A lot of the amps do not have high level inputs, they have a mix of features for specific models. The dual driver models are not available with high level inputs, so that's why I need to use an outboard converter. I'm really not worried about the amp qulaity though because it doesn't seem to matter how much audio products cost, they all can have amp problems, just name a company, I don't know of a single company that hasn't had failures - just ask Bob Carver and his failing Amazing Line Source (they're start'n to fizz'n'spark, something in the crossovers). I've been seeing a lot of exploding parts on power amps and speaker amps lately. Lots of blowed up transistors and capacitors ("That blowed up real good!" (SCTV: Farm Film Report skit)). So even though I don't like pudding, that's where the proof will be.
The Rel 212/SX is about 5.3 cubic feet, the Rythmik E22 is about 3.7 cubic feet (based on outside dimensions). They each have two drivers, but 212/SX also has two passives while the E22 is sealed, so the extra weight of the Rel might be the two passive radiators in addition to the larger cabinet, so I gotta believe the cabinet thickness is probably the same. The Rel weighs 30lbs more.
After reading quite a bit of Rel info I decided to try something that is a furthering of what I'm already doing, which is separating LFE into dedicated subs. I've had my system setup for a few months with my subwoofers dedicated to LFE only and using the Expressions for Bass Management. But Rel has it going a step or two farther by having dedicated subs for at least 5 channels and setting up those speakers as Large and using the High Level connection.
The Left/Right each having their own sub, AND the Center having its own sub, all three set as Large and no LFE. The Center dedicated sub makes a lot of sense, and really doesn't need to be very large being that it's mostly voice. So I'm going to pickup a Rel T/5i for the Center channel.
Then Rel says to also use the High Level method for Surrounds. In my system that would mean two more subs, one for Surrounds, one for Rears. Now as crazy as this sounds, it begins to be a little more reasonable because Rel also says to pass the LFE to the Surround sub(s). So for this, I just happen to have a couple subs in the right locations for Surrounds and Rears, so I'm going to try this JUST FOR FUN!
So how is this denoted? I've been using 9.1(3).4 to denote that my system has 9 bed channels, 1 LFE channel with 3 subs, and 4 Height channels (Tops). Adding subwoofers to speakers doesn't increase the channel count, it just makes the "speakers" larger and multi-piece. So maybe it would be 9(3).1(3).4 ?
edit: The main reason for adding subs for the Expressions is to extend bass lower and support bass up to maybe 50Hz or so, which would mean setting the Bass Control on the Expressions to a lower setting. This obviously reduces the muscle needed for those lowest frequencies, which the Expressions do quite well, but if these are relieved a little there "might" be an improvement in clarity? Remains to be heard.