Subwoofer with Thiel 2.4s?

Hi all, I'm in the process of building a new system and am considering adding a sub to my Thiel system. I'd love to get one of the Smart Subs, but they're just too damn expensive to fit into the budget. Any opinions on the other alternatives? Although I do use the system for TV and occasional movies, I'm really only interested in 2 channel.

I've read good things about the REL Strata III, but would like to hear other's opinions on the available < $1000 (used) options.
This may seem like an odd choice but I would go with Vandersteen if it is for music. If you look at the design of both speakers, they are similar in many ways. I just listen to music and I have a pair that work very well for me.
These speakers have a -3db FR bottom at 33 hz. That is pretty low. That presents a couple of problems for using a sub. You would have to (I would anyway) drive the Thiels full range so balance wasn't screwed up (let alone signal degradation) by putting it through a crossover to roll off the bottom end to accommodate a sub. Next I would want a sub that was flat at 20hz or close, think big and expensive, and one which had a sharp roll off starting at about 32hz so the sub didn't extend up into the mid base.

Which leads me to suggest that you insure that you have already maximized the bass potential of the Thiels by careful use of boundary reinforcement (use a SPL meter and test disc) by changing speaker placement AND the listening chair. Both play a large roll in perceived bass.

I've only one been successful once in making a good sonic match with speakers and sub's (I like 2 more than 1) and even then I had to cede that the crossovers did cause the loss of a bit of resolution in the main speakers. It was worth it only because the sub was substantially better for overall bass and the cross over was sharp at 200hz for the subs and gentle for the mains.
Here's what I would recommend (and what I do with my CS 2.4's).... get a good subwoofer (I have a pair of Epik Legend) and only use them with the movies/tv. The 2.4's do have enough low-end that you're not really missing anything and adding a subwoofer and getting it perfectly integrated is not easy and very expensive (the subwoofer would be magnitudes of that you're willing to spend).
Used RELs are a often a steal, and it mystifies me why anyone wouldn't be able to dial them in to fit with most speakers. Level (the most important knob IMO), frequency point, phase, etc., should allow for just about anybody's taste for bass needs. I have heard that if you have bass heavy main speakers you can risk a wallow in some mud, but in that case just remember the level knob, or move the damn thing older, bought used ($200!) Q150e is astonishing...I stand astonished.
Some of these details are in a couple amp threads that I initiated as I worked to build this system, but my real issue is that I am currently driving the 2.4s with a Pass Labs INT-30A. This combination, while sounding drop dead gorgeous with the right material falls flat on some more complicated stuff (e.g., rap, dance, & movies). I've tried another higher power amplifier (a 400 W Mac 402). This amp sounds great and solved the bass problem, but doesn't image quite as well as the Pass (or reveal as many recording details). I'm also considering a Pass X-250.5, but am still concerned that I'm going to end up missing what the XA amp gives me. It's just so good at imaging (which is the most important sound quality for me) and sounds so natural and grain free that I really don't want to lose it. I know the sub route is a cheating solution, but I'm on a budget and was just hoping that a little augmentation may let me fill in the low end without losing all of the positive qualities of the Pass XA series.

Thanks for the thoughts.
I'm in agreement with Newbee, I prefer subs in pairs rather than in mono.
The SS2s do sound amazingly well integrated with my old Thiel CS2.4SE and the Thiel CS3.7s.

I have heard the JL Audio and it just seemed a tad slower off pace than the SS2s in the same dealer showroom

The SS2s don't call attention to themselves and just make the 2.4 and 3.7s into much larger speakers.

I think one reviewer said not to look at it as an expensive subwoofer but making a Grade A speaker (band limited) into a Grade A speaker (with full bandwidth) :)
Thiel has a new Sub out for this year, which is a little smaller in size than the previous model. I am looking to get that for my SCS4's.
There was an SS1 on here that just sold for $900. I was a day late on getting it. Really kicking myself over that one, but I had to finish my taxes to know what the money situation was going to be. Damn.
Anyone aware of the "charge the room" theory of subs? Although it might seem like another example of "audio mysticism", it appears to be real. Listen to music that has seemingly no bass with and without a (well designed, like a REL) sub. Without it the mojo disappears. Mandolin stuff illustrates this point...some say the sub sort of "charges" the air. Without the sub you could be experiencing a "mojo filter".
I like Thiel's warranty 10YRS.
Most others 1-3 tops.
I had bought some used JL's(113'sX4)from different sellers they were two yr. old.
Got them from the US.had them for a 8 months,one died,the other had next to no vol left.
As there was no warranty it was going to cost me a 1000 for each sub to send to JL to fix.I sold them all as is.
I wonder how many other JL sub s have crapped out over the 2-3yr period.
I liked them better than my DD-15's.
Warranty is very important to have.
I'd rather pay a nice chunk of change for a sub with warranty(10yr),than buy a cheaper sub and it's gonna crap out anyway.Save for a great sub with alot of warranty and
save alot of grief later,2-3 yr warranty doesn't seem to be even close for the price a person pays for a sub.

Well, I picked up a REL Storm III. My plan was to use it as a high quality "hold-over" until another appropriately priced Thiel USS/SS1 comes up. I'll comment on the sound when I get the REL in later this week... and will update the thread if I end up comparing it to a Thiel Smart Sub.

Hopefully adding those final low frequencies to the Thiel 2.4/ Pass INT-30A combination will allow me to focus on buying new music...
I have to say that I'm extremely impressed with what this sub did to my system. Like others have commented, adding the sub opens up the soundstage and adds depth to pretty much all the music I listen to. I also watched Salt and listened to Tupac's All Eyes on Me, and the sub really made up for the previous bass deficiencies that had made these types of material feel flat and lifeless before the sub. Yesterday was really the first time I've been fully satisfied with the stereo since beginning the upgrades in December. I may eventually upgrade to a Thiel sub just because of the Thiel main speakers, but honestly, the REl does integrate very well. Sounds great.
The smartsub was designed to accompany model SCS4 monitor speakers.
A REL sub is very fine for any of the Thiel floor-standers.
^ There were different smart sub offerings that could adjusted various Thiel models. Thiel stopped making true full range speakers after the CS 5i's and the subs were necessary for those  wanting all that might exist in and on their music collections, if of course they had the room and budget to accommodate them.
 I love the strata 3 ,IMO its superior to the storm models which  I have owned and never liked...Easier to integrate and much quicker.Im running a Rel strata with a pair of sc1.2s as a third system with great results
I'm a 2 subbed (2 subster? "sub" stantial?) listener as I scored another REL from the same era as my Q150e…(a Q108II). 2 subs actually help remove some of the corner roll off boom by introducing an in-phase signal to the bass that escapes along the wall from the other sub to meet up and MODE so to speak. The Q era REL subs have lots of adjustability so integration into the room isn't so difficult at all…and you can buy these damn things pretty cheap (both of mine are perfect and cost about 200 bucks each…you simply have to wait for one to come along).
I love and endorse REL subwoofer(s).  Happy Listening!
"I love and endorse REL subwoofer(s). Happy Listening!" 

Are all the election spots rubbing off on you Jafant . I endorse this post !
Reviving an older thread here;
hope you guys are still enjoying the CS 2.4 and a REL or SmartSub.

Happy Listening!
Just received a pair of SVS SB2000 subs to integrate with my 2.4s. My plan is to have the 2.4s well into the room and have the subs located in the same plane just inside the mains. Because I will hook them up so that the preamp will line L and R into each sub, which will fixed cross the line outs to the monoblocks at 80 Hz (12 dB per octave drop, and which will now be working less hard), it will be interesting to see where the ideal crossover adjustment betwen 50 Hz (the lowest point on the subs) and 80 Hz for the subs will land. My guess is somewhere in the 50-60 Hz range. I’ll let you know how they work out.

Keep me posted- stevecham

Happy Listening!

Initial results are nothing short of impressive! The clarity of low bass is equaled only by Vandersteen Quattro and 5A models I have heard several times in friend’s systems. These subs play very clear notes with proper texture and speed during rapid passages while blending well with the Thiels. I will continue to fine tune them but with the crossover on the subs set around 60-63 Hz, I can hear all the upper bass notes clearly without suckout, and with appropriate attack and decay. When the subterranean notes hit, they are not louder or softer than those higher in pitch but they are certainly felt as well as heard. Volume is set about half way. I can’t say enough about the clarity and texture of deep bass notes; they integrate very well in my set up. Stay tuned for more as I fine tune and they break in. One of the best bargains in modern subs. I am happy I went with the sealed version; they sacrifice maybe a couple of Hz (19 vs. 17 for ported) but the speed, timbre and smaller footprint are worth it. Plus, 45 day in home money back if you don’t like them, well, what’s not to like?
Right On! stevecham-
The CS 2.4 will certainly play low in the Bass region without drawing attention to itself. The passive radiator does more than most think.

I look forward in reading more about your thoughts/impressions as you massage those subs into your room / system. Keep writing.
Happy Listening!