High quality subwoofer - which one?

I’ve owned my C4’s for about six months now, and they are excellent. But, you can’t ask a speaker to things it isn’t big enough to do. What that is, is to go FLAT to 20 Hz. The Vandersteen Quatro’s had built-in 250 watt class B powered subwoofers that are to die for once you hear them. The blemish on the Quatros, and it is a small one, was the slightly veiled lower midrange. The C4’s are absolutely seamless everywhere they go. The lowest bass can be fixed and most would probably say it’s not even necessary...until you hear a real sub system that is. Once you hear the effortlessly smooth low-end of a dedicated sub woofer you just can’t forget about it.

I started looking at subwoofers, and they are expensive, but relative to what this hobby’s cost(s) can be on some item(s), they are affordable. Well, ONE is affordable, anyway. I have three models that seem to all be nice products, and was curious what the feet on the street have used and your likes / dislikes. One model that I have not included needs an external hi-pass filter and I may be dismissing this model out of hand…and shouldn’t be and if you use this model, convince me.

I have a pretty large room (16’ wide x 40’ long x 8.5’ high (ceiling is split at 7.5’ and 9’)) so a bigger sub may be needed. Right now, I’m thinking ONE sub crossed-over pretty low. The C4’s do go pretty deep, but I probably agree that two would be “best” but expensive and the narrower room might make double placement hard. One is a snap, between the speakers away from the wall or near the right corner. I do not play “loud” (80-85 dB SPL average based on my radio shack SPL meter) but still like the smooth deep bass of a sub. Crazy loud isn’t the issue, but the sound quality is.

The choices are mind boggling in cost (JL Audio in mono or stereo) or mono (VELODYNE DD15+) verses stereo (SVS PB13 Ultra) set-ups at the same price. I have three options below to illustrate this.

The set-up that seems too expensive but outrageously good;
JL Audio Fathom f113 - $3600.00 / 13” / 2500 watts peak class D amplifier / sealed box.
But the sub needs a high-pass Cross-over like a Bryston 10B-STD @ $3,500.00

This is expensive compared to the SVS, but is it better than TWO SVS units?
Velodyne DD15 Plus - $4,000.00 / 15.0” / 1250 watt continuous class D amplifier / sealed box.

This seems like a good price but is the product good enough even if the price is? Use TWO of these in place of one DD15 Plus?
SVS PB13-Ultra - $2,000.00 / 13.5” / 1000 watts continuous class D / ported box.

So what have we done with subwoofers and why? This got real complicated real fast. Ported, vented, stereo at the same price as a mono sub ETC. The odds of auditioning these monsters are about zero as you hear the room. My room seems to be pretty good down low based on my Quatro set-up with powered subs. If a decision isn’t easy, I’m missing something…a lot of something’s it turns out.

Try running your C4s full range with 1 or 2 subs running only up to 40 or 60 Hz. You should not need an external crossover. Try this and find the point where the sub(s)
blend well.
I'm running my Avalon Avatars with 1 James EMB-1200 like this, right now.
Two of any of these subs is probably better than one of any of the others. The SVS seems to be in the sweet spot for you $-wise, so that is the route i would recommend for you. They are all very decent subs, once setup. BTW, the JL does not require an outboard crossover.
I have a Rel with my B&Ws and love what It can do. My low end is deep & smooth and the sound stage and imagining is great. The best think I did was put a Rel in my system. I would love to see what two of them would sound like.
IME, the answer is a little involved:

The Velodyne DD series subs have (DRC) software that is effective (when set up manually, the auto mode sucks) in smoothing bass response by correcting room induced effects. If you are listening to music only, "not that loud", then one 12" DD will probably be all that you need. Two will almost certainly be more than sufficient for that application in that room.

The JL has rudimentary software and SVS sells a separate (SVS-Audyssey) DRC box that is purportedly terrific. The same solution can be provided by any pre-pro equipped with Audyssey (or similar, like Anthem's ARC). HK also includes a variation in their HK990 integrated amp.

The caveat:

AFAIK, DRC is always managed in the digital domain. That means that your analog audio signal will see "ADC - room processing - DAC". I know that this does not appeal to many 'philes, particularly those using vinyl. In my book, the benefits of the software are worth the multi-conversion trade-off, but....

If you forego DRC, then 2 subs (if properly located) will provide smoother response than a single sub. You can place them so that room effects on one sub are (more or less) balanced out by room effects on the other. An extreme variation on this theme comes from A 'goner Duke at Audiokinesis, who sells a four sub solution called the Swarm. I haven't heard it, but, for a non- software corrected subwoofer system, it's the most conceptually appealing approach that I know of.


BTW You might also check out Ryhtmik. I use a pair of their 12" subs (w/ Audyssey) in my 2.2 channel, music only system and get great results.