Sub users...

Depends on the crossover point. If you are using the sub to just augment the lowest notes (30 hz and below), then one sub in mono can sound very natural. However, if you are crossing over substantially higher--say 60 Hz or above, then 2 subs in stereo will sound more natural.

For 2 channel music I personally use 2 subs, but they are in mono and rolled in at 30 hz. The 2 subs are used to flatten out the room modes.

Rives summed it up well...I also use 2 subs to even out the modes and to enhance low end weight and impact below 30hz which is where my Sophias begin to roll off:O)

Bass frequencies are sent to both channels in 99.9% of mixes. Below around 100 Hz you cannot tell where a sub is anyway (if you can it is because leakage of higher frequencies - you can use a steeper filter in the case of a poor quality distorting sub). Your fear is really unwarrented if you intend to get a high quality subwoofer and correctly match it with your mains.

If you buy a ported boom box of a subwoofer then it will indeed ruin Dave Brubeck but not because drums will jump around but mainly because of masking from all the bass resonance and poor transient response from a cheap sub. The most expensive driver on large mains is usually the big woofer. The hardest and most energy demanding driver on any speaker is the woofer and the LF. Logically you might expect to pay as much (or more) for a subwoofer as your mains in order to maintain a similar level of quality.

Thank you all for the great replies. While I have not researched subs, the JL Audio F113 is the one that has my attention. I would be using it to augment the lowest notes as you hint Rives, 30hz'ish and below.

I use a pair of Vandersteen 2Wq subs. Since these are fed from the amplifier speaker taps, they are indeed stereo subs. I have them positioned behind and outside the mains. I have no issues with imaging of low frequencies - images are stable in the range covered by the V2qs.

Did you consider a Wilson Watch Dog? Your speakers have a Q resonance bump around 80 Hz - you can see this on Soundstage measurement plots. This probably affects group delay also and the way the speaker integrates in the room. (speaker may resonate after the music stops up to an extra cycle or so due to this "tuning")

I have no experience adjusting to this speaker but it may be important to match this resonance to get smooth integration. For example, an SVS PB13 Ultra has three ports which you can block or unblock in order to adjust Q resonance (will affect group delay) and this might allow more seamless integration (you get four options of resonance and group delay by blocking none, 1, 2, or all three ports)

Perceptively, lower group delay will give a tighter bass sound kind of like a traditional Basie jazz drum set (just a hint of kick through room pressure). Higher group delay will give you a fuller rock kick drum sound in the bass.

Thanks for the info Shardone, but if I go with a sub it will not be with the Wilson's, but rather Ridge Street Sason's. My bad.

2- subs will be better in a 2ch system but one will still work well --I have the f113s and they are very good subs---since you have never owned any subs --you might just buy one and can always get another one later--you can experiment with diff xover points and find the one that is best for your system --you may surprise yourself that it will be higher than 30hz !!!

Thanks Bob. In talking with a friend tnight, we concluded I'd probably be crossing over at higher than the 30, closer to 40; all a guesstimate of course.

Another question. I'd be connecting the sub from my preamp. I haven't a clue if I will be able to place the sub close to my system or not, but this may lead to some lengthy IC's. How big a role do the IC's play? A loaded question, I know.

I have my subs on wood platforms next to my Sophias and even with the mid range drivers. I use MIT Oracle V1.1 IC's fed by my preamp outs. The integration gives me the range and slam of the Watt/Puppy 6's I used to have in my previous house.

First of all don't place it near that cute baby :) great pic---there will be some disagreement about whether or not ic's make much difference on subs --in my 2ch system I found that the better ic 's did make a difference on both subs jl f113s--in my HT system I just use a relatively inexpensive xlr cable- on an f113 -you will have to play around with diff positions and find out what works best for your very nice system--can use a less expensive one first and once happy with the position of one or 2 subs then upgrade the ics---Rich

Take Five - one of my all-time favorite cuts! I have two 12", sealed subs (wired stereo) dialed in around 55Hz. No deleterious effects on this (or any) cut whatsoever. In fact, I detect beter (truer, deeper) tone and broader spaciousness with the dual subs.

Thanks again to everyone for their great responses.

I have been reading about the JL Audio Fathom F113 and one concern I have is that a couple reviews stated that the F113 lacks a high-pass filter, which can be an issue for two-channel use, unless I use an external x-over, which I do not desire to do.

I have also read a few comments here on AG where users have integrated them fine into their two-channel systems with no extras.

Any thoughts on this?

Ras422 - The little guy is now 2 and depending on the song he runs around "dancing" to the music.

Brian

I have been reading about the JL Audio Fathom F113 and one concern I have is that a couple reviews stated that the F113 lacks a high-pass filter, which can be an issue for two-channel use, unless I use an external x-over, which I do not desire to do.

You can always use the sub to fill in and run the mains full range.

Shardone, I have read this elsewhere too, can you explain more?

If I used an external x-over I would cut some of the speakers lower end and control the output of the sub? Without the x-over, the speakers perform as normal and I control the upper limit of the sub, and "fill-in" the bottom? I guess I always imagined the speakers running full range and the sub filling in the bottom.

Sorry, I am a sub newbie! I hope I follow. Can you expalin possible negative effects of running the mains full range?

Lastly, if I were to go the external x-over route, does one have to spend a lot of money to get a good x-over?

I very much like what I read about the F113's, specifically using two of them, and desire to go this route. That said, while I want to do it right, cost is a factor.

i have found that the only way i can get seamless integration with my sub (for 2 chan) is to center it between the l/r. this is most noticeable in situations like you describe, drums that move across the soundstage. this is also thiels recommendation for placement if it is primarily 2 chan listening, 1 sub.
i rarely use it for 2 chan as i think the bass is adequate without.

you can try the subs with your speakers running full range and fill in the botoom ie 35-60 hz and down or get an external xover which I use and get increase in dynamics etc from your mains --2 schools of thought on this with lots of opinions either way --you just have to try and decide which way you like it---rich--glad the little one is dancing :)

Can you expalin possible negative effects of running the mains full range?

Possible problems are matching the large LF phase swings in your mains (due to the double ported design) and/or too much bass at some frequencies.

FWIW: I use the sub to fill-in because I want to take advantage of the different room placement of the sub to allow it to reduce suckouts at the listening position due to inevitable room rear wall reflections and room modes from a symmetric placement of the full range mains. I think this is the best approach if you have good full range speakers and a sub that matches (the drivers and overdamped tuning in my sub precisely match the mains - differing by only a few hertz at resonance). The only reason to restrict full range speakers with a crossover would be in the case of small satellite speakers with 6 inch woofers that can't really handle the LF.

A sub can easily be EQ'd with a Paremetric Equalizer (or TACT or PARC) so that it "fills-in" leaving a pure unfiltered signal to go to your mains. Some subs come with great auto-EQ features. For other less sophisticated subs you can look up Room EQ Wizard for suggestions.

The essential thing is to get a sub that integrates with your speakers! If your speaker resonates and has a highish group delay then a sub that is overdamped and does not resonate will be a waste of money (huge expense for poor SPL output that is tighter than the bass from your mains and therefore a largely inaudible benefit)

According to this article, [url=http://www.stereophile.com/floorloudspeakers/920/index6.html]the WATT/Puppy 7 offers enigmatic measured performance[/url]. This is why it might be safest to get a Wilson sub that is designed to go with them. This speaker is not designed to easily integrate with a sub, IMHO.

Shardone, you must have missed my previous post, I will not be using the subs with W/P's, I need to update my page; I will use them with Ridge Street Sason speakers, a stand mount two-way. Thanks, Brian

will not be using the subs with W/P's

Oops sorry - if they make a matching sub then I'd recommend that.

In the meantime, I found a good example of what typically happens to phase and group delay in different type designs of bass response. It is worth remembering that when you add a sub to full range mains that you may be trying to integrate responses from two completely different designs (different delays of phase). Note how the phase response really separates below 40 Hz for different tuning.

So depending on the different design between speaker and sub you might be out by as much as 90 degrees or more (quarter wavelength) at 20 Hz and yet in phase at 80 Hz or vice versa.