Single vs Dual Subs

Let's assume the budget is around $2k.

On the one hand, you could pick up a used/demo JL Audio or Velodyne DD-series. On the other, you could get a pair of new subs from Hsu Research or SVS. Given that the solution has to work well for 2-channel music as well as 5-channel movies, what would sway one in one direction or the other?

If you have the room, go with two subs, you wont regret it. Most people only can fit one of these beasts in. I had two SV Ultra 12/2 subs in the same room andit was pain scary. Think car spl in a 24x17 room. Will shake your throat bass!
2 subs are much better for imaging. Go for 2.
I use to use a single sub(double duty for 2 channel and HT.
I purchased another for dedicated 2 channel and other for HT.
I then experimented with 2 for 2 channel(WAY BETTER)
lays a nice blanket of bottom end for the high pitched instruments.
Using one sub for 2 channel before was like a bird with one wing,she just couldn't fly.lopsided if you will.
Now when I do movies I just connect the rca to my sub and disconnect the XLR for the music side(until I aquire another).one doesn't do it for me anymore.
Ditto! And with two subs it is actually easier to integrate with a 2 channel system, IME.
Thanks for all the responses. I was thinking about how the connections, should I go the 2 sub route. If I set the pre/pro to "no sub" and ran both front left and front right full-range, then couldn't I have both 2-channel and 5-channel covered and not have to do any cable-swapping? Or would I be messing something up by not using the sub/LFE channel out of the pre/pro?

Thanks again,
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Yeah, it hit me while I was out with the wife and kids that I should just use the high-level connections and forget the .1 channel. I'm not a "purist" in that sense; I just want the sound to be well-integrated and, of course, get sufficiently low without boom, echo, overhang, etc.

Thanks again, all. Looks like I'm headed for dual subs.

Given my theoretical budget, I'm thinking Hsu and SVS. Others I should consider?

2 Dual woofer push-pull subs. Dual element push-pull subs are smaller in size than single element subs
Assuming you have freedom of placement, two subs can provide a smoother response than one.

I would use the LFE output from the pre/pro -- simply chain the two subs together with shielded cable. For movies the LFE is a discrete channel, so why not take advantage of it? I would set the left & right speakers to small, so the bass goes to the LFE channel. The speaker setup in the pre/pro should take care of level matching and distance.
Somec59 said:
Dual element push-pull subs are smaller in size than single element subs
OK. Manufacturers?

Bob said:
For movies the LFE is a discrete channel, so why not take advantage of it?

Sure, the LFE is there. The question would be, "Since the LFE is mono, might one getter better 2-channel performance by keeping the L and R signals distinct?" The idea would be, to me, that the subs are just making the mains more full-range, while the LFE is combining all the LF into a single channel.

I do appreciate all the thoughts here. It's helping me think through my approach to this.


I recently spent about 6 or 7 months researching subs; listening when I could and studying test results as well. My quick take:

1) Audyssey, SVS/Audyssey, Velodyne SMS allow parametric EQ below the x-over frequency. The benefit in seamless integration and smooth deep bass (i.e. "fixing your room")is amazing. If your pre/pre-pro/receiver doesn't have this feature, I'd budget $450 (Velo SMS) to $800 (SVS/Audyssey) to add it.

2) 2 subs have many benefits - at your budget, I'd definitely go that way.

3) I spent a LOT of time with the JLs. They are great subs, but expensive. The Hsu product looks good, but the SVS subs appear to be superior all around performers for similar $ (caveat: based on test results here -not listening sessions). I did a lot of research and picked the Rythmik subs (which are very satisfying in my music only system), but if I wanted dual use - music AND ht - I'd probably go with the SVS.

Good Luck,


I suspect that any of the 12" models from Rythmik, SVS, or Hsu will be satisfying. The Rythmiks don't test as well below 35hz (as a practical matter, this is strictly HT territory), but they allow variable damping that's proven quite useful in system matching/fine tuning. In actual use, my pair of 12" subs reproduce 25hz test tones at high spl without breaking a sweat. They'd also go well below that if I adjusted the EQ and susonic filter to allow it.

As far as the LFE goes - try it both ways. Depending on your room and the main speakers in use (with the attendant selection of the best x-over point) it may, or may not, make a difference.

Didn't this issue come up in a series of posts a short while ago? One of the posters cited the Harmon web site. Their expert advice based on psychoacoustic research differs from that given in these posts. Given that LF has little or no directional information, a high quality sub well placed is usually sufficient except for very large spaces. Well placed is often in a corner. You might Goggle harmon, where you will find a series of technical papers dealing with various aspects of audio, including LF reproduction.


I don't know the paper in question, but IME 2 subs vastly simplify the task of achieving smooth response. In room, you WILL get peaks and valleys which can be smoothed (to an extent) by varying the location of your sub. When you have the option of varying the location of 2 subs (and their phase/polarity), the chance of significantly mitigating all major anomalies is much greater. Again, IME.


The actual performance of the sub itself may also benefit significantly from the addition of a companion, depending on room size and placement (as you noted), as well as desired spl and program material.
Most subs are crossed oved at a point high enough where the sound is directional.
Dbphd, I didn't comment on your post in the other thread about the Harman paper. I don't see how you took away from it that a single sub in a corner was their recommendation. The results, both simulation and actual, showed that two subs were better than one and that four subs were better than two. And the room placement was quite symmetrical in each case. From the Conclusions:
Four subwoofers are enough to get the best results of any configuration
tried. Two subwoofers is very nearly as good and has very good low frequency support as well. Click on White Papers and then Subwoofers: Optimum Number and Locations.


Lhf63, that same paper addresses the issue of "stereo" subs.
In this investigation, bass management is assumed, i.e.
there is one and only one audio low frequency channel,
which is sent to all subwoofers. There are many
advantages to bass management and only questionable
advantages to using multiple bass channels (“stereo” bass
etc.). There is much debate on this subject. Much of it has
to do with the implementation of the bass management –
headroom, mixing of LFE etc. This is another subject
entirely, and is not considered here.

Some have argued that there is a subtle envelopment which
can occur at low frequencies when out of phase material is
reproduced on the left and right side of the listener [9]. This has not been shown conclusively, and in any case is likely outweighed by the more immediate advantages of bass
Srwooten, if by directional you mean can be localized, that's probably not true. The THX standard of 80Hz is low enough to not be localized. From the same paper:
Some will also argue that bass below 80 Hz IS localizable.
This is often the result of:
Port noise in ported subwoofers which are poorly designed
and/or overdriven;
Non-linear distortion in subwoofers which are poorly
designed and/or overdriven;
Visual cues or knowledge of the subwoofer location, which
in the absence of actual audible cues cause localization.

Obviously, if the level of the sub is set too high relative to the other speakers, you'll localize the sub.
1) Audyssey, SVS/Audyssey, Velodyne SMS allow parametric EQ below the x-over frequency. The benefit in seamless integration and smooth deep bass (i.e. "fixing your room")is amazing. If your pre/pre-pro/receiver doesn't have this feature, I'd budget $450 (Velo SMS) to $800 (SVS/Audyssey) to add it.

Anybody got an idea how much practical difference there is between the Velo SMS-1 and the SVS/Audyssey AS-EQ1? The AS-EQ1 is just in the process of being released -- I haven't seen any used available on the 'gon yet. The SMS-1, on the other hand, can be had for under $400 used at present. So, any idea which of the following would be best?

- 2 Hsu VTF-2 + SVS AS-EQ1
- 2 Hsu VTF-3 + SVS SMS-1

They all come in around $2k, though the VTF-3 combo is a little more than the other two, which come out nearly identical.


A-gon'r Kr4 has compared many of the available room correction devices (not sure about the SVS) in his work for Stereophile. You might want to drop him an e-mail.

IME, The Velodyne requires some time/effort. The process of flattening the FR is a lot less logical than you might think - sometimes it feels a bit like a game of whack-a-mole. However, the SMS is very flexible and it will get you there, eventually. Also, you can tailor/tweak response to taste, which may prove useful. The thing works as designed and it's fairly priced. That noted, KR has indicated in previous threads that he prefers Audyssey, as implemented in the Audyssey powered devices to which he's compared the SMS.


PS The SVS requires a x-over ahead of it (so budget accordingly), while the SMS includes a built-in x-over. Alas, if you require low cut for the mains, the built-in x-over in the SMS will subject your main speakers' signal to ADA conversion. I found this audible (I think), but "benign" - it sounded SLIGHTLY different, but not necessarily "worse" than the non ADA signal. Nonetheless, it bothered me in principle, so I added an NHT X-2 ($300) to low cut the mains.

For the money ($450 at, I can tell you that the SMS does a great job - particularly if you're not acutely stricken with audiophilia nervosa, like me.
There's little doubt that Audyssey provides excellent technology, but as it is implemented in AV receivers and pre/pros it is not limited to the bass channel. It's possible (likely) that between 80Hz and 300Hz EQ could be of benefit -- neither the Velodyne nor the SVS product (that I'm aware of) can impact that region.

Also, I was disappointed to see only unbalanced connections on the SVS product.
I know I'm late to the party, but must chime in.
Bass below 80hz or so is not localizable. Unless your room is HUGE.
The advantage of double subs is reduction in standing wave peak/null situations.
Subs located asymetrically will tend to cancel out each others standing waves producing a more uniform in-room response and a larger sweet spot....which is important for HT duties where a crowd may show up.
Budget is around $2k (...) you could get a pair of new subs from Hsu Research...
That is the answer to your query, IMO.
Not perfect but good performance. Start with placement on the same plane as spkrs & take it fm there.
To Bob's point on EQ to 300 hz.
This is obviously room dependent. Every listening room I've had (and measured) has had obvious issues below 150hz. IME, above this point (including the falling treble response I usually get above 10khz), room effects are still present, but much less severe/troublesome. Between 80ish hz and 150ish hz, room treatments (hemholtz resonators or "Bassbusters") have proven very effective in my efforts to "clean up". Below 80ish hz, it's either soffit or EQ, unless your room is large enough to approximate an anechoic chamber.

My bottom line: I can usually live with the "bottom end" room effects between 150hz and 300hz, "resonate" them away between 80ish and 150ish, and EQ them below that. This is just my preferred solution. FWIW.

A-gon'r Kr4 has compared many of the available room correction devices (not sure about the SVS) in his work for Stereophile. You might want to drop him an e-mail.

I did. Unfortunately, he's in the process of reviewing the SVS/Audyssey right now, so he couldn't comment.

I think it's boiling down to this. Two identical subs from either SVS or Hsu, and see how well I can work things manually. The PEQ can be added later in several different ways. Leaving some budget for such future devices, I'm probably looking at a choice between 2 SVS PC12-NSD ($569 each) and 2 Hsu VTF-2 ($549 or $649 each depending on finish). I lean to the cylinder concept for subs, but I know my wife would prefer boxes. Hmmmm...

Thanks again,

I'd strongly recommend you check out the subwoofer test results at Click "forums" and "subwoofer tests". There's lots of info there to help you make an informed decision. I know that the results for many Hsu and SVS subwoofers are included, but you'd have to check for the specific models you're considering.

Thanks, Marty. Will do.

SVS AS-EQ1 review just submitted. Will appear in the September issue.

Get the best sub you can afford now. Get another later if you don't have enough $$ left over ...

I wanted 12" drivers minimum for my sub(s) so I was only able to purchase one - the best 12" sub I could find. It helped a lot, filling in the last octave for a much fuller sound. I started saving again and eventually was able to purchase a second 12" sub. Now the sound is awesome! With two, located sort of kitty-corner from one another, I am able to get an even smoother and deeper response than with one. Now I get within +-3dB to 20Hz. Dual subs (or more) is the way to go, fur sure!
Bob Reynolds,

I refer you to pages 2, 22, and 28 of the Harmon paper re a single sub in a corner location. Of course that may not be ideal for every room and equalization is usually desirable for LF.

I use a Velodyne SMS-1 with an HGS-15 located so the center of the cone is about 18" from the rear and adjacent side wall. Experienced listeners say they cannot identify the sub as a separate sound source. Crossover is 80 Hz.