Thoughts on having 2 different sized subs in same room

We are currently in the process of redoing our living room and "Managment", or should I say my, wife does not want any funiture in the design that will provide a place for my equipment. Luckily I still have my main system in my man cave / media room and now since I have an extra sub was considering incorporating into my main system.

Main system breakdown:

Bob Carver Crimson 275 Tube Amp

(80w x2 @ 8 ohms)

Parasound ZPre3 Pre-Amp

U-Turn Orbit TT w/ Ortofon Super OM20 

Ifi Zen Phono Pre Amp

Warfedale EVO 4.3 Speakers

SVS SB12-NSD subwoofer 

Potential Sub to add:

Audio Source SW15" 200 w Sub

Any thoughts?

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It may take a bit to set up the crossover,and volume match. Other than that,why not. More subs is more gooder. 

I think it's a good idea but put the best sub on the right hand side as that is where the most bass comes from a symphony orchestra.

it is best to go pre-out to self-powered subs, then line level (less low bass) back to the preamp to amp. thus neither the amp or main speakers try to make low bass. that will help you with the carver 275 driving your 88 sensitivity mains which I imagine already sound real good. If you ever want to try a lower powered amp, you would be ready.

your existing preamp lacks pre-out, main in, so other changes ... perhaps think long range.

for home theater, small office, I use only 1 sub, my main music system has 15" woofers which you could think of as a stereo pair of subs. bass can definitely be directional

music system: I reccomend self-powered, front facing, no ports, stereo pair of matching subs. Subs located adjacent to the mains. It is both the fundamentals and the overtones of bass notes that give directionality.

you could use a Y splitter to go to two self-powered subs.


The Parasound ZPre3 has bass management with Sub Pre Outs 

not ideal, but workable, might need a good bit of effort to integrate well

I'd sure add it and try to keep the crossover very low on both to avoid localization. I think 80Hz is for the birds...and tiny little main speakers. Yours are not tiny. Good luck; I think it can be integrated.

IME, using two different subwoofer as stereo pair is not ideal and very hard to integrate well.

My suggestion is connect the SVS SB12-NSD to ZPre3 preamp and position the sub on the front.

Use the high level (speaker level) connect the Audio Source SW15 to the Crimson 275 output (so you can use small gauge speaker wires and don't need long interconnect cables) and move the sub for best bass response in the room, it could be in a corner, front wall, side wall or rear wall. 

I would think different sub sizes would be perferred as the sweet spot of each would allow you to support a wider frequency range

When it comes to subs, low frequencies make so many large bass modes and cancellation areas that more than anything else it pays to simply have a lot of them. Because more subs in more different locations adds up to more small modes spread around more and this winds up sounding a lot smoother, faster, and more articulate. Regardless of what subs are used.

Take a look at mine.

 Five subs of 3 different kinds. One powered, two ported, two sealed. Each on a different wall and/or different distance from corners. This way each one has a different set of modes and they all add up to incredibly smooth powerful deep bass. 

As long as you keep the crossover below 80 and avoid symmetry (do NOT follow advice on timing, stereo, etc!) then all you have to do to get superb bass is adjust levels. Integration is a canard. When the subs are crossed over low and distributed asymmetrically and levels are right they will blend seamlessly. Regardless of what type of sub they are.

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Different resonance frequency = good. Might take some effort to get it to sound really smooth, but don't give up.

I have tried several combinations of different subs, currently using 2 x Definitive Technology SC 4000's.  By far the best control and sound yet. 

Why that subwoofer?  Why not one of the new SVS subwoofers that allow of DSP control throught their phone app?

Yes you can use two different brands. It's all about proper placement of the subs then a little fooling with separate volumes and crossovers.Hook them up with speaker wire or using the preamp,whichever sounds best to you.They don't need expensive cabling IME to sound great either.

Different IS better. You're gonna do it anyway so chop chop.

Through a strange chain of events I ended up with 3 different SVS subs at the same time... SB3000, SB4000 and a PC2000 Pro. Through much experimentation with many other subs and the SVS trio, my preference was the 3 subs of like build characteristics but different drivers. In my situation more did seem better no matter what combination I tried, but the SVS triad integrated very well together using their phone app..

Possibly of interest. As I read this, he not only inveighs against *one* subwoofer but also against the idea that one should be satisfied with a monoaural effect from subwoofers.

From Jim Smith’s “Get Better Sound”

“One of the greatest disappointments for me has come from listening to stereo systems that incorporated subwoofers at shows and in home installations. I suppose it’s the complexity of getting so many variables correctly adjusted. This section is aimed at assisting you in improving this area if your system employs subwoofers.

Tip #31: Don’t believe the "experts" when they tell you that you only need one subwoofer

Low bass may be nondirectional, but the experts are dead wrong when they say you only need one good subwoofer. Unfortunately, while this "nondirectional" theory is based on some fact, the end result is far from correct. Especially for the playback of acoustic recordings.

No matter how great a single sub may be, a single sub kills acoustically recorded music. Over the years, we’ve proved this fact to many skeptics by playing acoustic recordings that contained no apparent bass at all! I guess I should say that multitrack studio recordings can also have some of the same qualities of an acoustic recording, but not always to the same degree. Here’s the reason why: Direct and reflected longwavelength, low frequency cues will arrive at each stereo microphone at slightly different times. Therefore, stereo subwoofers play these differing timearrival spatial cues in each channel.

Subwoofers provide the cues for a sense of space that can transform a system from simply sounding good to sounding uncannily real. This is accomplished because our ears decode spatial cues by picking up reflected sounds off of walls and ceilings. The time of arrival tells us how big the space may be.

Low frequencies have long wavelengths (meaning greater travel dis tances) and our brain decodes them as spatial cues. Acoustic recordings carry these low frequency spatial cues that are essential in our ability to suspend disbelief. This is how we hear and accept the illusion presented by recordings with a "we are there" perspective.

A virtual threedimensional image can be created, with each instrument or voice seemingly occupying a palpable space in the stereo sound stage in front of the listener. This is related to the earbrain low frequency, spatial cues.

When the bass is combined into one channel (as with a mono subwoofer), the differing time arrivals from each channel are simply canceled as outofphase information. A portion of the acoustic signature of the space is irretrievably lost. It no longer qualifies as a realistic recording of real instruments in a real space.

As a dramatic test of our theory, we’ve played our master recordings of handbell choirs recorded in a church or cathedral (predominantly high frequencies with some midrange and no apparent bass).

Sophisticated skeptics (an oxymoron?) are dumbfounded when they hear the ambient sound field collapse when we use one monaural woofer instead of a stereo pair. (Of course, the bass level was precisely adjusted to match that of two woofers when one woofer was played).

It’s important to note that the practice of using two subwoofers for home theater does not usually solve the problem for music. Although there are two subwoofers, they are both getting the same monaural signal from the A/V processor, so the stereo soundfield information on your CDs or LPs is still irretrievably lost.

In fact, increasing the mono bass channel to even more output than is required adds nothing to the acoustic signature of the space. As a highend designer, I typically wouldn’t install a single subwoofer in a music system due to its detrimental effect on the illusion.

Additionally, with two subwoofers, each sub has to work much less hard, dramatically reducing speaker cone movements (aka driver excur sions), resulting in lower bass distortion. But the primary advantage is more spatial cues with acoustic recordings (as opposed to studio mixed recordings).

Finally, locating a stereo pair of subs relatively close together is another recipe for less than the best reproduction. You don’t want them behav ing as if it was a stereotomono foldback in the bass, thereby essentially reducing the bass to mono. You’ll lose that wonderful spatial quality that properly placed stereo subs can provide.”