Benefit of 2 subs vs. 1

[bstran11693 10+ year member]

What are the pros/cons of say two 12s at 400 watts rms each, versus one 12 at 800 watts rms?

I can see a benefit of having one would be saved space obviously. What would some benefits be of having 2?

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[MONSONwarrior Premium Member]

PROS: double the cone area, double the motor force, more coil to dissipate heat better.

CONS: larger box

 

[ahole-ic]

1 sub has a lot of advantages. Phasing issues is what we are battling all the time. Multiple woofers introduce phasing issues no matter what you do. If a single subwoofer works for you, it will usually render the best results.

 

[97maxima 10+ year member]

I

 

[sacsking916 5,000+ posts]

I prefer single over dual. Just makes life easier for me. Plus like ecrack said no out of phase issues.

 

[09civic 5,000+ posts]

single ftw

 

[audioholic 5,000+ posts]

If we are worried that much about phase issues with our subs, why do we use ported enclosures? //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

Yes, acoustically speaking fewer drivers is better, even with subs. But mutiple drivers have their fair share of advantages also. Power compression means the setup with more motors to dissipate the heat will likely display more output potential (all other factors being equal). 800 watts to one sub, or 400 to each of two... the single sub will not double its displacement going from 400 watts to 800. Technically, the two sub setup wont double its displacement when the second sub is added either, but it will come much closer to doing so than will the single sub going from 400 watts to 800.

Single sub setups have a second advantage... they are usually a more cost effective setup for someone on a budget.

In other words, there is no cut and dry winner in this comparison when we are talking in generalities like this. In some situations, a single sub setup is the best choice, and in others the multiple sub choice is best. So, the best choice is number 3... educate yourself on the advantages and disadvantages so that when it comes time to make that decision, you know which option is best for your goals.

 

[bstran11693 10+ year member]

thanks for all the input guys. right now i have 2 12s but i'm thinkin bout upgrading o a real nice 12

 

[keep_hope_alive Premium Member]

Not to mention the sonic benefits of one great sub vs two decent subs. More engineering and time is spent on better subs and you get what you pay for. Spend what you can on one good sub and you'll usually sound better than two cheap subs.

 

[zako 10+ year member]

The pros of dual subwoofers, if both are getting the same signal (e.g. wired together in parallel) is increased efficiency. That is, two subs running off a single 400watt channel will sound louder by about 3dB compared to just one sub running off the same 400watt channel. So to achieve a desirable sound volume, the amp needs to work less. Another benefit is increased SQ. If your goal is to achieve the same loudness level with two subs compared to what you used to get with one, now each of the two subs needs to work less, so less excursion, and hopefully more SQ. Of course, dual setup will also play louder when needed. Of course, there are also disadvantages. Cost, weight, and space.

Having said this, there are plenty of SQ subs that can achieve great SQ and more SPL than what the front stage can keep up with while running off a modest amplifier in a single sub setup. However, I personally still want to fiddle with a dual sub setup just because I can. I am thinking of getting two Dayton HO12 DVC subs for the next build. Space is not an issue as each one can work fine in a 0.7 cu ft chamber and the cost is not that high. Sometimes they're sold as low as $125 each.

 

[zako 10+ year member]

1 sub has a lot of advantages. Phasing issues is what we are battling all the time. Multiple woofers introduce phasing issues no matter what you do. If a single subwoofer works for you, it will usually render the best results.

What phase issues? Even if two identical subs are running off the same amp channel?

 

[audioholic 5,000+ posts]

What phase issues? Even if two identical subs are running off the same amp channel?

Path length differences caused by two sound sources playing the same freq range. But imo this is very minor for subwoofers since subbass is mostly omnidirectional. And also considering most people here completely ignore phase issues when talking about how good their ported setup sounds. The output from your sub, and your port, will always be out of phase from each other.

There is also the positive benefit in multiple sub setups of a coupling effect. Again, this is a pretty complex comparison to make, lots of positives and negatives on each side. There is no easy answer.

edit: after thinking about it, Im not sure the bass being omnidirectional will matter, the waves would still be somewhat out of phase with each other due to the speakers being different distances from your ears. Maybe keep_hope_alive, being an acoustical engineer, could pipe up and answer that. Either way, I think its a fairly minor issue with subwoofers.

 

[keep_hope_alive Premium Member]

Phase issues are HUGE with subwoofers and dominate performance characteristics. Yes, a port is out of phase at some frequencies, but coherent at others, hence the concept of tuning. The increased output is due to coherent coupling of the front and back waves.

Bass can be considered omni-directional when the enclosure is placed in a space. You get loading or directionality effects from adjacent surfaces. You also get reflections. Reflections are the killer and why boxes in trunks perform poorly of not baffled. Simple math can determine the reflected path lengths and resulting phase interference. If a sub is placed 4 feet from a reflecting surface, the additional path length is 8 feet, meaning cancellation for a 16 foot wavelength.

With multiple subs, the cones are usually side-by-side, creating a line array. This is usually ok. Where people run into issues is with complex configurations with larger distance differences. Again, it is all about path lengths.

Another thing to consider is that below a certain frequency, we are simply pressurizing the cabin since the wave never fully develops.

And when comparing one vs two subs, excursion comes into play. Two subs don't have to work as hard to have the same output as one, assuming coherent sources. This reduced excursion allows the voice coil to operate in the magnetic gap, increasing accuracy. But with one nice sub you can get an underhung model which eliminnates this benefit.

So much to consider, a lot is personal preference.

I run two because they are trunk baffle mounted and coherent. I also have fairly low power and efficient subs, and given their age I want to operate them at lower excursion. I could get one nice sub to outperform these.

 

[Phoenix Risen 10+ year member]

i love my single sub setups.

 

[audioholic 5,000+ posts]

Phase issues are HUGE with subwoofers and dominate performance characteristics. Yes, a port is out of phase at some frequencies, but coherent at others, hence the concept of tuning. The increased output is due to coherent coupling of the front and back waves.
Bass can be considered omni-directional when the enclosure is placed in a space. You get loading or directionality effects from adjacent surfaces. You also get reflections. Reflections are the killer and why boxes in trunks perform poorly of not baffled. Simple math can determine the reflected path lengths and resulting phase interference. If a sub is placed 4 feet from a reflecting surface, the additional path length is 8 feet, meaning cancellation for a 16 foot wavelength.

With multiple subs, the cones are usually side-by-side, creating a line array. This is usually ok. Where people run into issues is with complex configurations with larger distance differences. Again, it is all about path lengths.

Another thing to consider is that below a certain frequency, we are simply pressurizing the cabin since the wave never fully develops.

And when comparing one vs two subs, excursion comes into play. Two subs don't have to work as hard to have the same output as one, assuming coherent sources. This reduced excursion allows the voice coil to operate in the magnetic gap, increasing accuracy. But with one nice sub you can get an underhung model which eliminnates this benefit.

So much to consider, a lot is personal preference.

I run two because they are trunk baffle mounted and coherent. I also have fairly low power and efficient subs, and given their age I want to operate them at lower excursion. I could get one nice sub to outperform these.

Thanks for the info, Hope.