2 different subs?

I have read on a few different audio websites that running two different subs is a bad idea? is there any truth to this? any info would be great thanks

Two different sizes or two different brands?

two different subs like a wetsounds 10" and xxx 12" off of two different amps

i've been running and MTX and a kicker comp both 10s with diff amps for a while. the only problem i have i hearing anything.

what?

Murph,

We just had a dealer do an Epic with a XS-XXX under the dash and a XS-10 in the factory location because there was already a hole. The XXX is so powerful that the 10 was gained down and is there just for fill and crossoved over higher to hit some more upper bass and lower mid bass. If the hole wasn't there, dealer would have just done the XXX. But the boat pounds!

Many have used different sized woofers in boats. The main issue is phase cancellation. Which is why most do not do it. If you have them in different locations in the boat, for instance under the dash and another in a locker, down firing or something, it becomes less of an issue. And you can also face the woofer a different direction or reverse the phase of one etc...

Tim
Wet Sounds

What does "phase cancellation" mean Tim? In Lehman's terms.

That is a tough one in lehmans terms. Phase cancellation occurs when two waveforms of the same frequency are out of phase with each other and can cancel each other out. Each woofer has it's own waveform. If you have two different sized woofers or the same size woofer in different locations. The waveform can be different lengths. And result in some phase cancellation. The best way to tell is of course with meters etc…But if you have a good ear and have one sub playing and connect the other sub and the perceived output lowers, then you have some cancellation issues. You can then try to flip the phase on one of the woofers and re test. Or change locations or directions etc…

Tim
Wet Sounds

take tim's comment and consider it more like rollers...they can wash out or interfere with each other

the same subs would create the same outputs...different subs may clash or just not sound very good.

thanks for the info! tim I think I will just replace my sub when the time comes and do an upgrade on the amp

Probably more problematic than the inequity of distance and arrival time for multiple subwoofer locations are the conflicts caused by different loading methods.

An acoustic circuit has all the elements of an electrical circuit. Mass and compliance equate to inductance and capacitance. Changes in subwoofer loading result in non-linear changes in the phase response.

Typically when you're seeking secondary locations you're having to load the individual subwoofers in an asymmetrical manner. And usually the secondary locations are a compromise and less effective than the primary location.

How a woofer loads, ie: sealed, ported, bandpass, direct-radiating, down-firing, vented from within an enclosed locker, helm console or bench seat, creates different phase characteristics. For example, a subwoofer mounted in a port locker, even though it's vented, has energy that is stored and released differently than a direct-radiating subwoofer. The phase response varies across the spectrum. The two different loading methods don't combine well. The sum doeasn't equal the parts the same as symmetrically mounted and loaded subwoofers.

Reflective boundaries, reinforcing planes, locker displacements and more have an impact on the amplitude response which has an effect on the phase response. The two are inseparable.

Also, its better to have a little excess power for your woofer. Having more woofers or woofer mass than your amplifier can fully control is counterproductive. It's better to have fewer woofers and maintain the right power to mass ratio than it is to dilute your power into multiple woofers that may be in some degree of conflict.

For those who have added additional subs in different locations and were a little disappointed with the results, hopefully this gives some explanation as to why.

With enough subs and power you can have enough leverage to overcome just about anything. It may sound a little muddy and may not be the most effective way to proceed.

Multiple subs mounted in the same location and mounted symmetrically relating to their boundaries, combine very will with no downside.

So I would recommend a single sub, the best you can afford, with lots of power, in the most optimum location.

Yep, in phase = double up out of phase = powerturn rollers messing your water