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[Sam Costa]

Recently picked up a pair of SB600e (2x15" sub cab) and all my life I've always used 18" sub cabs, but I gotta say I was really impressed with these cabs.
I guess my question is, since these cabs have a freq response of 39Hz to 200Hz which is  what my dual 18" cabs are running, could it hurt anything by running these along side those dual 18" cabs?

Thabks.

[Tim McCulloch]

Recently picked up a pair of SB600e (2x15" sub cab) and all my life I've always used 18" sub cabs, but I gotta say I was really impressed with these cabs.
I guess my question is, since these cabs have a freq response of 39Hz to 200Hz which is  what my dual 18" cabs are running, could it hurt anything by running these along side those dual 18" cabs?

Thabks.

You won't damage anything but whether or not you will get more SPL across the subwoofer pass band can't be determined on line so the answer is "it depends."

How many/what brand & model are you using now?

[Chris Grimshaw]

Recently picked up a pair of SB600e (2x15" sub cab) and all my life I've always used 18" sub cabs, but I gotta say I was really impressed with these cabs.
I guess my question is, since these cabs have a freq response of 39Hz to 200Hz which is  what my dual 18" cabs are running, could it hurt anything by running these along side those dual 18" cabs?

Thabks.

Mixing and matching between subs is difficult. If the cabinets operate on similar principles and are tuned to the same frequency, then you should be able to get them to align, as the phase curves (once EQ'd to have the same frequency response) will be similar.
So, matching two bass reflex cabinets with the same cutoff should be okay. Matching a front-loaded horn to a bass reflex would be much more involved - reflex cabinets have a phase inversion where the port becomes active, while horns have a fixed path length and a sealed back chamber.

Either way, you're going to need a measurement setup if you want to do anything more than "try it and see".

Chris

[Sam Costa]

You won't damage anything but whether or not you will get more SPL across the subwoofer pass band can't be determined on line so the answer is "it depends."

How many/what brand & model are you using now?

Hi Tim. I've been using the TRX 218 cabs (Carvin), I know not a lot of people are fans of  them but they have been solid performers for me for many years. Floor stack one on top of the other, two cabs per side on most shows.

[Ivan Beaver]

I guess my question is, since these cabs have a freq response of 39Hz to 200Hz which is  what my dual 18" cabs are running, could it hurt anything by running these along side those dual 18" cabs?

Thabks.

Maybe.

The freq response "numbers" are not really all that important.

What is important is the phase relationship between the different cabinets.

The BEST way is to measure it (even a free RTA can help a little here).

At some freq you may get addition, but at other freq you may get cancellation.  It all depends on the phase.

The best way is to match levels between cabinets (this is for the test to see how well they play together-NOT for a show).

Put them side by side and unplug THE INPUT TO THE AMP of one of the cabinets-DO NOT simply disconnect the speaker cable.  That will throw your measurements off.

Note the freq response.  Now turn on the other cabinet and see if you get additional where you want it-or not.

If everything is "perfect", it should be 6dB louder across the operating range of the cabinets.  If it is not perfect, then it will be less and you may have some holes in the response.

It only takes a couple of minutes and will give you an answer, and you will probably learn some things in the process.

[Mark Wilkinson]

Maybe.

The freq response "numbers" are not really all that important.

What is important is the phase relationship between the different cabinets.

The BEST way is to measure it (even a free RTA can help a little here).

At some freq you may get addition, but at other freq you may get cancellation.  It all depends on the phase.

The best way is to match levels between cabinets (this is for the test to see how well they play together-NOT for a show).

Put them side by side and unplug THE INPUT TO THE AMP of one of the cabinets-DO NOT simply disconnect the speaker cable.  That will throw your measurements off.

Note the freq response.  Now turn on the other cabinet and see if you get additional where you want it-or not.

If everything is "perfect", it should be 6dB louder across the operating range of the cabinets.  If it is not perfect, then it will be less and you may have some holes in the response.

It only takes a couple of minutes and will give you an answer, and you will probably learn some things in the process.

Yes sir, ..you give a very easy to do exercise, that is quite revealing.
Been doing this a bit with horn loaded, bass reflex, and sealed subs.

When using the exact same high pass and low pass filters on ALL the subs, freq/type/slope all the same, I've found them to play remarkably well together.  Surprisingly so, given conventional wisdom. 
I'm kinda wondering if the difficulty in matching subs is maybe due more to phase mismatches from using different filters, than from the phase mismatches of the raw box's responses.  Just guessing from my experiences......

But I haven't compared any bandpass boxes with their higher order, or tapped horns ..
And I've only compared using 100Hz lowpass...I have to believe phase matching gets more difficult up past that...

[Ivan Beaver]

Yes sir, ..you give a very easy to do exercise, that is quite revealing.
Been doing this a bit with horn loaded, bass reflex, and sealed subs.

When using the exact same high pass and low pass filters on ALL the subs, freq/type/slope all the same, I've found them to play remarkably well together.  Surprisingly so, given conventional wisdom. 
I'm kinda wondering if the difficulty in matching subs is maybe due more to phase mismatches from using different filters, than from the phase mismatches of the raw box's responses.  Just guessing from my experiences......

But I haven't compared any bandpass boxes with their higher order, or tapped horns ..
And I've only compared using 100Hz lowpass...I have to believe phase matching gets more difficult up past that...

It is a combination of everything.  The individual box response, along with the phase/amplitude response of the xover filter and eq applied.

As with most things, you must look at the entire system to get a true idea what is going on, not just a single component.

[Sam Costa]

It is a combination of everything.  The individual box response, along with the phase/amplitude response of the xover filter and eq applied.

As with most things, you must look at the entire system to get a true idea what is going on, not just a single component.

Well, I'm finally going to get a chance to pull everything out of the garage this weekend and fire everything up, neighbors are in for some fun!

I will perform the tests mentioned above and see what I hear.
Keep you all posted.

[Gordon Brinton]

...Put them side by side and unplug THE INPUT TO THE AMP of one of the cabinets-DO NOT simply disconnect the speaker cable.  That will throw your measurements off...

I assume this is due to the impedance load changing on the source, (mixer)? Does the power amp present some load to the mixer even if the speaker is unplugged?

[Chris Grimshaw]

I assume this is due to the impedance load changing on the source, (mixer)? Does the power amp present some load to the mixer even if the speaker is unplugged?

Nothing to do with the mixer.

A muted amplifier acts as a dead short across the terminals, which means the cones will experience a lot of damping when external pressure acts on them. It's to stop nearby cabinets "absorbing" some of the output from the active cabinet.

Chris

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