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[BenWalker]

Hi all,

Hopefully quick and easy question. I know mixing subs is generally not a great idea. How do folks feel about mixing the same type and brand / line of subs, with different driver sizes? I have a pair of Yamaha DXS18 and would really like a second pair, but have a line on a pair of DXS15. So, I would appreciate your thoughts on mixing DXS18 and DXS15 - fine idea, terrible idea, or something in between?

Thanks very much, as always.
Ben

[Chris Grimshaw]

Bad idea. They still have different tuning frequencies, and therefore different frequency/phase responses. Getting them to work together over their entire bandwidths would be a difficult undertaking.

What you could do is send different instruments to different subs. ie, kick to the 18"s and bass guitar to the 15"s. That'd work okay, since they're producing entirely different signals, but it does eat up a couple of Aux sends at the desk.

Chris

[BenWalker]

Bad idea. They still have different tuning frequencies, and therefore different frequency/phase responses. Getting them to work together over their entire bandwidths would be a difficult undertaking.

What you could do is send different instruments to different subs. ie, kick to the 18"s and bass guitar to the 15"s. That'd work okay, since they're producing entirely different signals, but it does eat up a couple of Aux sends at the desk.

Chris

Thanks, Chris. I had a feeling... I appreciate it.

[Tim McCulloch]

If you have access to the unmatched size but in the same model line subs, TRY IT AND SEE.

It may make things worse, it may add some SPL, it may appear to do nothing.

The usual caveats about mixing subs tends to regard topology - band pass, bass reflex, horns - or between brands & model lines.  If you're using JBL SRX of the same vintage mixing 15" with 18" may be less of a problem than Chris assumes.

[BenWalker]

If you have access to the unmatched size but in the same model line subs, TRY IT AND SEE.

It may make things worse, it may add some SPL, it may appear to do nothing.

The usual caveats about mixing subs tends to regard topology - band pass, bass reflex, horns - or between brands & model lines.  If you're using JBL SRX of the same vintage mixing 15" with 18" may be less of a problem than Chris assumes.

Thanks, Tim.

[Ivan Beaver]

If you have access to the unmatched size but in the same model line subs, TRY IT AND SEE.

It may make things worse, it may add some SPL, it may appear to do nothing.

The usual caveats about mixing subs tends to regard topology - band pass, bass reflex, horns - or between brands & model lines.  If you're using JBL SRX of the same vintage mixing 15" with 18" may be less of a problem than Chris assumes.

The BEST way is to simply hook them up and try.  But be sure to listen in more than one location to be sure.

I have mixed completely different styles of sub designs pretty easy.  Some times you get lucky and just need to add a little delay to one or the other.

Other times you get a good bit of cancellations at some freq, and addition at others.

That is the reason is FAR better to measure, so that you take the subjective out of the equation.

A flat phase tuning is what I go for.

[Ivan Beaver]

Bad idea. They still have different tuning frequencies, and therefore different frequency/phase responses. Getting them to work together over their entire bandwidths would be a difficult undertaking.



Chris

Just to expand on this a little.

The reason that different tuning freq is an issue, is that with a ported sub, the freq from the port is 180* out of polarity with the freq from the front part of the driver.

So if you have 2 different tuning freq, the freq range above where the ports are working will be fine.

But if at a lower freq, 1 cabinet is producing the sound mainly from the front of the driver and the other is producing the sound mostly from the port, they will cancel each other at those freq, due to the different phase response.

So some music will sound fine, and other music not so fine.

Also if you try to use different high pass filter freq, the phase shift associated with the different freq can be another issue.

Without being able to measure, all bets are off as to how well they will be able to work together.

But you might get lucky.

[Stephen Kirby]

Note that these are bandpass boxes so what Chris is referring to is that neither of the ports will be doing the same thing at the same frequency on both boxes.

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