Xmax

[RomanZ]

How big of a difference does xmax make? is the difference noticeable or just on meter?

[ChevyBoy95]

air displacement doesnt directly mean SPL.

[SavantStrike]

It makes a pretty big difference, but not in SPL.

Think of it this way, when you tune a box, a speaker will travel a certain amount of distance to produce a given frequency at a given power output based upon Thiele Small parameters. You can sometimes run into a situation where you have a speaker reaching Xmax before it has reached rated power at a given frequency. This is especially true of a ported box tuned low - where Xmax increases rapidly below F3.

That can be modeled pretty effectively in software though, so as long as you don't go designing a box that is going to push a driver past Xmax, then if one driver has more Xmax than another, the added Xmax isn't going to do anything for you - they would both travel the exact same distance (assuming that they had otherwise identical T/S paramaters). The paramaters of two drivers are never identical, but they can be pretty similar.

So, no, Xmax makes no difference on the meter, but it can if it means you can drive one speaker harder than another given the same box design. Some manufacturers will also give you another field - xmech, which is larger than xmax, and is the maximum distance a cone can travel without mechanical damage, but it may distort at that level (whereas it should not distort at xmax).

[CleanSierra]

What's Xmax?

[RomanZ]

It makes a pretty big difference, but not in SPL.

Think of it this way, when you tune a box, a speaker will travel a certain amount of distance to produce a given frequency at a given power output based upon Thiele Small parameters. You can sometimes run into a situation where you have a speaker reaching Xmax before it has reached rated power at a given frequency. This is especially true of a ported box tuned low - where Xmax increases rapidly below F3.

That can be modeled pretty effectively in software though, so as long as you don't go designing a box that is going to push a driver past Xmax, then if one driver has more Xmax than another, the added Xmax isn't going to do anything for you - they would both travel the exact same distance (assuming that they had otherwise identical T/S paramaters). The paramaters of two drivers are never identical, but they can be pretty similar.

So, no, Xmax makes no difference on the meter, but it can if it means you can drive one speaker harder than another given the same box design. Some manufacturers will also give you another field - xmech, which is larger than xmax, and is the maximum distance a cone can travel without mechanical damage, but it may distort at that level (whereas it should not distort at xmax).

Ok, sweet! Thanks for the explanation.

[bkolfo4]

Man forums went from Xmax means everything to Xmax means nothing.

Maybe Xmax is not as important if you are burping at 60 Hz, but if you are trying to get loud playing music, Xmax is important, just like the other t/s parameters. If you are trying to play 30 Hz at high SPL levels and cannot maintain BL force, or you are reaching the subs mechanical limits, you will find Xmax is important. . .

[SavantStrike]

Man forums went from Xmax means everything to Xmax means nothing.

Maybe Xmax is not as important if you are burping at 60 Hz, but if you are trying to get loud playing music, Xmax is important, just like the other t/s parameters. If you are trying to play 30 Hz at high SPL levels and cannot maintain BL force, or you are reaching the subs mechanical limits, you will find Xmax is important. . .

That's all down to box design though for the most part until you start putting more and more power on the driver and you just can't do anything but move the same cone with the same surface area farther.

As for burping, xmax is the same mechanical problem whether it's for a fraction of a second or it's sustained - it can mechanically damage a driver to go past excursion. Which is why manufacturers who provide xmech are awesome, because they'll tell you how far past design you can push it without causing damage.

[Krakin]

Are you going out and physically measuring how much excursion you are getting to even care about xmech?

[SavantStrike]

Are you going out and physically measuring how much excursion you are getting to even care about xmech?

Heck no. I'm just obsessive compulsive and like to know how conservatively rated the Xmax is. It helps when modeling a box in software - if it's conservative then you know you can take the full xmax and possibly even a little more and not run into trouble, but if it's relatively close to the ragged edge then you know that designing for a little less than xmax might be advantageous.

But I've gotten plenty of drivers before that didn't have a listed xmech. It's just one of those things where you always wonder and you want to know it.

[Joe X]

Are you going out and physically measuring how much excursion you are getting to even care about xmech?

Heck no. I'm just obsessive compulsive and like to know how conservatively rated the Xmax is. It helps when modeling a box in software - if it's conservative then you know you can take the full xmax and possibly even a little more and not run into trouble, but if it's relatively close to the ragged edge then you know that designing for a little less than xmax might be advantageous.

But I've gotten plenty of drivers before that didn't have a listed xmech. It's just one of those things where you always wonder and you want to know it.

Xmax looks good on specs sheets so don't expect too conservative numbers, to me 70% of BL method which is commonly used is not very linear, in a SQL setup at least I wouldn't want to go that far at all.