Xmax, Qts, Qes, Qms? Whats all this mean?

[B_Rad_NC 10+ year member]

Ive looked at the higher end subs and they dont seem THAT much different then the less expensive stuff out now. And ive also noticed some of the less expensive subs have a better frequency response as well. Thinking for the next build ill go with 4 cadence wild beast 15"s, or either 2 CV stroker pro. Was looking at lanzars too but im not sure so much about those. Im thinking the subs wont be that much diff overall as far as loudness as long as i got everything tuned right in a good box, since all of them are close to the same amount of power handling. Or does anyone have any input on my last statement?

 

[JimJ 5,000+ posts]

Ive looked at the higher end subs and they dont seem THAT much different then the less expensive stuff out now.

Specs are important, to a point. There's still no substitute for actually hearing the thing in person.

And ive also noticed some of the less expensive subs have a better frequency response as well.

FR is a useless spec for a sub - it's totally box dependent.

 

[Beginer 10+ year member]

Ok, so maybe someone can tell what parameters are important for SPL subs? And what they should be.

For example Atomic APXX 12" have very little XMAX, ~12-14mm, while my Type R 12" XMAX is 18mm. So why lower XMAX is better for SPL subs?

Also let's say I burp at 60-65Hz, so what sub is better with higher Fs or with lower Fs?

PS. I think everyone agree that APXX is SPL sub //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[T3mpest 10+ year member]

Ok, so maybe someone can tell what parameters are important for SPL subs? And what they should be.For example Atomic APXX 12" have very little XMAX, ~12-14mm, while my Type R 12" XMAX is 18mm. So why lower XMAX is better for SPL subs?

Also let's say I burp at 60-65Hz, so what sub is better with higher Fs or with lower Fs?

PS. I think everyone agree that APXX is SPL sub //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Wow, old thread, but I'll answer anyway. Xmax is lower for SPl subs in general because Xmax measures linear excursion. That's essentially how far a sub can move while still accuractly reproducing the signal sent to it (sq). (it's also where bl drops below 70% of resting value)

A SPl sub doesn't worry about clean excursion. It might only have an xmax of 4mm, past that all the excursion is non-linear. However, since all we are doing is trying to move air, we don't care if it accurate or not. You'll be more concerned about a stat like xmech or xsus. Those stats will tell you how far the sub can move period, regardless of whether the excursion is linear. A SPLsub might only have 12mm of clean excursion, but can move 60mm if you take into account it's non-linear travel.

Secondly a SPL sub is usually used in ported boxes. When you play a note near the tuning frequency of a ported box, excursion is minimized. The port will be making most of the noise. Usually when you play notes near tuning it would take stupid amounts of powe for sub to run out of excursion, especially if its' mechanical limits (xsus, not xmax) are like 60mm. You could need as much as 60,000 watts to make it move that far. That's why subs that are SPL oriented have high power handling ratings, they arent' going to move very much near tuning unless they can handle ALOT of power.

 

[Beginer 10+ year member]

Wow, old thread, but I'll answer anyway. Xmax is lower for SPl subs in general because Xmax measures linear excursion. That's essentially how far a sub can move while still accuractly reproducing the signal sent to it (sq). (it's also where bl drops below 70% of resting value)
A SPl sub doesn't worry about clean excursion. It might only have an xmax of 4mm, past that all the excursion is non-linear. However, since all we are doing is trying to move air, we don't care if it accurate or not. You'll be more concerned about a stat like xmech or xsus. Those stats will tell you how far the sub can move period, regardless of whether the excursion is linear. A SPLsub might only have 12mm of clean excursion, but can move 60mm if you take into account it's non-linear travel.

Secondly a SPL sub is usually used in ported boxes. When you play a note near the tuning frequency of a ported box, excursion is minimized. The port will be making most of the noise. Usually when you play notes near tuning it would take stupid amounts of powe for sub to run out of excursion, especially if its' mechanical limits (xsus, not xmax) are like 60mm. You could need as much as 60,000 watts to make it move that far. That's why subs that are SPL oriented have high power handling ratings, they arent' going to move very much near tuning unless they can handle ALOT of power.

Thanks a lot for answer.

And what about Fs? Does it important for SPL sub? Because as I know it's not good when sub plays lower than it's Fs. And usually you don't want to play low frequencies in dB Drag. For example I burp at 60-65Hz. So what sub better, with let's say Fs=28Hz or with Fs=40Hz? Or it doesn't important?

Thanks.