One way xmax or peak to peak for Unibox

[Confusedsoul 10+ year member]

Trying to model 2 Phoenix Gold RSd12d subs but am not sure if I should use the one way xmax of 13.5 or peak to peak in Unibox. Going with the one way xmax, it shows that 2 of them in a 3.6 cu ft box will exceed excursion easily with 700w but people are using 900w on 1 in a 1.8 cu. ft sealed box.

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[helotaxi 5,000+ posts]

The amp may be capable of putting out that amount of power under optimal circumstances, but the in-car environment is far from optimal. Playing music rather than test tones limits the amount of power actually applied to the subs that much more. I wouldn't worry about it too much. if you feel like obsessing, simply use a subsonic filter to limit excursion.

 

[Confusedsoul 10+ year member]

The amp may be capable of putting out that amount of power under optimal circumstances, but the in-car environment is far from optimal. Playing music rather than test tones limits the amount of power actually applied to the subs that much more. I wouldn't worry about it too much. if you feel like obsessing, simply use a subsonic filter to limit excursion.

I wouldn't consider it obsessing when unibox shows your subs extending beyond xmax at almost 40hz and below, and I'm certaintly not going to use a SS filter that high.

 

[GSRswapandslow 10+ year member]

the smaller the box, the more power it'll take to excurte (lol) farther

 

[helotaxi 5,000+ posts]

You won't get that amount of power to the subs. That's what you're obsessing about. According to every box building program I have, and I have a few, my XXX should be long dead with the 1500w going to it because it reaches Xmax with less than 800 below tuning. Same with my Assassin 8s. Neither of the above has ever broken a sweat. Why? Because despite the rating of the amp, that amount of power never gets to the subs when playing music. The next consideration is that Xmax is where the motor runs out of steam. Mast decent subs have more suspension capability than that it's just that the motor is not strong enough past Xmax to continue to drive the cone in a linear fashion and distortion increases. Until you hit Xlim (the smaller of Xsus and Xmech), you aren't doing any damage to the sub and you're obsessing about a non issue.

Also to demonstrate a point about the effect of a subsonic filter, use Unibox to model the effect of a 18dB/oct filter at around 25Hz. That should fix your excursion non-issue.

 

[Stem 10+ year member]

the smaller the box, the more power it'll take to excurte (lol) farther

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[GSRswapandslow 10+ year member]

i meant to have a "?" on that....

i was asking...only becasue i've heard that from people before

 

[Confusedsoul 10+ year member]

You won't get that amount of power to the subs. That's what you're obsessing about. According to every box building program I have, and I have a few, my XXX should be long dead with the 1500w going to it because it reaches Xmax with less than 800 below tuning. Same with my Assassin 8s. Neither of the above has ever broken a sweat. Why? Because despite the rating of the amp, that amount of power never gets to the subs when playing music. The next consideration is that Xmax is where the motor runs out of steam. Mast decent subs have more suspension capability than that it's just that the motor is not strong enough past Xmax to continue to drive the cone in a linear fashion and distortion increases. Until you hit Xlim (the smaller of Xsus and Xmech), you aren't doing any damage to the sub and you're obsessing about a non issue.
Also to demonstrate a point about the effect of a subsonic filter, use Unibox to model the effect of a 18dB/oct filter at around 25Hz. That should fix your excursion non-issue.

I think you should model those subwoofers and you'll see what I mean. Even 300w to to each will let them reach xmax easily.

First is 400w /ea

Second is 300w /ea

I may not put a constant 400w to each, but even 300 ea at the right frequency could make them distort, even if its not a perfect world. I must be doing something wrong me thinks. And I'll be setting the amp for 700-750w constant on a 50hz tone. It'll allow me some headroom as the amps been benched at 800+ at 4 ohms.

 

[bk12321 10+ year member]

lol I dont see why it matters cuz if people are sending 900 to theirs without killing them then yours will surely be fine

 

[Confusedsoul 10+ year member]

lol I dont see why it matters cuz if people are sending 900 to theirs without killing them then yours will surely be fine

Thats just it, I don't see how its possible that they are without blowing them. Its like they gained some extra xmax somehow or something. And I just did some searching, they're feeding 900w to each in 2.0 cu ft box. Still shows them being over powered. I've heard they're good for the money, but they don't have super powers......or do they?

 

[spoonraker 10+ year member]

Are you not paying attention? Your question has been answered numerous times.

All those graphs and numbers show what will happen in theoretical ideal situations. Just because your amp is rated at 900W RMS doesn't mean that your sub will see 900W on music. They aren't reaching xmax because they aren't "actually" giving their subs that much power.

 

[Confusedsoul 10+ year member]

Are you not paying attention? Your question has been answered numerous times.
All those graphs and numbers show what will happen in theoretical ideal situations. Just because your amp is rated at 900W RMS doesn't mean that your sub will see 900W on music. They aren't reaching xmax because they aren't "actually" giving their subs that much power.

So are you saying they're not even giving them 500w with an amp set to 900w? My point is with even 500w in the same box they could reach mech limits. Bah nevermind, too hard to get my point across.

 

[helotaxi 5,000+ posts]

The excursion plot also doesn't account for power compression or the real power applied due to impedance rise.

That's an excursion plot of a pair of Assassin 8s in an enclosure that I built and installed in my car with 800W on the pair. The red line is the Xmax. I ran them without a subsonic filter and was not what I would call easy on them. They never showed any sign of distress even when playing stuff well below tuning. Don't take any excursion plot as gospel.