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peak level db ?


brian222

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in reference to ported/vented enclosures -- I was playing around with a box calculator that would allow me to change the volume of the box and in turn changing the fc and f3 but when doing so I noticed the "peak db level" went higher not matter if I went bigger or smaller than the ideal size that the calculator gave. Way small gave me higher db and goin big eventually starting goin into the negative once db passed .999 db. so I was just wondering is this basically the same as gain when it comes to a fourth-order boxes and if so would it be wise to stay below +3db

is there any correlation between qtc and peak level db like in sealed enclosures - as in lower peak db meaning more of a flat .707 curve bigger box lower qtc small hox higher qtc thus higher peak db ....

Lemme kno if im on the right track or way off...tried google no help for the most part lol so dont let me down guys.

Ex.scenario

.56qts

144l

26hz =

409l vb peak db lvl .09 fc 18 f3 15

But 200l vb peak lvl 2.27. Fc 23 f3 22

And 570l vb peak lvl .91 fc 16 f3 13

So will going bigger as in Too big eventually end up lower your output level? Also would decreasing vb increase spl a tad but diminish the sq ??

Thanks for any input!

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I have no idea what your software is telling you about "peak dB". Generally Qts between .7 and 1.0 is what people shoot for with sealed alignment. Most box calculators should give you a rather accurate response plot/graph.

Don't expect any huge "gains" in sealed enclosure from fiddling with box volume.

As you say, though, going bigger will increase low extension (so more output down low), but possibly lower elsewhere in the bandwidth you're after, and too small often gives you a little more output around Fs, but at the expense of some low extension. That being said, once you start going smaller and smaller, overall efficiency will suffer, so it'll be more a matter of relative response than for example a 1 cube box will be louder at it's peak frequency than a 4 cube box.

I think you're over-thinking this. If you have a sub that's designed for sealed alignment, use the manufacturer recommended size or a little larger, sealed alignment is pretty forgiving.

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Oh theres no doubt im over thinking it lol but I was just wanting to know if anyone could tell me because I had never seen that on other sites and being that the subwoofer has no recommended enclosure specifications online [Have not bought yet] and besides that's another thing most calculators that I put in the TS parameters it usually is not what the manufacturer's recommended box sizes are anyway for ex. The skar zvx v2 15 1500rms calls for 2-2.5 @34hz but two dif calcs give me like over 8cf which I believe bcuz qts is high but anyways heres the one site so u can see the peak db readout im talking about

http://www.mh-audio.nl/reflexboxcalculator.asp

The other site I use is carstereo.com

I kno I should be using alot better software but im on my phone most times just playing around but I guess like I was saying I just wanted to know what that term meant exactly but for the most part I'll focus more on the qtc thanks

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Oh theres no doubt im over thinking it lol but I was just wanting to know if anyone could tell me because I had never seen that on other sites and being that the subwoofer has no recommended enclosure specifications online [Have not bought yet] and besides that's another thing most calculators that I put in the TS parameters it usually is not what the manufacturer's recommended box sizes are anyway for ex. The skar zvx v2 15 1500rms calls for 2-2.5 @34hz but two dif calcs give me like over 8cf which I believe bcuz qts is high but anyways heres the one site so u can see the peak db readout im talking about

http://www.mh-audio.nl/reflexboxcalculator.asp

The other site I use is carstereo.com

I kno I should be using alot better software but im on my phone most times just playing around but I guess like I was saying I just wanted to know what that term meant exactly but for the most part I'll focus more on the qtc thanks

Most manufacturers recommend bare minimum or sub-optimum box sizes because 95%+ of the market just want's to prove how big their dick is by having as much cone area as possible. In other words, the brand that claims their 15" is good in 3 cube will sell more 15's than the brand that claims theirs needs 5 cube.

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