bigger box less power!?

[audioholic 5,000+ posts]

My personal experiences, plus look at the DB numbers section in competition section... Almost 90% of those with high scores have huge boxes for the subs they are using. I personally like to go 1-1.5 cubes more than what the manufacture recommends, im not saying use a 9 cubes for a 10" woofer though

Again, its frequency dependant. A larger and larger box will increase low end output, but on average (across the whole spectrum the sub plays) output will actually be down. Squeak just talked about this the other day and showed some frequency response graphs that showed this phenomenon, unfortunately the search function on this board is broken for me anymore and I cannot find it to link to.

 

[SPL140.2 5,000+ posts]

Again, its frequency dependant. A larger and larger box will increase low end output, but on average (across the whole spectrum the sub plays) output will actually be down. Squeak just talked about this the other day and showed some frequency response graphs that showed this phenomenon, unfortunately the search function on this board is broken for me anymore and I cannot find it to link to.

Is this phenomenon due to impendence fall of the enclosure??? Just wondering if these tests were used on sealed and ported enclosures??

 

[audioholic 5,000+ posts]

Sealed iirc. Impedance rise will be greater in the larger box.

 

[Crown_amps]

hey i have a stroker 15 in a six cube box although the manufactur suggests 3 cube for it. now i only have a kicker 1200.1 on it even though my sub is rated for 2000 watts rms.so i am employing the bigger box lower power rule by making my box twice an big now my sub is smoked. its no big deal cuz a new cone for it is only 40 bucks since they are field replacable. to avoid blowing it up again can some one explain the sience of bigger box less power to me??for those who dont understand this concept it is used in competions to get the same spl from a sub in a bigger box with less power as if it was in a regular box with max power.

why don't you just make the box to the spec's to the model you are running?

Then you can power it to the full rms rating //content.invisioncic.com/y282845/emoticons/cool.gif.3bcaf8f141236c00f8044d07150e34f7.gif

 

[Crown_amps]

Sealed iirc. Impedance rise will be greater in the larger box.

so a larger box has more resistance? why ? has to move more sound i guess?

 

[PhatTonyDeMarco 5,000+ posts]

why don't you just make the box to the spec's to the model you are running?Then you can power it to the full rms rating //content.invisioncic.com/y282845/emoticons/cool.gif.3bcaf8f141236c00f8044d07150e34f7.gif

If you would have read the thread, you would see that he does not have an amp to put out 2000w at 1ohm. He should change the box though....

 

[audioholic 5,000+ posts]

so a larger box has more resistance? why ? has to move more sound i guess?

Impedance rise is what occurs as the speaker cone moves away from its home position. The further the cone is allowed to move, the more drastic a change in it's impedance. A larger box shows less restriction on cone movement, therefore the cone moves more, and this 'impedance rise' increases.

 

[SPL140.2 5,000+ posts]

Sealed iirc. Impedance rise will be greater in the larger box.

What about ported, since thats the #1 choice for spl enclosures???

 

[Mackenzie 10+ year member]

He should just get a bigger amp, and run the sub in its correct box.

 

[Raven 10+ year member]

What about ported, since thats the #1 choice for spl enclosures???

Well it's common for SPL enclosures to be absolutely huge, but ported is only the #1 choice for SPL because horns, bandpass, and transmission lines are too complicated.

 

[audioholic 5,000+ posts]

Not because they are more complicated, because they are larger. Some SPL rigs acheive comlexity well beyond what it takes to build those non-regular enclosure types. But at some point making the box type different/bigger has less gain than simply adding more cone area and dedicating the extra enclosure space to that (bigger speaker or more speakers).

Impedance rise is more complicated in vented systems, as impedance rise is depedanct on cone motion, which in vented systems is very dependant on frequency. But generally speaking a larger box will allow more.

Professional SPL competitors know exactly what impedance their driver(s) are at when burping at the appropriate frequency. They also factor their amplification power at this impedance for obvious reasons. Might as well, not like the system will ever play any other note. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[SPL140.2 5,000+ posts]

Not because they are more complicated, because they are larger. Some SPL rigs acheive comlexity well beyond what it takes to build those non-regular enclosure types. But at some point making the box type different/bigger has less gain than simply adding more cone area and dedicating the extra enclosure space to that (bigger speaker or more speakers)

I agree to a point, but there are rules and classes which people cannot do that, depending upon the sanctioned body.

Impedance rise is more complicated in vented systems, as impedance rise is depedanct on cone motion, which in vented systems is very dependant on frequency. But generally speaking a larger box will allow more.

larger enclosure size will do that //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

Professional SPL competitors know exactly what impedance their driver(s) are at when burping at the appropriate frequency. They also factor their amplification power at this impedance for obvious reasons. Might as well, not like the system will ever play any other note. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

I agree 100%, I burp at 53hz impedance is 1.8ohms/amp 2500wrms at 13.8volts@1ohm=rms at 11.8 volts@1.8ohms, you guys do the math. On the other hand at 47hz the impedance falls to .8ohms. Im still trying to figure out how to match the impedance fall to my peak note of 53hz in my enclosure/res. frequency of my car which is also 53hz, Anyone know how to do this??? Great info keep it coming... Audioholic help me match those //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[SPL140.2 5,000+ posts]

Well it's common for SPL enclosures to be absolutely huge, but ported is only the #1 choice for SPL because horns, bandpass, and transmission lines are too complicated.

Thats why I said its the #1 choice //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[audioholic 5,000+ posts]

I agree to a point, but there are rules and classes which people cannot do that, depending upon the sanctioned body.
larger enclosure size will do that //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

I agree 100%, I burp at 53hz impedance is 1.8ohms/amp 2500wrms at 13.8volts@1ohm=rms at 11.8 volts@1.8ohms, you guys do the math. On the other hand at 47hz the impedance falls to .8ohms. Im still trying to figure out how to match the impedance fall to my peak note of 53hz in my enclosure/res. frequency of my car which is also 53hz, Anyone know how to do this???

Great info keep it coming... Audioholic help me match those //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

Honestly Im not sure Im following your question. You already know your burping freq (53hz) and you know your actual impedance at this frequency (1.8ohms), so you simply want an amp that will output the powere you require @ 1.8ohms. But you already have your amp so that's really relevant (although gain adjusting can be tweaked as well). I think most people would check a cone excursion plotting prigram to determine the power they will need (at that freq) to acheive the displacement they want. Sounds like you are already heading down the right path. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
My comments about enclosure size and cone area were generic. I was not speaking regarding any one sanctioning body's rules.

 

[SPL140.2 5,000+ posts]

Is there a way to match my impedance drop to my enclosure peak?? Impedance drops at 47hz and my enclosure peaks at 53hz. Id like to find one of those accumatch gadgets but I dont see them around anymore, plus there only rated for 1000wrms