Tuning a Sealed Box?

[Goldtaz1 10+ year member]

Guys,

With so many people running 4th order BP boxes these days, I was wondering exactly how to figure out the tuning frequency on sealed boxes? It's certainly not like a ported alignment where volume and port area dictate the tuning. Can someone please help me understand exactly how to figure out the tuning if it's simply a function of volume?

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[statonburrell 10+ year member]

pretty sure it has to do with the airspace, Fs of the subs, vas of the subs, qes, and xmax... but i could be an idiot..

 

[TMali 10+ year member]

air space

 

[PV Audio 5,000+ posts]

http://www.caraudio.com/forum/showthread.php?t=446197

Read my section on sealed boxes //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Stalin-ohaulic]

You cannot tune a sealed box. WTF

 

[DBfan187 5,000+ posts]

Qtc

 

[PV Audio 5,000+ posts]

You cannot tune a sealed box. WTF

Yes, yes you can. As Dbfan said and as I explained in my link, the Qtc determines how the speaker performs in the enclosure. Every enclosure has a Q, and the Q of a sealed enclosure can either make it a peaky boomy box, or a low frequency monster, or an IB setup or anything in between. It all depends on how you design it. A sealed enclosure is not just a dead airspace behind the speaker; there is a rather lot of science behind it. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[boogeyman 10+ year member]

QTC .707 will give the flattest frequency response (most musically accurate)................Qtc.9 - 1.1 most people prefer wich produces emphasized bass........QTC values above 1.2 are unnatural and sound boomy...........Enclosure volume requirements decrease with higher QTC values

 

[SicAudio 5,000+ posts]

Yes, yes you can. As Dbfan said and as I explained in my link, the Qtc determines how the speaker performs in the enclosure. Every enclosure has a Q, and the Q of a sealed enclosure can either make it a peaky boomy box, or a low frequency monster, or an IB setup or anything in between. It all depends on how you design it. A sealed enclosure is not just a dead airspace behind the speaker; there is a rather lot of science behind it. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

//content.invisioncic.com/y282845/emoticons/ohsnap.gif.17c4c91be09a7a4a3995fb7145adac39.gif

 

[Stalin-ohaulic]

Yes, yes you can. As Dbfan said and as I explained in my link, the Qtc determines how the speaker performs in the enclosure. Every enclosure has a Q, and the Q of a sealed enclosure can either make it a peaky boomy box, or a low frequency monster, or an IB setup or anything in between. It all depends on how you design it. A sealed enclosure is not just a dead airspace behind the speaker; there is a rather lot of science behind it. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Maybe I'm more wrong than right. It was my understanding that "tuning" meant adjusting the port for the frequency at which the air inside of the port resonates with the highest efficiency. Thereby making use of the rear wave. This isn't really translated into "Q" because rather than a nice peak with a gradual, steady rolloff, it sharply rolls off below tuning and more gradually above tuning. Sealed boxes have a nice little peak, but the "q" is much more consistent above and below. There is no radiator making use of the rear wave... so even though you can adjust the peak of the box, does that really equal tuning? Maybe so... I could always be wrong.

 

[SicAudio 5,000+ posts]

it definately does it also has a major effect on the f3 as well. tuning a sealed enclosure is very important if you want good sq . the size is what determines the tuning and f3.

 

[PV Audio 5,000+ posts]

Maybe I'm more wrong than right. It was my understanding that "tuning" meant adjusting the port for the frequency at which the air inside of the port resonates with the highest efficiency. Thereby making use of the rear wave. This isn't really translated into "Q" because rather than a nice peak with a gradual, steady rolloff, it sharply rolls off below tuning and more gradually above tuning. Sealed boxes have a nice little peak, but the "q" is much more consistent above and below. There is no radiator making use of the rear wave... so even though you can adjust the peak of the box, does that really equal tuning? Maybe so... I could always be wrong.

You can tune any enclosure since tuning is not limited to just ported enclosures. Sealed enclosures only really have a peak with a high Q which IMO is undesirable, but some like it.

 

[BassMechkanic 10+ year member]

then we can through in polyfill type substance to change the whole **** thing.

 

[joeybutts 10+ year member]

and nonparallel walls!

 

[PV Audio 5,000+ posts]

and nonparallel walls!

Been fondling standing waves too I see? //content.invisioncic.com/y282845/emoticons/naughty.gif.94359f346c0f1259df8038d60b41863e.gif