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DIY For Audio
Novice DIY Subwoofer build - need some advice...
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<blockquote data-quote="tangmonster" data-source="post: 135675" data-attributes="member: 1581"><p>if you are going sealed you will need a big amplifier 200W rms per channel at the very least. the bigger the better.</p><p></p><p>in a sealed enclosure the bass will drop off fast and you will be down around 11db at 20hz. So you will need to use some sort of Linkwitz transform to boost the bottom end.</p><p></p><p></p><p>help me someone if my math sucks but here is an example:</p><p></p><p>lets say you use the jbls , and they are 10db down at 20 hz. You want them do be nearly flat down to 20 hz. SO you need to boost signals at that frequencies +-10 times. you have an amplifier in total of 400W</p><p></p><p>You have a movie and you set your volume so that 80hz you have lots of signal using 40W of energy.</p><p>Now the tyranosour jump on a car. A loud 20hz thump is needed at the same volume level. At 20hz you need 400W to have the same volume. Phew your amp made it.</p><p></p><p>tomorrow your mate is their. "dude check out his tyranosour" you put the volume up high so you need 80W levels at 80 hz. nect second the tyranosour jumps on the car.</p><p></p><p>all you hear is THUMP wack ,distortion distortion distortion because you needed 800W at 20hz for the same volume level.</p><p></p><p></p><p></p><p></p><p>The other option is too use a ported enclosure. Much harder to build but you won't need a transform. And a much smaller amplifier. you will have to ask the speaker builders on ideas for that . I like sealed.. But you need big amps for movies</p></blockquote><p></p>
[QUOTE="tangmonster, post: 135675, member: 1581"] if you are going sealed you will need a big amplifier 200W rms per channel at the very least. the bigger the better. in a sealed enclosure the bass will drop off fast and you will be down around 11db at 20hz. So you will need to use some sort of Linkwitz transform to boost the bottom end. help me someone if my math sucks but here is an example: lets say you use the jbls , and they are 10db down at 20 hz. You want them do be nearly flat down to 20 hz. SO you need to boost signals at that frequencies +-10 times. you have an amplifier in total of 400W You have a movie and you set your volume so that 80hz you have lots of signal using 40W of energy. Now the tyranosour jump on a car. A loud 20hz thump is needed at the same volume level. At 20hz you need 400W to have the same volume. Phew your amp made it. tomorrow your mate is their. "dude check out his tyranosour" you put the volume up high so you need 80W levels at 80 hz. nect second the tyranosour jumps on the car. all you hear is THUMP wack ,distortion distortion distortion because you needed 800W at 20hz for the same volume level. The other option is too use a ported enclosure. Much harder to build but you won't need a transform. And a much smaller amplifier. you will have to ask the speaker builders on ideas for that . I like sealed.. But you need big amps for movies [/QUOTE]
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DIY & Tutorials
DIY For Audio
Novice DIY Subwoofer build - need some advice...
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