Subwoofer build - where do I start?

I acquired an 8" passive sub a long while ago, and I built a 2x50W amp into a new enclosure with the same dimensions as the previous one so now it's active. It gives me good results - it's really impressive for a no-namer, but I want something to complement my Celestion F20's better.

I recently completed the electronics of a 4 channel amplifier for bi-amping my speakers, and I get excellent volume and quality out of them, but I've always wanted that in-your-face, move-the-room, shake-the-earth bass. A friend of mine has an Energy 8", which is mind-blowing. I want similar pounding bass.

I've always loved and wanted huge lows, but I've never had the capability to put out strong SPL's below 35 Hz. Where do I start? I have a 140 W amplifier (currently in an unsuccessful bass amplifier), and it powers 8 ohms. I have two 4 ohm 10" car subs - is it at all possible to use them to good effect, or do I need a better driver?

I also have a 2 x 140 W amplifier which I can sacrifice to power 2 drivers (8 ohm each though).

I live in South Africa, so if anyone knows cost-effective drivers around here, that would be most appreciated!

ETA: I'm looking for high-quality for music and movies.
 
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Hi,

You start with the specifications of the 10" car subwoofers.

Though if typical car specs they will work best in about 1.5 cuft
for both, sealed and stuffed, with the drivers on left and right
faces for some force cancelling, but you really need specs.

rgds, sreten.

That 12" is a nonstarter for a sub, Fs is way too high.
 
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just a guy

Member
2006-05-12 6:59 pm
In as much as that is contrary to accepted wisdom, do you feel we are worthy of an explanation of what you just might mean?

Ben

Whose accepted wisdom?

It's pretty simple really.

If the box is sealed and the f3 is too high you can eq the response curve to any shape and any qtc and any f3 you want.

If the box is ported (or mltl or tl, etc) a high fs will just give you a rising response, this often works very well to match the inverse of the room gain curve for a summed flat(ish) in room response. And of course you can eq to any response you like.

If the box is a horn a high fs is usually very beneficial, certainly higher than the horn's low knee. For a tapped horn a fs up to 2x higher than the low knee can still give a flat(ish) response.

I'm sure you've seen this picture a few times now, it's a tapped horn with a 6 inch driver I built in 2009. What do you think the fs of the driver is? I'll give you a hint. It's 47.35 hz. This is measured response, not a sim. So you see it's pretty basic. High fs isn't really a problem, there are other far more important considerations.


[IMGDEAD]http://i64.tinypic.com/aosyz4.jpg[/IMGDEAD]
 
Hi All,

FYI:

b:)
 

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silverprout

Member
2008-04-03 4:19 pm
Whose accepted wisdom?

It's pretty simple really.

If the box is sealed and the f3 is too high you can eq the response curve to any shape and any qtc and any f3 you want.

If the box is ported (or mltl or tl, etc) a high fs will just give you a rising response, this often works very well to match the inverse of the room gain curve for a summed flat(ish) in room response. And of course you can eq to any response you like.

If the box is a horn a high fs is usually very beneficial, certainly higher than the horn's low knee. For a tapped horn a fs up to 2x higher than the low knee can still give a flat(ish) response.

I'm sure you've seen this picture a few times now, it's a tapped horn with a 6 inch driver I built in 2009. What do you think the fs of the driver is? I'll give you a hint. It's 47.35 hz. This is measured response, not a sim. So you see it's pretty basic. High fs isn't really a problem, there are other far more important considerations.


[IMGDEAD]http://i64.tinypic.com/aosyz4.jpg[/IMGDEAD]

You should take care to the membrane self ringing, some cones are ringing a lot at their Fs and equalizations can't solve that.
 
"Originally Posted by sreten
No such thing as too high an Fs for a subwoofer."

In as much as that is contrary to accepted wisdom, do you feel
we are worthy of an explanation of what you just might mean?

Ben

Hi,

I have no idea what I actually meant to say,
but I certainty did not mean to say that.

I said in a post further up the 12" is a not
a good choice as its Fs is way too high.

rgds, sreten.
 
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"Originally Posted by sreten
No such thing as too high an Fs for a subwoofer."



Hi,

I have no idea what I actually meant to say,
but I certainty did not mean to say that.

I said in a post further up the 12" is a not
a good choice as its Fs is way too high.

rgds, sreten.

The fs is fine. It will give a high f3 in a closed box and a rising response in a ported type box. There's no problem with that, as presumably eq is going to be needed anyway to sort out room issues.

For a 30 or so hz horn the 69 hz fs is just about ideal.

The much bigger problem with that driver is the very low 6 mm xmax.