Nooby-noob thread. Appreciate pointers.

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Thanks about the ply. its only about £60 a sheet after tax. they also do an oak veneered ply which is cheaper that i might use. Cross bracing, gotcha.

I'm confused, I've checked the infinity in 3 different sources and its usable frequency only goes down to 23Hz, is it that is just close enough or is there something I'm missing? While we're on the subject can a human being destinguish between 20Hz and 23Hz?

Cheers

All speakers have a set of parameters describing their operation, called Thiele-Small Parameters, after the chaps that figured them out.
The parameters allow simulations (via a computer program - WinISD Pro is a useful one) of any given driver in any given cabinet.

http://uk.infinitysystems.com/tl_fi.../Reference/Reference/1260w/REF1260W_PI_EN.pdf

Here they are.

Have a look on t'interweb for what they all mean.

The 23Hz cutoff frequency (quoted by the manufacturer) is irrelevant - don't worry about it. The T/S parameters are what's needed to tell you what its going to do in your cabinet.

Chris
 
Ahh thanks. I've ordered a book. I'll look at that software right now. I had thought I'd be able to get away without doing the graphs and such, just build a box of the recommended size (most drivers seem to say 'designed to work in enclosures 45L-70L'), shove in a driver that specifies 20Hz and be done. Ah, we'll. I'm not against learning the math and software, just hoped I wouldn't need to. However my obsessive personality has snagged on this project so I have to see it through. I won't even get to play it that often because the darn thing will wake/terrify the kids. They'll thank me when they are old enough to play X-box games through it 'pew pew'.

I've also gone off TL it'd need to be about 80m long to tune it to 20 Hz. Thats a big box. sealed or vented will need to do.
 
Just a basic reality check. Good clean subwoofer for $200? Sorry. About the cheapest I would call tolerable would be maybe a Dayton RS with an O-Audio plate. By the time you are done, you probably still have $350 in it.

Every car woofer I tested had terrible levels of distortion compared to what I can live with in my home. I still like my old Peerless XLSS 12's for music. Go read what Siegfried Linkwitz has to say about subs.
 
GM, thanks for the comparison. I am curious, though - why would the JBL need the bigger vent?
Surely the extra 1mm of Xmax isn't enough.

If they'll both hit 20Hz, I'd take the JBL for the cast frame - not much risk of bending it while tightening screws.

You're welcome!

It's a function of Sd, Fb, Xmax: TA Speaker Topics: Vent FAQ's

Sorry, but that's about the most ridiculous criteria for choosing a driver I've ever heard.

GM
 
You're welcome!

It's a function of Sd, Fb, Xmax: TA Speaker Topics: Vent FAQ's

Sorry, but that's about the most ridiculous criteria for choosing a driver I've ever heard.

GM


I fail to see how my criteria is ridiculous: Two different drivers will achieve similar performance for the same price, but one has a cast frame, the other being stamped steel.
I've heard of people over-tightening drivers with stamped frames, resulting in misaligned voice coils. In order to avoid that, surely it makes sense to go for the cast frame driver?
 
Have a look at the Legend of El Pipe-O'.
It is a subwoofer design that needs a room that is "Long On Space" and is suitable for 12"+ subwoofers.
It uses the transmission line design for loading the sub.
If I had a LARGE living room you bet I'd have one.

Superb! I've seen that design before and was intrigued. Grat atricle. Unfortunately only standard ceiling height. My living room is approx 4 x longer than it is wide and the positioning of power/tv sockets and doors puts my entertainments unit at one end facing side on to the, length.
 
Just a basic reality check. Good clean subwoofer for $200? Sorry. About the cheapest I would call tolerable would be maybe a Dayton RS with an O-Audio plate. By the time you are done, you probably still have $350 in it.

Every car woofer I tested had terrible levels of distortion compared to what I can live with in my home. I still like my old Peerless XLSS 12's for music. Go read what Siegfried Linkwitz has to say about subs.

Yeah. I know you are right. I'm new to this, I love base like Mt Eden -Sierra Leone. My stereo just isn't doing it justice so I need a sub I think. I can't spend a heap of cash and I really like the idea of DIY subs. It just sounds fun and cool. How cheap can I do it and it sound relatively clean? Plus I guess I'll need to build an amp with cross-over.
 
Yeah. I know you are right. I'm new to this, I love base like Mt Eden -Sierra Leone. My stereo just isn't doing it justice so I need a sub I think. I can't spend a heap of cash and I really like the idea of DIY subs. It just sounds fun and cool. How cheap can I do it and it sound relatively clean? Plus I guess I'll need to build an amp with cross-over.
Receivers with built in sub outs can go really cheap, used would be cheaper than anything you could build.
Check out the Tub Sub, post #8.
Used two 5 dollar speakers, can do a clean 114 dB outdoors with about 15 watts, extension in to the 20s.

http://www.diyaudio.com/forums/subwoofers/227541-500-diy-subwoofer-challenge.html

So far, the Tub sub looks to be the winner under the very ambiguous terms of the challenge. If not the winner, it still is the only sub that has been measured and shows the cabinet design ;).
 
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