Going too build an budget Sub woofer.

[Dylan_Creswell1]

Hello, so I did a little looking around for a new theater sub for my computer speaker system. I currently have three Logitech's x-530 but have always felt the subs were limited and didn't create enough pressure and volume.

A friend told me for my budget an better option would be to build my own sub.
I have no experience in this area but I'm very handy with DIY projects.

My budget range for parts is $100-$200 and I would like to hit the best dollar to quality ratio. I know this budget isn't large enough for audio enthusiast but is all I can afford. Don't know if it's even possible/worth attempting with such a low budget.

If anybody could link me to part resellers and have any part recommendations I would be very appreciative.

I do have a couple of questions. Such as:

Best way to make the sub compatible with an 3.5mm audio jack,
10 inch sub vs 12 inch and other sizes,
The best budget wood for box.
A passive sub vs self-powered.
Sealed box vs unsealed.
Amplifier built in vs external.
Volume of the box in comparison too size of the sub.

A similar forum post helped inspired this. http://forums.overclockers.com.au/sh...d.php?t=709508

[protecon]

Originally Posted by Dylan_Creswell1

Best way to make the sub compatible with an 3.5mm audio jack, 3.5mm Stereo to Two RCA Male Cable
10 inch sub vs 12 inch and other sizes, Depends on the driver
The best budget wood for box. 19mm MDF or 25mm if you can afford it
A passive sub vs self-powered. Active will give you the easiest setup
Sealed box vs unsealed. Depends on the driver - Sealed will give you tighter bass, Ported will give you higher SPL and lower extension
Amplifier built in vs external. As above
Volume of the box in comparison too size of the sub. Depends on the driver - Grab the Thiele-Small parameters of the model and do a bit of modelling with WinISD

For a budget build of $200, you're probably going to get the results you're after with an automotive-based subwoofer driver, ported with a plate amplifier.

[lithos]

Originally Posted by protecon

For a budget build of $200, you're probably going to get the results you're after with an automotive-based subwoofer driver, ported with a plate amplifier.

...as long as you can get a 4 ohm plate amp. That is very, very important.

What you'd be better of doing if you're budget is so limited is to use one of those small car amps with car subwoofers, and power 'em off an old computer PSU's 12V rails.

[lithos]

Originally Posted by Dylan_Creswell1

Best way to make the sub compatible with an 3.5mm audio jack,
10 inch sub vs 12 inch and other sizes,
The best budget wood for box.
A passive sub vs self-powered.
Sealed box vs unsealed.
Amplifier built in vs external.
Volume of the box in comparison too size of the sub.

To make it compatible with a 3.5 jack? Most amps will have simple line-level inputs. RCA jacks or similar.

The diameter of the woofer won't make as much difference as other factors, like the suspension, cone material, etc, but it's an OK indicator. Generally, though, the bigger the diameter, the lower the frequency response.

Wood? MDF'll be fine for your budget. Cheap, solid, easy to work with, uniform quality, it's what a lot of people use anyway. Only downside is that since it's basically dust held together with glue, you'll get a LOT of dust working with it. If not, plywood's good, too, but don't get the cheap stuff, as knots are both a bastard to drill through and fill. If you're keen on making a big sub, 20mm thickness is the minimum, preferably 25. You're going to have to brace the shit out of it internally, too.

An externally-amped sub is easier to build, an internally amped one is easier to use (less cables running around.)

I take it by "sealed versus unsealed" you mean sealed (acoustic suspension) versus ported. There's pluses and minuses of both:

* Acoustic susp- dammit, sealed is easier to type, is easier to build. Because of the resistance ("damping") from the fixed amount of air in the box, sealed enclosures tend to have the more "solid" bass, thumping bass, that stops and starts quickly. This also means that it's very hard to over-extend and damage the speaker. They're also a little less fiddly to tune. The downsides are that the proper size for a sub will be fucking huge (see Thiele-Small parameters below,) which is one reason why you don't see that many large sealed subs, and that the bass extension won't be all that low, which isn't what you want with a sub. The bottom-end roll off is gentle, but not really relevant in a sub.

* Ported boxes give you a lower bass extension, and are much smaller for a given woofer. They lend themselves more to "shaking" bass than thumping bass, as what's coming out of the port won't totally be in phase with the speaker cone. The downsides are that ports need to be properly tuned and built, else the sub will just sound like it's farting at certain frequencies, and that if you use a port that's two narrow or sharp-edged, you'll get port noise. The rule of thumb is to have a port 1/3 the diameter of the woofer, preferably flared. While the bass extension is much lower than a sealed box, below the port tuning frequency the woofer can get uncontrollable and can get damaged.

The volumed of the box isn't necessarily tied to the size of the sub, but rather to a combination of other measurements called the "Thiele-Small parameters," named after two blokes at the uni of Sydney who got together and worked out what box volume and ports, etc, were suitable for a given woofer. Good drivers will have these listed with the sub, and punching them into something like this ported box calculator (there's also calculators for a variety of enclosure designs on that site) will give you a good starting point.

Car subs, unfortunately, tend to just say something like "Eh, stick it in a 30 litre box and it'll be fine" on the carton.

Remember, whatever you do, don't forget to internally brace the shit out of the box and for the love of god don't build a cubic box.

[Smokin Whale]

If you want dylan, I can give you my old 10" sealed tube sub enclosure for free?

[Dylan_Creswell1]

Thanks guys you have really helped and that "Thiele-Small parameters," as well as the modelling program "WinISD" are really impressive! but I think I will take Smokin Whale's offer and save myself a lot of time with the box.
However one day when I am a bit better on the cash side of things I will build my own box sub and no I won't forget too "internally brace the shit out of the box"

I really like the idea of using a PSU too power the set-up to keep costs down.

So I think my next step is too pick a speaker. Here are some I think might do the job and fit into Smokin Whale's sealed box, but I am still new to all this and don't really know how to compare.

http://www.caraudiobargains.com.au/p...ofers?sprod=91

http://www.caraudiobargains.com.au/p...ofers?sprod=57 <--- that's if I decide to go really really cheap.

As for a amp I still have not got around too looking at them yet.
If anyone has better suggestions for a cheap driver? remember I am looking for best dollar to quality ratio.

An other idea was just too look for 2nd hand subs in places like cash converters and hope I get lucky.

Btw I found a awesome link for anyone who might be trying to build a cheap sub and came here http://www.overclockers.com.au/wiki/...ld_A_Subwoofer

[GTR27]

The PSU wont have enough amps in the power rail (wont allow enough current through) to properly drive any amp (and it will introduce a shitload of noise into it - i.e. baaaaad sound quality)

Something like this for an amp (if they still did the 80 that would be OK)

http://www.jaycar.com.au/productView...=&SUBCATID=443

Use a car subwoofer 10" or 12" driver - should be able to get for ~$80-100

Build the box out of MDF - can get a sheet for ~40 bux i think last time i checked. Some glue and screws $30. Get some dacron (or yum cha brand equiv) for damping - $~40

Cheapest for any decent sort of sub would be ~$340 but if you research the driver that you buy (second hand better on of CAA forums is the go) then you will get a kick ass sub for not a lot of cash.

Maybe just buy
http://www.jaycar.com.au/productView...T&SUBCATID=831

[Dingostolemyghz]

Using cheap automotive subs is a good way of keeping costs down. Often car audio places will do a cheap sub in box option cheaper than you could ever build one yourself + buy the same driver, so maybe look out for those. If you were gonna go this route, then you'd wanna make sure that you knew ur plate amp will fit (if using a plate amp). About the only bit of extra hardware you'd need then is foot spikes - pro tip: use 3 spikes not 4.

Building your own box, sealed is definitely a lot less fussy of actual box size, and the safer bet when using auto subs imo. The trick to building a sealed box is to make sure its sealed (funny that). I would only consider building a ported box for a sub that has complete theile/small parameters provided, so you can model up the ideal box. If winISD recommends a sealed over ported based on the woofers specs, don't go ported.

Getting a cheap amp is pretty hard task though. This could easily be where the budget is blown.

Good Luck

[Smokin Whale]

I've been helping dylancreswell out with his little project and we managed to get him a decent 12" sub setup for his room, for only about $60 (we got a free car amp off a friend). Sounds fairly decent and certainly shakes the house. I've taken a load of pics and stuff and I'll do a write up on what we did when I get a moment

[radz74]

I thought a $200 budget would be to tight but it sounds like you guys have managed it.

It will be interesting to see what you guys have put together.

I got into the DIY sub thing a while ago and have been really happy I took that path.