Page 1 of I`m thinking of building my own sub - need help!

After looking at a couple of self-build websites, I`ve decided to have a go at building a cheap subwoofer - even it it turns out to be a bit iffy, at least I might learn a thing or two along the way.

Anyway, the point is, I can`t seem to find any half decent electronic component suppliers. The main thing I`m after is a reasonable speaker driver. After checking out Maplins online, they don`t seem to quite have what I`m looking for and I can`t seem to find anyone else (in the UK) after hours of searching. Any ideas anyone?

Cheers.

I`ve been mulling this over myself, too, but am not sure I have the time.

Try http://www.bkelec.com/ - they have some good amp modules, too (which they used to supply to REL!). Not many drive units on the site (except some car stuff). but give them a ring and ask for Tom - he`ll sort you out, and send you PDFs of speaker specs etc. He recommended a 10" drive unit with a passive radiator to go into a box size of 30 litres (about a cubic foot) - trying the modelling out in WinISD it didn`t seem to compute, but he recons they`re building such a unit for a customer at the moment. I think they supply a lot of manufacturers, he mentioned REL (maybe in the past), Ruark and MJ Acoustics. Obviously he`s not going to give away all the specs for a model they do for one of them, but speaks for the quality of the kit they supply.

If you are looking to build a small sub, I found a really good drive unit at http://users.classicfm.net/williamshart/seas.htm - the H0956 L21RN4X/P. £60, though.

I assume you have downloaded WinISD for your modelling - the easiest to use that I found (may not be the most comprehensive).

My idea was to just build it for movies - therefore I don`t really need a crossover, as the amp will output the .1 signal (and if pushed, the amp has a corssover frequency defined). So, in theory, all you need is one of those mosfet amp modules (100W - £42), a power lead, a drive unit and a box (and a cable!).
I started getting paranoid about low frequency cutoff and speaker protection circuits (Maplin do a speaker protection circuit - around £10), plus also the lack of any auto power off (as I don`t really want to start rooting around behind the sofa every time we watch a film).
I had a thought of using the extra power output of the amp (Yammy A5) first to power the sub, but it wouldn`t supply the amount needed, so then had this mad idea of using it to switch a mains relay, which then powered up a 4 way from another socket, to allow me to switch everything on with the amp. I may need to have a chat with someone in Maplins about the wiring for something like that, though. I did post here wondering if anyone had the wherewithall, but got no response.

Let me know how you get on - mail me if you like - see my profile.

Thanks for your help Richard.

The sort of thing I was thinking of knocking out would be very unsophisticated - sealed box, not ported and I was even considering using a cheap in-car speaker driver (after looking at this webpage http://www.kevinboone.com/subwoofer.html). It`s probably worth my while using a better driver, such as the one you pointed out.

I hadn`t yet downloaded WinISD - I had rather put the calculating bit to the back of my mind! (that`s a black mark for not doing my homework)

Don`t laugh but I am initially going to use an old JVC amp I`ve got lying around to power the thing, plugged into the back of my Denon 1602 until I get round to sorting out a dedicated amp.

I hadn`t thought of anything as sophisticated as auto power-up or low frequency cutoff, but as time goes on I`ll probably upgrade it and possibly make subsequently better units - depends how hooked I get!

I predict a steep learning curve (should keep me off the streets for a while). I`ll let you know how I get on.

JVC amp - not a bad idea! Why not. BK do cheaper drivers - the 10" unit they suggested to go with a passive rad was under £30. Give em a shout! He may be able to recommend a decent driver for a sealed box.

Re all the other bits - I was just meandering, really - but it all made me start thinking I shout just buy something, but you`ve got me going again.....

Go for it dude!

Just knock something together and see how it turns out.

That WinISD program very useful, by the way - I was originally going to work out the box size with a spreadsheet program!

Slighty off topic, Richard, read your switching thread.

Dave

Well, I took the plunge and built my own subwoofer - and I`m pretty chuffed with the results.

Most of the stuff I already had lying around - a 120 watt amp, mdf, screws, wood glue, that kind of stuff. It meant that all I had to buy was the speaker driver. The recommended box size for the driver was over 6 cubic feet - about the size of a fridge - but I compromised and made it around 3 cubic feet - still a bit of a beast. I opted for a 12" driver from empire-direct http://www.empiredirect.co.uk/productdetails.asp?Modelcode=PRP-BRT300&affiliateid=65 (originally intended for in-car use).

I`m sure it`s not the best sounding sub around, but I bet it`d give the budget jobs a run for their money. For films and low level grunt it is awesome and it still adds a new dimension to music (perhaps a little boomy). The sound could probably be much improved with a better constructed box - I used the 12mm mdf I had available, instead of 18mm or 25mm and I haven`t cross braced it properly. I can see myself building something more sophisticated in the near future - dedicated amp and crossover and a more expensive driver (or two!).

Because I only needed to buy the driver, I am now the proud owner of a seriously powerful subwoofer that cost me less than £36!

Can I suggest that Stage 2 could be to simply reinforce it with another layer of 12mm MDF to stiffen it up?

Dave

Good stuff Alfie! Afraid I wimped out and bought a sub (special offer at Richer), but still hanker after making a real monster some time....

To be honest, I don`t think stiffening up the box will really make enough difference to the sound to be worth the trouble, the box is already quite stiff despite not being cross-braced (it has got corner bracings) - but thanks for the suggestion. I`m very fickle and have a very short attention span (a big kid, basically) so I`m already planning a new box - I know a carpenter who can do a far better job than me of cutting all bits out.

Richard, don`t blame you for buying a sub when you get a good deal. I reckon that if you are building a sub from scratch it is easily going to cost you around £100 or so for the driver, amp, MDF, etc. anyway.