I've just picked up a large FREE chipboard box, size-

90cm wide x 30cm high x 70cm deep.

Sides are 1inch chipboard, top/bottom is 1 cm chipboard. Bottom is stapled (lots of them) top is screwed- removable.

What subwoofer driver would you recommend in this size box?

Shall I make it ported or sealed?

I'll find out the internal dimensions soon.

Thanks

[alexs2]

Nathan....you'd need to match the box dimensions very carefully to the driver selected,and the dimensions/resonant frequencies are going to be massively different depending on whether you opt for reflex or sealed cabinet loading.
Its also very likely that the unbraced cabinet you have will develop significant resonant modes across the unbraced walls.
1cm chipboard isn't noted either for it's rigidity,or damping properties.

www.wilmslow-audio.co.uk may be able to help you find something suitable for that cabinet,but I feel that trying to match a driver to a ready made box will be very difficult and likely to end in poor bass reproduction.

I'll probably double up the top & bottom (increase to 1 inch) and add a "+" bracing in the middle to add strength.

Might not be perfect- but first sub so can't expect awesome result. I'm pretty useless at woodword (plus I don't have the tools), so ready made box is handy.

All I need to do is cut a circle for the driver, add a brace, lining, add speaker connectors and I'm away!

I'm only going to send frequencies upto 80hz.

What s/w shall I use to narrow down the correct make/model/size driver and ported/sealed options?

[RichardH]

Have a play with WinISD (link in another recent thread).

I'd say the cutting the circle is the hardest bit!!

[alexs2]

Those ideas sound fine...would add a set of screwed and glued cross braces,and also screw the joins between the sides of the box.....(I built a set of transmission line speakers some yrs ago and can still count the bloody screws we used!)
The following link may be useful for software,although I havent used it....

http://www.mc-h.demon.co.uk/speakers.html


If not,a google search on speaker design software may be useful.

Good luck!

[deckard]

What happened to the SVS CS ultra's?!!!

Rel Storm + CS Ultra + DIY sub!!!

[edit] Here's my cab internal dimensions..

64 cm deep, 26cm high, 85cm wide.

Max budget for driver- £200.

I've downloaded Win ISD. What is the capacity of my cabinet (in litres?) Not sure what I should be looking at Gain graph- what is ideal- near the 0 point until the LF drop-off (ie 20hz)

What driver shall I use? What will work best- ported or sealed box?

Thanks

[ReTrO]

Your internal volume is 141 litres. Pretty large enough for a lot of drivers. The REL Studio 3 is only 110L.

I calculated than with a decnt port and a pair of JL Audio 10W7 drivers (10") you can go flat to around 20hz. The drivers are damn expensive mind.

ED: That requires a 182L enclosure with a port at 23Hz.

I'll just have a play around and see what else can be done.

Thanks for that Richard, I was staring at the graph going (huh?) I guess it's harder to work the box round the cab, but perhaps I could get some suggestions for good driver(s), then decide for my size cabinet one design works better than the other.

Would you say a single driver is better- I would rather have a low LF sound rather than several drivers- boomy sound.

Basically want it to sound the best at ??- 80hz (?? depending on whether to use ported enclosure or sealed)

Do I need to line the inside with foam? (for both types?)

Thanks

I've taken a photo.. I think I'll create a downfiring sub (add feet to raise off the floor)

See below..

[RichardH]

All this is just what I have picked up from reading around, and not definitive by any means - I'm sure those with more experience will chip in on the bits I am wrong on.

Ported designs generally need a lining of foam, sealed tend to be stuffed - this increases the apparent size of the cabinet (as far as the speaker is concerned). 141 litres sounds pretty close to one of the alignments used for the Shiva - do a search on this forum for plenty more on that beast. Just had a quick play, and a ported enclosure with a Shiva comes out at 135 litres by default in WinISD. 142 litres is the EBS design on the Adire site for a ported Shiva. Have a look here for links to the Shiva design PDFs.
Remember that you need to deduct the volume of the driver and any bracing you put into the box from the 141 litres you start with.
If you play with WinISD, you'll find that ported designs tend to go flat lower, and then roll off much quicker than a sealed enclosure. This looks great (and was originally what I was going to go for when building a sub), but I understand that there can be problems with this approach, and sometimes a more gradual roll off is to be preferred. The room will add some lower freqency lift to get the curve up again.
Sealed enclosures are easier to build, as there is no port to get to exactly the right length. Ported enclosures can sound "flabby" if not quite right, whereas sealed are generally "tighter" sounding, and are often preferred for music reproduction.

Good place to look is diysubwoofers for more on the various types of design.

What amplification are you going to use?

Cheers for that info. I'll think a sealed version is probably the better design for me then (less to do, less chance of it sound whoomy)

[edit] Found out the vented Shiva is closest to my cab, so I'll use a vented design.

Rather have a subwoofer that is fast + low output, to a high output "boom box" It'll only compliment my overall system.

Probably use a channel from a Audiolab amp. I'm looking into getting a SVS CS-Ultra, so if I get a Samson S-1000 I could use one channel for the SVS, and the other for my DIY sub.


If I use one brace, at most it'll take is 4.1 L (but I'll cut a couple of holes for airflow)

So I'm pretty close to a sealed Shiva sub, I know the Shiva is supposed to be quite good (and at a affordable price)

[RichardH]

Only pain is that the sealed designs seem to be with a smaller encloseure, but I'm sure it would sort itself out. IIRC, GaryG might have a Shiva up for sale.

[RichardH]

...One other thought. You could use a Linkwitz circuit to bump up the lower frequencies if it flattens off too quickly - I'm planning to add one to my sub - when I get round to building it.

Hmm. Had a look at the Shiva PDF's, seems my cab is close to a vented spec (141 L) -right about that Richard. So looks like I'll settle for that design.

It might be a few L out 141- 3L for bracing (see below pic) but shouldn't be too bad. I hope!

[GaryG]

Originally posted by RichardH
Only pain is that the sealed designs seem to be with a smaller encloseure, but I'm sure it would sort itself out. IIRC, GaryG might have a Shiva up for sale.

Yeah, I've got DIY sub kit coming out of my earholes, one day I may actually be satisifed and stop tinkering.

Nathan, if you're interested here's my 'for-sale' thread.

http://www.avforums.com/forums/showt...threadid=68955

The Hypex amp has a pretty decent 'eq' circuit which will give you the low-end boost of a 'vented' design and still keep the 'tight' low group-delay sound of a sealed sub. Saves having to buy a low-pass filter and an LT circuit for a monobloc.

Ta for that Gary, but I'll find out as much info as I can before buying a driver (only got the cab this week)

I'll strengthen the cab for now, and get the design ready.

Anyway I have other priorities!

[GaryG]

Here's a good forum to whet your appetite!

http://www.hometheaterforum.com/htfo...?s=&forumid=22

Nathan

If you have WinISD (mentioned above), try modelling Adire's DPL12 in a vented box and compare it to the Shiva. An f3 of just over 16Hz on paper, in a box around 140litres!!

The DPL12 won't reach the same max SPL levels though, due to lower sensitivity and power handling - depends what you want really at the end of the day!
To put it anoher way, you'll need a bit more amp power to drive the DPL12 to similar levels as the Shiva, and ultimately, the Shiva will out-SPL it.
Personally though, I'm really not that interested in massive (eg 120dB) output levels - it would probably cause structural damage to you house anyway, let alone your ears!
However, some people are, so like I said, it depends what you want!

BTW - I haven't used or heard a sub with a DPL12 in, so don't have any experience of it directly. Looks good on paper though (low Fs, decent Xmax, what looks like good quality construction, blah blah blah) which is where we all usually start, and seems to have a good reputation in dipole subs! Looks a very interesting candidate for a DIY jobbie
Would be interested to hear the thoughts and opinions of anyone who has actually used one though, so if anyone out there has........ please post back