Help pick me a new subwoofer - whats your bet?

[Psinet]

G'day all. Greetings from Australia. I am looking for a little help and it would be great if you could bare with me as I am somewhat new to this. I did some forum searching but my questions were specific, so here goes..

My intended DIY project is to make a simple but powerful subwoofer. The sub is to be merged with my current 2ch stereo setup, which is 2X 350W 8ohm Quest speakers with 1" compression drivers and 12" woofers being driven by a Peak Audio USA-900 amp at 300WX8ohms per channel. The problem is I am finding that the system lacks oomph in the bottom end, especially when you start to apply more volume - the highs and mids tend to outperform the bass the louder you go. I will be running it from the 1/4" subwoofer out jack on my Denon DN-X400 mixer, which has a cutoff starting at 200hz and can be set down to 40hz.

The first step I am planning is to buy this 350WRMS 4ohm subwoofer amplifier from Jaycar for $US250:

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

Then, I have to find a suitable 12" or 15" 4ohm driver for that amp. Thats where you guys come in. Next, I have to design and build the enclosure, put it all together and finally set the appropriate output frequency from the mixer.

So whats your bet? Which subwoofer driver should I get for this particular application and amplification? I am guessing a 15" is in order since I am only planning on buying a single amp and sub, and the system already has a 12" speaker on each channel....... but then I am not sure. Probably a vented enclosure, unless I am convinced otherwise.

So please, what are your opinions? BTW I dont want to spend more than $US175 if I can manage it..............................will I need more or less?

[paulspencer]

Is this for PA or home use?

What kind of extension are you looking for? 40 Hz? 30 Hz? 20 Hz?

What kind of SPL?

What approx room is this going into?

A 15" home theatre sub with that much power can be a good match for hifi speakers but won't come near the oomph of your mains.

There are some different directions you could go based on those questions ...

[Psinet]

Really? I thought that 350w RMS sub amp was powerful enough. I think it has 700w peak and it is certainly the most powerful sub amp available through Jaycar (they are right down the rd) . I guess I am trying to do the impossible and develop the system for all things - the system is used at home for a number of things - listening to music, watching movies and previewing and monitoring mixes from my recording studio at a moderate SPL.
But now and then it is used for parties (both indoor and outdoors) for friends and myself (usually no more than 100 ppl). Then it is used at a high SPL. I dont have a great deal of money, so that was why I was considering the amp that I was.

Being a 4ohm amp I was assuming I would be purchasing a car audio subwoofer and creating a large enclosure for it and the amp.

[Psinet]

I guess I should add that the room the speakers are normally in is a medium sized 14ft X 20ft room - I guess I neglected to mention it as I move it around a lot.

[Psinet]

A little help NE1?

[pinkmouse]

Hi Psinet

The reason why you may not be getting many answers is simple, this is a very common first project, and your questions are too vague. May I suggest you check the availability of drivers, find what you can afford, then if you search here with the driver name you will likely find a thread(s) dealing with it already. Then, once you have read up on the wealth of info already on this site, you can ask the more detailed questions and people will likely be more willing to help.

Good luck!

[paulspencer]

I wrote some articles on choosing a sub driver and design, and how to design it in the wiki (see link in my signature)

Your mains are probably about 95 db sensitive while a typical sub will be more like 87db, hence the sub won't come close to the output of your mains unless driven with about 8x the power (which the drivers won't handle). A home sub won't do parties very well in a large space with 100 people. It will just get lost.

Firstly I'd choose a pro amp rather than a plate amp. Behringer EP2500 is a good bang for buck amp and very flexible to allow for upgrades. It will put out 650w into 4 ohms x 2 channels, or 2.4kw bridged into 4 ohms! You can get it for about $600 which is more than a single plate amp but less than two of those plate amps with a lot more power and flexilbility.

One way to go is a pair of bass horns. They will actually get high SPL for parties, and a cheap driver can sound very good. You can make a number of them so each one isn't so big, and divide up the horn mouth area by the number of boxes.

Another way to go is do a pair of say 12 or 15" high excursion drivers in sealed or vented boxes for home use. For parties you could put them in some bass horns if you have somewhere to store them. Another alternative is to make a bandpass box for the parties, which is smaller.

[paulspencer]

Here is a fairly simple bass horn project:

http://diy.cowanaudio.com/hornsubjr.html

I've heard from one guy who built it using some cheap Jaycar venom drivers, and he tells me they sound slightly better than his Tempest sub, which is quite good since those venom subs in a normal alignment sound terrible!

If the width of the sub is an issue, then I'd make a pair of single driver versions and stack them on top of each other and fire both into the corner. This way they would be big but would not project much into the room.