Sub setup for Home Theatre use

[SweetWagon]

Hey guys,

Anyone had any experiencing selecting a sub and amp/ building sub boxes for Home Theatre? I'm slowly building up the setup in the loungroom at home, got a decent amp for the speakers and some very nice front towers. After looking at the price for a decent HT active sub, $500-600+ for something only 200wrms. I'm now thinking of building my own using a plate amp from jaycar or the like. Such as these

600WRMS Sub Amplifier Module - Jaycar Electronics
O Audio - 500W BASH Subwoofer Amplifier

Then purchasing a good second hand 12" 500wrms car audio sub, and building a nice MDF box for it all. Whats your thoughts, will it sound any good? or atleast better than the 2x ~100w sony subs i got with the package? Also ported or sealed? Any suggestions would be great. VERY bass hungry
Cheers!

[HCVP]

There's still the issue of the amps impedance. Unless you used a SVC sub, (can't think of any decent one's) and wiring multiple coils to increase the load, is not recomended. Also plate amps aren't exactly ideal for music use , they are more suited to HT.

There are many dedicated HT subs that fall within your budget such as Peerless, Scanspeak, Exodus, Mach 5 , just to mention a few.

[StoneX]

Exodus Audio - Shiva and Tempest are excellent DIY home theatre sub drivers. There's an Aussie online distributor who has them for pretty good prices.

[SweetWagon]

Exodus Audio - Shiva and Tempest are excellent DIY home theatre sub drivers. There's an Aussie online distributor who has them for pretty good prices.

Thanks for the tips, if i can get something around the $500 mark that produces plenty of bass I'll be happy. Interested in this aussie online distributor, link?

[StoneX]

http://tinyurl.com/y3wr8bt

[holdenboy]

lol @ StoneX

[acarmody]

HAHA I'm gonna keep that link.

[SweetWagon]

Cheers for the link lol. I did find that site just wasnt sure it was the right one. Have been doing heaps of research today and fairly certain i'll purchase the Shiva x2, build a nice sealed box with a decent plate amp to go with it. That sub seems to be fairly highly regarded in the HT industry (even car audio industry) so can even throw it in the car later lol.
I'll update this thread during/after the build.
Cheers!

[SweetWagon]

Ok so sub is on its way (shiva x2).. have been looking into boxes, still not certian whether to go sealed or ported.. biggest i can go is 3cu ft, (600x400x500) sealed. is this volume big enough for a ported box, if so what port specs would you recommend?

[StoneX]

If you're limited to that I'd go for the "Medium Ported (3 cubic feet), 24oz. Polyfill tuned to 22Hz" from the Application Notes.

[SweetWagon]

I did read those application notes.. but just a few more questions, have been looking into porting alot more today.. regarding sizes/lengths/freqencies etc.. so have a much better idea now. A few more questions though, what is polyfill, and where can i get it? I have seen someone mention pillows, and what is its effect?
Would a 4" port be too small for a 3 or 3.5" cu ft box? Also slot ports, how are these calculated to give the right tuning freqencing and sizing? This is looking more prefferable as cheaper and easy to incorporate into the box..

Cheers

[StoneX]

Polyfill is also called Dacron. It's the white fibre stuff you find in some pillows. You can go to a store that sells material like Lincraft to buy it. As far as I know, the polyfill reduces the air movement inside the box. Some people say polyfill makes the box seem larger to the sub box I don't see how that works.

I can't really comment on the port size or slot ports. I have a old 15" Tempest (big brother of the old Shiva) with 4" port and at high volumes in the car I could hear port noise (air turbulence around the port entrance) but now that I have it as a home theatre sub it never gets anywhere near the volume of in the car so I don't have the turbulence problem.

[HCVP]

From my knowledge, Dacron, makes the enclosure act as though it is larger, by slowing down the rear firing soundwaves. You could read many a debate as to whether it works, or not. I'm of the opinion that in theory, it would work, however i'm yet to use it myself, so i can't comment any further.

If your concerned about port noise, just use a slighlty larger port diamater, flaring your ports at either end can also help reduece turbulance also.

There's tons of DIY build threads out there amongst the HT forums using the X2, (some may require that your a member otherwise the images people have uploaded will not appear) so it might be worth your while having a look through some of them.

[StoneX]

I've also tried with and without Dacron in a car sub box but couldn't hear the difference. But if the application notes instruct you to use it, then you should do so

[SweetWagon]

No worries, thanks for the info im still learning heaps!. I have been doing a lot of research on HT forums and some crazy builds out there.. Have now convinced myself to sacrifice some space and make a bigger 5-6cu ft ported enclosure. along with an appropriate slot port it should sound great. looking at the application notes, should have a nice flat response, and be good for 120db with room gain!! just have to research into my slot port so I dont get any chuffing or unwanted noises, but another quick question, does it matter what direction the port faces? (ceiling/floor wall) Really looking forward to the build.
Cheers

[HCVP]

I'd use a round port for the simplicity of it. There's no advantage/dissadvantage for either slot, or round.
I'd lean towards a downward firing round port. At the tuning frequency, the sound is coming from the port, not the driver. So i would want the port facing downard, rather than to a certain direction. Allthough the sound is not directional at the tuning fq, IMO it makes it a bit easier for positioning of the sub.