Building a home cinema subwoofer

hi, i need a bit of guidance here, im looking at building myself a subwoofer system for my room, am i correct in thinking that i can buy an amp like this one

http://cgi.ebay.co.uk/Audio-Intimida...iFi_Amplifiers

and then just 2 subs to go along with it like these

http://cgi.ebay.co.uk/Edge-Orange-ED...ar_Speakers_PP

just ensuring that they both run at the same ohms.

I will then build or buy 2 ported boxes for either side of my room.

The amp will be connected to the subwoofer output of my receiver.

Is this an ok plan? or is there something im missing

[dizzyblonde]

Said in another thread, years ago hooked up one of these babies up as a subwoofer, to a Kardon Harmen amplifier reciever jobby, used for the volume control.



Bloodddy blew the doors off!!

not helping you though

haha im hoping ill still be able to control its volume with the receiver! but yeah the big subs are fantastic.

[Viney]

Use home speakers and not car subs. They have different peramiters that work in different eenviroments.

To get the best from the speakers you will need the Thiele Small perameters of the drivers. This way you can build the proper size enclosers for the subs. Then there is a formula used to create the correct sized enclosure for the box and if ported, the correct port size for the frequecy that you require.

S for the amp, that ould be good, but you will need a crossover to make sure the sub gets the right frequencies. This can be in the form of Active or passive. A passive one is simple enough and again you can buy these.

A good project but the cost effort and faff value, i would just go and buy an active sub. You can get a decent 10" jobbie for about £150 and trust me, it will chuck enough bass out to annoy the neighbours but 3.

Remember that the 'bass' elemant of any system should compliment the rest f the system and not over power it. I can do this in my car and after a while its quite fatigueing, just keep this in mind.

+1 just pick up something that has had a lot of R&D money thrown at it already.

And also why two? Sub bass is non directional so one is normally all that is ever used. Mr Vines comments regarding both Theile Small and faff value are very much on the money.

Garry

i like the sound out of a 12" sub, if i can find a klipsch synergy 12 i would buy it. But being in northern ireland its impossible to find any sort of decent home cinema stuff. I have an 8" sub atm but its freq responce only goes down to 38hz, and im not a fan of boomy bass. With my room being square it already isnt a fan of low freq's.

All those amps have 2x outputs, so i may as well get 2 woofers for it, rather than needing to spend hundreds of £ buying a speaker that can take the power of a bridged connection. Plus the freq responce of that amp goes down to 20hz, and i know from experience that car subs are very good at reproducing these freq's. and it would be nice to have one for each side of my room!

As for the crossover i would be plugging it into the subwoofer output of the amp, so it should be only getting bass. However a crossover would be nice for fine tuning

[Viney]

Warren, trust me i have spent a lot of money on stuff like this over time and car subs really will not be ther right speaker. I have a twin 12" cab in the car and that happily rumbles down to sub 20hz in the car and produces silly SPL levels. However, even running a 1200wrms QSC powerlight indoors, you just dont get the same sound. My little 5" system on my PC and the 8" that i have on my surround sound go lower than the box in my room.

Also always run an amp like that in bridged mode. The speaker neadent be that expensive. To get really goo frquency response, try loading your current speaker at the wall, or mount it on something a little firmer. To get below 30hz in the home is very difficult. It a car, it uses the space around it to help create the sound.

If its still something you want to do, then go for it, but i really do think you are throwing good money after bad. And 38hz, isnt boomy bass, that starts around 95hz up to around 200hz, anything below that is really sub bass.

I used to have 4 18" subs in an XR2 many years ago and that produced 149.7db. When put into a van, it got about 138db again to do with the surround and pressure within the vehicle. Remember that +3db is twice as loud.

38hz is indeed not boomy but the subwoofer itself is in general. You do seem to know your stuff tho.... so any idea where i am likely to come across a subwoofer that is designed for home use? or what i am looking for that can disignuish between the 2?

thanks

[Viney]

It would be the corssover and box that will make the speaker boomy and the nature of the home cinema units will always make them a litle more boomy than usual so that they intergrate with the satelite speakers hence the slightly wider frequency range.

Try to search out a better crossover than you can put between your current amp and the sub. You may have to find a car unit that you can add a 12v supply to.

What is your current set up? amp, speakers etc.

Yamaha RX-V420RDS receiver

Jamo S50 centre channel
Jamo S506 main floorstanders
Jamo S502 surrounds

and a Jamo Sub200

It can shake the house plenty, but i feel the need for more....

and yeh i was looking at the 12v crossovers there in work, they dont look too bad!