OK... 8 HX2 12" powered by two amps 2 seperate chambers or 8?

[AZ Vic]

I am doing a huge install on my K-5 blazer. I have been building it up for about two years now.
I have 8 yes eight 12 " HX2 subs that will be powered by two PPi 1200 watt amps.

My question is, should I build it with two chambers (four subs and one amp to each one) or should I make a seperate chamber for each and every sub?

Thanks,

Vic

 

[87 we4 gray t]

thats not enough amp. the subs need more power. i have the same ones. 8 chambers. each sub needs its own air or it might cancel each other out.

 

[AZ Vic]

I have 2 Precision Power amps that deliver 1200 watts RMS...each. These are the ones that are two feet long!

You don't think that is enough?

I thought that with the amps being bridged that all four subs on one amp and one channel, they would act simultaneously. I am even going as far as equal length speaker wire.

still eight seperate chambers? damn that's gonna be a b****.

Thank you for your input...

Vic

 

[87 we4 gray t]

im running one fosgate bd1500 for each 2 subs. wire lengh has nothing to do with it.

 

[TType84]

each sub will pull 400w rms right? i went to rockfords site.. if thats the right one you have enough amp to drive 6 of them at full power..

as it stands they will all have 300w rms apiece, which isnt a bad thing. youre not gonna hurt them by underpowering them, just dont clip em.

 

[87 we4 gray t]

theyre 500rms each.

 

[GNandTTA]

theyre 500rms each

thats thermal power handling. That is only 1 part of how much power they will handle safely. The type and size of enclosure is the other determineing factor in how much wattage the speaker can safely handle - this is called displacement power handeling. If you want them to handle the true 500 watts you will probably need to go with a bandpass or maybe a small sealed enclosure. Obviously the bandpass will sound much better than a small sealed enclosure. But it will also be bigger. Ported boxes usually have a much smaller displacement power handeling rating than the given thermal wattage rating. So your Rockford's in a ported enclosure will not handle 500 watts, not for long anyway. This is because the port allows the speaker to loose control and over drive itself. But then again you get a bigger db gain from a ported box over a sealed box. So it would take less power to attain the same level of sound using a ported box. I would get design plans right from Rockford's site. You will get more impact if each speaker is in it's own enclosure.

Speaker enclosure design is a game of tradeoffs. There is no one perfect enclosure. You need to find the type that suits your application best. IMO when seeking the loudest bass with most impact, a PROPERLY designed bandpass box is hard to beat.

 

[AZ Vic]

Thanks for the input guys!

Gray T- My intentions with equal length speaker wire was to ensure all 4 subs acted simultaneously...

I talked with a few designers at fosgate yesterday and they said a seperate chamber for each amp i.e. four subs per chamber per amp. I did not get along with them far enough as to discuss ported or sealed though...

I like the deeper dound that comes with proper porting... but I do not believe I have enough room for that. I am working with about 12.5 cu ft. these 12" HX2's require 2.5 ft each when ported. I may redesign my box, hell I don't know. Everything says ported equals 3 db, is that true or is it more?

GNandTTA- I totally agree with you on the band pass. A good band pass box will make even the cheapest subs hit good... But sound Q suffers... like a low voice sounds all muffed... Or are you talking about a fifth order style box?

TIA,

Vic

 

[GNandTTA]

like a low voice sounds all muffed

It's doing it's job. A sub has no business trying to reproduce vocals. A good bandpass box can respond just as well as a sealed or ported, only louder (better). I think a 5th order is just a single reflex with a passive crossover on it. A 6th order is a double reflex. I never liked putting any type of passive crossover on subs. The crossover is a possible source of colorizatin and loss of power. The 6th order boxes are hard to get right. Too many variables. Highly recommend getting plans for any 6th order right from the sub manufacturer. Let them do all the hard work and trial and error building. For me a well built single reflex (4th order) is the best. You have a sealed chamber to help prevent woofer destruction and still get the increased output from the vented chamber. Plus they look cool - all you see is the big port.