Subs & Amp deciphering...help!

[orangebooboobearcrew]

Hello, me again.

As I have mentioned on previous posts, looking to put a sub in the plinthe under the bed and got the following questions:-

Will a sub work okay in the plinthe under the bed as the is not a true enclosure (Bluebird R&R bed fitted)?

My neighbour has offered me a Vibe sub for £40 that he has knocking around but not sure if it will do what I need. Plan was to fit a 300w RMS 10" sub (other speakers will be powered via the head unit).
The amp on offer quotes ' 4 channel amplifier, 4 x 50 watts RMS @ 4W stereo, 4 x 75W RMS @ 2W stereo, 2 x 150W RMS @ 4W bridged'.
What does all this mean and will I be able to run a 300W RMS sub from this and if so, how would I connect / wire it?

If I did go for another sub option I have in mind (450W RMS), would this amp be able to support this?

Cheers,

Chris

[kevtherev]

Will a sub work okay in the plinthe under the bed as the is not a true enclosure (Bluebird R&R bed fitted)?

it'll work but it won't sound right

The amp on offer quotes ' 4 channel amplifier, 4 x 50 watts RMS @ 4W stereo, 4 x 75W RMS @ 2W stereo, 2 x 150W RMS @ 4W bridged'.
What does all this mean and will I be able to run a 300W RMS sub from this and if so, how would I connect / wire it?

is there a sub channel on the head or sub out?
you really need an amp to run a big sub

If I did go for another sub option I have in mind (450W RMS), would this amp be able to support this?

not with out an amp

[orangebooboobearcrew]

Soz Kev, I probably haven't explained properly - I potentially do have an amp to run the sub (the one mentioned on offer from my neighbour) but not sure it will do what I need?

(there is a sub output on the head unit).

Also, you say the sub won't sound right under the bed. How is the best way to get around this and how are other doing it as I'm sure I've seen subs in under the bed in other buses?

Cheers,

Chris

[kevtherev]

Also, you say the sub won't sound right under the bed. How is the best way to get around this
Cheers,

Chris

Best box it in under the bed.. there is a ratio of box volume for the best resutls.

as long as the sub amp is pokey enough to run the sub (300w output) it'll work.
Activate the sub channel in the head then connect it to the amp.
Power the amp from the head then it will turn off when you turn off the head.

Oh and it will suck a weak and feeble leisure battery power like a demon, flattening it in hours.

[orangebooboobearcrew]

Cheers Kev.

D'oh that sounds like a lot of work boxing it in under the bed and I am also limited for space under there. Any idea what the calculator is to determine the size of the enclosure or why I might find this?

Still not clear if the amp my neighbour is offering will power a 300W RMS sub given the specifications I've quoted. Anyone got any idea?

Cheers,

Chris

[kevtherev]

this the amp?

2 x 150W RMS @ 4W bridged'

so you'll be running the speakers from this too?

it'll power the 300w sub
Most new heads these days pop out 4 X 50watt any way...what head is it?

[kevtherev]

enclosures...
The primary role of the enclosure is to prevent sound waves generated by the rearward-facing surface of the diaphragm of an open driver interacting with sound waves generated at the front of the driver. Because the forward- and rearward-generated sound is out of phase with each other, any interaction between the two in the listening space creates a distortion of the original signal as it was intended to be reproduced...

[uniB]

If the amp you're getting is four channel as you say, it'd be silly to still run the other speakers from the head unit, you would be better using two of the channels on the amp to power the speakers and the other tow bridgeable channels for the sub. You'll get much better sound from the amp than you would the sub. You will just need to connect the amp from the RCA output on the head unit – it will then be able to filter the output for the amp and front speakers.

Do you know what 10" sub you'll be getting? They generally don't need a huge amount of volume in the enclosure. Mine needs about 0.5 cu ft which is about average, this needs an enclosure about 10in x 10in x 10in (or it could be proportions as long as it adds up – obviously the front needs to be big enough to accommodate the speaker). It's best to make the enclosure out of something substantial like mdf, and then fill the space inside with wadding – you can use upholstery wadding or the proper stuff from here http://www.caraudiodirect.co.uk/phonoca ... panel.html

Hope that helps!

[mike_gee32]

Hi, what headunit are you using and do you know if it has RCA outputs, these are the best way to run an amp. Vibe amps are pretty decent for the money and £40 isn't bad (although I've just bought an Alpine V12 4 channel amp off ebay for £50 - was £500 when new) from the specs of the amp it will bridge to 150w rms to run a sub and run 2 front speakers at 50w rms each, probably not enough to make your ears bleed but plenty to feel even at motorway speeds, your head unit will probably put out 50w a channel peak power which could be anything from 12w to 25w RMS depending on make and how it's measured.
There is no reason why you couldn't put an unboxed sub in the seat panel if you get one designed for 'infinite baffle' mounting BUT (and it's a big one) the seat panel would have to be pretty substantial (18mm MDf/ply minimum) and very well fixed, you also risk damaging the sub with whatever is in the storage space, not to mention the fact that the sound would change depending on how much stuff you cram in there. A much better way is to stick it in a box, as uniB says most modern 10's work well in small boxes.
You've not said what your other speakers are but I'm in the process of sorting my stereo out and have put 5" components in the front doors, main driver mounted low and the tweeter at the top of the panel, I'm making MDF mounting plates this weekend as the door cards aren't stiff enough and the bass goes very woolly when loud. I've put flashing tape in both front doors to act as sound deadening, this is probably the best upgrade you can make to your stereo in a T25 (or any car really) as the undamped doors really resonate and the bass response is so much better once it's done, these will be run of two channels of the Alpine amp I've just bought, the plan then is to stick an 8" sub under the seat (I would use a 10 but the reinforcing bar of the RnR bed gets in the way) powered from the other 2 channels bridged, then I'm going to replace the standard 10cm Blaupunkt rear speakers with some better ones and run those from the headunit, the amp will be wired from the leisure battery but I'm going to put a switch in the remote power feed so I can turn it off when camping, I don't think I'll need all that power late at night when parked up and the battery will last much longer.
I'm only 15 miles or so from Tamworth so if you need any help with installing or setting it up when you do get the kit let me know, it's been a few years since I've done a proper system in my cars (got fed up with having them nicked from where I used to live then had company cars for a few years) but I spent 4 years selling and installing stereos when I was younger.
Mike