hey guys ive finally decided to start my first major project for my car considering ill have 3 and a half months of holz before uni starts up again.

Anyway first for the info part of the post.

My setup is currently a Pioneer DEH-P6850MP h/u, 1 ts306c 400wrms sub running off a jaycar 800watt watt mono amp. No new speakers yet for two resons: 1) im happy with the stockies for now, 2)im saving up for a decent pair of splits for the front

My main question, If i was to add a second sub to my system do i assume correctly that all i would have to do is just run another get a of speaker wires from my amp to the second sub and then wire them in parrallel to present a 2ohm load to the amp and hence get about about 750wrms total to both subs, so around 375wrms to each sub?

How exactly do u wire up in parrallel? ie diagram would be helpful

Also im currently running a 28.3L's sealed box from pioneer (the 306c box so its the right size) would i need the equivalent of 2 boxes (~56-57L) to run the 2 subs or can the box be smaller? Becuase from the measurements i took, the max size box i want to have is about 58-62L's so that would be perfect.

Also is there a point when a box can be too big? I mean would being 2-3 L to big affect the bass adversedly?

Now for my project part of the post.

My plan is to built a custom box that will have the subs sitting in wat would look like a wall which would end just after the boot goes wide (u know how the gets narrower us u look into it... from the narrow point back to the back seat.) That way ill still have acess to my spare tyre and room for cargo too.

My main query is... What is involved in makeing such a box?

I already have the specs for it in terms of size up in terms of construction what should i know?

At the moment the plan is to use 20-25mm MDF, and guel and nails to hold it all together. (and carpet or vynil to spruce it up afterwards, but thats something yet to be decided). What else would i need?
ive read that the inside needs to be lined with something absorbant? is this tru?

i was thinking of using feather, stuff the box full of it so make the bass tighter?

Also where would be the best place to mount the terminals for the wires...im thinking the back of the box go i can get to it from the little hatch thingy in the back seat. im assuming i would need 2 lots of them, 2+ve 2-ve

also 2 mount ethe sub onto the box, would i first use a mdf space,mount that to the box then mount the sub to the mdf spacer+box? make sense?

Also what sort of wires to u run from the subs to the little terminals things into the box?

Think thats it for now... really would appreciate this info as im gonna be starting this in about 2-3 weeks and am really looking forward to finally doing some decent lookin mods to my car.

alright first up do you have any more info on your sub? like the full specs on it?
once this is know they you will be told the best way to wire up the subs if you were to add another one
i built a box not to long ago and just used 18mm mdf and just screwed it together then sealed up the inside with some fill a gap, this goes around the joins eg corners and long the top and bottom
as for the terminals mine a on the side but you should be able to put them anywhere but most of them are on the side

ok here are the stats on the sub ig to off pioneer website:

Design & Specifications
Xmax = 8.7mm
12" Subwoofer for Enclosure applications
1,000 Watts Max. Power Handling
400 Watts Nominal Rating
Qts = 0.42
Fs = 32.6 Hz
Vas = 55.6 litres
Frequency Response: 18 ~ 500 Hz.
Efficiency: 89 dB
Impedance: 4 Ohm
fo(Lowest Resonant Frequency) : 31 Hz.
Recommended Sealed Enclosure : 35.4 Litres

Construction & Materials
Interlaced Kevlar (Aramid Fibre) Reinforced IMPP Cone
3-Layer Fibre Woven Radial Surround
4-Layer Copper Round Wire Voice Coil
Long Voice Coil Design
Extended (8mm) and vented pole yoke
Large diameter Conex damper with damper ring
4-Spoke Stamped black-coated metal basket
Silver ABS Magnet Cover
Spring Compression push-type terminals
2.40 Kg Dual-Mass Ferrite Magnet
56mm Aluminium voice coil bobbin with 12 cooling slits

Dimensions
Mounting Depth:157mm
Dimensions: 327 (diam.) x 177mm
8 Mounting Screw Holes
Cutout Opening: 278mm(Diam.)
Mass : 6.7 Kg
Carton: 365 x 215 x 365mm(WxHxD)
Carton Weight : 7.4 Kg

seen as your sub is 4ohm there is no way of adding another sub in parallel to end up with a 2ohm load when it hits the about but you will end up with a 4ohm load, there is a way of wiring it up so each sub is 2ohm but that will require another monoblock

ahh damn it to hell... so there is no way i can add another sub to my system without gettin another mono block or gettin rid of this sub and gettin some that can be wired properly?

ahh damn it to hell... so there is no way i can add another sub to my system without gettin another mono block or gettin rid of this sub and gettin some that can be wired properly?

if u realllyy want to add another sub that badly just wire them up in series. get 8ohms...at least its not going to catch on fire, explode or go into protection like it would at 2 ohms

well wouldnt that mean that my amp would produce half the power it is producing now?

so instead of 400wrms it would produce 200wrms... thats assuming that they amp accepts 8ohm loads

The amp encountering higher impedance (if you wire them in series) won't damage it, lower impedance (if you wire them in parallel) will, I've had a home stereo amp blow up due to too low impedance. But yeah, the RMS and peak power will be halved if you wire them in series.

How exactly do u wire up in parrallel? ie diagram would be helpful

Check out this wizard (http://www.rockfordfosgate.com/rftech/wiringwizard.asp) on the Rockford Fosgate website - it's very handy.


if u realllyy want to add another sub that badly just wire them up in series. get 8ohms...at least its not going to catch on fire, explode or go into protection like it would at 2 ohms

Forgive my ignorance, but the Jaycar Monoblock (http://www.jaycar.com.au/productView.asp?ID=AA0428&CATID=24&keywords=&SPECIAL=&form=CAT&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=595) is rated down to a 1ohm load... surely it'd work wired at 2ohm, or am I missing something?

but i dont get it then... the stats on the amp say it can handle impendences as low as 1ohm (its a D-class mono), if it states that it can ran at the load shouldnt it do so safely???

also i dont think this amp recognises 8ohm loads and if it did it i would still be better off running just one sub as it would probably make more bass then 2 at 8ohms with only 100wrms each...

i wasnt to sure about amps before but im really freaking confused now

<random trivia>
FYI halving power doesn't halve loudness. Going from 200W to 100W reduces the sound level by 3dB. You'd need to go down to 20W to halve the loudness (which would be a 10dB reduction).
</random trivia>

<random trivia>
FYI halving power doesn't halve loudness. Going from 200W to 100W reduces the sound level by 3dB. You'd need to go down to 20W to halve the loudness (which would be a 10dB reduction).
</random trivia>

but isnt gaining 3db equivallent to adding another sub to ur sytem? so ive read nuomarous (so??) times?

therefore taking 3db's will be like taking away a sub therefore not worth adding the second sub???


Forgive my ignorance, but the Jaycar Monoblock is rated down to a 1ohm load... surely it'd work wired at 2ohm, or am I missing something?

thats eactly what im thinking...

but isnt gaining 3db equivallent to adding another sub to ur sytem? so ive read nuomarous (so??) times?

therefore taking 3db's will be like taking away a sub therefore not worth adding the second sub???

I've never read that, but I'd be surprised by it. A 3dB change is the smallest change in sound level that the human ear can perceive. That is, if you increased or decreased volume by 1dB or 2dB you wouldn't notice.

But if that was right.. you lose 3dB by halving power, add a sub and gain 3dB, net effect is zero change lol

I've never read that, but I'd be surprised by it. A 3dB change is the smallest change in sound level that the human ear can perceive. That is, if you increased or decreased volume by 1dB or 2dB you wouldn't notice.

But if that was right.. you lose 3dB by halving power, add a sub and gain 3dB, net effect is zero change lol

:confused: thats beside the point atm (by in large becuase i got no idea what to say in return :redface: lol )

:bump:

anyone have ne opinion?

personally with my experiances (mainly in the shed, because i aint no electrician) the jaycar should go handle it no problem, jaycar build high quality amps that should last for ages. but the way i wire subs in paralell is just take the wires from each sub and put both posetive in the posetive terminal, and both negative in the negative terminal, but i could be wrong but that's the way i do things in my car and all my friends setups i've done.

personally with my experiances (mainly in the shed, because i aint no electrician) the jaycar should go handle it no problem, jaycar build high quality amps that should last for ages. but the way i wire subs in paralell is just take the wires from each sub and put both posetive in the posetive terminal, and both negative in the negative terminal, but i could be wrong but that's the way i do things in my car and all my friends setups i've done.

yeah you can do this but by only using one positive and negitive on each sub that goes to the terminal and the positive and negative that left over on each sub get joined together

if the amp can handle a 1ohm load it can also handle a 2,4,8,16,200000... etc ohm load. That is the impedance of the load, you only run into dramas with lower impedances as it is getting closer to shorting out the terminals and using too much power from the amp. If you double the impedance you halve the power output. so a 1000w rms amp at 1 ohm will usually only produce 500 w rms at 2 ohm and 250 w rms at 4 ohm. But as the impedance increases the control of the amp is also increased (dampening factor) which is good for SQ.

Hmmm this has confused me, my only advise is that when you ask a question, don't write such a long one or set it out better.

No idea what most of these people are going on about. If you add another Pioneer you will be sweet and as Tim said you will feed the amp a lower impedence which should double the output of the amp. This should get you a 6db gain if you keep it all sealed. :D

Just a quick note. These figures are not entirely accurate but a good guide.

1 sub at X power in a sealed box is the benchmark 0db.

2 subs at X power ( i.e 1/2 X each ) will see +3db

2 subs at 2X power ( i.e X going to each ) will see +6db

1 sub at X power with a passive radiator +1.5db

1 sub at X power in a ported box +3db ( N.B. only for the octave above the port tune ).

1 sub at 2X power will gain +3db

1 sub at 5X power in a 6th order bandbass.. priceless.

As I said, only a guide. Subs with long excursion capabilties and high power handling will effect the gain.:D

cool cool... i asked on the CAA forums and all people came to the conculsion that it would in fact work....

now heres a question.... what should i do the boot in, new/morone vynil or carpet?

i reckon vynil would look pretty good
but it really depends on your budget and if your going to show it off
people just stick to the plain carpet and spice it up abit to make it look good

yeah suppose the vynil would be took much...

another question.... with the carpet, is it a simple matter of rip out the old in with the new?

also how to people manage to make the box so that its like a flat wall no gaps?

would it be like adding extra parts to the main box to fill in the gaps?

like this....

well what i was going to do to my install was add a bit of say 3-6mm mdf and just fix it to the box when you put your subs in :D
but then again it might be too hard to actually get the box into your car :doubt:
ive already made the box which is currently sitting in my boot and just put the mdf sheet over the top too make it look like its built in and just carpet that bit of mdf
if your going to do it this way i recommond you cutting the bit of wood thats sitting on top of your spare down a little off the back edge so its easier to get you spare out without having to take the box out