subs

[FMH]

I have NO spare wheel well

[TouringTash]

gotta keep busy!

and keep away from ya front discs?

[mrLEE30]

Ha ha, as it happens I test fitted them this week and the calipers are too wide for my wheels. Need some silly spacers so the brakes may not work. The shocks are welded to stub axels now so they get fitted next week, first need to pay for full control arm and bush renew on my 540 why does one car need so many control arms???

[BadDave]

Can modern car amps push a 8ohm driver?

I have a few ideas

No reason why they can't as 8ohm is 1/2 the load of a 4 ohm driver,meaning less work for the amp,although amp output will drop by 50% if you opt for 8ohm units.

For decent power find an amp that's stable to 1/2 ohm or at the very least 1 ohm and get hold of a pr of DVC subs wired series parellel to 1ohm.

[BadDave]

Any idea on the size/design of a box for my sub, will it sound good?

as a rough guide(without seeing the specs) an 8" driver needs about 0.4-0.5 cu.ft

10" driver requires 0.6-0.75 cu.ft

12" driver needs about 1 - 1.25 cu.ft.
Optimum internal dimensions of any cabinet will depend on the Thiele small parameters(TS) of the speakers you opt for.

[TouringTash]

Cheers Dave.

[BadDave]

If it were me using 8ohm drivers, I'd wire 2 in parellel for a 4 ohm load or 4 in parellel for a 2ohm load

Wiring diagrams here,just input the details

http://www.rockfordfosgate.com/rftech/woofer_wizard.asp

[TouringTash]

Ah fosgates woofer wizard.

Still on topic-ish would you recommend second hand fosgate amps over an equivalently priced new amp, if the RMS values were close?

I'm not after silly levels, just a crisp, tight unruffled system with plenty on head room.
Studied C&G electronics whilst doing my alarm apprenticeship so I understand the basics after a little read up, wish I kept my note, thought they were carved onto stone it was so long ago.
400 RMS split over 4 componants and two 8s would do the trick.

[e30maddog]

personally im not a fan of second hand audio stuff, i would go new every time, rockford gear is very good gear but still.. nowdays even the cheepie amps still sound good. 8 years ago if you wanted a good amp you had to pay good money for it but if you are only running light gear i wouldnt worry too much about it. but ofc if you are running heavy compertition gear etc, the high end gear always pwns the cheepie stuff. in other words nice sound can be easy obtained with low cost new gear.. head splitting sound is a diff story

[TouringTash]

Cheers fella, looks like I'll be spending around a monkey on some Kenwood stuff, or would you say Alpine?

[e30maddog]

alpine all the way m8, kenwood gear is nothin on alpine, in my experiance anyway..

[BadDave]

I still use a (very)old skool RF punch 150HD (2x223W/ch)to power 4 4ohm 8" drivers and they offer just as much punch than the 2 12" Alpines with Alpine amp(2 Cu Ft enclosure)until I tweak the bass cube.

Tash. PM on it's way

[TouringTash]

cheers bud, just have to pull a few parts from a fragger and have a sweep up and I'll have a read, and no doubt a good think.

[jonny323i]

pm'd you e30maddog

[chu346]

Any idea on the size/design of a box for my sub, will it sound good?

Your sub wants a 1.6 cuft box with a 3" port 2.5" in length and it will sound as good as the sub can.

All the info is in the manual you should of got with the sub, or you can download it from www.pioneer.co.uk like I did.

If you want me to design a custom box for you, you need to give me the maximum box size you can have like I ask for.

[FMH]

Any idea on the size/design of a box for my sub, will it sound good?

Your sub wants a 1.6 cuft box with a 3" port 2.5" in length and it will sound as good as the sub can.

All the info is in the manual you should of got with the sub, or you can download it from www.pioneer.co.uk like I did.

If you want me to design a custom box for you, you need to give me the maximum box size you can have like I ask for.

i'l measure up the cabby boot when i see it next, its in the garage. just the height is an issue, i also want the side facing the front of the car parrallel to the metal cabin.

Should i face the sub forwards and cut a hole or two in the metal to allow the bass to travel through or is that not needed?

[chu346]

I wouldn't cut any holes.

I didn't on my old cab.

[mrLEE30]

Do NOT cut the rear firewall, it is structural. It is also unnecessary. The bass will travel through with no issues assuming your box is designed correctly. It also makes little difference which way the speaker faces.

[Rav335uk]

I wouldn't cut any holes.

I didn't on my old cab.

I haven't either,and the bass comes through OK

[FMH]

Do NOT cut the rear firewall, it is structural. It is also unnecessary. The bass will travel through with no issues assuming your box is designed correctly. It also makes little difference which way the speaker faces.

Reason i want to face the sub towards the front is cause i do not want any device visible when the boot is open. Will be fitting a mdf board and carpet over it.

[chu346]

I always had my boxes facing to the front of the car, but it's best to try it different ways because it can make a big difference.

[ImysE30]

Mine was cut and had no problems. I'd face the subs towards the cabin.

[mrLEE30]

if the reasons are asthetic the very good, but you can only fit a 10 inch sub upright under the rear shelf in a cab - hence why mine is angled, i also tried my box facing the rear seat and it made NO real difference, but with the angle part facing back it allows slightly more boot space (this is why i put a el cheapo grill over the cone - to protect it from junk flying around in the boot)

for info bass or low frequency waves travel outward from the source in almost all directions - and in a boot of a car you can argue it will move in all directions, thus it makes little difference which way the cone physically faces, what does make a difference is the distance to your ear as low frequency waves attenuate quite quickly, so the cone further away from your ear will make it sound different - but again in a car you tend more to feel the bass rather than hear it. high frequerncy waves do not display this pheonomenon and hence why your tweeters and mid range are best pointing straight at your ear. This is why the direction of the sub maked very little difference.

[chu346]

for info bass or low frequency waves travel outward from the source in almost all directions - and in a boot of a car you can argue it will move in all directions, thus it makes little difference which way the cone physically faces, what does make a difference is the distance to your ear as low frequency waves attenuate quite quickly, so the cone further away from your ear will make it sound different - but again in a car you tend more to feel the bass rather than hear it. high frequerncy waves do not display this pheonomenon and hence why your tweeters and mid range are best pointing straight at your ear. This is why the direction of the sub maked very little difference.

Whilst this is true, there is more to it than that.

The sound waves from the subwoofer can reflect and cancel each other out depending on box size, speaker and many other factors. So the best thing to do is to try the box in different directions if possible, because everyone here has got different setups in different types of cars.

[FMH]

I always had my boxes facing to the front of the car, but it's best to try it different ways because it can make a big difference.

chu, i haven't been to my car yet so didn't get measurements, but imy posted somewhere, so i thought i'd ask for a box designed please.

11" under the hood compartment (electric hood) and then 35" wide IIRC

i dont mind going wide as it has to be, but not too long

[chu346]

So you can go upto 35" wide, fine.

11" under hood, is that the height or depth? I recall that being the height on my old cab, so that means you can't fit your 12" speaker in the 11" piece of mdf on the front of the box.

If you want to build your box like this you need to buy one or two 10's and that will still be a squeeze.

To give you and idea when purchasing some subs. If the area under the hood lid is 35x11x11 that would give 2.45cuft. You can normally check the recommended box sizes online.

H x W x D = cuft
11x35x13=2.9
11x35x09=2

[FMH]

What if i was to make a box 11 inch high, x inch wide, etc etc, so the sub is facing up, would that work?

[chu346]

If you made a box that was 11" high, after adding the sub to the top how high would the box be? Is there enough room for that?

You can make a sealed box 17x10x10 that would fit. Don't know if it will sound any good, never tried it myself.

[rancido64]

All this talk of ohm drivers, RMS, box capacity and whatnot has gone miles over my head..
but...

I got a €50 gift card for Halfrauds for xmas and can't think of anything i really need from there as such so i'm considering buying a sub as my standard sounds are treble treble treble and i had intended on eventually upgrading all my speakers anyway.
So, a couple of questions;

The sub i'm considering is this one: http://www.halfords.ie/webapp/wcs/store ... yId_212567

Would anyone be willing to design a box for me? (to fit in the boot of a more door with as much boot space left usable as possible - i know, i don't ask much )

Also, I'll be adding some extra speakers into the rear shelf at some point (stealth styleeeeee under a cloth cover) but this is where things get way too complicated for me to fathom, what kind of power amp would i be needing to power both the sub and say a pair of 6x9's or some 3way component speakers?

Any advice, input or criticism welcome

[_Jay_]

Before anyone can recomend amp power, they need to know the exact speakers your getting because it will be different for each set.

[rancido64]

Hrrm, i'll have to do a bit of looking around then. Thanks

[chu346]

I'd say this amp would be good for you http://cgi.ebay.co.uk/ROCKFORD-FOSGATE- ... 2c55f693fa

This amp is 4x50wrms. So you would use 2x50 for the front speakers and bridge the remaining channels for the sub, the amp will then make 150wrms for the sub. I like the jbl subs, but you shouldn't push them with too much power so 150wrms will be more than enough.

Ask at halfords for a box.

[rancido64]

That's great, Chu, thanks for the info
I saw a box there in Halfrauds alright, but going by the quality of most of their own-brand stuff i wasn't overly keen to be going for it