How many amps do you need?


Staff member
Deal, Kent UK
A3 1.4 TFSI 150 COD
When setting up car audi with a large bass speaker and say 6 or more mid range and tweeters would you use 1,2 or 3 separate amps? What are the benefits of having a separate amp for each speaker/woofer?
The basic idea is supposed to be 1 amp to 2 subs. But it depends on the amp's power. The speaker's are just for putting out the sound, but stock speakers will need replacing if your putting a big system in. Although, extra speakers should increase the sound quality. A lot of stock speakers rattle just turning up a cd player too high. Seperate amps also depend on the power you trying to achieve. I don't think it makes a difference if you use 1 amp or 2 amps to get the same power (i.e. 1 500 watt amp or 2 250 watt amps). Don't forget that the size of the subs will also increase the bass. 12/15 inch subs are a good option, but go with high powered amps. Although I've never done it, I think this is about right! Another thing to think about is will you ever want to put shopping your boot, if not...go all out, but if yes...your gonna be limited.
Just do what pimp my ride do, put one amp in the car for every brake horse its got.

so what happens with folk who have 250-300 bhp thats not much room for the subs :D

im running 2 12" sony subs with max power 1200w each ( i think there around 700w RMS )but im running them off 1 alipne 1000w monoblock amp with the subs insatlled in series ( +ve from amp to +ve on 1st sub, -ve 1st sub to +ve 2nd sub and -ve 2nd sub to -ve amp

i have tried them in parallel but it kept tripping the amp out for some reason every time the bass jumped too high. i also tried running them independently ( 1 amp each) but this caused to much problems with trying to get them going at the same time as well as only one would adjust gain from the headunit although the wiring was spilt between them, something i couldnt work out same rca leads went to both and all 3 amps at the time were feed by a relay operated by the remote wire (used a relay as had neon light installed as well :oops: so they only came on with the stereo)

as prince said if your going to use the boot your limited i currently have the preamp (lifts the headunit voltage up so the amps not working as hard currently set around 7v, head supplys 4.5), amp, power cap, distribution fusebox (1s unused put i couldnt be bothered buying a single one when i had a twin one anyway )and both subs in a sealed box which measures approx 900mm x 420mm x 400mm made outo 15mm plywood (better for the bass than MDF but more expensive) it weighs a ton but within 10 mins i can have it in the flat and have a empty boot otherwise ive still got use of around half of it

looking at redesigning it as want to sit the subs up to take up less room

but in answer to the original forum heading im using a 40amp fuse as 30a one blew while setting up the amps

in answer to the question

i would use 3 amps (1 mono & 2 2channel) or 2 ( 1 mono and 1 4channel)

so the mono can run the sub and the 2channel ones ( or single 4 channel) can be set up for front and rear speaker for better control
4 speakers in the back controlled by 1 set of channels or 1 amp and 2 speakers up front controlled by the other set or amp

should say just incase anybody doesnt know
  • mono / single channel - only 1 speaker output, mainly for a sub
  • 2 channel - 2 speaker outputs. 1 left and 1 right
  • 4 channel - 4 outputs 1 front left , 1 front right and 1 rear left , 1 rear right
goes the same with 6 and 8 channels amps
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In my Ibiza i currently have 2 JBL 12 channel amp (1200W) and one JBL Sub (1200W)

connected into the amp i also have 2 x 6X9 in plywood and 2 door mounted tweeters and 2 subs infront connected to 2 crossovers

and for me that causes enough music

some things i have learnt on the way:

never stretch on the cables expence, i think getting high quality cabling makes the sound in your car i noticed the difference.

use plywood to mount your speakers, it provides a realy indistructable surface and makes them sound great.

try and find the rattles, it bugs me when you hear little noises in the car because things are rattling from the bass.

but thats me anyone else know of any other tricks?
Sure i will put some on soon as i get 10 posts

1 ment to write 1 amp, i dont need 2 with so little speakers lol. typo :s
right couple of pointers more speakers will not give you better sound quality.
filling the car full of amps wont achive anything either .
mounting speakers on wood wont help but whats around them does use dynamatt or a sound deadening product tape or foam all cables to stop rattling .
and if you must use wood use mdf its denser than chip or ply but illeagle in the usa because cutting it causes cancer if not using a mask .

for most cars the simple way to achive a really nice system is a pair of nice components in the front .a good not cheap head unit 1 x4 channel amp and one twelve inch sub in box .
a sealed box will make the bass punchy and tight but a ported box will allow the sub to flex moving lots of air creating more bass .bass is what they call in the business spl Sound presure Level .
in an audi id recomend a good headunit two amps one four channel to power two sets of components front and rear and a two or mono block amp to either power two or one twelve inch sub the box ( ported or sealed ) depends on the music you like listening two . this is a very simple system but will sound very effective .

if you like fast beats like garage or house then use sealed
if you like rnb ragga hip hop then id recoment a ported box so the bass drops to deep frequencys.

back of asc audio s old a4

front components in builds

subs cut into rear shelf
Really handy tips there ASC - thanks! I thought the A4 had quite a bit of boot space. Not in yours though! ;)
There's little point in running more than one sub enclosure (two drivers in one box is fine) in a car. Mono is fine up to around 80-100Hz as human hearing doesn't have much ability to detect source of sounds at such low frequencies. Multiple subs can also lead to phase cancellation issues.

One of the biggest problems with cars and bass response is getting the pitch of the bass notes audible. Quite often all you hear is the start and end of 'em.

This is common when the subs to main X over frequency is too high and the rolloff curve is too steep. Pitch in bass notes is more often determined by the ear from the harmonic overtones rather than the fundamental itself. If the main (mid/high) speakers can't cross over smoothly into the sub's region the you get a trough in the response curve.

Bass units do need some motive power as well. You could mate a 4x25w RMS main amp to a 400w RMS dedicated sub amp without going over the top. Subs shift large volumes of air and need some serious current to do it.

That's also why they need a really meaty DC supply. 400 watts at 12 volts is nearly 35 amps load so it's best taken via a dedicated wire straight from the battery post (via a fusible link) . Dedicated earthing sorts out all manner of issues as well.
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:lol: You could be right - plus hes doing the reasearch on sport coils. Perhaps he's going to be a mobile auto electrician now :D
good reply hdi .
thing is unless you spend the money on a point of reference system with time analysis to get the right signals and frequencys which some humans cant hear youll never get the right sounds lets face it cars stereos loud thats it simple as lol
Good reply by you as well ASC - thanks.

No audio system is perfect, as is no pair of ears or any musical performance either. It's what floats your boat, I suppose.

Loud is subjective, and I like loud my way, you might like it differently.

What I do like is solid and extended low end response. I want to hear the start and end of each bass note, and it's pitch.

Whether it's orchestral, classical organ, or Neil Murray (Whitesnake) bass is worth more than booms and thuds.

Reproducing bass is ALWAYS a problem. Cars are not the best of environments for it.

Quite often a decent pair of cans gives more believeable results.
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