marky_g

although ive been fittin this for customers from time to time ive never understood any of it because im just told what to fit so here goes

i currently have 2 infinity reference subs but no amp for the pair

got 1 in my daily with a tiny amp i had laying round and it sound good for what at it is im rely happy with it

this is the confusing bit

to find the best amp for the set up do i find the rms of the sub and match to the rms of the amp ?

so if there 100w each i need a 2 channel 200w amp?

will it say what ohms on the sub itself? this is also a point of confusion lol

also finding it hard to find amps advertised with RMS figures

cjwood555

Yeah that's roughly right. You can, however, wire the subs in parallel and connect to one amp channel.

Assuming they are 4-ohm subs, the load becomes 1 / (1/4+1/4) = 2ohms

Most car audio amplifiers will be happy at 2-ohms, especially those designed for subs.

The advantage of running and amp into a lower impedance is that you'll get more power out of it. It should go up in negative proportion (i.e. half the load, double the power) although the power may be limited by the amp's max current so you might not quite get double.

Something like a second hand Genesis Profile Sub would do you nicely.

Chris

Dal_

iTrader: (2)

^^ What he said ^^

I've a decent Pioneer amp that'd be happy to run them for sale.

https://passionford.com/forum/alloy-...ion-100-a.html

cjwood555

Puma_dal's amp would do you nicely for the subs - and give you 4 channels for amping the front/rear speakers.

This would be useful if your head unit doesn't have a HPF facility for the front/rear speakers. (Subs do low - use a LPF (low pass filter), front/rears do high - use a HPF (high pass filter)).

cjwood555

P.S. if you want some nice cables making up give us a shout

marky_g

christ this is all abit involved thats what a read on the net and confused the shit out of me lol i hadn't given any thought to amping my other speakers they just run from the head unit at the moment. So assuming i have 200watt rms subs i'd wither want 400 watt 2ohms 2 channel amp or 200watt 4ohms single channel? And run them parallel

cjwood555

You can run them with whatever amp you want - it's generally better to run with MORE power than the subs are rated at than not enough, so long as you don't use it at full volume, obviously. This is because over-driving the amp will cause clipping which destroys speakers.

You've got your sentence back to front - 200 watts per channel @ 4ohms, 2 channels; or a 400watt @ 2ohms single-channel amp.

You could also use a bridge-able 2-channel amp - when bridging, power double for the given impedance. So a 100WRMS @ 4ohm 2-channel amp, bridged into a 4ohm load = 200WRMS (in theory), or into a 2ohm load (your speakers paralleled) = 400 WRMS. You're actually likely to get slightly less, so probably need a 150W channel amp.

N.B amp must specifically support bridge mode.

Chris

marky_g

right this is all getting very confusing what idealy should i look for so i could try and buy that so its as effective and efficient as possible?

marky_g

Think is abit over kill for my needs bloody good price tho

marky_g

anyone?