This has been bugging me for a long time now, so i decided to do a post.

If i had a Sony 8" 500w sub do i have a amp with 500w out put as well.

do i have to match a Sony amp with a Sony sub?

when looking in mags why do amps have this. 2 X 80W or 1 X 250W

What to have 1 channel, 2 channels or 4 channels. Whats does this mean?

Ray

 

Ray,

In short, "no".

Bit more explanation...

Speaker ratings are notoriously inaccurate. If you try to put 500W through most 500W rated speakers you'll end up with a sad twisted mess.

one of the reasons is the box that a speaker is put in massively affects the power handling characteristics and response. As an example, if you use a ported box (box with a length of tube sticking into it) and "tune" the port to 100Hz or more, things will destroy themselves quickly with a little power. Reason is that the box provides no suspension underneath the port frequency, so isn't doing anything to support the speaker.

Amp power is slightly more realistic, but compare like with like. To get an accurate picture of an amp's power, you need to know the RMS (root mean square) power figure at a given impedance (normally 4 ohm) for a given level of total harmonic distortion (THD, normally 0.01% or thereabouts).

Many quote "peak" power output and some speakers quote peak power handling. It's good for pub talk, but that's it.

Amp and sub brands can be mixed quite happily.

"Channels" refers to the number of separate amplification paths in the amp (can't think of a better way of putting it, sorry). So a 2 channel has 2 inputs, 2 outputs and is used for a stereo pair. 4 channel has 4 inputs, 4 outputs, and gives two stereo pairs.

It gets more interesting with "bridging", too. On most amps, if not all nowadays, you can bridge a pair of channels to give you a single large output. So a 2 channel amp can be bridged to make a 1 channel amp. A 4 channel can have one pair bridged to give 3 outputs, or both pairs bridged to give 2 channel. YOu can't bridge a bridged pair (normally)

Finally, you've got the notion of "3 way" amps. This allows you to connect three speakers to a pair of outputs - a stereo pair and a mono speaker.

For flexibility if you're not sure what you want, I'd take a 4 channel every day. You can then run your front speakers from the amp, and bridge the other two channels left to make one output suitable for driving a sub.

Hope this helps.

Nick.

 

Another thing about matching power ratings.

It's nigh-on impossible.

Get an amp that is suitable for the job. If you "overdrive" your amp by turning the gains up too much, it'll clip the signal on the outputs, meaning that what was a smooth AC signal is now a DC signal. This destroys speakers.

A speaker wants to move. It doesn't want to stay still apart from at its resting position. If you apply a DC signal to a speaker, it will try to sit in one position as the voice coil (thing that makes it move) will be working against the suspension (thing that resists movement). The voice coil will heat up and before long will destroy itself.

So pick an amp with enough power to happily drive the speakers to the level that you want to drive 'em to.

Not an exacting science I'm afraid.

I run 2 JL 10W6s off a Rockford Punch 200. Strictly speaking, the amp is probably underpowered for the subs but as long as I know the limitations I'm fine.

Nick.

 

dont they say that you should find an amp which is roughly half the power of your sub??

Doesnt really work though as i had 2 JL 12W3s which were only rated at 250wrms each but they took alot more from my phoenix gold xs4600! lol

 

Thank you. Im sort of with you on that, but when i come to buy an amp and sub i'll think i'll come and ask you first .
You have not updated (finished) your web site for a long time. when is that happening?

 

Aaah, when I get a sudden rush of inspiration to do it. At the moment, it's a bit stagnant yes. Needs revamping.

I'm working on a new project at the moment (incar multi media player - immp) and that'll start being documented soon...

Nick.

 

i have a jbl 10W0 powerd buy a RF Power 400 amp the amp pushes 687W RMS the sub is not rated for anyway near that but it thumps away like a bitch

 

How about 3 x JL 10w6 powered by a Genesis Monoblock certified at 1200w RMS



[Edited by russell hayward - 11/20/2002 10:34:51 PM]

 

That'll do it Russell!!!! Given the rattles that my 2 have inflicted on the car, god only knows what's left of yours

 

i know a mate that has 3 Jl 12W3s in his punto running off a big alpine amp and that really shakes! Sit in the car and it vibrates right though you. Its seriously is mad!

Another mate has 2 15 mtx subs running of the mtx digitial amp and they move very nice! lol

 

Had all my kit transplanted from the P1 to the STI 7.

Well, what a difference. No rattles and it all just sounds so much better.

Didn't need any dynamat either.

 

thats really good!

Doesnt anything rattle then????

 

Russell

So the metals a lot thicker in the sti7

I've just about given up on my sti5 - with Genesis amps and Diamond subs ala Cheltenham Car Hi fi bits...

Just rattles to bits..... and thats with full dynamatting

Wonder what an Evo 7 is like?