Amp ratings

[Lunner]

Im slightly confused about a few ICE terms, i know that if you have an amp 4x100W RMS @ 2ohm that it has 4 channels and normal output is 100W per cahnnel, but i often see power quoted at different resistances (ohm values), i was wondering what this ment.

Also some infor on power caps, how necessary is it to have ne of these? At what level of power consumption shoudl you fit one? How do they work?

 

[MAXIBOY]

you need bambam. but rms@ 4ohms is what you want. at 2ohms the rms doubles so it looks better. apower cap stores energy so that it has back up when the subs really drop. if you need one depends on the battery cable and amps your using. you may or not need one. correct me if im wrong bambam?

 

[RB_172]

I understand that capacitor wise, they recommend 0.5 farads for every 500watts RMS of power.

Youre spot on about the rms/ohm values. Look for the 4ohm ones because thats what your speakers will be. If youre going to be running a sub off channels 3+4, look for the bridged values too. They wont generally quote 2ohm bridged values because very few amps support it.

 

[16vneil]

Caps are a total waste of money in my opion

Upgrade ur earths and a decent diesel battery should be more than goog enough for ur system

neil

 

[Rorrie]

they are rated at different ohms(resistance) as different speakers have different resistance. Eg a sub may be 2 ohm were as normal speakers are 4ohm.

They are also rated at 2x... into 4ohms - eg both pairs of chanels bridged into a 4 ohm load will give you ... .It also dictates to what ohmage the amp is stable to - as lower resistance more power output - more stain on amp ect.

If speakers are wired in parrell resistance is added, - eg 2 4ohm amps in parrelle - shows amp a 8ohm load to amp

If speakers are wired in series resistance is divided, - eg 2 4ohm amps in series - shows amp a 2ohm load to amp



RMS - is the constant power that the amp can out out - max power can be tweaked - thus is a useless figure to go by. as you can get 1000 maxpower amps with 20amp fuses!!



Power caps are of very limeted use - eg if you lights dip, but for very short periods eg under 1 sec, they may help - if longer - they wont - get a split charge with a yellow top battery



hth

Rorrie

 

[Dink]

Quote: Originally posted by Rorrie on 31 December 2003


If speakers are wired in parrell resistance is added, - eg 2 4ohm amps in parrelle - shows amp a 8ohm load to amp

If speakers are wired in series resistance is divided, - eg 2 4ohm amps in series - shows amp a 2ohm load to amp

I think that these should be the other way around

 

[Lunner]

thats wrong!!

In parallel it is 1/total = 1/r1 + 1/r2 etc.

inseries it is Total = r1 + r2 etc.

So in parallel if you have two 4ohm 1/total = 1/4 + 1/4

=1/total = 0.5

1/ 0.5 = 2

That is the correct way to work it aout, although for those resistances it gives the same answer, but I did A-Level electronics and that is the correct way.

 

[Dink]

whos wrong???

 

[RB_172]

Rorrie is wrong, lunner is right (and so were you therefore)

 

[16vneil]

DVC (Dual Voice Coils) Subs

1 x 2 OHM DVC Sub = 4 OHM Series or 1 OHM Parallel
1 x 4 OHM DVC Sub = 8 OHM Series or 2 OHM Parallel
1 x 8 OHM DVC Sub = 4 OHM Parallel
2 x 2 OHM DVC Subs = 8 OHM Series or 0.5 OHM Parallel
2 x 4 OHM DVC Subs = 1 OHM Parallel
2 x 8 OHM DVC Subs = 2 OHM Parallel
3 x 2 OHM DVC Subs = 0.33 OHM Parallel
3 x 4 OHM DVC Subs = 0.66 OHM Parallel
3 x 8 OHM DVC Subs = 1.33 OHM Parallel

SVC (Single Voice Coil)Subs

1 x 2 OHM SVC Sub = 2 OHM Series
1 x 4 OHM SVC Sub = 4 OHM Series
1 x 8 OHM SVC Sub = 8 OHM Series
2 x 2 OHM SVC Subs = 4 OHM Series or 1 OHM Parallel
2 x 4 OHM SVC Subs = 8 OHM Series or 2 OHM Parallel
2 x 8 OHM SVC Subs = 4 OHM Parallel
3 x 2 OHM SVC Subs = 6 OHM Series or 0.66 OHM Parallel
3 x 4 OHM SVC Subs = 1.33 OHM Parallel
3 x 8 OHM SVC Subs = 2.66 OHM Parallel

hope this helps

neil

 

[Rorrie]

yer sorry just read the post!! typing too fast for my brain!!