Ohms

[BassBus]

Can anyone explain how speaker resitance works in layman's terms. Will an 8 ohm speaker work with an amp that fires into a 4 ohm speaker. It all just baffles me.

[Stewart]

Have a look at this first:

[url="http://wiki.basschat.co.uk/info:amps:impedance_and_wattage"]Wiki entry[/url]

[josh3184]

8 ohms plus 8 ohms makes 4 ohms. Its very simple really

[EdwardHimself]

Okay it's pretty simple. If it's a solid state power stage then you can plug the amp into a speaker different than the rated impedance (or impedance range) of the amp, however it won't be as loud and it'll reduce the life span of the amp. The way to work out impedances is pretty simple really:

For paralell curcits (which is what it'll be from the amp to the cab, it usually is) then 1/total impedance= 1/cab 1 impedance + 1/cab 2 impedance etc....

So if you have 2 8 ohm cabs, the total impedance will be 1/8 + 1/8= 1/4 so the total impedance is 4 ohms.

[EBS_freak]

[quote name='EdwardHimself' post='477799' date='May 2 2009, 04:48 PM']If it's a solid state power stage then you can plug the amp into a speaker different than the rated impedance (or impedance range) of the amp, however it won't be as loud and it'll reduce the life span of the amp.[/quote]

Not true.

Only if the speaker load is less than the rating of the amp will it cause your amp a problem.

eg running an 8 ohm load on your 4 ohm amp is fine... and you'll find that you'll reach the limit of the speaker before the amp runs out of puff... (assuming you have a moderately high output amp)

[BassBus]

Thanks for the replies guys. So it would be OK to run my Acoustic Image Contra out into a 15", 8 ohm cab. The AI site states that the amps detect different impedences down to 2 ohms. The internal speakers are 4ohms. Ta!

[bassbloke]

[quote name='EdwardHimself' post='477799' date='May 2 2009, 04:48 PM']Okay it's pretty simple. If it's a solid state power stage then you can plug the amp into a speaker different than the rated impedance (or impedance range) of the amp, however it won't be as loud and it'll reduce the life span of the amp. The way to work out impedances is pretty simple really:

For paralell curcits (which is what it'll be from the amp to the cab, it usually is) then 1/total impedance= 1/cab 1 impedance + 1/cab 2 impedance etc....

So if you have 2 8 ohm cabs, the total impedance will be 1/8 + 1/8= 1/4 so the total impedance is 4 ohms.[/quote]

running a amp that handles 4 ohm minimum load into an 8 ohm cab won't hurt it in the slightest. In fact, the sound of a higher rated cab may even be preferable - it's likely to sound much smoother than an otherwise identical but lower impedance cab.