Power output....ohms?

[jc_lark]

When a bass head is rated as 240 watts @ 8 ohms, and 350 watts @ 4 ohms, can some one explain what this means please?

For example, if I've got a cab with a power handling rating that says 500 watts, what am I getting from the amp?

[Noisyjon]

[quote name='jc_lark' post='847265' date='May 25 2010, 10:18 AM']When a bass head is rated as 240 watts @ 8 ohms, and 350 watts @ 4 ohms, can some one explain what this means please?

For example, if I've got a cab with a power handling rating that says 500 watts, what am I getting from the amp?[/quote]


If your 500 Watt cab is rated at 8 ohms then your amp will put out 240 Watts at full volume and, you guessed it, If your cab is rated a 4 ohms it'll put out 350 Watts at full volume.

Have a look at the Wiki at the top of the page for loads more info.

Cheers,
Jon

[jc_lark]

[quote name='jonthebass' post='847269' date='May 25 2010, 10:21 AM']If your 500 Watt cab is rated at 8 ohms then your amp will put out 240 Watts at full volume and, you guessed it, If your cab is rated a 4 ohms it'll put out 350 Watts at full volume.

Have a look at the Wiki at the top of the page for loads more info.

Cheers,
Jon[/quote]


Thanks for the prompt reply

[OldGit]

Short answer is that it's the ohms rating of your cab that makes the difference to how much oooomph your amp can put out.
So if you cab's ohms rating is 8ohms you'll have the potential to get 240 watts out of your amp. If it's 4 ohms you have the potential to get [i]{edit}[/i] [s]500[/s] 350 watts out.

[i]Sorry for the confusion, I misread your initial post.[/i]

There's a [url="http://wiki.basschat.co.uk/info:amps:impedance_and_wattage"]Basschat Wiki entry on Ohms (impedance) and Wattage here[/url]

Edited May 25, 2010 by OldGit

[Stylon Pilson]

And if you have two 8 ohm cabs, then their combined impedance is 4 ohm, and the power output will be 350W, shared equally between the two cabs (ie 175W each).

S.P.

[algmusic]

[quote name='Stylon Pilson' post='847275' date='May 25 2010, 10:28 AM']And if you have two 8 ohm cabs, then their combined impedance is 4 ohm, and the power output will be 350W, shared equally between the two cabs (ie 175W each).

S.P.[/quote]

what happens when you but a 8ohm can and 4ohm cab together?

[yorick]

[quote name='algmusic' post='848412' date='May 26 2010, 12:52 PM']what happens when you but a 8ohm can and 4ohm cab together?[/quote]

A potentially blown amp......

[algmusic]

[quote name='yorick' post='848418' date='May 26 2010, 12:58 PM']A potentially blown amp......[/quote]

Really?.. sh*T. I'm glad I only did it once years ago.. both cabs are paired the same at 8ohms

[Stylon Pilson]

[quote name='algmusic' post='848412' date='May 26 2010, 12:52 PM']what happens when you but a 8ohm can and 4ohm cab together?[/quote]

Combined impedance is (1/4 + 1/8) ^ (-1) = 2.66 ohm. If you are using an amp with a minimum impedance of 2 ohm then the power will be split in a 1/3 : 2/3 ratio (the larger share going to the 4 ohm cab). Your amp's minimum impedance is 4 ohm, so in your case, you would get fireworks.

S.P.

Edited May 26, 2010 by Stylon Pilson