Cab ohms

[Bellyheart]

I have a 16ohm cab and a head that can be 4, 8, or 16. I noticed a sound difference in the other plugs but don't know the consequences. Any ideas?

[elbandito]

I plug my Peavey Classic 50 amp into my 16ohm 2x12 cab, but use the 8ohm out. I find it makes everything sound a little punchier and seems to have slightly better bass response. I don't know the technical reasons behind why this is but I know there's a significant difference in the tone. It hasn't wrecked my amp or my speakers yet...

[Astricii]

Highlighted relevant info if you want to skip the rest.

Speakers function by the coil of wire making a magnet move. impedance is the overall resistance of any circuit. Imagine your amp punching a brick wall (infinite resistance) vs punching a wall made out of a sliver of latex (near zero resistance) when the speaker moves back into position after going out it makes a voltage just the same as your guitar string does when it moves in front of the pickup. that voltage and current backlashes into your amp. setting up the output impedance of your amp helps deal with that in some way.

From what I understand, solid state amps don't have the same kind of output stage design or transformer that tube amps do. this is why they have a minimum impedance. if any lower impedance (overall resistance) is used. then the speaker has less resistance than what the amp is expecting and current flows faster (i'm a little hazy this early and new to this electronics thing so please correct me) which can heat up things in your amp and make it go Kaboom.

Think of a tray filled with water on one side you have the output of your amp and the other is your speaker. the water is current (go figure) when you play something it's like tilting the tray toward the speaker side and curent goes out. hits the speaker and makes noise. then as the speaker returns it's like the little waves that come back. now imagine some blocks or something to stop those waves. that's resistance. it slows down or lessens the current which keeps your amp from getting flooded and burning up.

I make no claim to be an engineer. but from what i've read that's about the best description of how it all works

So if you're running a 16ohm cab at 8ohm on your amp it just means your amp is sending more current to the speakers not sure if that is bad for them or not though. usually you're safer going higher or lower by a factor of 2.

a 4ohm Bassman can take 2ohm fine

My 8ohm Hotrod can take 4ohm fine but 2 ohm wouldn't be a good idea.

etc.

ok I gotta go to work . Hope that helps.

[Bellyheart]

So running it at 8 ohms would be alright?

[elbandito]

So running it at 8 ohms would be alright?

sounds like it... plus, mine hasn't blown up yet so I say do it.
then again, the Classic 50 is a tube amp with a solidstate rectifier... what amp are you using, JahSoul?

solid state amps don't have the same kind of output stage design or transformer that tube amps do.

what's the significance of this? and thanks for the info!

[Scruffie]

As far as I know regards damage, the rule is, you can mismatch ohms as long as you mismatch lower rather than higher...

So that means don't use a speaker cab rated for lower than what's being outputted by the amp or else you can blow the speaker and output transformer.

So a 16ohm amp into an 8ohm speaker, bad, a 8ohm amp into a 16ohm speaker, okay.

[Astricii]

Solid state amps you don't want to go lower than the minimum impedance.

tubes are usually ok going lower by a factor of 2 so 4 can go down to 2ohm 8 can go to 4 ohm etc.

higher impedance is generally ok for solid state amps. Tube I'm not sure.

[elbandito]

Here's some more info I found about amplifiers and ohmage: http://www.legendarytones.com/ohms.html

The answer to the first question regarding whether a 16 ohm cabinet can be run safely with an amp that has settings for 8 or 4 ohms is yes. However, when running the head at a lower ohm rating then the cabinet, the result will be a significant degree of power loss. In the second case of using a 4 ohm cabinet with an amp that must be run at 8 ohms, this will stress an amp and cause it to overheat. Technically, you’ll get more power output (not efficient or stable power output mind you!) to some degree, but again, at the expense of burning out a transformer and/or other components. Not a good idea!

[Bellyheart]

Sweet, new tones here I come...and call me Jon.