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[Graham]

im looking at an ampeg bass combo on amp on ebay which has an extra output on the back for another speaker cab. the back pannel on the amp says the max load is 4 ohms. the speaker cab i have just now (ashdown 4x10) is rated at 8 ohms. does that mean its not possible to use the cab with the combo? if its not possible would it just not be able to power the cab or would it damage it?

[Strat Harry]

Originally Posted by Graham

im looking at an ampeg bass combo on amp on ebay which has an extra output on the back for another speaker cab. the back pannel on the amp says the max load is 4 ohms. the speaker cab i have just now (ashdown 4x10) is rated at 8 ohms. does that mean its not possible to use the cab with the combo? if its not possible would it just not be able to power the cab or would it damage it?

yep, ideally you want to match the impedances, if you cant match, the 4ohm output impedance rating on the amp means it can drive the current required that a 4 ohm speaker would draw. in your case the impedance you are driving is larger (8 ohms) meaning it will not draw so much current, ie should be ok.

i'm not familiar with ashdown cabs, by any chance does it have a small selector switch on the rear? this might give you an option of 4, 8, 16 ohms.

the other point, can you tell me what the impedances of the four speakers are?

[soundian]

I think the 4 ohm max is more to do with possible damage to the amplifier if you attach a higher load than damage to the speakers.

[Graham]

Originally Posted by Strat Harry

yep, ideally you want to match the impedances, if you cant match, the 4ohm output impedance rating on the amp means it can drive the current required that a 4 ohm speaker would draw. in your case the impedance you are driving is larger (8 ohms) meaning it will not draw so much current, ie should be ok.

i'm not familiar with ashdown cabs, by any chance does it have a small selector switch on the rear? this might give you an option of 4, 8, 16 ohms.

the other point, can you tell me what the impedances of the four speakers are?

i dont think the cab has a selector switch but i'll have a look. this is my cab here Ashdown Engineering | Bass Amplification im not too sure what the impendances of the speaker are. had a look at the specs of it on the website but didnt see anything.

Originally Posted by soundian

I think the 4 ohm max is more to do with possible damage to the amplifier if you attach a higher load than damage to the speakers.

so i shouldnt do it then? wouldn't want to get the amp then to damage it.

this is the amp im looking at by the way Ampeg bass combo SVT-100T 100W 2x8" + tweeter on eBay, also Bass, Amplifiers, Pro Audio Equipment, Musical Instruments (end time 23-Apr-08 21:13:19 BST)

[Strat Harry]

Originally Posted by soundian

I think the 4 ohm max is more to do with possible damage to the amplifier if you attach a higher load than damage to the speakers.

ian:

have you ever seen a higher load than 4 ohms on a cab, ie 2 ohms? i haven't.

i do agree with you though, the 4 ohm rating is to protect the amp, not the speakers.

graham:

quick way to blow an amp, attach no load at all ie no speaker and you will probably cook your output transformer... or do it slowly by connecting a 16 ohm amp output to, say, a 4 ohm speaker (load)

do you or dont you? i think it will be ok, may sound brighter/ toppy, i am guessing though, give me a sec, i'll see what i can find.

[stuartmaxwell]

can only agree with what has been said here.

is there two outputs from your amp? i.e one to the speaker and another one?

[jamesbroonbreed]

an 8 ohm speaker into a 4ohm amp output is fine but it'll only use half the wattage kind of.

don't know technicalities but that is wot my old amp was

[Graham]

yeah there is 2 outputs on it.

[soundian]

Originally Posted by Strat Harry

ian:

have you ever seen a higher load than 4 ohms on a cab, ie 2 ohms? i haven't.

I take it you meant lower. No, don't think I have but that's probably because most amps can't handle 2 ohms loads.

[soundian]

I had a look, it says 4 ohm minimum total load impedance, not maximum.
I thought that was a bit strange having a max load.