One more Idiotic Question regarding Ohm's and all that!

lamf68

the 2 pics I've included here have had me perplexed all evening. My newly acquired Artisan 30 head and 2x12 cab have a couple of options regarding input, can someone explain to me the choices I have with them..When I bought it off Gareth1973 from here the head was set to 8 ohms, should I leave it like that what input on the cab do I plug it into. Next question, if I turn that dial on the amp to 16 what do I plug it into then....and finally what difference does it make if the amp is set to 8ohm's or 16ohms, is there any benefit to fannying around with the impedence selector on the amp, and if theres no point me twiddling with it, why is it there in the first place.

ive no doubt your probably spewing at my lack of knowledge here, but every cab/head I've had in the past I've always (at least I think so) had the head set at 16ohms...cheers for any help lads.

Jaden

ok, the mono input on the cab is 8 ohms so if you usually just plug one speaker lead from the head to the cab, use the 8 ohm input to the cab.
the output impedance is set correctly right now so leave that alone.
use either output from amp to match impedance to cab

paulmapp8306

Yep.  
Using the left input will auto switch the cab to stereo - where each jack will feed one speaker only, therefore the impedance for each input is 16 Ohms.  Useful if your feeding it a stereo output from an FX unit.  

For normal use - just plug a single cable into the right socket, and set the amp to 8 Ohms as it is.

lamf68

paulmapp8306 said:

Yep.  
Using the left input will auto switch the cab to stereo - where each jack will feed one speaker only, therefore the impedance for each input is 16 Ohms.  Useful if your feeding it a stereo output from an FX unit.  

For normal use - just plug a single cable into the right socket, and set the amp to 8 Ohms as it is.

Are you saying use the input that has the word Right on it, or the one you're looking at in the picture which actually says Left...

ICBM

Use the 8 ohm mono input on the cab and set the amp to 8 ohms.

The reason the amp has a selector is so you can use different cabs, or two cabs (two 8-ohm cabs is a 4-ohm total load, for example).

It's not meant to be used for anything else - you *can* run it with the amp and cab mismatched, but there is a small risk of damaging the valves or in rare cases the amp, so it's best not to really. You will always get the most power and the fullest tone with them matched, as well as the longest valve life.

steamabacus

To clarify this, the cab can be used in two different ways

MONO - from a single amplifier (of up to 120W, 8 ohm output), use the input labelled 8 Ohms mono input 120W above the socket.

STEREO - from two amplifiers (of up to 60W, 16 ohm output), use both inputs labelled 16 ohms left/right stereo 60W/ch below the sockets.

It might be wise just to put a piece of gaffer tape over the 16 ohm right input just to prevent mistakes (on a darkened stage, for example). If you did use just this input, you would only be using a single speaker at 16 ohms.

lamf68

lovely...cheers