Impedance

What is the impedance of my cabinet?

Your cabinet should have a model number and rating plate on the back, if there is no rating plate the cabinet will need to have the impedance measured by an engineer. We do not recommend using the cabinet until the impedance has been checked as it could damage both your amplifier and cabinet if either is used incorrectly.

If your cabinet has a rating plate the impedance of the cabinet must match the impedance of the amplifier you are connecting it to. For example our standard mono 1960A/B will have an impedance of 16 Ohm. The 1960A/B stereo cabinet has a selectable mono impedance of either 4 or 16 Ohm and a stereo impedance of 8 Ohm.

Impedance ratings for all our current cabinets can be found in the applicable product sections on this website. If you would like any specific information on an older cabinet which has no rating plate, then please e-mail us with a description of the cabinet and details of the speakers fitted along with some good quality photographs. We will do our best to tell you the impedance.

Which Impedance speakers do I need to work with my amplifier?

The impedance of your cabinet should match the impedance stated on the back of your amplifier. With regards to valve amplifiers these will normally have a selector or different speaker sockets for different impedances.

Can I change the impendence of my cabinet?

To change the impedance of your cabinet will depend on the impedance of the individual speakers. If your 4 x 12″ is fitted with four 16 Ohm speakers it can be wired for 16 Ohm mono, 4 Ohm mono or 8 Ohm stereo. If the 4 x 12″ cabinet is fitted with 8 Ohm speakers this can be wired for 8 Ohm mono, 2 Ohm mono, 16 Ohm stereo or 4 Ohm stereo. If you have a 2 x 12″ cabinet fitted with 16 Ohm speakers this can be wired for 8 Ohm mono or 16 Ohm stereo, or if you have a 2 x 12″ fitted with 8 Ohm speakers this could be wired for 4 or 16 Ohm mono or 8 Ohm stereo. All work of this nature must be carried out by a qualified engineer.

Can I convert my cabinet to stereo?

Any 2 x 12″ or 4 x 12″ cabinets can be converted to stereo providing the amplifier you wish to use it with can match the impedance and the speakers can handle the power of the amplifier. All work of this nature must be carried out by a qualified engineer.

What extension cabinet will work with my combo and which impendence do I set my amplifier on?

Most of our combos have an extension cabinet designed to match its size and sound. Our website has full details of which combos and extension cabinets work together and the user manuals, available to download from the support section, give full explanations on how to connect them. We recommend going to your local Marshall Dealer so you can test out the combos and cabinets to see which one suits you the best.

Can I still buy the old style impedance selector for my amplifier?

Unfortunately the old style selectors are no longer available. We recommend having it replaced with the new rotary selector. All work of this nature must be carried out by a qualified engineer.

What do you mean by impedance (Ohms)?

Impedance is the load connecting to the speaker socket on the amplifier or combo to give maximum power transference. This must match the stated impedance value on the amplifier or combo to ensure no damage can be caused to the speaker or amplifier.

Does the user manual have the different impedance settings in it?

Most of the user manuals show where you connect the speakers and the impedance either by using a selector switch or different speaker sockets. All our manuals are available to download from the support section on this website.