Will it do any harm?

Jimmy Gibson · From: Cornwall, England

I have been thinking about using my 4ohm Black Widow speaker cab as an extension speaker with my Yamaha G100 112 combo the speaker in the amp is 8 ohms.

Would this or could this do any harm to the amp?

Thanks Jimmy G.

Dickie Whitley · Posted 9 May 2013 2:16 pm

Donny Hinson · From: Glen Burnie, Md. U.S.A.

It's probably not a good idea. Amp manufacturers usually recommend that if you use an extension speaker, that the extension speaker should have an equal or higher impedance than the built-in speaker. In your case, the total impedance would be less than 3 ohms, and with you driving the amp harder (the usual reason for using external speakers) there is a chance for overheating and subsequent damage. This is an earlier solid-state design, so it's not heavily protected like most modern amp.

Dave Mudgett · From: Central Pennsylvania and Gallatin, Tennessee

I agree with Donny. With a solid-state, direct-coupled amp like this, the lower the impedance, the harder it is on the output section of the amp. Assuming the extension speaker jack is wired to parallel the main speaker, the combined impedance of both speakers would be 1/(1/8 + 1/4) or 2-2/3 Ohms.

Most solid-state amps like this have a minimum impedance, and that value is typically (not always) 1/2 of the nominal rated impedance (in your case, 1/2 of 8 Ohms or 4 Ohms). There are some solid-state amps like this (the Lab L9 amp comes to mind) which permit NO impedance lower than the rated impedance - i.e., rated for 8 Ohms means don't use any load less than 8 Ohms, period.

So I absolutely wouldn't do it unless you can verify that the minimum rated impedance is 2 Ohms or less. But even then, I probably wouldn't run it less than 4 Ohms regardless. That would mean an 8 Ohm main speaker and an 8 Ohm extension speaker.

Jimmy Gibson · From: Cornwall, England

Thank you guys..

Jimmy G .

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