Guitar Gear Forum

Hi, I've been considering on doing a speaker replacement in a Marshall Master Lead Combo. It currently holds a Celestion G12M-70, 12", 4ohm and puts out a approx. 35 watts. What do I need to consider when researching for a replacement? Strictly the impedance? Or do I need to consider the wattage as well? I understand that if I replace with a larger impedance, ie., 8 ohms, that the volume would drastically be affected. Any insight would be greatly appreciated. Thanks.

If that is the amp I think it is (there were a few varieties of Master Lead combos), that 4 ohm G12M-70 is stock. You will want to look for another 4 ohm speaker in order to match the impedance that the output transformer wants to see. A mismatch could potentially damage your output transformer.

As for wattage, a good rule of thumb is to at least match the wattage of the amplifier. I believe that amp is 30 watts, so look for something that is at least 30 watts. If you play the amp at high volume levels, you may want to bump that up a bit.

Summary: The stock speaker is 4 ohms and 35 watts, so get a speaker that is 4 ohms and at least 35 watts.

SS amp - yes the volume will be affected if it is higher ohmage than 4, but it won't really change the tone.

You want at least a 15 watt speaker, but there aren't many less than that, so you are pretty safe there.

Thanks a lot guys for the valuable info. I've been doing some research and there does not seem to be many to choose from, at least that are 12" and 4 ohm. I think I'll probably go with the Eminence Texas Heat 4... meets all the requirements and has really good reviews.
Cheers!