Adding ext speaker jacks. Any 'rules'?

[RichardG]

I have a couple of amps that I want to add external speaker jacks to (ie they don't have one at the moment), mainly as I have a great old Vox 15-inch speaker that seems to sound great with any amp.

My DIY solution would be to take the existing speaker wires in the amp to a new jack socket, then take the speaker output wires in the amp to a jack plug. Then I could either plug in the internal speaker or an external one.

Seems simple to me BUT I want to check: is there a risk associated with possibly plugging in speakers with ohm ratings different to the speaker in the amp? I know next to nothing about ohms by the way (as you can guess), hence this plea for sensible advice before I start blowing amps up!

[Kommerzbassist]

Re: Adding ext speaker jacks. Any 'rules'?

Seems simple to me BUT I want to check: is there a risk associated with possibly plugging in speakers with ohm ratings different to the speaker in the amp? I know next to nothing about ohms by the way (as you can guess), hence this plea for sensible advice before I start blowing amps up!

Yes, plugging in a speaker with the wrong rating can damage your amp. You could look at manual of your amp where it will tell you what kind of speaker you got in there right now... then compare it with the rating of your cab.
Also make sure your external speaker can handle the power your amp puts out. As it is old it could be kinda low raten wattage wise...