Amp to extension cab question

[kjrocks]

I have an 8 ohm second speaker out on my 1x12 amp. If I have an extension cab that has a 4ohm mono and 8ohm stereo setup what should I be doing? I know I shouldnt run it straight into the 4ohm but do I just use the 8ohm? What makes it stereo? Do I need to feed each input or something like that?
I'm just looking to keep my amp safe

 

[Rich_S]

Re: Amp to extension cab question

Plug one of the stereo input jacks on the cab into your 8-ohm extension jack on the amp. You'll end up with half of the cab running, though. How many speakers are in the cab?

 

[kjrocks]

Re: Amp to extension cab question

Its a 2x12. So I would need to feed both jacks with both my speaker outs rather than my internal speaker and probably switch the cab to 2 16ohm speakers?

 

[jeremy]

Re: Amp to extension cab question

yeah. i run two 16 ohm speakers in parallel for 8 ohms in my 2x12 so i can run the internal and the cab just like you want to.

 

[Rich_S]

Re: Amp to extension cab question

BUT...

assuming the speaker in the combo is 8 ohms, Jeremy's setup will put half the power into the combo's own speaker, and 1/4 of the power into each of the cabs (2) speakers. Not good or bad, just the way it works.

Another solution would be to unplug the internal speaker (if so equipped) and use two cables to connect the amps internal and external jacks to the two stereo inputs on the cab (with the existing 8-ohm speakers). That would give you the two cab speakers, sharing power equally.

 

[kjrocks]

Re: Amp to extension cab question

The two speaker outs from the amp say 8 ohms. So that doesnt mean there is 8ohms coming from each output? One going to the 8ohm speaker in the amp and one going to the cab inputs to be divided there?

 

[Reload in 5]

Re: Amp to extension cab question

The two speaker outs from the amp say 8 ohms. So that doesnt mean there is 8ohms coming from each output? One going to the 8ohm speaker in the amp and one going to the cab inputs to be divided there?

The cab inputs in stereo are 8 ohms per side, so if you plug into 1 only 1 speaker works. If you plug into both, you get a 4 ohm load.

On a side note, using 2 16 ohm speakers would give you 1/4 power to each cab speaker and 1/2 to the built in speaker, but the cab would still be 3db louder then the built in speaker.
I would try it with the 2 outputs running to just the cab, and try it with half the cab and the internal speaker running. See which you like.

 

[kjrocks]

Re: Amp to extension cab question

Thanks for your help guys and Rich_S, I get what you meant by power now. I was so focused on trying to understand to ohms I didnt realize your were talking about actual power
Thanks Guys

 

[kjrocks]

Re: Amp to extension cab question

Yes , I just came across 2 16ohm speakers I grabbed last year thinking I might build a 2x12 sometime, so I should be all set if I decide to swap the 8ohms out

 

[kjrocks]

Updated question, same cab

Updated question, same cab

I now have the cab and this is what I found. The back plate has the 4ohm input marked as use first and the other is the 8ohm input. If I plug into the 8ohm I dont get half the cab I get nothing. So I guess need to plug into both speakers and not the one in the amp or get different speakers in there?