I just purchased a tube amp head (Peavey Windsor). I don't currently have the funds for a proper cabinet, so I was considering rewiring my Line6 Spider 212 combo amp to behave as a 2x12 cabinet.

It doesn't have an external amp input jack or anything, so I presume I would have to disconnect the speaker leads from the combo "amp head" and wire in a phono input jack. I understand that I need to match the impedance of the speakers vs the amp output, but I have no experience with amp modification. Has anyone tried this? Is this even possible?

I will eventually purchase a Marshall 4x12, but I'd like to get some use of the head in the mean time.

3 Answers 3


You are correct- as long as you ensure the load is correct (eg 4 ohms) and you remove the existing connection to the amp it becomes a speaker cabinet.

Should be very straightforward.


I figured it out using Shavano Music as a reference for the wiring. Since both speakers are 8 ohms, when wired in parallel, the total impedance is 4 ohms.

2 speakers wired in parallel

I disconnected the original wires from the speakers and used a 1/4" phone jack from Radio Shack to connect a guitar/speaker cable to the speakers.

Rewired Line6 Spider

You can't see the phone jack in the photo, but the red-ish cable coming out of the Windsor head is connected to the speaker wire on the floor (via previously mentioned phone jack). I've since drilled a hole in the back center of the Line 6 near the top (directly below the Windsor output jacks) and inserted the 1/4" phone jack there.


Connection-wise...you're correct. The other thing to keep in mind is, though guitar and speaker cables both have 1/4" plugs...the wiring is much thicker (heavier gauge) in a speaker cable. As that amp is an EL34 (4 tube output) head, I would have just soldered a 1/4" plug onto the copper speaker wire I see there. Looks like it would reach. That would give you a proper gauged wire for the speaker connection. It will then free up the guitar cord for something different.

If you used the amp at high volumes for lengths of time, you could end up heating the guitar cable...possibly to the point of melting the separate wire insulators in the cable...hence, causing a short and possibly burning up the transformer on the amp.

Cheers! Brad

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