Rewiring a Mesa Cabinet;

[Lurch]

I have a recto cabinet with 4 Celestion 8 ohm V30's.

The jackplate has inputs for:

Mono 8 ohm total
Stereo Right 4 ohms
Stereo Left 4 ohms

I want to rewire the two stereo jacks so each input is 16 ohms instead of 4 (by putting each two sets of speakers in series instead of Parallel).

My confusion is where it connects to the 8 ohm mono jack. I still want that connection to be Parallel (still giving it a final mono value of 8 ohms) but the jack and the way Mesa wires it are very odd.

Has anyone seen this odd looking jack or have any experience with it? It has a built in mechanical switch that activates when a cable is plugged in. (instead of having an external ohm selector switch like a Marshall).

So my question is, if I only change the wires at the speaker connections, will that mono jack still be connected correctly in Parallel?

Someone has to have done this mod before. Any diagrams?

 

[Lurch]

I thought I'd post my solution so anyone else who needs the mod has the answer:




I figured it out by putting each side in series so in stereo they're 16 ohms each.

These two circuits were then put in parallel at the single 8 ohm mono jack by soldering the +'s together to the tip and the two -'s together at the ring.


I had to use two switching jacks for the stereo connections (the kind found in Marshall cabs) so both +/-circuits were broken when not using the mono jack. (since they are connected at the mono jack they would bleed over to each other there if the switches didn't break the circuit)



Anyway, the whole purpose is because I use a full stack and two amps in stereo. (my rack)

On a small stage I have to stack the 2 cabs and I run 4 speaker cords (R/L on top, R/L on the bottom). They're all 16 ohms, so each head see's 8 ohms. Before the mod it would have been 2 ohms per amp- meltdown!

On larger stages I run 1 cab Right and 1 cab Left so each head see's 8 ohms.

 

[siggy14]

the only downfall to your set up is, if one speaker blows you have no load on your amps and you will blow your amp. That is why it is always best to have a parallel circuit in your speaker setup.

 

[Lurch]

Very true, thanks for the warning. 8)