Help with wiring!!

[mikelitzguitar]

I have a modded combo amp that is re-wired to an output jack to allow expansion to a speaker cabinet. However, the way I have it wired, when a cab is plugged in, sound only comes out of the cab, and when a cab isn't plugged in the sound comes out of the combo speaker. Is there a way to wire the speakers in the two amps so that when I plug the combo into the cab sound will come from both speakers?

 

I currently have the modded combo wired like so:

 

The wire running from the amp head, originally attached to the positive terminal on the combo speaker is re-routed to the switch tip on the 1/4" jack. The wire running from the amp head to the negative terminal on the combo speaker stays. Another wire runs from the negative terminal on the speaker to the switch sleeve (ground) on the jack. And another wire runs from positive terminal on the speaker to the ring terminal on the jack.

 

 

The speaker cab is wired like so:

 

The negative terminal is wired to the switch sleeve on the jack. The positive terminal on the speaker is wired to the switch tip on the jack. And there is a wire running from the negative terminal to third conductor on the switch as a ground.

 

 

 

Sorry it's such a long thread but I hope someone will read it and have a solution as to how I can get sound coming from both speakers when a cab is plugged into the modded combo... THANKS

[guitarbilly74]

first question should be do you have the option to change the impednace on the amp? Because adding another cab will chnage the impedance no matter what?

 

Second question is what are the internal speaker and extension cab impedances?

 

At any rate, there are 2 options here:

 

1- parallel wiring:

 

cut the wires from the amp in half and add a pair of wires to each end.

one +/- pair goes to the speaker, the other pair goes to a jack

 

2- series wiring:

 

leave the wires on the amp as is but solder an extra wire to each speaker terminal. solder the other ends of those wires to a jack.

 

The impedance of the speaker/extension cab and what impedance the amp is capable of handling should determine whether you should use parallel or series.

[mikelitzguitar]

You sound like the right guy to talk to haha. Well the speaker in the combo is 8 ohms and the speaker in the cab is 8 ohms also. The cab does not have the cabability to switch impedances. Do you think that If I like everything exactly as is, but just added another jack wired to the positive and negative terminals in the combo that this would give me the option of plugging in to the original jack and playing through just a cab, or plugging in to the new jack that were talking about to play in a series and play through both speakers?

[guitarbilly74]

You sound like the right guy to talk to haha. Well the speaker in the combo is 8 ohms and the speaker in the cab is 8 ohms also. The cab does not have the cabability to switch impedances. Do you think that If I like everything exactly as is, but just added another jack wired to the positive and negative terminals in the combo that this would give me the option of plugging in to the original jack and playing through just a cab, or plugging in to the new jack that were talking about to play in a series and play through both speakers?

 

 

2 8ohm speakers in series will double the impedance to 16ohms. If it's a tube amp, I don't recommend it unless it has a very hefty OT.

 

If it's a solid state amp it is fine but it will cause the wattage to drop and reduce the headroom.

[mikelitzguitar]

Funny situation, it's a peavey vypyr, and has "transtube" technology. Its part tube, part solid state. I may sound dumb but what is a "hefty OT"? And what do you mean by reduce the headroom? What would you reccomend I do?

[guitarbilly74]

 

Funny situation, it's a peavey vypyr, and has "transtube" technology. Its part tube, part solid state. I may sound dumb but what is a "hefty OT"? And what do you mean by reduce the headroom? What would you reccomend I do?

 

 

1- Transtube is not part tube part solid state, it's all solid-state just voiced to be more tube-like.

 

2- OT is the output transformer

 

3- headroom is how much you can turn up the amp before it starts clipping

 

4- with this amp, I recommend you do nothing just keep it the way it is now. But you INSIST in doing something look at the series wiring procedure I put on my first post. But it will reduce headroom and power and 75w SS is not much to begin with.

[mikelitzguitar]

I was told the vypyr was part tube! Weak... anyways, the 2 speakers have very different sounds so I thought it would be cool to have them both playing at once. I suppose I can always try it out and see if I like it. I have an EQ that displays clipping to let you know if ur clipping so if that happens I can adjust. Thanks for all the advice, Very helpful!

 

+1!!

[mikelitzguitar]

Wouldn't parallel wiring be better then if wiring it in a series will reduce headroom and power?

[madryan]

 

Wouldn't parallel wiring be better then if wiring it in a series will reduce headroom and power?

 

 

Parallel will create a 4ohm load which will most likely blow up the amp.

[guitarbilly74]

Parallel will create a 4ohm load which will most likely blow up the amp.

 

 

this

[mikelitzguitar]

Ah, ok

[mikelitzguitar]

Hey, thanks a lot for the advice, I added another jack to the combo in addition to what I explained in the original post! The jack adds the option of playing through both amps in a series and it sounds really good!! So thanks again man!