Changing a 2-way switch to a 3-way

[iant412]

So here is the general idea:

I have a double neck Carvin bass/guitar. It has 2 outputs & a 2 way selector to switch between the bass & guitar. The current 2-way switch has 6 terminals on it. It is wired such that on the guitar 1 wire goes to the pickup selector & 1 to the output jack. Same with the bass.

I want to be able to select either the guitar, the bass, or both. They each have volume controls for each pickup, tone control + coil splits.

Do I simply need a DTDP On/On/On switch?


Stock info on the guitar is here:
www.carvinmuseum.com/decade/images/80-dn640.html
Wiring info here:
www.carvinmuseum.com/decade/images/80-controls.html

As far as I know, and from what I can tell, no mods have been made to it...yet.

[wolf]

I'd say what you need is just a single-pole double throw center on switch. This is the switch found on the millions of Gibson Les Paul's and SG's but I wouldn't use the official Gibson switch. It is huge and requires a lot of wood to be removed from the guitar body.

[iant412]

Are you sure about that? There is a DPDT On/On in there now. Guitar On/Bass On. A single pole would only have 3 terminals. 4 terminals are being used right now. 1 wire from each volume control (bass & guitar) and 1 wire to each output jack (bass & guitar).

Don't I need a DPDT On/On/On?


I wire Bass volume to top right terminal, Guitar volume to bottom left terminal. Bass to jack middle right, Guitar to jack middle right.

Thus I am not using the top left or bottom right terminals. Should this not give me what I'm looking for?

Up position - Bass
Middle position - Bass + Guitar
Down position - Guitar

[wolf]

iant412

Here's how to do this with a SPDT center-on switch:



and since I previously mentioned the Gibson type of switch, here is how that works:

[newey]

Bass to jack middle right, Guitar to jack middle right.

I think you mean "guitar to jack, middle left"

I'm a bit unclear on what you intend here, and the Carvin diagram doesn't help matters much, it's more stylized than informative.

As I understand it, you currently have 2 separate output jacks, one for the bass and one for the guitar. Currently a DPDT switch selects either the bass output or the guitar output, but not both at once.

Correct me if I'm wrong, but you want a 3-position switch to allow both outputs to be active at once. Presumably, you want to do this so you can be a-bassin', and just move over to guitarin' without flippin' a switch.

You should consider that, with both outputs active at once, sympathetic vibrations from the bass will likely induce a signal through your guitar pickups, which will also be active in the mid position. And vice versa, if you're on the guitar- although the bass is probably more likely to cause an issue.

I'm not sure the resulting effect is going to be to your liking. I suspect Carvin had a good reason for the either/or setup they used.

But, to answer your question, and assuming I'm right about what you want here, you are correct, you need 2 poles to feed 2 separate output jacks. Wolf's way of using a SPDT center-on would result in the guitar and bass outputs being combined (and going to both jacks at once); I don't think he understood you were talking separate outputs.

[iant412]

Newey...I think you are right.

Christian from El Ten Eleven modified his Carvin in a similar way. I talked to him about it, but he didn't do it himself so he didn't have specifics.

I put in the DPDT switch, however only one pickup each seem to work on both the bass & guitar and tone control doesn't work. I'm going to diagram out the wire routing that they had. Perhaps that will help.

Stay tuned.

Ian

[iant412]

Can anyone post a picture of the diagram that I drew? Does it have to be hosted somewhere & linked to?

[newey]

I put in the DPDT switch, however only one pickup each seem to work on both the bass & guitar and tone control doesn't work.

Inserting the new guitar/bass selector shouldn't have affected any of these things. If your wiring of the new switch were a problem, you'd either get no output at all in one or more positions, or not get the output you wanted at a particular setting. Does the new switch work as intended?

Sounds like you may have joggled a connection (or a couple of connections) loose in the modding process.

And, yes, a diagram would be a good start . . .

EDIT:
Iant-

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