wiring question (I'm confused)

[zliminator]

New here, hi all. I'm wiring a new p.u. in and starting from scratch. I have a Custom custom by itself with only a volume control. I'm looking at 2 schematics. I took both diagrams and removed the switches and tone controls and boiled them down to just pu and outputs.

guitarnuts2.proboards.com/page/gn1-pages/wiring/shielding/compareschematics.php
and
www.1728.com/guitar.htm

the latter shows the volume as either pu -> output or pu-> gnd
the former (from guitarnuts sheilding) shows pu -> output or output shorted out.

wouldn't shorting out the (output) amp be bad? Are these 2 different or essentially the same?

Dan

[pete12345]

Technically speaking, you are inputting to the amp. The guitar is what generates the signal.

Both the connections you mentioned are essentially the same. The difference is the guitarnuts one has a separate 'shield ground' protected from electrical shock by a capacitor. The pickup- wires go to 'signal ground' which is ultimately connected to the jack. The '1728' diagrams connect the jack directly to the ground connection. In terms of the pickups, they are connected to the same place in both cases.

Pete

[ashcatlt]

There isn't actually any current flowing through the cable between guitar and amp unless the pickups generate it. All of the internal current of the amp circuit (not including "signal current") is DC, and generally blocked by a capacitor somewhere very close to the input.

Actually, there will be other current in the cable - that induced into it by way of electromagnetic radiation. That is, the cable acts as an antenna. It is prefered to ground the input of the amp, rather than grounding the pickup and leaving the amp's hot lead hanging. Makes the amp go (mostly) silent, rather than turning it into a lo-fi radio.


Edit - wow, only half a beer and I messed up that bad? This is the reason I don't get up before noon on purpose!

[sumgai]

ash,

I keep telling you, you have yet to "mess up" all that badly, just because you've imbibed a bit of Dr. Murphy's Snake Oil, errr, Miracle Tonic. Your answer to z was spot on.


~!!~!~!~!~!!~

zliminator,

Hi, and welcome the NutzHouse! ;D

You've heard about shorting the amp's input, and how that's a good thing at certain times. But you were specific in your question, and I'll adhere to the letter of your wording.

When dealing with standard guitar pickups (passive components), you can short the leads together, and there won't be any problems. The same holds true for all the rest of the parts inside of a guitar (or bass), where there are no batteries on board. In active circuitry, shorting anything unintentionally will bring on a case of the Major Blues, and I don't mean some kinda new scale, either.

Active or passive, the amp's input still wants to be grounded when there's no signal, to keep the noise down.

HTH



sumgai

[ashcatlt]

Yes, but you didn't read it before I edited did you? It was just some gramatical type stuff...

[ashcatlt]

BTW - Gibson uses the suboptimal "backward" volume wiring on their 2 pickup guitars (like the LP) in order that turning one pickup all the way down won't turn the whole axe off.

Some people around here feel that this is a little silly since if you want one of the pickups all the way off you can just use the switch. I think I agree with that, but have yet to change the way I've got my LP wired.