EB3 Volume Controls Question

Polkahero · December 30, 2010, 09:16:10 AM

Just want to confirm a response I got on another forum. Going through the varitone control on my 1970 Gibson EB3 it seems like there's a problem in the third (both pickups on) position. In order for both pickups to work I have to have both volume controls all the way up. If I turn either down, it turns off both pickups. Shouldn't each volume control affect its own pickup rather than both acting as a master volume? The other settings all appear to work correctly.

Nocturnal · December 30, 2010, 09:10:10 PM

Welcome to the Outpost Polkahero! Hopefully someone can chime in with some input for you.

Pilgrim · December 30, 2010, 09:28:44 PM

This sounds all too much like a problem I had with two pickups in an EB-0. The problem turned out to be that one pickup was wired backwards - reversing the leads solved both a hum problem and a similar volume problem. But the addition of a varitone makes this a different situation.

The other gents on this forum are more familiar than I with the EB-series wiring. i'm sure they will comment. But keep in mind that sometimes it's as simple as reversing the leads.

Question: have you (1) recently done any re-wiring on this bass, (2) gotten it from someone who may have messed with the wiring, or (3) is it supposedly the way it came from the factory?

jumbodbassman · December 30, 2010, 09:37:18 PM

If they were wired out of phase that would only happen when the volume was up full on both. I have no idea what the correct wiring should be on the switch but sounds like the switch is bad. Did it ever work or did this just start happening. if it just started i would guess it is the switch. I will take a few pictures of my e70's eb3's over the weekend and post so you can check that out.

Polkahero · December 30, 2010, 10:13:11 PM

Several years ago I had a local music store wire in a Dimarzio Model One pickup. I decided this year to put the original pickup back in which I wired myself. I've never really used that position on the varitone before (always used position 1, neck pickup only) so this is the first time I noticed this before. I've attached a picture on the innards if that helps at all. Thanks for the welcome, glad I discovered this site!

Highlander · December 31, 2010, 05:09:57 AM

That's an almost identical issue I have with a Mudbucker I fitted to my Peter Cook... no tone controls fitted and nothing I can see in my wiring...? as far as I can tell it is a resistance issue and the severely "unbalanced" nature of the circuit... the other pup is out of an RD Artist and has barely a third of the resistance value...

This is what the wiring should be in your beastie (from Jules' site)

Oh yeah... and welcome...

uwe · December 31, 2010, 06:38:36 AM

Willkommen zu unserem Förüm, Kamerad!!!

I dutifully checked my 1969/70 Slothead all maho, my 1972 long scale maple neck and my 1975/6 short scale maple neck as well as my noughties Epi Elitist (unlike the regular model a very faithful reproduction) EB-3s and here are ze rezülts of ze Tshörmän jüry:

Position 3 is wired identically with all four of them which means: Turn either of the vol controls down fully and all sound is gone, alas! -no operation of a sole pup possible. But that is not to say that the vol controls are on/off and nothing else. Reducing either vol just a quarter will bring out the other pup in full force more, the signal becomes louder and more prominent, not as meek, no doubt cancelling out is reduced, actually a preferable sound either way in my book. Once you get past the quarter vol turn though the sound loses again and finally dies. Given that I did not fiddle with the electronics of any of them and their electronics look unfiddled with from previous owners to me, I'd say this is the way things are supposed to be.

Uwe

Highlander · December 31, 2010, 07:10:35 AM

This surprises me... has this "issue" gone un-noticed all this time...?

This is how I wired mine with an original (style) 4 position switch... nothing "fancy" - all fairly straight options (excluding the coil split) - as I mostly use as one or t'other I never bothered to resolve - it's only an issue with both pups - the 'bird is all mahogany so replicates an EBO sound rather well...

Polkahero · December 31, 2010, 02:58:58 PM

I did a Google search and found a modification that is supposed to solve this problem. Apparently it involves just switching a couple of wires on both volume pots. Not sure if I want to mess with this as I primarily use just the neck pickup but I'm attaching a schematic with the mod. This is a much easier schematic to read, BTW!

doombass · December 31, 2010, 03:26:57 PM

This subject has been up before, maybe over at Jules place. The original wiring is indeed made so that both vol controls act like master volume controls when both pickups are being used. The same goes for LP guitars and basses. I switched the wires on my LP Standard bass the way the picture above describes (I drew those red marks in MS Paint btw, hah hah). I never quite understood why Gibson wired up so many models this way to begin with.

Edit: Found the thread. Initially a choke removal question:http://forums.vintageguitars.org.uk/showthread.php?t=1521

chromium · December 31, 2010, 04:22:00 PM

That discussion at Jules' site spilled over here too - fyi, just in case there's any relevant info...

http://bassoutpost.com/index.php?topic=1408.0

Between those threads, you should find plenty of scintillating EB3 wiring banter - more than you could ever possibly want to be subjected to!

The EB 2-vol/2-tone setups I have all work kinda like what you described. I tend to run the neck pickup volume at 100%, and the bridge at 75%.

Daniel_J · December 31, 2010, 11:17:47 PM

Switching the wires like it shows on the diagram will solve the volume issue, but it will present another issue with the tone controls: if you turn one of the tone pots all the way down to 0, it will work like a master tone and it will sound like both pickups have the tone at 0, even though only one really is. And that will happen independently of switch position.

So is a matter of chosing what issue you want: volume or tone.

Grog · January 01, 2011, 10:35:09 PM

I think all two pickup Gibson (non bass) guitars are wired this way, it makes sense that they would wire the basses the same way. My first day at my job 33 years ago, an old employee told me,
"When it all makes sense to you, you've been here to long" That might be true here also!

doombass · January 04, 2011, 02:35:02 PM

Quote from: Daniel_J on December 31, 2010, 11:17:47 PM
Switching the wires like it shows on the diagram will solve the volume issue, but it will present another issue with the tone controls: if you turn one of the tone pots all the way down to 0, it will work like a master tone and it will sound like both pickups have the tone at 0, even though only one really is. And that will happen independently of switch position.

So is a matter of chosing what issue you want: volume or tone.

Taking the risk of being silly but I don't see how switching the wires on the volume control alters the way the tone controls work. The only difference is you shortcut the pickup lead to ground when dialing down to zero, instead of shortcutting the output side to ground.

Daniel_J · January 04, 2011, 04:51:43 PM

Quote from: doombass on January 04, 2011, 02:35:02 PM
Taking the risk of being silly but I don't see how switching the wires on the volume control alters the way the tone controls work. The only difference is you shortcut the pickup lead to ground when dialing down to zero, instead of shortcutting the output side to ground.

I cant explain why that happens, but it does.