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Looking for an idiot-proof explanation... EB-0 Bass Wiring

#1 User is offline   JamGuy 

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Posted 19 November 2011 - 11:26 AM

Hi all,

Sorry to be posting here (as my bass is technically an Epi) but my last thread in Epi-ville was over run by some idiot's ranting. Anyhow, for the life of me I can't get my EB-0 bass wired correctly. Now having said that, I'm not sure what a "correctly" wired EB-0 behaves and sounds like. Here's a list of problems and associated attempts to remedy them. Please keep in mind that I have plenty of experience following wiring diagrams and feel pretty competent soldering (until this project...)

PROBLEM #1(As stock)- Quiet overall output, rolling off the volume slightly led to a complete loss of volume, tone control had little effect.
SOLUTION #1 -Rewired following the stock wiring, new input jack, new .047 Orange Drop Cap, new 500k Alpha audio taper pots.
RESULT: A freshly wired bass with the exact same problems associated with low output and even less tone control. ](*,)

SOLUTION #2 A local tech suggested that maybe one of my new pots was bad. So I purchased two more 500k Alpha Audio taper pots and tried again...
RESULT: You guessed it... no change whatsoever. ](*,)

SOULTION #3 Yesterday I tore out everything and rewired it completely as per a Seymour Duncan P-Bass schematic, using new wire, yet again two more new 500k Alpha audio taper pots, a new .047 cap (green chicklet looking one from radio shack)
RESULT: Same problem with low output. To make matters worse, the tone and volume controls now seem to function in reverse. What seems like it should be 10 is 0, and vice versa. Now, when I roll "off" the tone, I'm losing volume as well which renders the bass useless unless I keep the volume and tone at 10 (which again, is where 0 is on the knob) ](*,)

SOLUTION #4 Threw the bass off the roof...just kidding :rolleyes:

Here's what I'd like to have this bass wired to do...
*A nice even sweep of the volume knob
*A nice even sweep of the tone control which doesn't impact the volume

Is this possible?

I have yet to try any of the vintage wiring schemes as I don't fully understand what they are illustrating.
Am I to assume (and yes, I know the accompanying joke) that there is a hot and ground wire running through the same black coated wire in the diagram? Is there anyone out there who could explain this to me in terms that I might understand?
Posted Image

#2 User is offline   JamGuy 

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Posted 19 November 2011 - 11:42 AM

Before I go any further, here's a picture of how it's wired currently...
Posted Image

#3 User is offline   JamGuy 

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Posted 19 November 2011 - 11:48 AM

Thanks Moishe,

Do you happen to see what's frigged up in there? I don't care so much about the lower output (though at first I thought a re-wire might remedy this) My gripe is that the volume and tone knobs are now functioning in reverse, and even when they were wired "correctly" they didn't have a very wide sweep. Should I be using different pot values? Like 250k? Or a different cap value?

#4 User is offline   stein 

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Posted 19 November 2011 - 11:54 AM

THIS drawing shows coax wire:

COAX means there is one wire running through the middle, and the other conductor IS the ground surrounding it. 2 conductors total: one through the middle, and the other surrounding it.

The diagram is not exactly clear, but the center conductor is only connected to the center of the jack, and the center of the lug for the volume pot.

All the other connections shown by this wire are the outside conductor soldered to the back of the pots, and the outside of the jack.

Sorry if it seems redundant info here, but just want to clarify that what the drawing PICTURES as coax here doesn't exactly look like coax when we see it: the stuff we usually use for guitars (like Gibsons) have no outside covering.

You could easily use the same drawing to wire individual wires as a substitute for soldering the outer coating of the coax if you didn't use coax.

#5 User is offline   stein 

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Posted 19 November 2011 - 11:58 AM

View PostJamGuy, on 19 November 2011 - 11:42 AM, said:

Before I go any further, here's a picture of how it's wired currently...
Posted Image

This is missing a ground wire from the back of the volume pot to the back of the tone pot.

#6 User is offline   JamGuy 

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Posted 19 November 2011 - 11:58 AM

Quote

You state that the output is low, yet state that you don't know what a properly wired EB-O sounds like - confusing.


I guess I should clarify...
First of all I'm a guitar player, so I play through a Fender Twin Reverb even when I'm playing bass. I know this is a dangerous scenario but given the fact that I'm just laying down little bass loops, and not gigging with this set-up, I'm not worried about blowing a speaker. That aside, the output of the EB-0 is much less than all of my guitars, even single coil strats... maybe that's just the nature of the beast.

I say it seems low because I have a Fender P-Bass with output levels that are equal to, or greater than that of my guitar outputs. I just figured that the EB-0 would have be in the same ball park but it requires me to turn the amp volume up to 5 or 6 (usually 3 is plenty loud for home practicing with my other instruments) Perhaps that makes more sense... I just don't know if these EB basses generally have lower output and are quieter. I've seen that the actual Gibson EB-0 pickups and some replacements have outputs of 27-29k, which would lead me to think they would be very loud.

#7 User is offline   JamGuy 

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Posted 19 November 2011 - 12:03 PM

Quote

This is missing a ground wire from the back of the volume pot to the back of the tone pot.


So just so I'm hearing you right, I need to solder a ground wire from the top of the volume pot to the top of the tone pot? Might this remedy my seemingly upside down values of the tone and volume controls?

#8 User is offline   JamGuy 

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Posted 19 November 2011 - 12:04 PM

Thanks to both of you...

I'm going to heat up the ol' iron and get that sorted... I'll report back shortly. Cheers!

#9 User is offline   JamGuy 

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Posted 19 November 2011 - 12:19 PM

Quote

logical do-it-yourselfer


Yeah, that's where I lose it... the "logic" behind electronics and wiring is lost on me so if a schematic or diagram is funky or confusing, I end up following it blindly. The iron is heating up and I'll get back to you soon...

As far as the left handed pots... I hadn't thought of that, but that would explain the upside down function of the controls... I guess I can live with it.

#10 User is offline   stein 

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Posted 19 November 2011 - 12:29 PM

I would (if it were me):

Add a wire to the back of both pots.

Disconnect the cap from the back of the pot, and connect it to the bottom lug of the volume pot (where there is currently a white wire to the tone pot).

Remove the white wire going to the tone pot.

Connect the bottom lug of the tone pot to the back of the tone pot.

So what you end up with is something that looks like the diagram/pic you first posted, EXCEPT that .01 cap is not there, and the tone cap is on a different lug at the volume.

Why the cap connected to a different lug on the volume you ask? In the digram, the tone is connected to work on the total output produced regardless of where the volume is set. Connect it to the lug the pup is on instead, and it will have its effect on the the output of where the volume is set. That will result in preserving more highs and less treble being lost when turning down the volume.

#11 User is offline   JamGuy 

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Posted 19 November 2011 - 12:33 PM

AH HA!
Well, well, well... the ground wire solved two problems. The controls no longer function upside down and the tone control functions throughout a full sweep (though still without a huge variance of tone) At least it's not clipping my volume level when I roll off the tone anymore

As far as the overall output, it's still the same and rolling off the volume still renders silence below 7 or so... guess it's just the way things are meant to be


Thanks so much to you guys with the speedy responses! I guess I'm just going to leave it be now that it's "working" again (just as it did before I ever started trying to "fix" it :rolleyes:) ...it's a $200 bass after all.

#12 User is offline   stein 

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Posted 19 November 2011 - 12:39 PM

Right on!

#13 User is offline   JamGuy 

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Posted 19 November 2011 - 12:43 PM

Stein,

Now you've got me wondering if I should give your suggestion a go... as I stated, how all this wiring actually works is a mystery to me. I'm beginning to get it but it's not so intuitive to me. Perhaps I should strike while the iron is hot [lol]!

#14 User is offline   stein 

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Posted 19 November 2011 - 12:56 PM

View PostJamGuy, on 19 November 2011 - 12:43 PM, said:

Stein,

Now you've got me wondering if I should give your suggestion a go... as I stated, how all this wiring actually works is a mystery to me. I'm beginning to get it but it's not so intuitive to me. Perhaps I should strike while the iron is hot [lol]!

What is the worst that can happen?

I like to learn, so whenever I do the wiring thing, I try and listen to it before and after I make changes. That way, I might learn what sounds better (if anything) as well as what works better or worse.

You should know I have zero experience with Gibby basses. I suggested what I did because it looked like a diagram for Gibby bass in that the arrangement of the tone control/cap was typical of Gibson. And, also, the change of position for the tone cap connection for the volume control is what many are referring to as "50's" wiring. Many like this trend because it does solve some of the tone control/volume control issues of losing treble as you turn the volume down.

If you really wanted to go further with a hot iron, you might try the cap wired each place, and let us know what you think.

#15 User is offline   JamGuy 

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Posted 19 November 2011 - 01:39 PM

Quote

What is the worst that can happen?


Well, I gave it a go, and for the most part nothing happened so nothing lost. I swapped the little radio shack cap back out for the Orange Drop and again, no change I could hear, so I swapped the caps back again. No audible difference between the two. If anything, it sounds a little more crisp and full with everything set to 10 than it did before the latest wiring change, maybe I just want to believe it's sounding better. [rolleyes] The volume still drops like a rock and the tone change is still very subtle. I've read on other post that this is somewhat normal for these basses (at least the Epi version) so I'm going to just put this little project to rest unless someone knows about how to fix the sudden volume drop. Stein, I appreciate all your help and that of Moishe as well... it's been a good learning experience.

So what have I learned?

A $200 bass isn't going to magically perform like a $2000 bass with new pots, caps, and wiring.
Solder is hot (yes, I've burned myself again)
This forum is a fabulous resource for information and a great place to procrastinate when I should be studying [thumbup]

#16 User is offline   Lungimsam 

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Posted 20 November 2011 - 08:46 PM

Some of your probs sound similar to my SG Bass.

1. Output is much lower than my Pbasses. Almost zero punch on the attack, too.

2. My tone sweep was minimal with the stock 500k tone knob until I put a 1MEG tone pot in. Then it became a wide tone sweep, like on a Pbass. Maybe worth a try for your bass to go to 1MEG pots. I even tried a 250 pot to no avail. The 1MEG pot with a .05 cap opened it right up.

But the bass is still less powerful than a Pbass. Next experiment may be to try a Pbass pup, taped into place to see what it sounds like. Just for kicks.

#17 User is offline   Gaolee 

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Posted 23 November 2011 - 09:42 PM

I hadn't thought of a 1meg pot. That would be an interesting experiment.
Thump to live.
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#18 User is offline   pfox14 

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Posted 02 January 2012 - 01:47 PM

View Poststein, on 19 November 2011 - 11:58 AM, said:

This is missing a ground wire from the back of the volume pot to the back of the tone pot.


There should not be a ground connection between the back of the volume pot & one of the prongs. You should only have ground wires soldered to the chasis of the pots, NOT the prongs. Also, the capacitor seems wrong to me. It should also NOT be grounded. It should be connected between the center prong of the volume pot to the bottom prong on the tone pot. That's my 2 cents worth.

#19 User is offline   Goingdownslow 

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Posted 04 January 2012 - 11:11 AM

View Postpfox14, on 02 January 2012 - 01:47 PM, said:

There should not be a ground connection between the back of the volume pot & one of the prongs. You should only have ground wires soldered to the chasis of the pots, NOT the prongs. Also, the capacitor seems wrong to me. It should also NOT be grounded. It should be connected between the center prong of the volume pot to the bottom prong on the tone pot. That's my 2 cents worth.


But that is the way it is done.
Pete

#20 User is offline   ainaudio 

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Posted 24 May 2014 - 06:12 AM

Being over 40 years in music technology industry joined Gibson forum today :)

Grey conductive shielding paint looks not the best quality and not accurate put on. It must be carefully grounded, many case it is forgot to do, especially at pickup, switch and jack cavities, it can provide more noise and hum as without it !
Both pot metal caps/covers must be soldered together and grounded. There is as minimum partly lost ground of both - shielding and signal...
Look carefully to not contact any "hot" leg of connector or pot with shielding paint, it can result in "almost" short connection - weak and dull signal.
* It is just about elementary connection, right shielding, grounding and wiring is separate much longer talk. Almost all guitars are wrong wired from factory...

Green Tone cap is cheap but good enough, just question of nominal. There are many legends and bluffs about caps. Most "special", "vintage", "NOS", "hi-end", "oil", "paper", "military", "space", blablabla, etc caps are expensive and bad quality the same time (leaking, resistance, inductance, etc.) - providing different side affects on sound. "Orange drop" caps are higher quality as this green one, but have almost not any affect on sound quality in such application.
Pots are Asia made Alpha - working, but cheap and so-so in comparing with original CTS or Bourns made.
Jack socket is Switchcraft - it is still the best.

Pots must have Audio (A) character (not Linear (B), or Reverse ©, or something else; C must be used just for left hand reverse guitars). Higher pot nominal means higher presence peak and more brightness. Most case A500k on Volume & Tone is the best, but A250k, A300k, A500k, A1m, mixed combination - as you like can be used.
"No Load" pot is fine for Tone. At position "10" it disappears from circuit at all. "No Load" versions of A500k or A1m pots are better as Fender used A250k (250k has some click between 9 and 10). Most std pots (if can be open) can be easy modified to "No Load" version.
Right Tone cap nominal depends of pickup parameters. Try to select up/down from 0.022mF (22n) or 0.03 (30n) nominal for bass. For me right nominal is when Tone pot starts to work with some Wah-Wah like effect. To high cap nominal is "eating" of mids (not only highs) - you are loosing part of basic tone, sound becomes dull. Objective calculation, but subjective question of taste :)
If you are using lowered Volume pot positions - tone compensation circuit on Volume pot "hot" legs is good idea. Try 620pf cap serial with half of Volume pot nominal (respective - 120k, 150k, 250k, 510k) resistor, cap's nominal mostly depends of how high capacitance has your first cable, it is cable's compensation circuit at once. Using Volume pot without compensation circuit means duller sound at lowered positions, some case it is ok, especially for guitars - if you must move to background, just as is more handy for you.

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