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EB-3 Series 1 and Series 2 wiring.

doom

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EB-3 Series 1 and Series 2 wiring.
« on: January 16, 2008, 11:18:36 PM »
There's a Swedish bass forum where the wiring of the EB-3's came up. When I look at both schematics the positions of the varitone is the same ie choke activated in pos 4. According to the Gibsonbass site series 1 ('61-ca '73) had the choke active in pos 1 while series 2 ('73-'79) had position 4 to activate the choke. My '69 is a series 1. I've followed all the wires and it is correct and chokes in pos 4. Another member of the forum just bought a '71 slothead and also has the choke active in pos 4. However yet another member played a '73 which had the choke activated in pos 1.

What's right and wrong here. I seem to remember that some really early specimen had the choke in pos 1. Anyone with an EB-3 regardless of year of make. What does the switch do for you? I'm kind of confused right now.

EB-3 Series 1 and Series 2 wiring.
« Reply #1 on: January 17, 2008, 06:41:38 PM »
I have a '74 EB3 the choke was position 4 on mine..( I replaced with SG style toggle switch).

jules

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Re: EB-3 Series 1 and Series 2 wiring.
« Reply #2 on: January 17, 2008, 11:03:52 PM »
Quote from: doom
My '69 is a series 1. I've followed all the wires and it is correct and chokes in pos 4. Another member of the forum just bought a '71 slothead and also has the choke active in pos 4. However yet another member played a '73 which had the choke activated in pos 1.


This can get confusing - remember the positions are 1 (switch points to bridge) to 4 (switch points to neck)

So your '69 activates the choke, when the switch is pointed towards the neck yes?

doom

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Re: EB-3 Series 1 and Series 2 wiring.
« Reply #3 on: January 17, 2008, 11:19:39 PM »
Quote from: jules
So your '69 activates the choke, when the switch is pointed towards the neck yes?


Yes. Well actually my dial plate and chickenhead is facing upside down so position 1 is chickenhead pointing towards neck and that position is no choke. Rotating the dial plate and chickenhead 180 degrees would mean choke activated (position 4) towards the neck and position 1 full mud towards the bridge.

jules

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Re: EB-3 Series 1 and Series 2 wiring.
« Reply #4 on: January 18, 2008, 01:05:32 AM »
Quote from: doom
Rotating the dial plate and chickenhead 180 degrees would mean choke activated (position 4) towards the neck and position 1 full mud towards the bridge.


Full mud IS choke activated - or is that not what you mean by full mud? (do you mean plain mudbucker but a less muddy sound?)

doom

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EB-3 Series 1 and Series 2 wiring.
« Reply #5 on: January 18, 2008, 08:40:43 AM »
Ok. Then I've been wrong all the time. I thought the tone choke was active in pos 4 where the mid notch filter is activated (ie you don't get much bass out of it). To me the position 1 full mud sounds more like a Mudbucker straight to jack than pos 4 so I thought what alters the sound most must be the choke.

Does this mean that the EB-2 Baritone-control (exact same circuit) is  considered activated when you get most oompf out of it?

EB-3 Series 1 and Series 2 wiring.
« Reply #6 on: January 18, 2008, 06:13:44 PM »
What a confusing thread!

Full mud is NOT choke on.  The choke is a high pass filter, meaning that it cuts bass (i.e 'mud').

The positions on both Series 1 and 2 EB3s are the same - the differences can be accounted for by users turning the label plate around (as mentioned) and/or rewiring by a previous owner.

Yes, the EB2 Baritone is identical to the series 1 EB3 choke circuit.  Series 2 EB3s have a choke that is more like a Ripper's, it does not cut as much bass as Series 1 and there is therefore a much more subtle difference between position 1 and 4 (which may also be causeing some confusion here). Slotheads, being from a transition period, varry to a great deal as regards being more like a Series 1 or Series 2 - depends on year.

doom

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EB-3 Series 1 and Series 2 wiring.
« Reply #7 on: January 18, 2008, 09:29:50 PM »
That was what I always thought Jake but someone brought up this quote from Jules' site:

Quote
The following sheet (1978) shows Gibson's description of series 2 EB3 controls. Older series 1 controls are broadly similar, except that the tone choke (or midrange notch as it is called here) is activated in position 1 rather than position 4


Along with someone trying a '73 out with choke activated in pos 1 I was confused. However the choke circuit is still active in position 1 acting as a low pass filter right?

At the Swedish forum someone consulted an electronic signal theorist and I'll translate what he had to say:

Pos 1 "Mudbucker only" has a notch structure. When resonance occurs between L (coil my remark) and C (capacitor my remark) the resistors is almost shortcut at the output - 0 Volts out. It is not a high pass filter since at low frequensies the CL-path is abrupted and the voltage goes through the output resistances.

Pos 4 Mudbucker with choke is interesting. It's a high pass filter for high frequensies. The low frequensies is passed down to ground leaving 0 Volts. However there's a resonance circuit between C in parallell to R (the resistor my remark) and L  so if resonance occur we will have a fast transition between stop band and pass band in the high pass filter. A normal second order HP filter has a slow transition band but trimmed with a notch with fast transition band which makes it better. However a part of this circuit with R in parallell with C and L in series makes it something else but a regular series resonance circuit.


Bottom line without confusion is: In position 1 my series 1 '69 EB-3 has full mud (sub lows) and choke is position 4. I'm just trying to sort out the facts here.

jules

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EB3 circuitry
« Reply #8 on: January 18, 2008, 10:18:32 PM »
Well, you've got me thinking guys. Firstly, let me say (as I always do) electronics are not my strongpoint, so I am inclined to defer to your greater understanding of the schematics, and the exact function of the choke.... but

Quote
The positions on both Series 1 and 2 EB3s are the same - the differences can be accounted for by users turning the label plate around (as mentioned) and/or rewiring by a previous owner.


I am sceptical about this assertion. Perhaps they are the same with regards circuitry, but my '72 EB3 definately is more muddy in position 4 which has the choke applied - hence the statements on the site (and above that choke=full mud). I just played it again to check. Definately more mud on 4. It has not had the label turned, and I am also 95% sure it has not been rewired. I normally like to rely on several examples before I make a sweeping statement, but I admit this was based on one bass.
This is it by the way


I also have to say, the very detailed quote above means nothing to me  you may has well have left it in Swedish  :lol:

Do you guys understand it? Does it explain why my '72 is muddier in 4 than 1? Does the series 2 choke act in a different way than the series 1?

doom

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Re: EB3 circuitry
« Reply #9 on: January 18, 2008, 10:50:00 PM »
Quote from: jules

I also have to say, the very detailed quote above means nothing to me  you may has well have left it in Swedish  :lol:

Quit that moaning. You did'nt have to translate it. :lol:

Quote from: jules
Do you guys understand it? Does it explain why my '72 is muddier in 4 than 1? Does the series 2 choke act in a different way than the series 1?


And obviously you are not the first to discover this. Like I said, another Swede played a '73 with that feature as well.

doom

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EB-3 Series 1 and Series 2 wiring.
« Reply #10 on: January 19, 2008, 11:33:15 AM »
With series 2 wiring the choke is affecting the circuit in pos 4 only. In pos 1 and 3 there's only the regular vol and tone controls affecting the Mudbucker. There is no real point in replacing the varitone with a toggle in that respect since those functions are pos 1-3.

I can't understand what the choke is supposed to be. Gibson wired the coil and cap in series both being parallell to the Mudbucker. Second order filters would have one of those components in series and one in parallell. Cap in parallell and coil in series would be low pass. Coil in parallell and cap in series would be the opposite, a high pass filter. The series 2 choke is neither of those.

doom

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EB-3 Series 1 and Series 2 wiring.
« Reply #11 on: January 21, 2008, 06:33:47 AM »
Ok. Now I've done my reading. Series 2 pos 4 is a mid notch filter. Well actually it is a band stop filter for mids which is why Jules experienced pos 4 as muddier than pos 1 (there's no treble anyway. Filtering mids make it woofier). Case closed and sorry for stirring up things.

Re: EB3 circuitry
« Reply #12 on: January 22, 2008, 12:04:58 AM »
Quote from: jules

I am sceptical about this assertion. Perhaps they are the same with regards circuitry, but my '72 EB3 definately is more muddy in position 4 which has the choke applied - hence the statements on the site (and above that choke=full mud). I just played it again to check. Definately more mud on 4. It has not had the label turned, and I am also 95% sure it has not been rewired. I normally like to rely on several examples before I make a sweeping statement, but I admit this was based on one bass.
This is it by the way


I also have to say, the very detailed quote above means nothing to me  you may has well have left it in Swedish  :lol:

Do you guys understand it? Does it explain why my '72 is muddier in 4 than 1? Does the series 2 choke act in a different way than the series 1?


This is because (as I mentioned earlier) the Series 2 choke is not the same as a Series 1 choke.

The series 1 choke IS a high pass filter.  Since the Series 2 choke uses the same coil as the Ripper (which has a notch filter), then it makes perfect sense to me that the Series 2 choke is a notch as well (e.g. EB2 choke = EB3 S1 but EB3 S2 = Ripper choke).  I don't actually own a Series 2 so I never eally bothered to analise the choke.  On the ones I've played, I definately had a hard time being able to even tell the difference between pos 1 and 4.

Looking at the diagrams again, it does look like the choke on a S2 is not engaged in pos 3.  Guess I remembered wrong on that one.


edit: Ah, Doom kinda beat me to the punch I see

 

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