The EB2 Triple Bypass (Choke Bypass Modification)

[chromium]

I think I would just like to use a DPDT push button switch.  Could I use one of the stomp pedal switches that's an "on-on" configuration?

The only problem there is that the mod counts on that "center off" position that the toggle switches provide, to activate the three different modes.  With the push button, you'll only be able to engage the two outer throws of the switch.

The wiring could indeed be adapted to work with a push-button, though, if there's one of the original modes you'd be willing to sacrifice - full-mud or original baritone.  I'm happy to diagram a push-button-friendly revision for you, if you decide to go this route.

fyi- if it helps with finding a switch, this guy has been good to deal with.  He's priced comparatively low on stuff like orange-drops, too..:

http://www.smallbearelec.com/Categories.bok?category=Switches%2C+Relays&searchpath=352&start=1&total=52

[drbassman]

Could it be wired so it operated like the old baritone switch?  ON for bari or on for bass?

[chromium]

Could it be wired so it operated like the old baritone switch?  ON for bari or on for bass?

Yeah - that would look more like this:



(sorry I'm not artistic enough to draw this in terms of a wiring diagram)

Note that the "bass" setting of the switch will enable the unfiltered, full range sound of the mudbucker.  If you wanted that original filtered boom in the bass setting, then you would just use the original Gibson schematic.  


(EDIT: Doh!  Some days there's just not enough coffee in my life.  Schematic has been revised)

[drbassman]

Thanks for the supplier web site!  I hate to ask another dumb question, but which push button switch would you recommend?

The only problem there is that the mod counts on that "center off" position that the toggle switches provide, to activate the three different modes.  With the push button, you'll only be able to engage the two outer throws of the switch.

The wiring could indeed be adapted to work with a push-button, though, if there's one of the original modes you'd be willing to sacrifice - full-mud or original baritone.  I'm happy to diagram a push-button-friendly revision for you, if you decide to go this route.

fyi- if it helps with finding a switch, this guy has been good to deal with.  He's priced comparatively low on stuff like orange-drops, too..:

http://www.smallbearelec.com/Categories.bok?category=Switches%2C+Relays&searchpath=352&start=1&total=52

[Highlander]

Having one of Gibsons most "complicated" designs (albeit "de-Mooged"), but never having owned a "classic", I have no idea as to what a "choke" is... yes, the old designation meant a "soak" capacitive circuit, commonly used in inductive lighting design, but the drawings you've all posted here all relate to a "coil"...?

[chromium]

Thanks for the supplier web site!  I hate to ask another dumb question, but which push button switch would you recommend?

I'd probably opt for the Carling DPDT - http://www.smallbearelec.com/Detail.bok?no=80, or the similar Alpha - http://www.smallbearelec.com/Detail.bok?no=23.  Pretty sure either of those would work out just fine for you.  

The one thing about these pushbuttons (at least in my own past experiences) is that they take a pretty firm push to activate, and let out a loud "clack".  That's one of the reasons I just prefer the feel of that toggle I used... but that's all just personal preference.  Just mentioning so you're aware of it.  I haven't come across any "soft touch" DPDT pushbuttons (but I'd love to know in the event anyone else has).

Having one of Gibsons most "complicated" designs (albeit "de-Mooged"), but never having owned a "classic", I have no idea as to what a "choke" is... yes, the old designation meant a "soak" capacitive circuit, commonly used in inductive lighting design, but the drawings you've all posted here all relate to a "coil"...?

Ken - I only know enough of the theory to be dangerous, but I believe they refer to these types of circuits as inductive-capacitance filters (LC filter networks, L=inductor, C=capacitor)

A typical tone control in a bass is comprised of a resistor (usually a pot), and capacitor (known as an RC filter netowrks, R=resistor, C=capacitor).  They're almost always setup as a "low-pass" filter, meaning they will allow low frequencies to pass and will shunt the high frequencies to ground.

The LC filters that Gibson employed (here, in the Varitone, etc..) are tuned to pass certain bands or ranges of frequencies, and can also add an "emphasis" on these frequencies (sometime referred to as resonance, or "Q" - like the "Q" knob/switch on an Alembic bass).  That seems to be how the "baritone" setting acts.  It produces a very nasal sound, almost like spiking a select midrange frequency on a graphic EQ, and cutting all the other frequencies.  I think "choke" is just a slang term for the cutting (choking) of those other frequencies.

I found a good description of what an inductor is here, and it explains a bit about how it is used in filter circuits:

   http://www.williamson-labs.com/480_rlc-l.htm

[Basvarken]

Resurrection time!

A friend of mine bought a 1964 EB2 the other day.
I told him about the three way toggle that Joe installed to use the fully engaged Mudbucker in all its glory.

Now he's asking me if I could do the modification for him. But I'm afraid all the pics in this thread have been photobucketed...
Can anybody help maybe? Joe?

[chromium]

Resurrection time!

A friend of mine bought a 1964 EB2 the other day.
I told him about the three way toggle that Joe installed to use the fully engaged Mudbucker in all its glory.

Now he's asking me if I could do the modification for him. But I'm afraid all the pics in this thread have been photobucketed...
Can anybody help maybe? Joe?

Rob- here's the one post summary 


For an EB2/Rivoli, this depicts the tone switch mod:



I'll add the EB2D version here too - in case it helps anyone in the future:



This pic details the switching behavior.  Note that in the middle "choke bypass" position, one throw on the DPDT switch should not engage (between lugs 5 and 6 on the pic):




That throws a bit of a curve, since some DPDT toggles won't function this way.  It would require one with an "on-off-on" center position.

I opted to use a triple-pickup Les Paul toggle, and bent one of the pins in such a way that it supports that switching behavior. 

The pins are numbered 1-6, starting at the top.  The goal is to make is to make it so that pin #4 never comes in contact with #5 when in the middle position – otherwise, it would give the original unchoked mode as opposed to the desired bypass mode.

Pic below will explain that modification visually:




I liked the look of that switch better anyway, and if I recall it was a pretty close fit in the hole from the original pushbutton:




Hope that helps, and reach out if you still have questions.

[Basvarken]

Wow! Thank you very much Joe! 

[Granny Gremlin]

Thanks for refreshing the pics; I do hope to need this one day   

One question though.

Looks like Position 2 is open/nothing connected (I see you drew a connection between pole 1 input, or pin2, to pin 3, but since pin 3 isn't actually connected to anything, that's superfuous but indicates what the switch is doing).  Wouldn't a simple DPDT on-off-on 3 way work here?  (I have tones of those, but minis vs full size).  Since the LP Custom toggle is on-on-on, what you mean by bending 'pin 4 upward' is that you effectively defeat the connection of the second pole in middle position (which connects 2-3 and 4-5, as shown here ).

I get that these switches look cooler (though personally I hate the cream plastic tips, and nobody sees the guts when it's inside a guitar), but it'd be easier (and more reliable long term as regards performance - bending the leaves out of whack can slip back over time; also some tech being able to figure out what's going on in there without you explaining the mod to the switch itself) to use an on-off-on.  Mini's are nice and unobtrusive, but too small for the existing (baritone switch) hole I assume. They make full size ones, usually for use as main power switches (or battery handling switches in automotive applications - sometimes with screw terminals vs solder tabs); in either case solid metal lever (vs screw on plastic tip, so that's a plus for me personally) and sealed mechanism (vs exposed leaves) and they are cheaper ($5 or less vs 10 or more) except on Amazon or Home Depot who charge double/triple that for some reason, and easier to find (not specialoised guitar use only sort of thing). Sealed units are better these days (vs the mark of a cheap switch on an import guitar back in the day).

[chromium]

Jake - you are correct.  An on-off-on toggle (center off) would work just fine.  I went with this one more for the aesthetic, and I like the springy feel 

Also, if I recall correctly when test-fitting some other options, the big toggles (ala Carling) would have required boring the hole out a bit, and the minis were swimming in the old pushbutton hole.  This switch fit pretty well in mine as-is.

Another slick approach could be to implement using a couple of push-pull pots... Or even a combo of a push-pull for the orig sounds, and use of the stock pushbutton to cut the inductor's ground connection (for choke bypass).

Very worthy mod, no matter how you tackle it!  It's a testament that I still own that bass.  Really extended the useful sonic range, and I still enjoy playing it out from time to time.

[bobyoung]

I finally just did the simple mod that Chromium posted about ten years ago, haha! Went under the bridge, dug out the wire going to the choke which came undone all by itself. This thing now sounds unbelievable (1966 EB-2) Also the baritone switch still works for some reason except that there is still some bottom with it engaged and is usable unlike the original nasally tone which was devoid of bottom, it's been gathering dust for the past two or three years so time to take it out to a blues jam. Thanks.

[bobyoung]

I think I did the single bypass but what a difference, I have no need for the baritone sound so I'll leave it as is.