Gibson EB2 inductor value

[Mick Bailey]

Does anyone know if Gibson change the inductor over the years? I've just been working on one from '67 that has an 8.5H value. The schematic says 15H. I've seen another bass with three leads coming off the inductor - presumably some were tapped for use in other instruments. 8.5 is close enough to half of 15 to make me think this could be the case.

Regardless, 8.5H works very well with the 'triple bypass' switching arrangement.

[52 Bill]

Any numbers or markings on the choke? The only ones that I have seen were 15H, but I've only seen a couple of those basses. I always assumed that the basses all used the same choke.

[big_teee]

What effect does the choke have on the sound?
Wouldn't changing the inductor value, be like changing the tone cap value?
The only EB basses I've worked on, have had all that ripped out and wired normal, like a guitar.
T

[Mick Bailey]

I can't get to it as this choke is firmly embedded in wax under a plastic cover beneath the bridge and to preserve the originality I left it alone. The other I'd worked on had the choke attached to the volume pot.

The sound?

The text off the owner reads; "It's Amazing. Everything is amazing. Thanks, Man!"

I had been wired just with volume and tone and the original selector switch removed. Thankfully, all the original components were still present, as were the original pots.

The circuit acts like a fixed-position Varitone. I've installed a little machined dish in the old 3/8" selector hole and fitted a 3-way mini-toggle to give Baritone/Bypass/Normal positions. Baritone cuts the bass right out so that pretty much the fundamental disappears. It makes chords and arpeggios sound very clearly defined, but reduces volume. That is, unless you have some drive or fuzz. I tried it with a Fuzzrite and the baritone boosts the volume and increases drive, making for a very crisp bass sound. Bypass removes the inductor and associated capacitor from circuit, though it still has the 220k series resistor. I experimented with bypassing that too, but it would require extra complexity in switching and didn't make as much difference to the sound as I'd expected. This bypass position gives a more balanced sound with fairly even representation of frequencies - kind of flat frequency response. The normal position is with the inductor/capacitor switched in. It gives a fair volume boost and massive bass. The upper mids and treble are severely attenuated, but the fatness of the sound is unreal.

Overall it's like having three very different instruments. The baritone and normal positions are 'factory', but the original circuit doesn't bypass so is more limited with having two fairly extreme sounds. I sat down with this once it was finished and came up with arpeggios, runs and phrases that came from nowhere. Really inspirational.