Tokai EB-3 improvements.

[Alanko]

My Tokai EB-3 is copy on the bench! This is my stuck-in-the-house bass project for the next little while.



The combination of nickel bridge and chrome pickups will have to do for just now... 

There are bits of the bass that are pretty good, and bits that are a bit off the mark. The model is an 'SGB' something... different Tokai EB-3 models have bolt-on necks or control spacing that is like an early Gibson EB-3. I have plans to modify this bass a bit, which I will document here.

firstly, I've leveled the frets. They were generally level, but oddly the 10th and 11th frets alone were much lower than the rest. I'm not sure how that might have happened, but I remedied it. Oddly the fretboard is 'rosewood' according to the literature, but it has a walnut colour. It also hasn't taken my usual boiled linseed oil finish very well, remaining tacky and barfing oil out of the deepest pores after a couple of days.


I didn't entirely like the stock pickguard. It was quite warped, and seemed to have too much meat down by the controls but end a bit short by the treble cutaway. The screw at that end of the pickguard is also badly off-centre. I decided to prototype some pickguards to try and come up with a revised fit that worked with some of the stock screw-holes in the body but looked a bit more accurate.



I extended the horn on the pickguard and made that end of it a bit chunkier. I took some meat away from the section down by the controls. I added a new screw hole and rounded the shoulder of it where it meets the neck, a la '60s Gibson basses. I'm swithering about making a banana-shaped tug bar to mount on the pickguard, but this might be a step too far.



I can't find 5-ply pickguard material in the UK, so this is 3-ply like an old EB-0. I've not cut the route (a mud hole?) for the pickup yet as this is being swapped.



No decimal place. This is the DC resistance in ohms. Very odd.



Not a whole lot of magnet on this pickup either.


As for the bridge pickup, I ordered a Gotoh replacement, but this won't even begin to fit the stock pickup ring. The pickup ring on this bass is 100 mm long, and the stock bridge pickup has fairly unique dimensions (70mm x 32mm). This is close to some Chinese 'minibucker' or 'Firebird' pickups kicking around. I'm prototyping an adaptor pickup ring that would allow the Gotoh pickup to be used, but it might look a bit goofy having a small pickup mounted to a vast pickup ring.

The stock bridge pickup itself has a DC resistance of 5.5 k ohms, and a strong magnetic pull down the middle of the case. I wonder if it is in fact a fat single coil hiding under the cover.

[Dave W]

The new pickguard is better.

What's odd about the neck pickup reading? You did say it was 1.2K ohms in your other thread.

[Alanko]

1.2 k ohms is low for a high-z pickup, so I'm guessing they used a much thinner gauge of pickup wire to what we are used to. 600 ohms per coil is spooky low. The rather parsimonious magnet situation also doesn't help. Fundamentally this pickup isn't a mudbucker. It has a low output and distant, slightly brittle tone. There isn't enough glue in the low-mids to keep everything together.

Saying that, I wager that there will be limits to using an Artec mudbucker as well. Too hot, big woofy low-mids...

My Allparts/Gotoh EB-bucker bridge pickup arrived today.



It is on the bottom, and the stock bridge pickup is on the top. Notice anything similar? BHK/BHC means that Boo Heung Precision Machining manufactured the pickup, either in China (stock pickup) or Korea (EB pickup). Both pickups have a brass baseplate.

I've found a few pickups that share the same weird dimensions of the stock bridge pickup. Artec manufacture a 'Filtertron' humbucker that matches pretty nicely. Likewise Warman guitars in the UK make one that matches, though again Warman are just re-selling low cost mass-production pickups.

Out of curiosity I started pulling the stock bridge pickup apart. It was a bit noisier than the bridge pickup, and had a DC resistance of 5k. It also had a magnetic pull down the centre of the baseplate... so is it a single coil hiding in a big cover?



Yes!



A Strat-sized single coil powered by two chunky magnets. Thematically this is a bit like a P90 pickup with a rail instead of pole-pieces.

I picked up an Artec Firebird pickup as well. One Alnico bar magnet powers two steel rails in two small pickup coils. Sounds good! Maybe I can transplant this into the case of the stock Tokai pickup.

[Dave W]

All else being equal, thinner wire means more turns in the same amount of space and a higher resistance reading. Thicker wire results in a lower reading. In this case I don't know what else might be different.

[Alanko]

All else being equal, thinner wire means more turns in the same amount of space and a higher resistance reading. Thicker wire results in a lower reading. In this case I don't know what else might be different.

It beats me. I'm going to sell the pickup, otherwise I would dissect it and document it here for posterity.

I ordered lots of bits and pieces for this bass today, so fingers crossed I can progress with it over the next couple of weeks.

There's a couple of decisions I need to make about the wiring. I want to incorporate both a passive diode fuzz and a Varitone circuit with an inductor for tonal shaping. I'm thinking of wiring a 6-way varitone switch with five caps and the diodes in the 6th position, dumping straight to ground. I would then use one of the tone controls as a blend for the varitone.

[amptech]

These pickups use thicker wire. You are right, they are not
real mudbuckers, but there is nothing wrong with the reading. It's just how they make them. I had one before, but ended up rewinding the coils and used them for something else.

[doombass]

Epiphone EB-0 pickups has the same low DC resistance reading as yours. At least my '97 Korean made has it. They do sound distant and pretty boring.

[Highlander]

 

[clankenstein]

Anyone tried the Retrovibe Pickup?

[Alanko]

Anyone tried the Retrovibe Pickup?

The Retrovibe pickup will just be a rebranded Artec pickup. I have a set of Retrovibe pickups in my 4003, and I'm pretty certain 'Roswell' is the OEM. The bridge pickup is alright, but the neck pickup is weak and microphonic.

I got a replacement Artec mudbucker for the Tokai a few days ago. It is different to the Artec mudbuckers I used in the past. The new one has two magnets instead of four, and has a four-wire hookup cable. It feels a bit more sturdily built, though the pole pieces were loose in the keeper. I've used a 'no more nails' type adhesive gunk to keep them properly in place. This one measures 28.5 k on the meter, so a lot closer to original Gibson specs.



I know have the mud hole cut in my pickguard. I've also toned down the white layer on the pickguard a shade by using an alcohol based wood dye.

Today I did a bunch of wee jobs on the bass. I made a back-to-back Schottky diode pair for a passive fuzz option.



I've also finished off an adapter pickup ring, allowing me to use minibucker-sized pickups in a ring with the same dimensions as the stock bridge pickup ring:



I also dredged these Norlin-style witch hat knobs out of my parts bin to see if they work.

[gearHed289]

Looking good man!

[clankenstein]

Like the witch hats! Getting there-You will be earthquaking the neighours in no time.

[Alanko]

Earthquaking is maybe right! I need one bass that is passive and loosens the foundations.

I've taken another tack with the bridge pickup. I finally found a pickup that fits the bridge's weird dimensions. Artec manufacture a Gretsch-y with slimmer coils than a PAF-style humbucker, but bigger than a Firebird or minibucker. Again, looking East into the bargain bin to find a pickup that works.

Entwistle pickups offer a neodymium version, so I grabbed one of these.



Looking Gretschy. At this point I backed out one of the polepieces and stuck it in backwards, just to see how well I could pull off a pole-less look. Eh, 12 poles are ok but I wanted blades.



Luckily the coils have no inner walls, so I took the blades out of an Artec Firebird pickup and stuck these in.



I then cut out a wee plastic insert from a DVD case (black, textured and around 1.5 mm thick, so perfect for the job.



Hey, that might work. It isn't a Gibson-y move at all, but it gives me a small, bright and powerful humbucker down at the bridge. The neodymium element looks like a small pair of magnets adhered to the back of the existing magnet (maybe an alnico bar?) in the pickup. I didn't take a good look at it.

With a heap of wax potting this should work. I also polished off the 'Alan Entwistle' branding on the chrome cover, because nobody needs to see that.


On to storyboarding my wiring. I want to wire this up with enough slop in the wire  to allow the components to move around a bit. So far I have the pots, output jack, a cap for the master tone control, some 10 meg resistors for stopping the rotary switch popping, and an audio transformer to act as an inductor.

[Alanko]

I have been marching onwards with this bass, and it is pretty much finished.

My first step was to wire up my Varitone:



The diodes are grounded to the chassis of the switch, whereas the caps run into the primary of the transformer.



The other end of the primary is grounded to the chassis of the transformer, and the transformer and switch are all soldered together, giving me a mechanically solid unit.



After some initial testing I decided to double the capacitance for each setting, and remove one half of the diode pair as it was cutting too much signal. This still gives me this rats nest of wiring to fight through, so I used a bit of colour coding to try and keep tabs on what does what. I went with Fender-style cloth wire rather than running coax everywhere.

In practice the switch gives me four vague, vowel-like filter settings and a blatty, under-gunned fuzz setting that sounds like a torn speaker cone flapping in the wind. Perfect!

I also have a 1 nF capacitor over the lugs of the bridge volume pot. This allows me to back off the bridge pickup a hair and combine the twang with the thunder of the neck pickup. When both pickups are on 100% the bridge pickup dominates the neck pickup totally due to that hilarious impedance mismatch.





Not too shabby.

[Basvarken]

Very cool!
Got some sound samples?