Ever since I finished building "Jessica" a thought has been bothering me. What if I would ever build a electric bass completely out of birch wood?
After all, birch seems to be a very good wood to make necks and fretboards out of. But what would a birch body make the bass sound like? Well, only one way to find out...
Time to spend some time in the shed!
So I decided to make it almost identical to "Purple Haze", same body shape, neck and fretboard. However, the top of the body wasn't that that nice looking, so i removed about 10mm from the front and glued on a much better looking book-matched piece of "icy" birch.
Construction: 5-string bolt-on
Frets: 24, Dunlop 6130
Tuners: Schaller BM Light
Neck: Birch, 5-piece
Pickups: EMG HZ40
Electronics: Artec SE-3
No new or special techniques was used compared to my earlier builds, except the fretwork since I had got me some proper fretfiles etc. which made the job just that more easy.
Years ago I had read about placing a piezo pickup in the neckpocket, between the neck and the body. So now I just thought it was high time to test that out.
So I just basically made a recess in the body inside the neck pocket with a 20mm forstner drillbit, and carved out a channel for the piezos wire so that it could be drawn thru the neck pickup cavity into the control cavity.
The piezo I use is a Shadow SH 721. To get some pressure put on it I just simply drilled a hole in the middle of the reccess for the piezo all the way through to the backside of the body. Then threaded the hole with a M5 tap drill and made a M5 pin from a ordinary M5 bolt. The pin is screwed in from the backside of the body and puches on the piezo transducer against the neck. Therefore the pressure on the piezo transducer can easily be adjusted, to maximize the output level of the transducer.
Of course a piezo transducer needs basically two things to work properly; a high input impedance buffer and a boost to get the signal level up to match that of a ordinary magnetic pickup.
So I started looking for a easy DIY piezo buffer that I could solder together on my own, and ran across the Tillman Preamp. The whole circuit consists of just 7 components, which makes it easy enough to be soldered together using a small piece of perfboard, and is designed to run on +9V.
The increase in gain this buffer gives is 3dB, but by adding a 10uF capasitor across R2 the gain increases significantly.
So I connected the piezo to one buffer with 3dB gain, connected the output of that to a volume pot, from there to a second buffer/booster and from there directly to the output jack.
That way the volume pot for the piezo transducer will have no effect on the preamp for the magnetic pickups.
Just as on "Purple Haze" I used EMG's HZ series pickups on this bass. Since these pickups contains two separate coils, it would be possible to either use them wired up in series-, paralell-, or singel coil-mode. However, by using a DPDT switch with a on-on-on function, you can wire the pickups coils to form one of the three modes.
So why would you need to have this possibilty on a bass?
Take a look-listen to this YouTube video. This will probably answer your question.
Quite a versatile feature to have, don't you think?
The neck bolts was made a bit different on this bass. I tried to get a more "asymmetrical" placement of the 6 bolts, yet trying to cover as much "real estate" inside the neck pocket as possible.
The placement of the battery compartment has always been a bit of a headache for me. On this build I got this idea of placing it between the pickups on the back side.
Below a few soundsamples recorded directly into my Focusrite soundcard. The playing, well, it is what it is. Perhaps I should practice playing a bit more. However, the combined sound of the piezo in the neck pocket and the neck pickup is quite interesting. Quite "organic" or should I say "woody" character. Almost like a half-acoustic bass.
Neck pickup & Piezo pickup: