Grounding and Shielding a Danelectro '63 Baritone

Supposedly the electronics in the original Danelectro guitars were very heavily shielded. When I bought this reissue '63 Dano baritone, I was more than a little disappointed that aside from the "lipstick" pickup covers, the instrument was practically unshielded. The back of the pickguard had a skimpy little strip of aluminum tape between the controls.

It wasn't a great surprise though, as this is a very noisy instrument.

The compartment cover was just a plastic disc held in place with an ungrounded metal strap. Of course grounding was also poor, with ground loops, potentiometer cans used as ground points, etc.

Although there wasn't any internal shielding (not even conductive paint— I checked with my ohmmeter) the pickup mounts seemed to be designed to work with shielding, since they had grounded copper spring mounts.

There's some decent advice on improving the shielding and grounding in a Stratocaster available at Guitar Nuts here: Quieting the Beast, Shielding a Strat™. I adapted some of the implicit goals of that article to the Dano '63. The most significant differences are related to the relative simplicity of the Dano: Two pickups, single volume & tone, single-pole selector switch with pickups in series. The way a Dano selector works is by shorting out the unused pickup when not in the center "series" position.

I used Copper foil tape with conductive adhesive to shield the electronics compartment, pickguard and back cover. Since the peculiarities of Danelectro body construction leave lots of inaccessible voids, I had to make little foil dams near the controls compartment.

I didn't end up creating a signal ground terminal as described in the article, since there were so few signal grounds to tie together: One from the jack & volume, one from the tone capacitor, one from the pickup selector. I just soldered them together and added some heat-shrink to insulate them from the shields.

I also omitted the large ring terminal under a potentiometer to connect shielding, as the pickup selector switch had a nice solder lug on its shield. I did use ring terminals to attach the bridge wire and pickup shields to the foil shielding.

I ended up replacing the tone capacitor, since the original was soldered onto the back of the potentiometer and had its leads cut too short to b

e usable in any other configuration. The new tone capacitor as well as the new 0.33μF coupling between ground ans shield are affixed with double-face foam tape.

Eric Barbour or Fred Nachbaur?

Recently, I mentioned in on an online forum my idea for a 15-ish-watt amp based only on Compactrons with a 6AS11 preamp and a pair of 6LU8s for the power amp and phase-inverter (each tube contains a beam tetrode and a medium-μ triode). One response was: "You should get a job with Metasonix". I suppose I could have taken offense at the comparison: While I think there is a place (and probably a need) in the world for a guy (Eric Barbour) who makes an amp called the F*%@ing F*%@er [grawlixes mine], that's not me or my style. Also, amusing as it is, I don't think I could bear to build an amplifier that uses 800 watts of power for just 30 watts of output.

I think the Metasonix comparison really came from the idea of using new-old-stock tubes for other than their original purpose. It wasn't Eric Barbour that gave me the idea, though; it was the circuits and writings of the late Fred Nachbaur. Fred's pages were one of my key resources when I decided to move from repairing & tweaking amps (like a Kalamazoo model 1 and a "Blackface" Fender Bassman) to designing & building from scratch. His design philosophy was mostly rooted in classic methods, but he loved to use oddball tubes, especially ones with atypical heater voltages arranged into series/parallel combinations. That approach seemed to border on obsession in some cases: Just look at the power supply for his "Spunky" guitar amp. It's a pretty cool arrangement that eliminates the need for a transformer with a heater winding. A bit of goofiness though is seen in the two 10-watt power resistors needed to set the voltages right, and the fact that there's an entire separate transformer for the bias supply. I guess it works if you have the parts on hand.

In any case, the all-compactron amp is not going to happen, at least not right away... Since I'm on the waiting list for a new Danelectro reissued '63 Baritone guitar, which will need an amp, I'm going back to a previous idea for the 15-ish watt amp. The power section will be a pair of Electro-Harmonix 6973s. Just like when I chose the JJ 7591S as the power tube for the Lama Kazu 8SE, (7591s are rarely seen in single-ended amps— they mostly turn up in old Ampegs) I couldn't bear to use the typical EL84 or 6V6 power tubes that are more common in amps of this size. More to come on that project.