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May 2014

More Wiring Tricks...

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Well, we’re off of the road at the moment. The Sheryl Crow/ John Mayer tour was a complete blast and I’m back home settling in for the holiday season.

When at home I’ll often find myself late at night at my work bench tweezing and tweaking amps and guitars … especially amps that I buy off of eBay. A note of wisdom: when buying an old amp, always be prepared to drop another 50 to 100 bucks into reconditioning it. It’s not that the seller was trying to rip you off, but when old amps sit around for a while and then are put back to use, things tend to fail or break.

OK, back to our main subject. Last month I discussed a few wiring tricks to improve the tone or versatility of your guitar. Here are a handful more worth considering.

Again, this is assuming you have a certain, at least minimal, amount of electronics knowledge and skill with a soldering iron. If you don’t, take it to a friend who does or professional tech. The important thing when working in the back of a guitar is to be patient and use common sense. Cover the surrounding area with cloth so not to scar the finish with an accidental bump of a hot soldering iron. Solder will tend to spit and a hot molten solder bead leaves a nice ding in a guitar’s finish.

Use a “flux” solder spreader for a clean quick connection. You’ll need a 40 watt soldering iron for soldering to the back of a potentiometer, but a 15-30 watt iron is plenty for all other contacts. You can risk melting pick-up leads using a 40 watt iron for these connections. I can go on and on, but again … any hesitation, go to someone who can help you.

“No Load” Tone Control
This potentiometer, marketed by Fender and sold as an accessory, disengages the tone knob entirely from the circuit when turning the knob to 10. The result is a noticeable increase of high-end clarity and more openness to your sound. A great option, but it is still nice to have the tone knob roll off some highs when you need to.

Changing filter cap values on the tone control
You can fine-tune your sound with this simple trick. The effect of your tone control can vary with each amp that you plug into. It should be thought that your guitar circuitry is really just an extension of your amplifier. If your tone control rolls off too much high-end, try replacing the cap with one of lower value.

Early Les Pauls commonly have a .022uf cap which works pretty well; try installing a smaller value .0022uf cap to roll off treble at a higher threshold. On Strats or Teles the original cap value was usually a .1uF. Try replacing with a .022 or even as low as 500pF.

Even the composition of the cap can make a tonal difference – ceramic disc caps are most common in Fenders and film caps are found in most early Gibsons. Even oilfilled capacitors might be worth the experiment, although they can get a bit pricey.

Probably the most famous capacitors are the Sprague Black Beauty “Bumble Bee” found in ‘50s and early ‘60s Gibsons (pictured).

These pop up on eBay quite often and are beginning to fetch a nice dollar, as they’re desirable in the audiophile world, as well as by vintage guitar enthusiasts. For those trying to recreate the ‘50s wiring in your Les Paul (discussed last month), the combination of CTS brand 500k potentiometers and N.O.S. Bumble Bee .022uF/400v caps are the essential ingredients. (Note that the voltage is not as significant, since your guitar’s input is at the lowest voltage stage of the amp circuit. Any capacitor of 25 volts or higher is fine.)

Potentiometer values
Most Fenders come with 250K pots, where most early Gibsons have 500k pots. Later Les Pauls I’ve owned from the ‘80s on forward sometimes have 350k pots. Generally, the higher the value (500k pot), the brighter the tone, the lower value (250K pot) the warmer the tone.

I guess this leads into the next subject of serious tone tweaking on guitars … pickups. There are so many, it’s like choosing lipstick at the drug store (errr…not that I wear lipstick or anything). Next issue, I’ll hit on some of my fave pickups I’ve landed on over the years.

Happy soldering!



Peter Stroud, Sheryl Crow Band
65amps/co-founder
65amps.com

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