The Audiophile, the Gourmet, and the Slightly Odd Guitar Circuit

May 4, 2012
Will this primarily passive circuit reduce noise emanating from single-coil guitar pickups?

True audiophiles and real food gourmets have one thing in common: they crave un-garnished physical experiences. Some operational definitions are in order.

A true audiophile is one who desires his or her musical listening experiences to sound exactly like a live performance or as close to an unaltered live performance as humanly possible. The electronic equipment involved in playback will add no distortion, colorization, special effects, or equalization of any kind. In essence, each experience will be mirrored image to the original recording.

Another quality of a true audiophile is, no matter how techno savvy he or she is, listening comes first. In other words the true audiophile will listen to equipment before asking about its design strategy. Anyone who will not listen to piece of equipment without first knowing the design philosophy is not a true audiophile. This is the person who salts his or her food before tasting it.

On that note, a true gourmet is one who seeks to amplify the true flavor of a given foodstuff rather than mask it with exotic sauces and garnishes. In turn, a true gourmet chef does not seek a compliment that goes like, “Gee, your asparagus really enhances the three pounds of garlic and four quarts of olive oil you cremated it in.”

Interestingly enough, there really are no hard and fast rules for being a guitar gourmet, a guitarophile if you will. There are people who are passionate about the instrument and strive for a personal rather than a definitively pure tone from the instrument, be it acoustic, electric, or both. Guitarists are no longer critical to the point of blows over the right and wrong ways to do things. In fact, the kingdom of guitars is truly one of both peace and tolerance …… for the most part.

A while ago I wrote about how my godson and I are in the process of building what may turn out to be the world’s biggest and quietest fuzz box. In the interim, a reader sent me a schematic for a front-end circuit that he absolutely believes will enhance and quiet the sound of a guitar with single-coil pickups. And it will do so beyond “compute”. See the schematic and parts list below.

On first glance, guitarophiles will immediately note the big similarity between this circuit and the Varitone circuit Gibson features in its ES-345 and ES-355 semi-hollow body, stereo electric guitars, both vintage and currently available. It is essentially a variable RCL filter with what one might describe as a variable depth control (VR 2). This circuit appears in some do-it-yourself hobby books, most notably Electronics Projects for Musicians by Craig Anderton.

From left to right, vintage Gibson ES-345 and ES-355 guitars

Both Gibson ES-345 and ES-355 stereo guitars feature a Varitone circuit that allows the user to change tonal qualities via a six-position switch seen here on the lower bout of the instrument.

As a historical note, the Varitone feature was not really all that popular and was often defeated or removed by most owners of these otherwise fine guitars.

The Varitone was not vastly popular and ES-345 and ES-355 owners either disabled the circuit or, as in this photo, completely removed it and the switch from the guitar.

Then there are those players whose personal sound and style take full advantage of the Varitone six-position tone filter, like Mr. B.B. King.

Left, King of the Blues, Mr. B.B. King cradles an early 1960’s Gibson ES-355. On his right is his Custom Lucille ES-355 signature guitar, which has been in production since 1980. Built to Mr. King’s specs, it keeps the six-position Varitone circuit, adds a fine-tuner tailpiece, separate output jacks for mono and stereo operation, and eliminates the F holes and tremolo bar.

Getting back to the circuit in question, it’s nothing particularly special and, yes, the passive portion could trim down some noise. Most likely it will slice off some higher frequency noise, but expect nothing significant in the single-coil noise and hum department.

Now here’s a kicker, the reader has added an active element to the picture: a 3 to 9 Vdc source that rides around the tone filter through one fixed and one variable resistor. Exactly what’s the purpose for that? I’ve not yet heard back from said reader/responder.

Well, it obviously won’t do any harm in that the dc merely circles along with the guitar signal and the reader claims that we can reverse the polarity to reduce noise more depending on the orientation of the filter, the guitar, and the amplifier.

I’ve not tried this out yet since my breadboards are full at the moment. I already know what the Varitone will do, I’m just curious what the sonic results will be when the dc source kicks in. Will it bring out the taste of my asparagus without altering my listening experience? Any forecasts?

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