Build a Lo-Fi Converter for Guitar

Maybe you don't want your guitar to sound all clean and crispy...

By Craig Anderton

When mixers, audio interfaces, direct boxes, and all-in-one recording “workstations” started including high impedance inputs for guitar, it seemed like a good idea. After all, high impedance—a characteristic of tube amp inputs—avoids loading your guitar’s pickups. This loading can dull the tone and reduce volume.

Well as Newton said, “For every action, there is an equal and opposite reaction.” And as I say, “For every action, the Law of Unintended Consequences may appear.” In this case, it turns out that some guitarists prefer the loading effects of a low impedance input, as found in many solid-state amps and effects boxes. The high frequency reduction can contribute to a smoother, rounder sound when feeding distortion and overdrive boxes.

If you find your fi a little too hi, don’t fret— eclaim your duller, vintage solid-state tone with this cheapo do-it-yourself box. As the parts list and schematic show, it’s ridiculously simple and doesn’t even use power. As long as you know which end of a soldering iron to hold, you can probably build the Lo-Fi Converter.

Note, however, that this box only applies to standard, passive pickups. It won’t have any effect with active (preamplified) pickups.

CONSTRUCTION

Drill three 3/8” holes in the box: two for the jacks and one for the switch, a 2-pole, 6-throw type. We’ll use only one of the poles, which connects to each jack’s hot connection. Leave one of the switch throws unconnected.

Connect one end of a resistor to each of the other throws, then run a ground wire from the other resistor ends to the jack grounds. Done!

USING IT

Plug your guitar into either jack (the two jacks are interchangeable), and patch the other jack to the high impedance input you’d like to degrade. With the switch set to the unconnected throw, the circuit doesn’t affect your signal because the input jack connects directly to the output jack. Different resistors load the signal by different amounts, with the 4.7k resistor causing the greatest loading. When using the lower-valued resistors, you’ll probably need to turn up overall volume to compensate for the loss in level.

Experiment to find out which amount of loading works best for you. Even if you’re a fan of hi-fi sound, you might be pleasantly surprised at how much a little loading can smooooth out your sound when feeding distortion.

PARTS LIST

(numbers indicate Radio Shack stock numbers)

S1    2-pole, 6-position switch (#275-034)

R1    4.7K resistor (#271-1124)

R2    10K resistor (#271-1126)

R3    22K resistor (#271-1128)

R4    47K resistor (#271-1130 )

R5    100K resistor (#271-1131)

J1, J2    1/4" phone jack (#274-312)

Misc.    Small metal case (#270-238), knob (#274-416), wire, solder

Craig Anderton is Editor Emeritus of Harmony Central. He has played on, mixed, or produced over 20 major label releases (as well as mastered over a hundred tracks for various musicians), and written over a thousand articles for magazines like Guitar Player, Keyboard, Sound on Sound (UK), and Sound + Recording (Germany). He has also lectured on technology and the arts in 38 states, 10 countries, and three languages.