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News: Washburn Resonator Series Guitars

September 30, 2011 by · Leave a Comment 

Washburn Resonator Series Guitars
Washburn Guitars adds a new line of Resonator guitars to their Folk and Bluegrass instruments.

Washburn recognizes the important role played by the Resonator guitar in the history of bluegrass music and has decided to honor the instrument with a new line of Resonator guitars. The current line up of Resonator guitars include the acoustic resonators R15R and R15S, and their acoustic electric brothers the R15RCE and the R45RCE.

The single cone resonator and spider-bridge design is a common denominator among the four Resonator guitars. This adds to the series’ classic sound and vibe which resonator players tend to look for. Read more

PRS SE Angelus Acoustic Guitars

September 29, 2011 by · Leave a Comment 

Acoustic GuitarsPaul Reed Smith is looking to expand it’s Acoustic Guitars with the new SE Acoustic Guitars series. Read more

News: Fender Telecaster stolen from a Casket

September 27, 2011 by · Leave a Comment 

Fender Telecaster stolen from a CasketA Fender Telecaster was brought back from the grave, allegedly stolen from a casket of a 67-year-old Army veteran by a Wisconsin cemetery worker. Read more

EHX Talking Machine Review

September 25, 2011 by · Leave a Comment 

EHX Talking Machine ReviewBuying a pedal that offers multiple exciting sounds and finding that you can’t save any of them is frustrating. Consistently re-creating onstage all of its cool effects is virtually impossible, forcing some players to buy multiple identical units, each set for a single sound.

Fortunately, Electro-Harmonix–purveyors of some of the coolest sounds ever–introduced its first programmable pedal a few years ago. Since then, they have been churning out amazing effects, like Ring Thing and POG2, capable of a wide range of usable tones, storable as nine presets. The latest addition is the Stereo Talking Machine, a vocal formant filter that offers wah, auto-wah, envelope filter, and talk box effects. Read more

Joe Trohman Telecaster & J Mascis Jazzmaster Fender Squier

September 23, 2011 by · Leave a Comment 

Telecaster  Guitar
Squier has teamed up with Joe Trohman of the Fall Out Boy and The Damned to create the Joe Trohman Telecaster, which is loosely based on the early ’70s Fender Telecaster Deluxe.

The Joe Trohman Telecaster guitar, like the other artist signature series of Squier was designed to provide inspiration to guitar players by making great value guitars that have the approval of great artists, ensuring quality workmanship and superb sound. Read more

Fender and Gibson 9/11 Tribute Guitars

September 20, 2011 by · Leave a Comment 

Fender Stratocaster GuitarsI’m a little late to the party, but thought this was something worth posting. I thought it was a classy move by both Fender and Gibson guitars. Below are the press releases and images of the 9/11 tribute guitars. Read more

Ibanez Destroyer Bass DTB100 – Bass Guitars

September 16, 2011 by · Leave a Comment 

Ibanez Destroyer Bass GuitarIf you are looking for a second hand electric bass guitar that has killer vintage looks and bold shapes, then you might want to stop looking at the classifieds and consider getting the revamped Ibanez Destroyer Bass. It sports a vintage look combined with a pointy shape that will cater to most metal music bassists. Read more

Basic Electric Guitar Circuits: Potentiometers and Tone Capacitors

September 15, 2011 by · Leave a Comment 

What is a Potentiometer?

Potentiometers, or “pots” for short, are used for volume and tone control in electric guitars.  They allow us to alter the electrical resistance in a circuit at the turn of a knob.

Potentiometers and Tone Capacitors

It’s useful to know the fundamental relationship between voltage, current and resistance known as Ohm’s Law when understanding how electric guitar circuits work.  The guitar pickups provide the voltage and current source, while the potentiometers provide the resistance.  From Ohm’s Law we can see how increasing resistance decreases the flow of current through a circuit, while decreasing the resistance increases the current flow.  If two circuit paths are provided from a common voltage source, more current will flow through the path of least resistance.
Potentiometers and Tone Capacitors

We can visualize the operation of a potentiometer from the drawing above.  Imagine a resistive track connected from terminal 1 to 3 of the pot.  Terminal 2 is connected to a wiper that sweeps along the resistive track when the potentiometer shaft is rotated from 0° to 300°.  This changes the resistance from terminals 1 to 2 and 2 to 3 simultaneously, while the resistance from terminal 1 to 3 remains the same.  As the resistance from terminal 1 to 2 increases, the resistance from terminal 2 to 3 decreases, and vice-versa.

Tone Control:  Variable Resistors & Tone Capacitors

Tone pots are connected using only terminals 1 and 2 for use as a variable resistor whose resistance increases with a clockwise shaft rotation.  The tone pot works in conjunction with the tone capacitor (“cap”) to serve as an adjustable high frequency drain for the signal produced by the pickups.  The tone pot’s resistance is the same for all signal frequencies; however, the capacitor has AC impedance which varies depending on both the signal frequency and the value of capacitance as shown in the equation below.  High frequencies see less impedance from the same capacitor than low frequencies.  The table below shows impedance calculations for three of the most common tone cap values at a low frequency (100 Hz) and a high frequency (5 kHz).

Potentiometers and Tone Capacitors

When the tone pot is set to its maximum resistance (e.g. 250k?), all of the frequencies (low and high) have a relatively high path of resistance to ground.  As we reduce the resistance of the tone pot to 0?, the impedance of the capacitor has more of an impact and we gradually lose more high frequencies to ground through the tone circuit.  If we use a higher value capacitor, we lose more high frequencies and get a darker, fatter sound than if we use a lower value.

Volume Control:  Variable Voltage Dividers

Volume pots are connected using all three terminals in a way that provides a variable voltage divider for the signal from the pickups.  The voltage produced by the pickups (input voltage) is connected between the volume pot terminals 1 and 3, while the guitar’s output jack (output voltage) is connected between terminals 1 and 2.  From the voltage divider equation below we can see that if R1 is 0? and R2 is 250k?, then the output voltage will be equal to the input voltage (full volume).  If R1 is 250k? and R2 is 0?, then the output voltage will be zero (no sound).

Potentiometers and Tone Capacitors

Potentiometer Taper

The taper of a potentiometer indicates how the output to input voltage ratio will change with respect to the shaft rotation.  The two taper curves below are examples of the two most common guitar pot tapers as they would be seen on a manufacturer’s data sheet.  The rotational travel refers to turning the potentiometer shaft clockwise from 0° to 300° as in the previous visual representation drawing.
Potentiometers and Tone Capacitors

How do you know when to use an audio or linear taper pot?

It’s really a matter of personal taste when it comes to volume control.  Notice how the rate of change is much more dramatic on the audio taper pot when traveling back from 100% to 50% rotation.  This means that the same amount of rotation would give you a more intense volume swell effect with an audio taper than with a linear taper.  Using a linear taper volume pot would give you a more gradual change in volume which might feel like you have more fine control with which to ease back the volume level.

For tone control, it’s basically standard practice to use an audio taper.  The effect of the tone circuit is not very noticeable until the resistance gets pretty low and you can get there quicker with an audio taper.

How do you know what value of potentiometer to use?

The actual value of the pot itself does not affect the input to output voltage ratio, but it does alter the peak frequency of the pickup.  If you want a brighter sound from your pickups, use a pot with a larger total resistance.  If you want a darker sound, use a smaller total resistance.  In general, 250K pots are used with single-coil pickups and 500K pots are used with humbucking pickups.

Specialized Pots

Potentiometers are used in all types of electronic products so it’s a good idea to look for potentiometers specifically designed to be used in electric guitars.  If you do a lot of volume swells, you’ll want to make sure the rotational torque of the shaft feels good to you and most pots designed specifically for guitar will have taken this into account.  When you start looking for guitar specific pots, you’ll also find specialty pots like push-pull pots, no-load pots and blend pots which are all great for getting creative and customizing your guitar once you understand how basic electric guitar circuits work.

Kurt Prange (BSEE) is the Sales Engineer for Amplified Parts (www.amplifiedparts.com) in Tempe, Arizona, United States.  Kurt began playing guitar at the age of nine in Kalamazoo, Michigan.  He is a guitar DIY’er and tube amp designer who enjoys helping other musicians along in the endless pursuit of tone.


Ibanez Artist Series ART300 Electric Guitar Review

September 8, 2011 by · Leave a Comment 

Ibanez  ART300 Electric Guitar Review

The electric guitar has surpassed the piano as the most popular instrument of budding musicians. While the reasons for this trend are numerous, it’s quite obvious that most households no longer have a piano, while many a dad or mom has an old guitar tucked away in a closet for junior to explore once the music bug starts to bite.

Of course, the goal for every young player is to buy a guitar of his own, and to that end, Ibanez has been most helpful. The company’s 30-year-old Artist Series has been continually updated to provide modern variations on the two-humbucker mahogany guitar theme, with prices that are commonly far below market value. New to the series is the ART300, an unusual and interesting single-cutaway that has active pickups and a raised reptilian finish. This kind of bold and inventive thinking is exactly what I love about Ibanez, the same company that cuts monkey grips into $2,500 works of six-string art. Read more

Ernie Ball Music Man HS Bongo 6 six-string bass review

September 6, 2011 by · Leave a Comment 

Ernie Ball Music Man Bongo 6 Bass GuitarWhen the Ernie Ball/BMW- designed Bongo bass came out in 2003, its innovative styling and brilliant tonal quality shook up the bass world. The four- and five- string models have garnered a rabid worldwide fan base; but now, with the introduction of the six-string version (the first-ever Music Man six-string bass), the Bongo is poised to carve itself a bigger niche. Read more

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