ECE313 Music & EngineeringElectric Guitars & Basses

Tim HoerningFall 2014

(last modified 10/13/14)

Overview

• Electric Guitar• Parts• Electronics• Simulated Circuit• Common styles of Electric guitars

• Other electro-mechanical instruments• Pedal Steel• Keyboard Based• Fender Rhodes• Hammond B3• Hohner Clavinet

The Electric Guitar

• Main Parts• Body• Wood• Routing

• Neck• Fret board

• Connection• Bolt on• Set Neck• Neck through

body neck

Electric Guitar Parts• Physical

• Neck• Tuners• Nut (possibly locking)• Fingerboard• Frets (typically 21 – 24)• Fret markers (3,5,7,9,12,15,17 19,21,24)• Wood type

• Main Part of neck• Truss rod• Construction (mirrored, skunk stripe, etc)

• Body• Bridge• Saddles• Variants

• Fixed (Stop tail, tele style)• Whammy bar (standard, 2 point, Floyd Rose, Kahler, Bigsby)

• Electronics• Controls• Pickups

• Body shape• Single Cutaway• Dual Cutaway• Other

Body

Strap Button

Strap Button

Pickups

Bridge(Whammy Bar)

Output Jack

Pick Guard

Pickup Selector Switch

Coil Split Switch

Volume Control

Strings

Tone Controls

NeckTuners & Tuning Pegs

HeadstockMaple Neck

Rosewood Fingerboard

Locking NutString Retainer

Manufacturer and Model

Fret Markers

Electronics

• Electrical• Pickups• Single Coil• Strat• Tele• P90

• Humbucker• 4 wires

• Switches• 1 pole 2 throw with bridging• 2 pole 3 throw with and without bridging• 4 pole 5 throw – Super Switch

• Pots• Standard Values• 250k, 500k, 1 Meg

• Variants• No-Load, Push Pull

Pictures of Electronics• Pots

• Switches & Jack

• Pickups

Pickups

• The Fundamental guitar pickup is• Source of magnetism• 1 magnet under 6 ferro-

magnetic pole pieces• 6 magnetic pole pieces• A coil of wire• Usually several thousand

turns of wire• The more turns• The hotter the output signal• The more higher frequency

components lost.

North

South

North

South

South

North

Humbuckers

• In 1955 Seth Lover invented the Humbucker for Gibson • It combines 2 coils with reversed magnetic fields and reversed windings.• When added correctly, the two picked up guitar strings (one from each

coil) will add in phase, but the hum from the 60Hz noise will add out of phase and be cancelled.

• The original humbuckers were called PAF humbuckers because of the sticker they carried.• PAF = Patent Applied For• The patent was granted. • PAF and Patent sticker Gibson humbuckers are very sought after and very

expensive

North

South

Potentiometers

• Electric Guitars use between 2 and 4 potentiometers as volume and tone controls.

• The volume controls are typically log taper pots configured as voltage dividers.

• The tone controls are usually log taper, and are simply used as a variable resistance.

• Variations occur with linear taper devices used as a pan pot or a more dramatic tone control

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

0.5

1

1.5

2

2.5x 105

Position

Res

ista

nce

Linear & Log Tapers

LinearLogLin-approx

Switches

• Guitar Switches are a little different in that they often use bridging positions• 1pole 2 through with

bridging – Les Paul• 2 pole 3 throw –

telecaster• 2 pole 3 throw with

bridging – Stratocaster• http://www.youtube.com/watch?v=DoCv5LQ1rvA

• 4 pole 5 throw – super switch

• DPDT on on on

Common

Common

Common

Common

1P2T w/ B

2P3T w or w/o B

4P5T

DPDT on-on-on (connections shown)

Basic Circuit

Pickup

Signal Source

Tone Control

Volume Control

Patch Cable

Amp Input Impedance

Pickup Simulated Circuit

• Based on the Lemur handout from class• Still under investigation• Parameters

• What the physical parts that are modeled by the lumped elements (L,R,C)

• How do we measure the parameters?

The Effect of Cable & Amp on Frequency Response

• The four circuits on the right represent the following• The guitar w/

amp at ½ volume

• The guitar w/ amp at full volume

• The guitar alone at half volume

• The guitar alone at full volume

Responses

• The top plots show the response without an amplifier connected • The lower volume is the same shape as the full volume

• The lower plot shows the response with an amplifier connected• There is an additional resonant peak in the full volume sweep that is not present in the low volume sweep

or the no amplifier case• This arises from the 2nd order interaction of the guitar and the cable

Treble Bypass ModificationAn extra capacitor can be added to the circuit to maintain the extra resonance at lower output levels

The 3 circuits top to bottom are as follows• Guitar at full output

(volume = 10 ) with the amplifier input impedance modeled as 1 Meg and the cable modeled 3nF.

• Guitar at 1/10 output (volume ~5 I think) with the amplifier input impedance modeled as 1 Meg and the cable modeled 3nF.

• Guitar at 1/10 output (volume ~5 I think) with the bypass cap added.

Responses

• With the treble bleed mod added, the resonant peak is retained at lower volumes.

Variations on a Theme: Popular styles of electric guitars and basses

Styles of Electric Guitars• Original designs were often focused on two types of guitars

• Hawaiian – Similar to the style of guitar now referred to as lap steel• Played with a slide bar• Used in open tuning

• Spanish – What more people now think of as an Electric guitar• The ES in Gibson�s ES-335 or other ES model line actually stands for

Electric Spanish.• The frets are used for fretting the strings (as apposed to as indicators for

the slide bar)• The 1950s saw the creation of the �big three� in terms of

classic guitar designs that are still sold to this day• The Telecaster by Fender• The Les Paul by Gibson• The Stratocaster by Fender

• Also created in the 1950s was the electric bass guitar. Leo Fender invented the EBG as a more convenient alternative to an upright acoustic bass.

Fender Telecaster® style• Original Model: Fender Telecaster

• Headstock: inline 6 tuners on one side, flat w/ retainers

• Nut: plastic

• Scale Length: 25.5�

• Pickups: 2• Neck: Single coil with metal cover• Bridge: Single coil with exposed pole

pieces

• Switching: 2 pole 3 position (neck, neck & bridge, bridge)

• Bridge: Fixed 3 or 6 saddle

• Controls: 1 volume 1 tone

• Associated Style / Songs: most typically associated with country, but played in just about all music.Neither of the above guitars are genuine Fender Telecasters,

but do represent the general design of one (Telecaster is a registered trademark of the Fender Corporation)

Fender Stratocaster ® style• Original Model: Fender Stratocaster

• Headstock: inline 6 tuners on one side, flat w/ retainers

• Nut: plastic

• Scale Length: 25.5�

• Pickups: 3• Neck: Single coil with exposed pole pieces

• Middle: Single coil with exposed pole pieces (sometimes Reverse Wound, Reverse polarity)

• Bridge: Single coil with exposed pole pieces

• Switching: 2 pole 3 position with bridging (neck, neck & middle, middle, middle & bridge, bridge)

• Bridge: 6 saddle vibrato system

• Controls: 1 volume 2 tones (1 for neck pickup, 1 for middle pickup)

• Associated Style / Songs: rock and roll, from Buddy Holly to Iron Maiden.Both of the above guitars are Stratocasters from Fender companies

(MII Squier on the left and MIM Fender on right) - (Stratocaster is a registered trademark of the Fender Corporation)

Super Strats - Strat® variants• Original Model: Various (Jackson, BC Rich,

etc)

• Headstock: inline 6 tuners on one side –pulled back

• Nut: locking or plastic with behind the nut lock

• Scale Length: 25.5�

• Pickups: 2 or 3• Neck: Humbucker or Single coil

• Middle: Single coil or not present• Bridge: Humbucker

• Switching: 2 pole 3 position with bridging (neck, neck & middle, middle, middle & bridge, bridge); 4 pole 5 position or individual toggles

• Bridge: 6 saddle locking vibrato system• Floyd Rose double locking

• Kahler cam based

• Controls: 1 volume varying tones

• Associated Style / Songs: hard rock and heavy metal usually.(Strat is a registered trademark of the Fender Corporation)

Gibson Les Paul® style• Original Model: Gibson Les Paul

• Headstock: classic 3 on each side with angled pulled back headstock

• Nut: plastic or bone

• Scale Length: 24.75�

• Pickups: 2• Neck: Humbucker (or P90 on some

models)• Bridge: Humbucker (or P90 on some

models)

• Switching: 1 pole 3 position with bridging (neck, neck & bridge, bridge)

• Bridge: 6 saddle Tune-o-matic bridge. Strings anchor in separate stop tail

• Controls: 2 volume 2 tones (1 of each for each pickup)

• Associated Style / Songs: Everything from Jazz to rock and Metal.Neither of the above guitars are genuine Gibson Les Pauls,

but do represent the general design of one. (Les Paul is a registered trademark of the Gibson corporation)

Other Variations

• Original Model:

• Tuners:

• Nut:

• Scale Length:

• Pickups:• Neck:• Bridge:

• Switching:

• Bridge:

• Controls:

• Associated Style / Songs:

Fender Precision bass• Original Model: Fender Precision

• Headstock: inline 4 tuners on one side, flat w/ retainers

• Nut: plastic

• Scale Length: 34�

• Pickups: 1• Middle: Split humbucker with each

portion covering 2 strings

• Switching: none

• Controls: 1 volume 1 tone

• Associated Style / Songs: rock and roll, from Sting to Iron Maiden.

The above bass guitar is a MIM Fender Precision bass

Fender Jazz bass• Original Model: Fender Jazz

• Headstock: inline 4 tuners on one side, flat w/ retainers

• Nut: plastic

• Scale Length: 34�

• Pickups: 2• Middle: single coil with 2 pole pieces

per string• Bridge: single coil with 2 pole pieces

per string (reverse wound from neck for hum canceling)

• Switching: none

• Controls: 2 volumes 1 tone

• Associated Style / Songs: Jazz, Fusion, Rock, etc

The above bass guitar on the left is a MIM Fender Jazz bass. The instrument on the right is a MIC copy.

Beatle bass• Original Model: Hofner Violin bass

• Headstock: 2 tuners on each side with a pull back

• Nut: plastic

• Scale Length: 30.3�

• Pickups: 2• Neck: single coil with metal cover• Bridge: single coil with metal cover

• Switching: on/off switches for each pickup and tone switch

• Controls: 2 volumes

• Associated Style / Songs: rock

The above bass guitar is a MIK variant on the original Hofner design

Steinberger bass

• Original Model: Steinberger XL-4

• Headstock: none – tuning is part of bridge

• Nut: plastic

• Scale Length: 34�

• Pickups: 2• Neck: humbucker with plastic cover• Bridge: humbucker with plastic cover

• Switching: none

• Controls: 2 volumes 1 tone

• Associated Style / Songs: rock, 80s

The above bass guitar is a MIK variant on the original Steinberger design, made with wood instead of the original composite design.

5 String bass• Original Model:

• Tuners:

• Nut:

• Scale Length:

• Pickups:• Neck:• Bridge:

• Switching:

• Bridge:

• Controls:

• Associated Style / Songs: - extra string is a B, a 4th below the low E

Multi-string basses (8 & 12 strings)

• Original Model: Hamer custom shop

• Headstock: 4 or 6 tuners per side, usually with a pull-back.

• Nut: brass

• Scale Length: 30� – 34�

• Pickups: 2• Neck: humbucker with plastic cover• Bridge: humbucker with plastic cover

• Switching: push-pull volume pot for active bypass

• Controls: 1 volume, 1 blend 3 active tone controls

• Associated Style / Songs: Cheap Trick, King�s X, Pearl Jam

Pedal Steel & Lap Steel• Electronics similar to a electric

guitar• Fixed bridge• No frets, only fret lines• More strings than a typical Spanish

style electric– 8 string– 10 string

• Tuning Modifiers– Foot pedals– Knee Levers

• Playing style– Like a Hawaiian guitar– Finger picks to select individual

strings– Bar to select notes on the neck

• Associated Style / Songs: Country Music, Robert Randolph, Pink Floyd (one of these days)

Hohner Clavinet

• Similar electric pickup to guitar underneath strings

• One string per note• Unique Sound

– String hammered to sound tone– Yarn at end immediately dampens

sound

• Associated Style / Songs: Stevie Wonder (Superstition, Higher Ground), Temptations (Ball of Confusion), Led Zeppelin (Trampled under Foot)

www.elecedge.com/Forsale/clavforsale.html

Fender Rhodes• Each key strikes a string connected

to a tine that forms an asymmetric tuning fork

• http://www.fenderrhodes.com/• Associated Style / Songs: Supertramp,

Beatles (Get Back), Billy Joel

Hammond organ (B3)• Designed as a replacement for pipe organs, but

developed a life of it�s own in rock and jazz• Synthesis is accomplished by rotating a tone

wheel in front of a pickup– There are 96 tone wheels for 91 tones (and 5 for balance)– The appropriate frequency outputs (9 per key) are connected

to switches under the keys• The timbre of the note is determined by the drawbars.

These allow the user to mix the partials to create the complex tone.

– Base on the system used in Organ– Has 9 levels from 0 (off) to 8 (all on)– Labeled

• 16� – 1 octave below fundamental• 5 1/3� – a fifth above fundamental• 8� -- fundamental• 4� -- an octave above fundamental• 2 2/3� – 1 octave and a fifth above fundamental• 2� -- 2 octaves above fundamental• 1 3/5� – 2 octaves and a major third above fundamental• 1 1/3� – 2 octaves and a fifth above fundamental• 1� -- 3 octaves above fundamental

• Often paired with a Leslie �spinning speaker� cabinet for vibrato & tremolo

• Associated Style / Songs: Spencer Davis (Gimme Some Loving), Kansas (Carry On Wayward Son), Deep Purple (Burn), Booker T & the MGs (Green Onions), Procol Harum (Whiter Shade of Pale), Niacin

Mellotron• Actually an analog Rompler• Samples of instruments were included on tape

loops, and played when the key was depressed.– Samples had finite length– Many mechanical issues– The modern version uses continuous loops– Homemade variants exist using cheap cassette

players• http://www.mysterycircuits.com/melloman/

melloman.html• Associated Style / Songs: The Beatles (Sgt Peppers and

later – Lucy in the Sky with Diamonds)

References

• http://www.geofex.com/article_folders/potsecrets/potscret.htm• The Secret Life of Pots – great intro to how potentiometers are

constructed and how they work.• http://www.elby-

designs.com/documents/tailoringpotentionometers.pdf• Similar to the secret life of pots, but with a bit more

• http://tangentsoft.net/audio/atten.html• More fun with pots

• http://www.maxim-ic.com/appnotes.cfm/appnote_number/838• Article on synthesizing log pots using a digitally programmable resistor

• www.wikipedia.org• Clavinet, Rhodes, Hammond B3 & Mellotron

• http://www.openculture.com/2014/10/oxford-scientist-explains-the-physics-of-playing-electric-guitar-solos.html• Physics of Guitar Solos