ECE313 Music & Engineering Electric Guitars & Basses Tim Hoerning Fall 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 body Main Parts Body Wood Routing Neck Fret board Connection Bolt on Set Neck Neck through 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 Bridge (Whammy Bar) Pickups Strap Button Strap Button Strings Output Jack Tone Controls Pickup Selector Switch Coil Split Switch Volume Control Pick Guard
Neck Locking Nut String Retainer Tuners & Tuning Pegs Manufacturer and Model Rosewood Fingerboard Maple Neck Headstock 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 North South North South The Fundamental guitar pickup is Source of magnetism 1 magnet under 6 ferromagnetic 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.
Humbuckers South North North South 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
Potentiometers Resistance 2.5 x 105 2 1.5 1 Linear & Log Tapers Linear Log Lin-approx 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 0.5 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Position
Switches 1P2T w/ B Common 2P3T w or w/o B Common 4P5T Common DPDT on-on-on (connections shown) Common 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.co m/watch?v=docv5lq 1rvA 4 pole 5 throw super switch DPDT on on on
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 2 nd order interaction of the guitar and the cable
Treble Bypass Modification An 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 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) Associated Style / Songs: most typically associated with country, but played in just about all music.
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) 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) Associated Style / Songs: rock and roll, from Buddy Holly to Iron Maiden.
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 (Strat is a registered trademark of the Fender Corporation) Associated Style / Songs: hard rock and heavy metal usually.
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) 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) Associated Style / Songs: Everything from Jazz to rock and Metal.
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 4 th 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.elbydesigns.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-explainsthe-physics-of-playing-electric-guitar-solos.html Physics of Guitar Solos