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Bass Guitar

Page history last edited by msunshine37@gmail.com 14 years, 2 months ago

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Project Summary:

I intend to build a relatively inexpensive electric bass guitar from scratch (except for the pickups, machine heads, and strings). I will focus on redesigning the bridge to arrive at an elegant solution that accomplishes the same functionality as current technology without sacrificing tone quality. Additionally, I will explore machine head technology to determine whether or not this can be accomplished more simply or inexpensively. Tonal performance will be quantified through harmonic content analysis. The quality of the instrument can also be framed in terms of clarity, attack, and sustain. Overall, I would like to keep the dimensions of the instrument within boundaries much more restrictive than they are for current instruments. This will produce a compact model, which is thus easier to transport than most (essentially all) current models.

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Introduction:

An electric bass bridge must accomplish a number of essential functions:

1. Bass bridges must be able to sustain great forces from four high tension strings while remaining securely fixed to the body of the bass. If the bridge and the body of the bass are fastened correctly so that they essentially move as one body, most of the vibrational energy from the strings of the instrument will be transmitted into the body producing good sustain. (String to instrument sonic transmission).

2. The bridge must be relatively massive (more dense than the body of the guitar). The material must be very hard and thick enough so that it does not deform under the particular loading state (string tension as well as fastening method).

3. Each string saddle must be independently adjustable in the directions toward the neck and away from the body. This functionality allows action and intonation control.

4. The arrangement of the bridge must be such that strings can easily be removed and replaced. The bridge should be stable and stationary when transitioning between the full loaded state and the unloaded state.

5. The bridge design should take into account the general aesthetic of the instrument since each bass is also a work of art.

Machine Heads:

Bass dimensions in general:

I would like approach the solution to this engineering problem differently than bass makers have in the past. Ultimately, I intend to accomplish all of the same goals simply and inexpensively.

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Background:

Currently, all electric bass bridges employ pretty much the same design to accomplish a number of desired functions:

Material: steel, aluminum, heavy brass, high-density zinc alloy

Bridges:

Hipshot A Style Badass Bass Bridge II Fender American Standard (5-String)

Machine Heads:

Grover 145C Titan Hipshot HB6C-1/2 Fender

Grover 145C Titan Electric Bass Machine Head Tuners

Bass manufacturers have produced designs in the past similar to what I will try to accomplish. Aside from these exceptions, all basses look pretty much the same in overall design. The first two basses below are examples of instruments with minimized bodies. In addition, the Steinberger has an alternative machine head design. The Chapman stick is not a bass, but has a bodiless design. The Fender below is an example of the general design that essentially all other basses share.

Steinberger Chapman Stick (not a bass) Fender Jazz

FenderJazzBass.jpg image by ruippires

Internet Sources:

http://www.ehow.com/video_4396346_adjust-bridge-saddle-bass-guitar.html

http://www.ehow.com/how_2188239_calibrate-electric-guitarbass-bridge.html

http://en.wikipedia.org/wiki/Bridge_(instrument)

http://en.wikipedia.org/wiki/Fingerboard

http://en.wikipedia.org/wiki/Neck-through

http://en.wikipedia.org/wiki/Machine_head

http://books.google.com/books?id=RpOcVLXime4C&dq=bass+body+material&source=gbs_navlinks_s

http://www.talkbass.com/wiki/index.php?title=Bass_Guitar_Luthiery&oldid=461

http://www.electricbasssecrets.com/

http://store.hipshotproducts.com/cart.php?m=product_list&c=3

http://www.stewmac.com/shop/Bridges,_tailpieces/Bass_bridges.html

http://www.leoquan.com/html/products.html

http://keeseh.com/

http://www.stick.com/instruments/frets/rails/

http://www.steinberger.com/XS1FPA.html

http://www.stewmac.com/freeinfo/Nuts,_saddles/a-nuts.html

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Intellectual Property:

Relevant US Patents:

Bass Bridges-

Quan combined bridge and string anchor. This device provides all of the functionality desired from a bridge.

http://www.google.com/patents/about?id=WbU7AAAAEBAJ

Another bridge design for basses and guitars, also with two dimensional adjustability.

http://www.google.com/patents/about?id=pFY2AAAAEBAJ

Bass Machine Heads-

The most common machine head design approach with a worm wheel system.

http://www.google.com/patents/about?id=vhwgAAAAEBAJ

Alternative design with a rotating arm.

http://www.google.com/patents/about?id=71ggAAAAEBAJ

Angled axis design for a machine head.

http://www.google.com/patents/about?id=yDokAAAAEBAJ

Classic worm gear design for locking string in place.

http://www.google.com/patents/about?id=0ml8AAAAEBAJ

Minimalist Basses-

Steinberger Bass 1987, uses a body that is much smaller than most other basses, tuning apparatus is included as part of the body so that the need for a head is altogether avoided.

http://www.google.com/patents/about?id=i-M8AAAAEBAJ

Steinberger Bass 1990, similar design to the 1987 version, though with head mounted machine heads.

http://www.google.com/patents/about?id=F6ImAAAAEBAJ

Steinberger Bass 1987, similar to the above patent except the machine heads are mounted on the head of the guitar as in a normal bass design.

http://www.google.com/patents/about?id=WBY8AAAAEBAJ

Basses-

Classic Peavy bass design with all the characteristics of a “normal” bass guitar: tuning apparatus on head, two pickups, bolt on neck, regular sized body.

http://www.google.com/patents/about?id=vOM7AAAAEBAJ

Classic Fender bass design similarly having all “normal” bass characteristics.

http://www.google.com/patents/about?id=jPBzAAAAEBAJ

Another classic bass design. The similarities between these three basses are apparent.

http://www.google.com/patents/about?id=I7dzAAAAEBAJ

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My Proposed Solution:

In general, I intend to keep the overall design of the bass guitar and of the specialized components as simple as possible both to machine and assemble. This must be accomplished without sacrificing in tonal performance of the instrument. Current machine head technology combined with a full body design produces an unweildy instrument in terms of transportation and storage. This undesirable product can be avoided by employing an alternative machine head configuration in conjunction with a bodyless construction. The body will be replaced by an aluminum component which will mount the electronics, the bridge, the truss rod receptacle, and the strap attachment pegs.

Sketch:

The following is a sketch of the intended dimensions of the instrument.

Four-String Electric Bass Design Decisions:

Body Material - maple, aluminum

Length Scale - 34"

Construction Type - neck-through-body, one piece

Fingerboard Material/ - rosewood

Fret Number/Type - 19 jumbo

Pickup Configuration/Type - 2, Seymour Duncan Basslines Music-Man ceramic SMB-4d

Electronics Configuration - 2 volume, 1 tone

Recommended Strings - D'Addario EXL230 Long Scale 55-110

Requirements:

1. Relatively simple design to fabricate

2. Relatively inexpensive

3. High quality tonal performance

4. Employs novel bridge design accomplishing all desired bridge functionality

5. Employs novel compact machine head configuration

6. Minimizes dimensions to maximize portability without sacrificing playability

Constraints:

1. Cost

2. Time/complexity of fabrication process

3. Minimal dimensions

Electronics:

http://www.seymourduncan.com/support/wiring-diagrams/schematics.php?schematic=musicman_passive

http://www.seymourduncan.com/support/wiring-diagrams/schematics.php?schematic=std_jazz_bass

Evaluation Criteria:

In order to determine whether or not the instrument has met its requirement of producing good tone, the harmonic content of the output signal will be quantified. This characterization of the tone can then be compared with that of an Ibanez SR500 bass to determine how well it performed.

Ibanez SR500:

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Theory:

The following document contains the formulation of a physical model to describe the vibrational motion of a string in the system of a bass guitar:

Physical Model: Theory (Bass Guitar).docx

String dimensions for theoretical analysis based on the E, A, D, and G strings from D'Addario EXL230 Long Scale 55-110 and the B string from XLB130 Nickel Wound Single String.

String	(B)	E	A	D	G
Length (inches)	34.000	34.000	34.000	34.000	34.000
Length (m)	0.864	0.864	0.864	0.864	0.864
Frequency (Hz)	30.870	41.200	55.000	73.420	98.000
Frequency (rad/sec)	193.962	258.867	345.575	461.312	615.752
Diameter (inches)	0.135	0.110	0.090	0.075	0.055
Diameter (m)	0.00343	0.00279	0.00229	0.00191	0.00140
Tension (N)	153.474	205.450	241.930	287.330	280.176

http://en.wikipedia.org/wiki/Vibrating_string

http://books.google.com/books?id=9CRSRYQlRLkC&printsec=frontcover&source=gbs_navlinks_s#v=onepage&q=&f=false

http://www.ee.washington.edu/research/sahr/pages/physics.html

http://paws.kettering.edu/~drussell/Demos/string/Fixed.html

http://www.varg.unsw.edu.au/beam_vibration.htm

http://paws.kettering.edu/~drussell/guitars/electric.html

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First Prototype:

Brainstorms:

The first prototype will be a preliminary model of the intended design for a single string anchor mechanism. This model will be useful in order to determine whether or not the selected dimensions and element relationships will function effectively in practice. This design can then be scaled up to a full four-anchor bridge all machined from one piece of aluminum. The first prototype will be machined from the same material (6061 Al) as the final bridge assuming the prototype functions correctly.

The anchor system must provide independent mobility for each saddle in the both x-direction (neck axis) and y-direction (away from bridge). Y-direction mobility will be accomplished by employing four screws (one for each saddle) threaded up through the bottom of the bridge, which contact the underside of each saddle independently. As these screws are turned, they rise or fall as desired changing the height of the saddle. This direction of mobility allows the bass guitar string action (height of strings above fingerboard) to be adjusted to a high degree of precision. X-direction mobility is accomplished slightly differently in that the x-direction screws thread directly into the saddle itself, rather than simply contacting it. As the screw is turned, the saddle slides forwards or backwards through the bridge channel. Due to the structural configuration of the component, the x-direction mobility screw cannot be threaded into the saddle exactly along the x-axis. The string bead receptacle cannot be moved, and thus the x-direction screw must enter the saddle with an angle above the horizontal. This is the main dimension that will be investigated through this first prototype. The success of the chosen configuration will become apparent depending on whether or not the saddle moves as desired.

Parts List:

Aluminum (6061), 2x Screws (8-32), saddle and anchor structure (machined from the Al)

Pictures:

Preliminary Bridge Prototype:

Bridge Prototype 1, Bridge Prototype 2, Bridge Prototype 3

Test and Evaluation:

The first single string anchoring system prototype functioned properly and the saddle had all of the desired mobility.

Results:

Various dimensions will need to be changed slightly from this prototype in order to scale up the functionality to a full bass bridge and be able to incorporate it into an instrument.

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Second Prototype:

Brainstorms:

The second prototype will be a full-scale working bridge, designed to be attached to the neck of a working bodiless instrument. This will scale up from the first prototype four-fold, and the functionality of the design will be demonstrated in its integrable form. The main section of this part will be machined out of one piece of aluminum. The machining process is outlined in the pictures linked to below. Four mobile string saddles will be machined out of steel and wil slide back ond forth in the saddle channels. The x and y coordinates of these saddles will be determined precisely and independently of one another by the states of the eight saddle mobility screws (8-32). Two holes in the y-direction and one hole in the x-direction will be present in order to firmly fasten the bridge to a neck (to be machined in a future prototype). In addition, a strap button and cover plates for the two rows of saddle adjustment screws will be added.

Parts List:

Aluminum (6061), bridge structure (machined from Al), Steel, 4x saddles (machined from steel), 8x machine screws (8-32), 2x steel cover plates, foam for x-direction screw cover plate.

Pictures:

Actual bridge for first prototype (machining stages):

Step 1, Step 2a, Step 2b, Step 3a, Step 3b, Step 4a, Step 4b,

Step 5a, Step 5b, Step 6a, Step 6b, Step 6c, Step 7a, Step 7b,

Step 8a, Step 8b, Step 9a, Step 9b, Step 9c, Step 9d, Step 9e, Step 9f

Test and Evaluation:

Results:

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Third Prototype:

Brainstorms:

Initially I had the idea to machine the entire bass shape from one piece of wood. Neck-through-plus-body machined fom one piece may not be feasible for multiple reasons: the required piece of wood to begin with would result in a great deal of wasted material due to the width of the desired body shape and the relatively narrow neck, the truss rod would be logistically difficult to insert as would the truss rod hole be to cut. A simpler solution may be to use a normally shaped neck-through cut mated to a relatively massive metal (aluminum?) "body". The metal body could then mount the bridge directly as well as house any electronics. In addition, the metal body could have the option to mount wood body wings to each side as in a normal neck-through bass construction. The problem

of housing the pickups and electronics in the small body (volume-wise) while mounting the bridge as well will pose a design challenge. The stress state throughout the body and neck must also be withstood by the system well within the material boundaries.

Parts List:

40" x 4.5" x 1.25" maple blank, 2x Music Man ceramic pickups, warmoth double expanding truss rod, 2L + 2R stew mac chrome tuners, d'addario exl230 long scale strings, machined aluminum nut, 2x machines aluminum brackets (pickup clamps), stew mac jazz bass wiring (pots + tone + jack), machined aluminum bridge system (4x steel saddles, 8x adjustment screws), 3x steel threaded inserts, screws for attachment of bridge and brackets, strap buttons, 3x chrome knobs. [fretting and fingerboard left to the next prototype]

Pictures:

Parts:

[fingerboard, fretwire, tuning machines, strap buttons, potentiometers, capacitor], [sidebar material], [knobs, truss rod, truss nut, pickups]

Laying out parts:

[bridge end], [head end]

Preliminary design drawings: