Archive for the ‘design’ Category

Introducing the Acoustic Ramp™ Diffuser

Monday, August 1st, 2011

As some of you already know, I invented a new type of number-theoretical diffuser a while ago and I have been working on developing it into a product and filing the necessary patent applications.  It’s called the Acoustic Ramp™ because it is wedge shaped.  The diffuser became my master’s thesis for my degree work at the University of Massachusetts in Lowell in Sound Recording Technology.  The degree that I will earn is called a Master’s of Music in Sound Recording Technology (M.M. S.R.T.) and will hopefully make it easier to get a job that pays the bills!

This past Saturday 7/30/2011 I spent the day running a series of tests on the diffuser and comparing its performance to that of a flat reflector.  Essentially what I am trying to show is how much better the back wall of a control room would be if it had an array of my Acoustic Ramp™ diffusers and wasn’t a flat wall.  When sound hits a flat wall it bounces back, a lot like a rubber ball might bounce.  The problem is that the sound bouncing off the wall interferes with the sound going towards the wall and causes problems like comb filtering, flutter echo and bass buildup. One option for handling the problem is to absorb all of the sound hitting the wall and preventing it from reflecting.  This works, but really changes the sound of the room, deadening the frequency response and creating an unnatural ambiance. The other option is to use diffusion to reflect the sound in many directions and to prevent the sound bouncing back in only one direction.

Testing the Acoustic Ramp

Testing the Acoustic Ramp at U. Mass Lowell's Concert Hall

Testing a diffuser is actually pretty complicated and involved, but in a nutshell the process is as follows:

Shoot an impulse burst of sound at the diffuser and then record what bounces back every 5 degrees in the semi-circle around the diffuser.

The white tape in the picture shows the test points where I placed the microphone. The first test point is at 0 degrees directly underneath the speaker.  This test point simulates what a listener might hear if they were sitting directly in front of the speaker and the sound went past them and hit the back wall of the control room and then bounced back.  A flat wall would reflect a sound very similar to what was coming out of the speaker, essentially an echo that hasn’t been greatly changed. A diffuser should have multiple smaller echoes spread out over time with seriously reduced sound pressure. This is what the 0 Degrees test results look like:

Flat Reflector vs. Acoustic Ramp

Diagram showing the difference between sound reflecting of a flat reflector and sound being diffused by the Acoustic Ramp

As you can see from the diagram, the large reflection in the top response is changed into a series of three smaller reflections  and greatly attenuated (reduced) amplitude when diffused by the Acoustic Ramp.  The reflection is spread across time and diminished greatly in amplitude.

Hurray! It Works!

Studio Construction Photos: Con-Fusion Entertainment

Saturday, June 12th, 2010

Several months ago I was approached by two former students (Evan Schlosser and Robie Rowland) at the New England Institute of Art to help them to design a studio in a rented space in Allston.  They introduced me to their partner Arjun Ray and I started consulting with them.  The space was being converted into rehearsal  spaces and construction was already underway in the space to convert it from an office building into a rehearsal room.  We would convert that into a fully-functional professional studio.

After measuring the space and investigating the existing construction, I came up with a design that would isolate the studio from their 3 neighbors as much as possible and that would provide them with 2 large and functional live rooms and  a good sized and well proportioned control room.  My initial design follows but had to be altered some to address problems such as sprinkler and HVAC locations.

Original Studio Design

The Original Design for Con-Fusion Entertainment's Studio

One of the things that is very nice about the space is the two large windows allowing natural light into the studio’s control room.  I designed all of the spaces to avoid parallel wall to help prevent problems with standing waves and the accumulation of low frequencies in less-than-ideal locations.  The rectangular space is broken up in such a way that the control room gets larger the further away from the mix position.  Both the live rooms have site-lines to the control room as well.  The control room, where the most time will be spent, is the largest room and will allow for comfortable seating for producers, engineers and their clients.

Here are some of the early construction photos.  In the pictures are Arjun Ray, Robie Rowland and Evan Schlosser (The 3 partners of Con-Fusion Entertainment), and Mike, Rick and Robie the Elder.  I tried to create some order to the photos to create a narrative.  At this point, nearly all of the metal studs are in place and drywall is starting to be hung.

Looking at control room from inside the large live room

Looking at control room from inside the large live room

View out of the control room door

View out of the control room door

View into the corner of the control room

View into the corner of the control room

View out the main control room window

View out the main control room window

The wall makes a slight job at the studio entrance

The wall makes a slight job at the studio entrance

Exterior walls filled with 703 fiberglass insulation

Exterior walls filled with 703 fiberglass insulation

Detail of the double wall construction

Detail of the double wall construction

3 Layer studio window in progress

3 Layer studio window in progress

Detail of finished studio window

Detail of finished studio window

Cutting metal studs makes sparks!

Cutting metal studs makes sparks!

Placing the first piece of gypsum board

Placing the first piece of gypsum board (from the left: Evan, Robie and Arjun)

Arjun sealing the top edge of the drywall

Arjun sealing the top edge of the drywall

Signatures of the builders on the first drywall

Signatures of the builders on the first drywall

So those are some of the pictures of the progress.  I would love to hear your thoughts!

Building a New 20-Space Rack

Tuesday, June 8th, 2010

I was really bummed when my 20-Space Raxxess mobile rack disintegrated on me with all of my most expensive gear in it.  The bottom collapsed and then the whole thing twisted breaking the sides as well.  I was not at all impressed with Raxxess’ design after looking at it closely.  The entire weight of both sides of the rack is held up by 6 metal pins in 3/4 inch particle board.  Not a good design.  So I called Raxxess and they agreed to send me the broken parts after they grilled me about how heavy my equipment was and what I was using it for.  It’s a rack and I put audio gear in it and it broke because the design is bad.  The guys on the phone were pretty snotty, but they did agree to send me the replacement parts and they did it pretty quickly.  Then I thought, “Do you want to put your favorite rack gear in a rack that previously disintegrated?”

Broken Raxxess Caster Plate

The broken pin holes on the bottom plate of the Raxxess rack

Detail of Broken Raxxess Rack

A detail of the broken particle board

So I decided to build a replacement instead.  The new version is MUCH stronger, better designed, has bigger casters and it is generally awesome.  I DIY.  It would have been faster and maybe cheaper just to buy a new crappy rack, but I wouldn’t be very proud of it!

Top Corner of New Rack

Top Corner of New Rack

Big Fucking Wheels

Big Fucking Wheels (For Off-Road Recordin')

Side View of New Rack

Side View of New Rack

Cable Tie Mounts

Cable Tie Mounts

Cable Tied Power Cables Down the Right Rear

Cable Tied Power Cables Down the Right Rear

Fully Wired Rack

Fully Wired Rack with Optional Squirrel's Nest

I would love to see other people homemade audio equipment racks!  This one is probably only going to be loved by me and the family of squirrels that made their home in the back!

Started working on 5 more baritone guitars!

Friday, March 13th, 2009

I have recently started building 5 more baritone guitars under the Indecent brand. All the bodies will be constructed from white ash, but the necks will be laminated from many different woods. I found a great piece of sap-wood walnut which is very strong, but also light-weight. The walnut will be laminated with purple heart like the original prototype neck. I will also be making maple/purple heart and mahogany/purpleheart laminates as well.

Jim Mouradian of Mouradian Guitars has agreed to hang one of the new guitars in his Winchester guitar store. Jim and his son own the business together and manufacturer their own line of gorgeous and innovative guitars and basses. Eddie from Carlino Guitars has also been quite helpful in the process and we probably be selling the instruments as well.

Please let me know if anyone has suggestions for new neck materials!

Designing a Baritone Guitar (Part III)

Saturday, January 17th, 2009

To the reader:

The following posts are part of a project that I completed in December of 2008 in which I designed and built a baritone guitar. I looked at existing designs and tried to correct the problems that I found with the available commercial production instruments. The end result was a great guitar that exceeded my aesthetic expectations and met my utilitarian requirements. The original paper from the project is 40 pages long, so I am breaking the work up into installments. Please note that the design of the guitar, the shape of the body, the neck and the headstock are all trademarks of Indecent Music. I do not consent to my ideas being used for commercial purposes, but I would be happy to talk to or help anyone that is interested in building an instrument for themselves. I am reviewing my options for Patents and the design of the instrument should be considered protected by the Patent Pending status. Thanks so much for your interest!

Hendrik David Gideonse XIX

4 Designing the Baritone Guitar

Based on my experiences with the production models that I tried, I resolved to design an instrument that did not fall prey to the pitfalls mentioned above. I would optimize the scale length and string gauges to provide for a firm but comfortable amount of string tension. Learning from bass designs, I would shift the strings towards the tail of the instrument by moving the bridge away from the neck and closer to the tail.

4.1 Woods, Tone and Rigidity

Electric guitars are nearly always made of hardwoods from a small number of deciduous species from around the world. Acoustic instruments, however, use resonating tops made of coniferous species like spruce and cedar. The most popular woods for electric guitar building are rock maple (also known as hard or sugar maples), mahogany (a tropical exotic hardwood native to the West Indies, Central and South America), alder, swamp/white ash (both native to North America), or rosewood and ebony (both exotic hardwoods becoming hard to find).
Each of these woods has its own tonal characteristics as well as grain type, grain figure, hardness and rigidity. According to Warmoth Direct Guitars [14], mahogany is the warmest of the neck woods, while maple is the brightest with the most defined high frequencies. Honduran mahogany is the wood used for Gibson guitars™ necks and bodies, while hard maple is the wood typically used in Fender necks. Body woods are often slightly less dense and softer to allow for a lighter instrument. Swamp ash, which is very popular with Fender bodies, is a softer, lighter variety compared to Northern hard ash which is harder and heavier. Alder, basswood and poplar are all slightly softer woods commonly used in body construction as well [15].
I opted to use swamp ash for the body because it would cut down on the weight of the instrument and would still provide a tone in between the warmth of mahogany and the brightness of maple. Ash has a natural rustic feel to it, even when sanded with 200 grit paper and it is an open-grained wood, which means the grain has deep pores that must be filled in order to get a smooth finish.

Figure 8 A close-up of swamp ash grain
A close-up of swamp ash grain

For the neck, I chose rock maple, which unlike swamp ash, has a closed grain and can be sanded almost as smooth as a polished rock or buffed steel. The neck is the part of the instrument that will be touched the most, and the feel of this critical part affects the player’s impression of the instrument as a whole. I also used purpleheart in the lamination of the neck blank mostly because of its striking color, but also to tone down the brightness of the maple.

The fingerboard is glued to the top of the neck over the truss rod and the frets are pressed into the fingerboard. I chose to make the fingerboard from macassar ebony which is a figured ebony with visible grain varying from black to browns and tans.
The lamination technique that I used is very similar to the style shown on the Ibanez bass above. I ripped three pieces of hard maple to ¾ by 1 and 2 pieces of purpleheart to ¾” by ¼” and then glued all five of the pieces together as shown in Figure 10. I made sure that I reversed the grain pattern for each piece to try to create the most stable neck blank possible. The notch cut down the length of the neck for the truss rod is centered on the middle piece of maple, so that the truss rod will not disrupt the various laminations.

Figure 9 A close-up of purpleheart and hard maple
A close-up of purpleheart and hard maple

Figure 10 5-piece neck blank lamination method with 3 1″ pieces of rock maple and 2 ¼” pieces of purpleheart.
5-piece neck lamination method

4.2 Angled Headstock and ˜V™ Neck Contour

The shape of the neck is another critical part of the design process that affects string tension, sustain and the feel of the instrument. The traditional method of the headstock configuration is the angled back headstock used in all string instruments from lutes, violins and viols, as well as guitars. This angle increases the pressure of the strings on the string nuts and eliminates the use of a string tree to hold the string down onto the headstock as required by the Fender instruments. Angles from 10° to 15° are common and I opted for 15° as it was an easy multiple of 90°.

Figure 11 A 3D rendering of the neck blank with a 15° angled headstock and radiused fingerboard
3-D rendering of the neck blank

Figure 12 A different angle of the neck blank before carving with guides to show where the frets will be installed
A different angle of the neck blank

The neck back contour is the shape of the neck as cut laterally through the neck. Historically guitars have used either a ‘C’ or a ‘U’ shape, but Fender pioneered the ‘V’ neck shape which optimizes the player’s ability to wrap his or her thumb round the neck of the instrument. The ‘V’ has been popular particularly with blues and country musicians. It makes playing open chords easier and more comfortable and is particularly useful for instruments with a longer scale like basses and baritones.

Figure 13 A comparison of the standard ‘C’ neck contour (black) with two more ‘V’ shaped contours [16]
Comparison of neck contours

I chose to use a slightly stronger ‘V’ shape than the two designs above because I was planning on tapering from the ‘V’ at the first fret to the flatter ‘C’ shaped neck by the 12th fret to make it easier to play single notes and bar chords. The Figure below shows the shape of the neck at the first fret.

Figure 14 The neck contour for the baritone at the 1st fret
Neck contour for the baritone at the 1st fret

4.3 Headstock Shapes

My design goal for the headstock was to use the least amount of wood possible, but still allow the strings to remain straight as they travel from the nut to the tuning machines. A smaller headstock weighs less and does not affect the balance of the guitar as much as a larger headstock.
The three-top, three-bottom (3+3) traditional symmetrical headstock used on early acoustic instruments and later adopted by Gibson, causes the strings to bend outward from the nut to the tuning spindle on the tuning machine. This can lead to problems of the string binding at the nut and intermittently slipping, causing tuning problems and unnecessary string breakage. The 3+3 style headstock is more user-friendly however, in that it is easier to feel which machine the player is tuning on dark stages while still maintaining eye contact with the audience or the panel of a digital tuner.
The design goal of a small headstock, in the 3+3 configuration, is difficult to achieve because the tuning machines on a symmetrical headstock bump into each other if they’re not offset. This is further complicated by the desire to maintain a straight angle from the string from the nut to the winder. Figure 15 below shows the many different iterations of the headstock that I went through to find a design that was both visually appealing and effective at maintaining straight string runs while allowing for the tuning machines not to touch. The center and lower right mockups became the actual headstock in my design.

Figure 15 Various iterations of headstock designs from the earliest to the latest
Various iterations of the headstock designs

The first prototype of the headstock was the upper left model. The symmetry was appealing, but the tuning machines would not fit so close together on the top holes, for strings 3 and 4. The second version to the right offset locations of the machines slightly, but the tuning machines still butted against each other. The next two designs, upper right and bottom left, solved the issue of tuning machine spacing, but they were quite unattractive. Figure 16 below shows the final contour of the tuning machines super-imposed through the surface of the headstock.

Figure 16 The final headstock design with tuning machines super-imposed on surface.
The final headstock design

The final design offset the machines substantially and added the style of an inverted Fender shape to balance the large hips on the body of the instrument. The final touch is the purpleheart cover over the truss-rod adjustment notch. The headstock was successful both in the elimination of extra bends in the string and in providing aesthetic balance to the instrument.

Figure 17 Photo of the baritone’s headstock from the front
A photo of the baritone's headstock from the front

Figure 18 Photo of the baritone’s headstock from the back
A photo of the headstock from the back

4.4 Joining the Neck to the Body

The neck joint is the critical connection through which vibrations travel from the nut to the bridge of the instrument. A poor neck joint will decrease vibrations and reduce the volume and sustain of notes as well as causing an unstable playing experience. The worst example of this is a bolt-on type neck where the neck pocket is routed too largely for the neck, allowing the player to torque the screws loose while playing. Over time this could lead to the screws or even the neck breaking.
There are three joint options for the custom guitar builder: bolt-on (actually uses screws), mortise and tenon glued or set neck, and neck-through where the neck continues all the way through the body of the instrument.
The bolt-on neck is the simplest method of attachment and also the least expensive, but is rarely used for custom guitars. The advantages of the bolt-on neck include non-destructive neck replacement and faster manufacturing because gluing time is eliminated. The primary disadvantage is that the bolt-on connection is often not as rigid as a set-neck or a neck through design, which are said to have increased sustain due to the improved mechanical connection between the body and the neck. The vast majority of bolt-on necks use Fender’s original measurements for the neck pocket: 2 3/16″ wide, 3″ long and 5/8″ deep.
The second type of neck joint is the mortise and tenon, also known as the set neck. In short, this is a glued neck joint that uses increased surface area to create a stronger connection between the neck and the body. The mortise is the neck pocket and the tenon (the end of the neck) is inserted into the mortise. Great care is taken to ensure that the joint has a high tolerance and that the joint will hold simply with pressure before the joint is glued.
This particular style of joint has been used to connect necks on string instrument bodies for hundreds of years. Instruments in the viol, violin, and classical guitar families all share the same neck join, which also includes the subset of the dove-tail neck joint. The classical guitars have a neck that is parallel to the top of the body, while the violin family has necks that tilt back from the face of the instrument. This angle increases the pressure on the bridge of the instrument and thus improves the length of the sustain of the instrument. The tilt-back angle (usually 2° To 3°) of the neck requires a taller bridge to prevent the string action from being too low.
In addition to the neck angle, often this style of guitar includes an angled headstock as well. The angle serves to increase the pressure of the strings on the nut and eliminates the need for a string tree to hold the strings down to work well with the tuning machines. A great example of this type of guitar in the Gibson Les Paul, which is a solid body guitar that borrows heavily from the look of arch-topped hollow body instruments like violins and viols.
The third style of guitar neck joint is the neck-through style. This construction technique actually is not a neck joint at all. The wood of the neck continues through the body of the guitar in one continuous piece. Les Paul™s œLog guitar was probably the first neck-through instrument. This type of design was originally found more often in electric basses than in guitars, but now many models of both are available. Body wings are attached to the neck core to obtain the traditional shape of the guitar. The pickups and bridge all are mounted into the neck piece, which contributes to increased sustain.
Most neck-through instruments do not have the angled back neck that requires a higher bridge. This may counteract the improved sustain of the neck-through design by decreasing pressure on the bridge and nut of the instrument. The neck-through body design is more complicated to build and manufacture than either the bolt-on or set neck styles. As a result, most neck-through designs come from higher-end instrument manufacturers and small custom luthier shops.
I chose the mortise and tenon set-neck option because I was interested in an extremely strong rigid joint, but did not want to give up the warmth of a full swamp ash body. In my design (see Figure 19 below), I allowed for a neck width of 2 3/16, but during construction opted for a slightly wider neck at the body around 2 5/16. In the Figure below you can see both the routing for the neck to fit into the instrument and the template on the left that was used as a guide to route the pocket accurately.

Figure 19 A router template and the neck pocket routed out of the body
A router template and the neck pocket routed out of the body

Figure 20 A 3-D view of the baritone body showing the neck pocket dimensions
3-D rendering of the baritone body

4.5 Body Shape

The body of the guitar makes up the bulk of the size and weight of the instrument and is the part of the instrument that rests against the body and determines the balance of the instrument, both in seated and standing positions.
I designed my instrument with the traditional 20 frets to avoid the need for a large cut-away. I positioned the bridge of the instrument towards the tail to move the entire length of the strings to the right, bringing the first position closer to me. I also created a full-sized top horn to position the top strap button at the 11th fret ensuring a comfortable playing position even with a longer neck of 27 ½.”
The unusual body carving has given the baritone its distinctive look. Some of the carving is merely ornamental, like the ‘S’ curve connecting the top horn to the bottom hip of the guitar, but other features of the carving are designed to make it easier or more comfortable to play.
The cut-away that allows access to the higher frets is a good example of a functional carving. By streamlining the edges of the instrument and thinning the body at the cut-away, I have improved access to the frets that normally would be difficult.
Another functional carving technique is called the tummy cut (see Figure 18), which removes wood where the player’s belly presses into the instrument. This allows the instrument to feel like it is wrapping around the performer, and removes wood to decrease the weight of the instrument. In addition, the top hip of the guitar is contoured to allow the arm to rest on the instrument without hitting a sharp corner of the instrument’s body. Both the tummy cut and the arm rest cut were pioneered by Fender with the sleek modern design of the Stratocaster.

Figure 21 An example of a tummy cut on the back of a guitar body [17]
An example of a tummy cut on the back of a guitar body

Figure 22 Front of the body of the baritone
The front of the baritone

Figure 23 Back view of the baritone’s body and heel
The back of the baritone's body and heel

Several guitars influenced the shape that I designed: the Parker Fly, Prince’s Cloud Guitar from the end of the 1980’s and the 000 Auditorium style guitars made by C.F. Martin. The shape of the Martin 000 has been a staple of American instruments for the past century. The smaller size body is very comfortable both to wear with a strap or to rest on a leg because of the depth and location of the so-called waist of the body. I used the bottom hips and the waist contour from the 000 guitar as the beginning of the shape of the baritone guitar (See Figure 24).

Figure 24 C.F. Martin’s 000 14 fret Guitar Body Shape used for the ‘hips’ of the baritone body. From the left to the right: Martin 000 [18], a 000 14-fret body mold [19], the borrowed shaped for the baritone.
000 body comparisons

Figure 25 The Parker Fly, probably the last major innovation in commercially available guitars
The Parker Fly

The contoured shape of the Parker Fly was also an inspiration for the body of the baritone. The Fly has a dramatically rounded arm rest which effectively shaves a lot of material off to lighten the instrument in addition to making it more comfortable to play. I also spread the tapered armrest across the entire top hip of the instrument to reduce weight and make playing the instrument more comfortable (See Figure 22).
Prince™s Cloud Guitar was another influence on the design of the body. This was the first guitar I had seen with an exaggerated top horn that moved the strap button towards the nut of the guitar. I suspect that this innovation would have made it easier for Prince, with his shorter arm length, to reach the lower positions on the neck. Prince was the first artist, that I was aware of, who had special guitars made for him to meet his needs both from an ergonomic and aesthetic point of view.

Figure 26 Prince’s Cloud Guitar at the Rock ‘n’ Roll Hall of Fame
Prince's Cloud Guitar

4.6 Pickup Types and Locations

There are a wide variety of pick-ups in use by manufacturers of baritones, with most instruments being targeted towards certain types of music. Instruments using single-coil lipstick pickups are targeted at the country-western and roots rock genre, while instruments with double coil pickups are targeted toward hard rock and metal. The traditional baritone sound used in spaghetti westerns, surf rock and country music comes from baritones equipped with single coil, twangy sounding pickups.
I chose to use a humbucking version of Gibson’s famous P-90 soap-bar pickups because I wanted the bright and growling tone of a single coil, but without the associated hum from a single coil P-90. Seymour Duncan carries a ‘stacked’ P-90 (Figure 28) that positions the second coil beneath the first so it is not visible and influences the sound only minimally. I placed the pickups on the body so that the pole-pieces of the neck pickup were beneath the 24th fret position and the bridge pickup was beneath the 36th fret position [20]. (See Figure 27)

Figure 28 Seymour Duncan P-90 Stack Pickups
Seymore Duncan P-90 Stack pickups

Figure 27 Baritone body design using fret locations as measurements for pickup placement
Rendering of baritone's body using fret locations to determine pickup locations

These two locations offer a much richer viewpoint to the nodes and anti-nodes of the harmonics of the string. The string vibrates the least at the nodes and vibrates the most at the anti-nodes. In addition, the location of the nodes and anti-nodes change as the player shortens the string length by fretting notes. Generally, pickups closer to the neck have a deeper sound and pickups near the bridge have a brighter sound. Gibson named the pickups, Rhythm and Lead, to suggest that the bridge pickup would be better for solos, while the rhythm pickup would be better for chords and accompaniment.

5 Conclusion

I created a new guitar design to improve on existing production baritone guitars and to correct problems with the instruments™ balance, rigidity, tone and ergonomics. The most significant innovation was to change the balance of the instrument by moving the bridge down the guitar to the tail of the instrument and ensuring that the strap button on the top horn of the body is above the 11th fret on the instrument. This change brings the first position on the instrument closer to the player and improves the ease of playing close to the nut.
The shape of the neck returns to the ‘V’ neck, which makes it easier to hold the instrument comfortably when playing open chords. As the neck gets closer to the body of the instrument, the back of the neck becomes flatter, making is easier to finger bar-chords.
The neck is laminated from 6 pieces of wood: a macassar ebony fingerboard, three thick layers of hard maple and two thin layers of purpleheart, in order to improve the sustain and tone of the instrument. The lamination improves the rigidity of the instrument and so it improves the length of time that the guitar vibrates after being plucked.
The pickup pole pieces fall beneath the 24th fret position and the 36th fret position, which are active harmonic locations. This improves the electric tone of the instrument. I will continue to make improvements to the guitar in hopes of creating a high-quality production instrument.

References
[14] “Guitar Neck Woods.” Warmoth.com. 2006. Warmoth Direct Guitars. 8 Dec. 2008 <http://www.warmoth.com/guitar/necks/necks.cfm?fuseaction=guitar_neckwoods>.

[15] “Body-Woods.” Warmoth.com. 2006. Warmoth Direct Guitars. 8 Dec. 2008 <http://www.warmoth.com/guitar/options/options_bodywoods.cfm>.

[16] “Back Contours.” WarmothDirect.com. 2006. Warmoth Direct Guitars. 13 Dec. 2008 <http://www.warmoth.com/guitar/necks/necks.cfm?fuseaction=back_profiles>.

[17] Works Cited
Allparts Licensed by Fender Stratocaster Body Sea Foam Green NEW! Digital image. Ebay.com. Ray’s Custom Shop. 12 Dec. 2008 <http://www.rayscustomshop.com/images/wood/sbf-sg-833-bl.jpg>.

[18] Martin 000-28 Norman Blake Acoustic. Digital image. Fullersguitar.com. Fuller’s Vintage Guitar. 8 Dec. 2008 <http://i131.photobucket.com/albums/p312/jermdaddy/martins/normanblake28005.jpg>.

[19] Hall Jr., John F. Martin 000 14 fret building mold. Digital image. Bluescreekguitars.com. Blues Creek Guitars, Inc. 8 Dec. 2008 <http://www.bluescreekguitars.com/catalog/images/000%20(small).jpg>.

[20] Tillman, J. Donald. “Response Effects of Guitar Pickup Position and Width.” Till.com Electronic Music Articles. 17 Oct. 2002. Don Till. 11 Dec. 2008 <http://www.till.com/articles/pickupresponse/index.html>.

Designing a Baritone Guitar (Part II)

Saturday, January 17th, 2009

To the reader:

The following posts are part of a project that I completed in December of 2008 in which I designed and built a baritone guitar.  I looked at existing designs and tried to correct the problems that I found with the available commercial production instruments.  The end result was a great guitar that exceeded my aesthetic expectations and met my utilitarian requirements.  The original paper from the project is 40 pages long, so I am breaking the work up into installments. Please note that the design of the guitar, the shape of the body, the neck and the headstock are all trademarks of Indecent Music. I do not consent to my ideas being used for commercial purposes, but I would be happy to talk to or help anyone that is interested in building an instrument for themselves. I am reviewing my options for Patents and the design of the instrument should be considered protected by the Patent Pending status.  Thanks so much for your interest!

Hendrik David Gideonse XIX

3 Problems with Existing Designs

After trying instruments from a variety of manufacturers and finding that I was dissatisfied with all of them, I wanted to start to define what the major problems were with these instruments and what I could do to improve the designs.

3.1 String Tension

Most of the instruments that I played suffered from problems involving string tension.  String gauge, instrument scale length, and desired pitch all affect the tension of the strings.  Lowering the intended pitch of a string decreases the string tension, as does decreasing the scale length of the instrument.  Thinner strings gauges require less tension to be tuned to specific pitches.  D’Addario, a string manufacturer, provides detailed charts to help musicians choose the proper gauge strings for their playing style, scale length and instrument [4].  Gauges, length and tension are all open to adjustment with the baritone guitar because of the lack of an agreed-upon standard.
Most of the instruments that I evaluated had loose string tension causing the strings to buzz badly even with moderate playing pressure.  Most of the instruments that I tried tended toward the shorter scales of the spectrum between 26 ½” and 28” and all used similar string gauges, usually in the following sizes: 1st: 013, 2nd: 017, 3rd: 026, 4th: 036, 5th: 046, 6th: 060 [5].
GHS carries a set of custom strings specifically designed for baritone in the following gauges: 1st: 014, 2nd: 018, 3rd: Wound 028, 4th: Wound 038, 5th wound 050 and 6th: wound 070.  These heavier strings probably would eliminate many of the problems that I was finding on the existing production models.  The manufacturers may have been using the lighter strings to attract players without the stronger fingers that are required to play this larger instrument.  I concluded that a better instrument would have increased string gauge (using the GHS set), increased pitch to C, or a longer scale length to stiffen the instrument’s action.
I experimented with increasing and decreasing pitch from the typical B to B tuning and tried a C to C tuning as well as an A to A tuning.  Most of the baritones were improved by tuning up from B to C and thus increasing the string tension.  Unfortunately this semitone transposition proved to be extremely difficult to fully remember while playing and in the end killed my hopes of the C to C guitar.  This is too bad because this tuning probably would have been very popular with the death metal bands that routinely tune down to D and then “drop” the lowest string to C creating the relationship of a major fifth in the bottom two strings. With standard lighter strings, the A tuning was completely unusable as the strings sat on the frets while playing and buzzed uncontrollably.

3.2 Balance, Ease of Playing 1st Position Chords and Bridge Position

On the production models, I found some difficulty in comfortably reaching to play chords in the lower positions, with a particular problem with 1st position bar chords. In the past I had also experienced this problem with modern style basses with 24 frets and a large cut-away to give better access to the additional frets.
Fender basses didn’t share this problem because of their extended horn on the body of the instrument. The body of the instrument finds a balance on the player’s body with the distance between the two strap buttons becoming a center point.  If the horn is further away from the bridge and closer to the string nut, the lower playing positions will be much more comfortable.  Notice in Figures 2 and 3 the difference between the location of the strap button on the Fender Stratocaster and the Telecaster.  The Strat’s horn balances the guitar in such a way that the player can reach closer to the string nut more easily.  Notice also that the Stratocaster finds its strap button above the 12th fret of the instrument, while the Telecaster’s strap button is above the 16th fret.  Even though both of these instruments share the same scale of 25 ½”, the Strat provides more comfortable access to the first position.

Figure 2 1957 Fender Stratocaster [6]
1957 Fender Stratocaster
Figure 3 Fender Thinline ’72 re-issue [7]
Fender Thinline '72 Re-Issue

Fender’s bass designs move the bridge closer to the tail in order to compensate for the longer neck of 34” (8 ½” longer than the guitars).  If you compare the basses to the guitars, the bridge on the basses is much closer to the tail of the instrument, and the strap button on the basses is located immediately above the 12th fret much like the Stratocaster.

Figure 4 Fender American Standard Jazz Bass and American Standard Precision Bass [8]
Fender American Standard Jazz Bass and American Standard Precision Bass

If you look carefully, you can see that the top horns of both Fender basses are identical.  The repositioning of the bridge and the strap button position has the benefit of pushing the entire length of strings towards the player’s right hand and bringing the 1st position closer to the player’s left hand.
Fender’s original basses have 20 frets, but newer designs from other manufacturers often incorporate 24 or more frets.  This creates a problem of access to the higher frets, so a much deeper cut-away needs to be provided.  The deep cut-away creates a somewhat unbalanced looking body like the Ibanez SR1000EFM.  The top horn looks exaggerated compared to the bottom horn with the cut-away, but the strap button still needs to be at the 12th fret to remain balanced.  For my taste, the visual balance of this Ibanez was disrupted by the cut-away that was needed to provide access to the higher frets.

Figure 5 Ibanez SR1000EFM Bass Guitar [9]
Ibanez SR1000EFM Bass Guitar

3.3 Rigidity for Tone and Sustain

The production models I played also had problems with neck rigidity.  The amount of force generated by the string tension puts a strain on the neck and causes the wood to flex and bow.  All the models I played used a standard 2-piece neck, featuring one piece of  ¼” stock for the fingerboard and then a ¾” or 1” thick piece of a different wood for the majority of the neck.  This technique is based on the tried-and-true method of neck construction for guitars, but it does not support the extra tension from the heavier strings very well.
Many modern bass builders solve this problem of neck flex with a technique of reinforcing the neck with rigid pieces of metal or graphite and also make use of laminated or multiple-piece necks.  The laminating technique adds a tremendous amount of strength and rigidity to the instrument by varying the grain patterns and species of wood in the neck blank.  Note in Figure 6 below that the Ibanez bass shows the layers of wood in the neck running through the whole body of the instrument.

Figure 6 Ibanez neck-through design showing the 5 piece laminate used in construction [10]
Ibanze neck-through design with laminated neck

As Ken Parker proved with his Fly guitar [11] (See Figure 6), sustain is improved by increasing the rigidity of the instrument, not by increasing the weight of the instrument. Parker’s graphite-backed mahogany instruments were extremely light, and the rigidity of the instrument resulted in much less energy being loss in transmission of vibrations [12].

Figure 7 The Parker Fly Guitar
The Parker Fly Guitar

The improved sustain offered by the Gibson Les Paul over the Fender Stratocaster was traditionally assumed to be a result of the increased density of the Les Paul’s mahogany over the lighter swamp ash favored by the Fender luthiers.  As it turns out, dense wood is also more rigid.  The joint where the neck attaches to body is critical to tone and sustain.  Running the gamut from a bolt-on neck favored by Fender to the dove tail mortise and tenon of the Les Paul, the neck pocket is the most critical construction feature of a guitar [13].

References

[4] “String Tension Specifications.” 2007. D’Addario & Company, Inc. 7 Dec. 2008 <http://www.daddario.com/resources/jdcdad/images/tension_chart.pdf>.

[5] Zentmaier, Kurt. “Agile AB-3500 Baritone Tribal Green.” Rondo Music. 7 Dec. 2008 <http://www.rondomusic.com/product931.html>.

[6] Woodlake. 1957 Fender Stratocaster [SketchUp Model of a 1957 Fender Stratocaster]. Digital image. Google 3D Warehouse. 7 Sept. 2006. Google. 7 Dec. 2008 <http://sketchup.google.com/3dwarehouse/details?mid=10b65379796e96091c86d29189611a06>.

[7] Botboyf. Fender Thinline ’72 re-issue. Digital image. Google 3D Warehouse. 19 Sept. 2007. Google. 8 Dec. 2008 <http://sketchup.google.com/3dwarehouse/details?mid=d63d106c12c3f759ad347847c4726934>.

[8] Fender. American Standard Jazz Bass. Digital image. Fender. Fender Musical Instrument Company. 8 Dec. 2008 <http://www.fender.com/products//search.php?partno=0190660712>.
Fender. American Standard Precision Bass. Digital image. Fender. Fender Musical Instrument Company. 8 Dec. 2008 <http://www.fender.com/products//search.php?partno=0190460706>.

[9] SR1000EFM [Ibanez SR1000EFM 4-String Electric Bass]. Digital image. Ibanez.com. 8 Dec. 2008 <http://www.ibanez.com/bass/guitar.aspx?m=sr1000efm>.

[10] SR1000EFM [Ibanez SR1000EFM 4-String Electric Bass]. Digital image. Ibanez.com. 8 Dec. 2008 <http://www.ibanez.com/bass/guitar.aspx?m=sr1000efm>.

[11] “Parker Fly.” Parkerguitars.com. 2008. Parker Guitars. 10 Dec. 2008 <http://www.parkerguitars.com/code/models/models_fly.asp>

[12] Cleveland, Barry. “Parker Fly Supreme, Fly Mojo, and Fly Deluxe.” GuitarPlayer.com. Feb. 04. 8 Dec. 2008 <http://www.guitarplayer.com/article/parker-fly-supreme/feb-04/984>.

[13] Hiscock, Melvyn. Make Your Own Electric Guitar. 2nd ed. Hampshire, UK: NBS, 1998. 20-31.

Designing a Baritone Guitar (Part I)

Friday, January 16th, 2009

To the reader:

The following posts are part of a project that I completed in December of 2008 in which I designed and built a baritone guitar.  I looked at existing designs and tried to correct the problems that I found with the available commercial production instruments.  The end result was a great guitar that exceeded my aesthetic expectations and met my utilitarian requirements.  The original paper from the project is 40 pages long, so I am breaking the work up into installments. Please note that the design of the guitar, the shape of the body, the neck and the headstock are all trademarks of Indecent Music. I do not consent to my ideas being used for commercial purposes, but I would be happy to talk to or help anyone that is interested in building an instrument for themselves. I am reviewing my options for Patents and the design of the instrument should be considered protected by the Patent Pending status.  Thanks so much for your interest!

Hendrik David Gideonse XIX

0 Anatomy of a Guitar

The Anatomy of a Guitar
[reference] Woodlake. 1957 Fender Stratocaster [SketchUp Model of a 1957 Fender Stratocaster]. Digital image. Google 3D Warehouse. 7 Sept. 2006. Google. 7 Dec. 2008 <http://sketchup.google.com/3dwarehouse/details?mid=10b65379796e96091c86d29189611a06>.

1 Introduction

Over the past year or so I have been in the market for a baritone guitar.  I had always thought that a baritone would be a great instrument for me because I started my musical career as a bassist and then developed into a performing songwriter.  The baritone’s range falls in between that of a bass guitar and a standard six-string.  I had the fortune to try out a number of instruments made by Danelectro, Ibanez, Schecter and Agile, but in the end none were very satisfying.  Of all the instruments, the Ibanez came closest to being acceptable, but still didn’t feel quite right.  All of the instruments had problems in the following categories: string tension and action, instrument balance, and the tone both plugged in and acoustic.  Unable to find a suitable commercial instrument, I started work on a design for a new instrument that would meet my specifications and requirements.

2 Baritone History

The invention of the original baritone guitar is usually credited to Danelectro during the late 1950’s [1].  This instrument set the standard for tuning, choosing to go a fourth below standard guitar tuning or B E A D F# B from the lowest string to the highest (see Figure 1).
A precursor to the baritone is the guitarrón, the Mexican bass lute, which is a six string fretless instruments with a rounded back that helps to amplify the strings.  The guitarrón has a rather short scale for a bass instrument and uses extremely heavy strings tuned A, D, G, C, E, A.  The “high A” string is tuned a full octave below the expected A, causing the E string to be pitched the highest of the strings.  Some baritone guitars take their cue from the guitarrón and start tuning with the low A and then follow traditional guitar tuning after that (i.e. 4th, 4th, 4th, Major 3rd, 4th .)
Another closely related instrument is the Fender Bass VI which is a short-scale 6-string bass, one full octave below a standard guitar.  The Supro Pocket Bass from 1962 was also in the same vein as the Bass VI [2].  Both of these instruments were usually used to double the bass lines, but the player played with a pick to get a more defined attack.

Figure 1 Pitches of the baritone guitar and related instruments
Ranges of common guitars

The baritone guitar is the least standardized instrument in the guitar family.  While for standard guitars, the scale length, or the distance from the nut to the bridge, hovers around 25, the baritone guitar scale length can vary from 25 ½ to 30”.

In standard guitars, the variations are minimal.  The Gibson scale is 24 ¾ inches, Paul Reed Smith and National use a 25 inch scale and Fender uses the longer 25 ½ inch scale [3].  Given that the pitch of each of the strings on a guitar fixed to standard E to E tuning, scale length seriously impacts the string tension.  String tension decreases when the scale length decreases allowing strings to be softer or easier to play and bend.  Conversely, the longer Fender scale is stiffer, the strings are harder to bend, and can tolerate harder strumming without being knocked out of tune.

Unfortunately, no real standard scale length exists for baritone guitars.  The scales range from 25 ½ with heavy strings all the way to 30” inch scales similar to short-scale bass guitars.  .  Not to be forgotten, there are quite a few models of guitars with 7 or even 8 strings which are often referred to as baritone instruments as well.  These instruments tend toward the shorter 25 ½” to 26 ½” scales closer to traditional guitars and are largely manufactured mostly by Schecter, Ibanez and ESP who all cater mainly to metal guitarists.

References

[1] “Danelectro Baritone.” Dan Guitars. 7 Dec. 2008 <http://www.danguitars.com/baritone.html>.

[2] Pomeroy, Dave. “1962 Supro Pocket Bass.” Bass Player Feb. 2007< http://www.bassplayer.com/article/1962-supro-pocket/feb-07/25446>.

[3] Hiscock, Melvyn. Make Your Own Electric Guitar. 2nd ed. Hampshire, UK: NBS, 1998. (pp. 14-16)

Designing a Teaching Studio for the Northshore Recovery High School

Monday, September 24th, 2007

Almost a year ago I was introduced to Michelle Lipinski, the director for the Northshore Recovery High School. One of the folks working at the school knew Woody Giessmann from Right Turn and Woody recommended that I might be a good guy for the job of designing and building a recording studio for the school. I have built 3 studios for myself and helped put together a bunch of others. I have done a lot of remodeling and design work, so recording studio construction really floats my boat!

Michelle won a grant to build the studio and she had several rooms at the school that she could convert into studio spaces. My task was to design a space that didn’t break any of the many rules for altering the building, that worked as a teaching studio, and had some security to keep the neighbor-hoods from wanting to break in and hurt themselves with police batons. There were a bunch of choices of spaces, but we settled on the existing computer lab for both security and ease-of-conversion reasons. This is what the space looked like last Fall:

Some of the things that are really nice about this space are that there are already rooms attached that are separated by glass, so making isolation rooms will be much easier. The room has tall ceilings and there a lot of space to move around in. The bank of windows makes for a lot of natural light which is (for me at least) MUCH more conducive to creativity than sitting under the flicker and buzz of the banks of fluorescents.

Due to the fact that the school is part of a public school system, I had to put together 3 different quotes from 3 different vendors for all of the equipment. As it turns out, this is much harder than it should be. The first problem is that not all vendors stock the same equipment, so you can’t really compare the price of one piece of gear to another. I found that I would have to price out similar pieces of equipment from different manufacturers, or find pricing from different vendors all together.

I got quotes from Guitar Center Pro Audio (Chaz from the Boston store), from Sweetwater, from Parson’s Audio and some pricing from Full Compass. The only vendor that could get all of the equipment that I wanted was Guitar Center, but initially they didn’t have the best price for everything (just most things.) Fortunately, they matched all of the prices and Chaz really took care of us. Guitar Center turned out to be the best as far as price went and Chaz is quite knowledgeable. Unfortunately he is drastically over worked and super busy. There aren’t a ton of folks at Guitar Center that know very much, so I found that I pretty much had to work with Chaz or the other managers of the departments.

I decided to go with a studio based around a Dell XPS super-swoopy computer and Cakewalk’s Sonar. The school’s tech consultant already had a good relationship with Dell and he was able to take care of ordering the computer and peripherals. The other equipment, software and hardware was my responsibility. The main components of the studio were as follows:

  1. M-Audio’s Delta 1010: a PCI based audio interface with great stable drivers and solid workmanship. I used these in my personal studio for years and I have always been really happy with the drivers and the stability of the unit. It works with all the software platforms out their and with Pro Tools.
  2. Mackie Onyx 1640. This is a premium version of the 1604 VLZ. It has much nicer pre-amps and EQ, longer faders and a much better feel. Another advantage is that all of the channels have direct-out via D-Sub to TRS fans.
  3. Mackie HR-824 Studio Monitors. These are my favorite monitors for under $2000. They sound great and are flexible for set-ups in many locations. They have built in power amps tailored perfectly for the speakers. The imaging is great and they have plenty of low-end for modern production.
  4. dbx 1066’s. My favorite mid-price compressors. Very flexible and transparent, the 1066 has a sidechain, expander and limiter built in. They work great as dual mono and in stereo link mode. I have been really happy with their performance and they are very common in lots of studios.
  5. Sonar Producer 6.2. I believe that Sonar is the best DAW available today. It has a suite of great sounding plug-ins, many software synths and drum modules, full looping tools, the best MIDI implementation around and fully customizable workspace.
  6. FL Studio Producer (Fruity Loops). Many of my fellow pro’s think that this software is a toy. It’s actually much more powerful than Reason and it works with VST and DirectX plug-ins. It has an amazing built in Vocoder and tons of capability for mixing and sound design. It can run as a Rewired app inside of Sonar. It is also one of the easiest software applications to learn and get started with that’s out there. I feel like it’s an ideal tool for teaching audio, sound design and mixing.
  7. Sony’s Sound Forge and CD Architect. This is the easiest to use audio editor out there and they actual have tech support. Steinberger’s WaveLab is great unless anything goes wrong and then you are completely out of luck. I gave up on WaveLab after spening about $600 for a full version. I didn’t upgrade because they completely suck on customer support. Sound Forge with CD Architect costs about HALF what WaveLab cost by itself. I did like Sonic Foundry a lot before Sony bought them, but they haven’t seemed to go down the tubes! Hurrah!
  8. Rode NT-2A, NT-5 Matched pair. Rode is an Australian mic company that I have worked with since 1997 when I bought the original NT-2. These are great mics and they are priced very competitively. These guys are flexible and sound great. The NT-2A will be our main vocal microphone and we will use the NT-5 both with omni and cardioid capsules.
  9. Sennheiser MD-421, Electro Voice RE-20, AKG D-112, Shure SM58, Shure SM57. These are THE mics to have to start a studio. Every single one of these is a classic.

The “Shark Fin” Cabinet Construction

Sunday, September 23rd, 2007

I have finished building the first cabinet prototype of the Shark Fin Portable PA. I used 1/2″ plywood for the shell of the cabinet and 2x stock wood ripped into specific shapes and angles for the frame of the cabinet. Elmer’s Carpenter’s glue was the main glue for the construction. I used GE Silicone II 100% Silicone Window & Door Caulking to seal the cabinet.


This the bottom panel or base of the cabinet. The wood frame was ripped from scrap 2×10’s that I had lying around the basement. I used the Google Sketchup tools to determine the proper angles to cut all of the bracing pieces. All of the bracing was glued to the base and not screwed so there would be no screw heads on the bottom of the shell to cause the cabinet to be off-balance or wobbly.


Each bracing piece was glued and clamped separately. Elmer’s sets quickly (30 mins), so it didn’t take very long to get all the base pieces attached.


I used 90 degree angle clamps to hold the sides of the cabinet in place to make sure that I cut all of the angles correctly. The angle clamps are essential in getting the pieces together plumb and square. The two side pieces are being glued in place and front panel is locked in to make sure that the side pieces are in the right place.


This is the front view of the panels’ alignment being verified.

Now that the side panels have been glued in place, I am gluing in the bracing pieces for the bottom front panel. Notice that the cross bracing has already been installed to hold the side panels apart. After the side panels were glued in I used self drilling pan-head screws to screw the panels onto the frame for additional strength.


This is the view of the previous photo from the inside of the cabinet.


The front panel has been glued and screwed down. The extension clamps were used to pull the sides of the cabinet into square before the panel was screwed down.


The view from the front after the front top panel has been added to the cab.


Another of the same.


Clamping and gluing the top panel to the frame. No screws will be used here so that there will be no screw heads to interfere with the PA’s controls.


This is the caulking I used to seal the inside of the cabinet. This small tube is much easier to work with inside the box. I never would have been able to get a full-size caulk gun in there.


Detail of the sealed seams inside the cabinet.


Detail of the + and – leads attached to one of the Galaxy Audio full-range speakers. Note that I used colored tape to clearly show the polarity of the speaker leads. I used a battery to determine the polarity of the actual speaker because they weren’t clearly marked.


The two audience facing speakers. The bottom larger speaker is the Selenium woofer.


A full view of the cabinet with the leads and the speakers installed.


This is a detail of the panel where the speaker jacks are installed. The top jack feeds the “monitor” speaker and the bottom jack feeds the bottom two “audience” speakers. The top jack is 8 Ω and the bottom with two speakers is 4 Ω. I used on outdoor blank switch cover plate for the jack panel. These cost about a dollar, are very easy to drill and come with a foam rubber gasket.


Full length view from the back before the cabinet is closed.


Front view of the closed cabinet ready for frequency response testing.

The next steps after testing are determining if a tuned port will be needed to extend the low frequency response of the cabinet, adding the amplifier and battery power to the cabinet, and adding mixer inputs and controls.

The “Shark Fin” Portable PA Project: Design Considerations

Friday, September 14th, 2007

Only a few battery powered PA’s are available on the market today and most of them have design flaws or limitations. My goal is to create a design that uses digital amp technology (Class-D) that runs on standard batteries AA, C or D, or on a lead-acid car battery, that uses small speakers to give a full-range sound. The hope is to achieve relatively flat response from around 85 Hz to about 18 Khz. Who knows if it will work, but here’s the story of the first round of prototyping.

DESIGN GOALS

  1. Ergonomics. The PA should be able to be adjusted and moved easily. The design should allow for the most typical uses of a battery powered PA. The first most common use would be for buskers (street performers.) In these situations the performer usually is riding public transportation to and from the gig, so equipment must be easy to carry or move.

    • They are using the PA both as a monitor of themselves and as the “mains” for the audience to hear as well. Most often the amp is placed on the ground slightly behind the performer. I designed the cabinet to be more effective at being both a monitor and a main speaker by angling one speaker up at a 45° angle and angling the 2 mains speakers at a 75° angle.

    • The controls must be easily accessible when the performer is in the middle of a set of songs. If you have a guitar strapped on and you need to bend over to adjust the volume on a typical amp, the guitar slides off your shoulder. Thus the volume controls (at least) need to be at typical counter height of approximately 36 inches. The design solution for this was to make the controls mounted on a telescoping bar which also serves as a hand truck or wheeled luggage handle.
    • The ease of movement and stability of the cabinet was accomplished by adding in-line skate wheels on the bottom rear corner. The heaviest speaker is mounted in the lowest hole in the cabinet and all of the batteries and electronics are packed in the bottom of the unit. All of these items serve to keep the center of gravity very low, as does the sloped back design of the “Shark Fin.”
  2. Electronics. The PA system should be battery powered, either with 8 AA, C or D batteries or a single 12V lead-acid battery. The amplifiers that we found that have the efficiency that we needed were made by Tripath, a company specializing in what they call Class-T amps (which basically are just Class-D with a T instead). The model that sparked our choice was the TA2024C as used in the Sonic Impact Original Class T Amplifier.

    I chose two different speakers for the project: 2 Galaxy Audio S5N-8 5″ Neodymium Full Range Drivers at 8 Ohms and the Selenium 6W4P 6″ Woofer. The Galaxy Audio’s are the speakers used in the new versions of the Hot Spot mini-monitors. The idea behind these speakers is that they are incredibly light (made from Neodymium) and they concentrate on mids and highs without getting bogged down in low frequencies which are much harder to reproduce. This makes them great for vocal and guitar detail. The Selenium drivers are their to provide some low end for the audience especially. I will probably need to use a low pass filter to get this driver to be as efficient as possible. I may also use a high pass filter on the audience facing Galaxy Audio speaker.

The next installment of the blog will be the actual prototyping of the speaker cabinet. We will be using 1/2″ plywood for the shell and 2x stock ripped to size for the internal bracing. In a production version of the cabinet, ABS plastic would be a much better solution, but it’s not easy to manufacture plastics in your basement.