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Improving the Plywood Bass

Improving the Plywood Bass

by Frederick C. Lyman, Jr.

Originally published in American Lutherie #10, 1987 and Big Red Book of American Lutherie Volume One, 2000

See also,
Our Great Spherical Friend, Part One by Frederick C. Lyman, Jr.
Our Great Spherical Friend, Part Two by Frederick C. Lyman, Jr.
Our Great Spherical Friend, Part Three by Frederick C. Lyman, Jr.



In our quest for a way to build an inexpensive but musically useful string bass instrument, we have gone on a brief detour. We have decided to explore a bit further an area mentioned in previous articles: the plywood bass. Could there be a way to improve an existing bass of this type, to raise it above the barely acceptable level in tonal response and playability?

Our conclusion, after one experiment, is yes and no. Yes, we think that an average Kay bass (the most common brand) can be altered so as to broaden its range of tonal capability and extend its useful register. No, we can’t work a miracle, it remains basically a hunk of plywood. The job we did on it turned out to be quite a lot of trouble, and like many such experiments it suggests further ways to proceed with the quest. But it seems unlikely that we can ever give this fiddle any real quality.

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Questions: Vaulted Back Guitar

Questions: Vaulted Back Guitar

by Sjaak Elmendorp

Originally published in American Lutherie #97, 2009

 

AG from the Internet asks:

Any tips on building a guitar with a vaulted back, such as the Baroque guitar in Plan #27? Little information is available on the precise shape of the back and effective ways of constructing it.


Sjaak Elmendorp of Nieuw-Vennep, The Netherlands
replies:

After having made some steel string and classical guitars, I wanted to try something a little more involved. I bought a plan of a Baroque guitar with vaulted back, such as GAL Instrument Plan #27 drawn by Bruné. The plan provided only scarce information on the shape of the back, so as a novice to this field I was left to my own imagination. I must not be the only one, as there seemed to be a variety of schools of thought on the subject. Among professional builders there seems to be consensus that the guitars were constructed to have backs that have the same curvature across the width of the instrument, i.e., the cross sections resembled part of circles. From there on, it was a matter of combining the beautiful and ancient design with some modern mathematics.

Using the location of the back braces along the centerline as position indicators, the width of the back and height of sides and center of the back was taken from the plan at these points. A simple calculation in an Excel spreadsheet allowed the radius of curvature of the back to be calculated from these three data points at each back brace position. The shape of the cross sections of the back were calculated and printed. (Note: the formula for this calculation can be found in John Sevy’s article in AL#58 p. 42 and BRBAL5 p. 355.) I am happy to make the spreadsheet available to interested readers. It is available on the Extras page of the GAL website: www.luth.org. (Look for “magazine extras” under the “publications” menu.)

The cross sections were made out of plywood, to serve as a mold. The spruce braces were bent and attached with a few small short nails to the plywood. The ebony (10MM wide ) and maple (3MM wide) strips for the back were then cold bent into shape and glued on the braces using rubber bands and a few small clamps.

The sides, also consisting of alternating ebony and maple strips with reinforcing spruce braces to provide cross-directional strength, were made on a mold. A heat gun was used to bend the strips into shape.

It is now strung up and it looks, plays, and sounds correct. Although I see many areas for improvement, the back looks all right.

Photo by Sjaak Elmendorp
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Questions: Making Your Own Amp

Questions: Making Your Own Amp

by Dave Raley

Originally published in American Lutherie #73, 2003 and Big Red Book of American Lutherie Volume Seven, 2015



Joe Oliver from cyberspace asks:

Do you know of a manufacturer of guitar amp kits? Years ago my father bought me a Heathkit, smug in the knowledge that I would never complete it. I fooled him. I played it through high school and into the local club scene up until 1980 or so; my interests changed and about 1990 I sold it to a friend, who promptly lost it.

Now I’m starting to play again and would like to build a bigger and better amp to go with my handmade bass. Of course, there is no kit maker alive anymore, so I’m kind of stuck. I would settle for a good book that catered to nonelectronic-type people.


Dave Raley of Laurel Hill, North Carolina responds:

Jim Oliver has rattled the cage of a die-hard tube man. I’ve been building and working on them since the early ’50s. I can furnish him a diagram or two if he wants to make up his own kit, transistor or tube. Transistor amps are much simpler to build for a given output power, but you can feed a tube amp into a reflex baffled speaker or a Klipshorn and get more and smoother loudness from 10w than you would from 100w solid state into a closed baffle. Solid state amps, lacking output transformers, handle the back EMF from open baffles poorly.

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Inharmonicity of Guitar Strings

Inharmonicity of Guitar Strings

by Mark French

Originally published in American Lutherie #100, 2009



Strings are uniquely well suited to make music because all their resonant frequencies are very close to being integer multiples of the fundamental frequency.1 The octave is the most consonant interval and the resonant frequencies of a vibrating string are separated from one another by octaves. The expression for the resonant frequencies of an ideal string is familiar to many luthiers.

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Questions: Damaged Ironbird

Questions: Damaged Ironbird

by John Calkin

Originally published in American Lutherie #94, 2008

 

Adam from the Internet asks:

I have a B.C. Rich 2003 Platinum Pro Ironbird. Got seriously damaged in shipping. The body has five cracks, in some places that I don’t know are even possible to fix. I play technical death metal, black metal, Gothenburg death metal, and all those styles, my favorite being neo-classical metal. The body is agathis. I have an EMG Zakk Wylde set in it. (I could care less about Zakk Wylde. The set, though, is the standard 85/81 combo.) There is a large crack that goes down the middle of the body from where the neck goes on (bolt on neck — the action is great though), then two cracks around the cutaway near the neck (I need to have that so I can have fast access to the 24th fret). There’s another on the back that’s spread just past the serial number plate. I think I’d just want to fix it so I could play it again. I’m not at all concerned about looks right now.

B.C. Rich 2003 Platinum Pro Ironbird. Photo by Adam G.

John Calkin from Greenville, Virginia responds:

Go to a hobby shop and buy water-thin superglue. Also buy superglue accelerator. Take all the hardware and electronics off the guitar. Mask off the cracks with a heavy coat of good car wax — don’t use tape. Push/tap the broken wood back into alignment and trickle in some superglue. It will wick into the crack. If it wants to run out of the crack into a cavity or out the other side of the guitar, use some accelerator to solidify it at the point of runout, not at the fill point of the crack. Keep trickling the glue in. Work slowly and keep looking for exit points for the glue so you don’t make a big mess on the other side of the guitar or something. Keep wiping the glue buildup off the wax and rewax as many times as you have to to keep the paint surfaces clean. Eventually the wood will be completely sealed inside and the glue will stop seeping in. It’s almost like welding wood. If you’ve been careful, there should only be a line of glue right at the crack to clean up. Scrape it clean with a razor blade, sand level with 1000 grit wet/dry paper, polish with automotive rubbing compound, and you are good to go.

I’d bet a lot of money that your guitar will be as sound as it ever was if you do this right. I also have to warn you that I’ve seen guys make a horrible mess of their guitars trying to do this, with glue drips and buildup everywhere. But unless they ran glue into the pots or something, their guitars were fixed. If this sounds intimidating, find a pro to do it. It’s not that big of a deal, you just have to be very careful.