Action: Term used to describe the height of the strings above the fretboard. The farther the strings are from the frets, the harder the instrument is to play. High action potentially would necessitate a neck reset.

Adirondack (Red) Spruce: Used for most prewar instrument tops (soundboards). Has a very high strength to weight ratio (stiff and light), so can be planed thin and still withstand string tension. This wood was used in the war in airplanes and there was not enough left for instrument makers to use after the mid 1940s. Second growth trees were deemed large enough to serve as guitar tops in the 1980s.

B-string or pick guard crack: The pickguards on vintage Martins are chemically bonded into the raw top wood. No air contact reaches the side that is bonded to the wood. The top of the pick guard does interact with air and temperature and can shrink over time, causing the guard to shrink/cup. The shrinkage can be powerful enough to pull cracks into the instrument top along grain lines. The most common place to see this crack is on the inside edge of the guard, right under and parallel to the B string. I'd say 6 out of 10 guitars have this issue. The crack can also be in the wood parallel to the outside edge of the guard.

Bar Frets: Just as the name implies, bar style frets are simple bars of metal inlaid into slots in the fingerboard. The thickness of the bar fret material varied, but is always just a hair thicker than the slot it is hammered into, which provides the compression needed to maintain a straight neck. If a neck bows, the frets near the midpoint of the neck can be replaced with slightly thicker ones to force less relief into the neck. Bar frets are exceedingly expensive to replace and require far more expertise than modern frets. On Martins, bar frets were replaced by the modern, typical T-frets (on all but Hawaiian guitars) in 1934. T-frets have a "tang" that is pounded into the fingerboard. This tang forms the vertical of what looks like a "T" when viewed from the edge.

Bellying: The slight 'swelling' or bulging of the instrument top just behind the bridge; a distortion caused by string tension over time. This can be caused by over humidification or loose braces too. A little "belly" is OK, as it is good that the top is under tension.

Binding: The plastic, ivory or hardwood strip that borders many guitar tops, sometimes the back and sometimes the fingerboard. It is there because it looks good, but also to take the "hit" and ensure that a blow to the edge surface does not crack the major structural element that it is bound around. Also see "Purfling."

Bout: The "shoulders" or side curve area of the guitar. An acoustic guitar has 4 "bouts"; upper and lower on the bass side and upper and lower bouts on the treble side.

Break angle: When the string passes over the bridge saddle and then disappears under the bridge pin, the angle of the string between the two is the break angle. A higher bridge saddle causes the strings to run at a steeper angle in this area. the amount of break angle determines, in part, how much down-pressure the strings are putting on the bridge, and how much the strings/bridge are "driving" vibrations into the top. This is why it is a bad idea, sound-wise, to shave the bridge saddle or bridge down.

Bridgeplate: On an acoustic flat top, pin-bridge guitar the strings disappear into the body of the guitar through holes in the bridge. On the underside of the top, the string balls sit against the bridge plate, a thin strip of wood (usually maple) glued to the underside of the top directly below the bridge. The bridge pins trap the string balls against the plate. There is often wear on the plate cause by the string balls eating into the wood. Since the bridge and plate is "where the rubber meets the road" in terms of transmitting vibration into the top, the bridge plate is an important structural (especially when it's tucked under the X brace legs as they were on Martins until 1948. (The plates were never "tucked" under the X-bracing on Gibsons.)) and tonal component of any guitar. Martin switched the plates to rosewood in the late 60's and made them larger soon after. This is often sited as a reason why Martins from the '70s and '80s are considered inferior to their predecessors.

Bridge Saddle: On an acoustic flat-top guitar, the bridge is the piece of wood (usually ebony or rosewood) were the strings terminate and go inside the guitar body. The saddle is the (usually) white strip of bone or ivory that the strings go over before going inside the guitar. Sometimes the saddle is just a fret wire. The height of the saddle can be adjusted, but its top should sit at least a 16th" above the bridge surface. A saddle that runs perfectly perpendicular to the strings is "non compensated" and was meant for slide playing or classical playing with nylon or gut strings. An angled saddle ("compensated) indicates that the guitar was probably built to handle steel strings and is angled to compensate for the varying thicknesses of the steel strings so that each is better intonated and the guitar plays in-tune all the way up the fretboard.

Compensation: See "Bridge Saddle" above.

Conversions: There are 3 main "conversions" in the vintage instrument world. The first is converting an acoustic guitar that was built for Hawaiian-style (aka lap steel) playing to a standard "Spanish" configuration. This usually involves resetting the neck, lowering the nut and the bridge saddle and sometimes "radiusing" the fretboard so that it has an arch along its width. Since Hawaiian playing involves sliding a "steel" along the strings, and not depressing them to meet a fret, the geometry desired is quite different. In some cases, Hawaiian style guitars came with no frets and very wide, or square-shaped necks with flat fingerboards. These issues can be addressed in a conversion as well, by reshaping and refinishing the neck. A conversion of this kind is a double-edged sword as you are trading originality for playability. The second conversion would be to take an old arch top or classical guitar, usually a Martin with Brazilian rosewood back and sides, and to then re-top/re-brace it as a flat top guitar. If the original guitar's top is cracked or in poor condition, it is a more likely conversion candidate. The resulting converted guitar will be likely worth more $ than the original, but conversions are not cheap. In the best case, it can make an unused, poor sounding guitar into something that sounds and plays great, while sacrificing the originality of the instrument. Finally another conversion has to do with banjos. There are very few tenor or plectrum banjo players around today, but lots of old 4-string banjos. If the pot and tone rings are high quality enough, it can be worth the cost to re-neck these instruments to become 5 stringers, for the more popular frailing, clawhammer or bluegrass styles of playing. The original neck can be kept, so the banjo could be reconverted back to original at a later date when big band jazz resurges (and hell freezes over?) Again, the instrument quality must warrant the considerable expense of conversion in order to be worth doing.

Drop-in or "closed" saddle: In Martin's early days the bridge saddles fit into a short, closed-ended slot on the top of the bridge ebony bridge. When the Belly bridge was introduced in 1929, the saddles were longer and open-ended, running the length of the raised middle bridge section and not "closed in" by ebony on the ends. Long saddles were glued in place. Drop-in saddles were re-introduced in 1965 as a labor-saving change, but with a benefit: Different climates (or the change of seasons) can make the top rise or fall due to higher/lower humidity, and different height saddles can be dropped in to compensate, since they are not glued in. Traveling musicians appreciate this.

Geib & Schaefer: One of the early case makers, most associated with Gibson guitars (not Martin). Geib manufacture is signified by one large raised diamond on the case pocket cover. (If there is a rivet in the middle of the diamond that means it is pre-1922.) Velour interiors are more valuable than felt.

Harptone / Bulls Head: One of the early case makers, manufacture is signified by two overlapping large raised diamonds on the case pocket cover. Often the Bull's Head trademark is stamped into the case exterior.

Purfling: The thin strips of plastic or wood (ebony, maple, rosewood) that run alongside bindings or rosettes. These are decorative and just add to the instrument's appearance and fanciness. When something is said to be "triple bound" that would usually mean a binding along with two different color strips of wood. However there is other more intricate marquetry that can be used as purfling; Martin's "herringbone" is perhaps the most famous. On the highest end Martin instruments, the purfling is abalone.

Note Separation: fancy term for "clarity." When two or more notes are played together, this is the sensation that both can be heard clearly on their own.

Scale length: The distance between the nut and the bridge saddle; basically the active string length. Longer scale exerts more tension on the instrument in order to bring it up to pitch but also makes the instrument louder/more powerful sounding. A shorter scale length is typically easier to fret since there is less string tension. Gibsons are typically short scale. Martin D and OM-size guitars are long-scale, and through the years there have been long scale versions of 00 and 000 sized Martins.

Endpin: Usually a plastic strap button inserted (by friction) into the tail end of the guitar. Sometimes the hole has been enlarged and the button replaced by an input jack for a pick up. That's OK on a modern guitar, but is a negative on a vintage instrument. If a guitar is dropped on its endpin, the pin can act as a wedge and crack the end-block of the guitar and leaving a tell-tale crack running on either side of the pin. So it is best to remove the pin, or put padding on either side of it when shipping.

Forward-shifted "advanced" bracing: This refers to the distance between the edge of the soundhole and where the two X braces cross, under the top of Martin guitars. Since the onset of X-bracing, in the mid 1800's, the braces crossed about 1" from the sound hole. This spacing is known as "forward shifted" but that is a misnomer... it's just where the braces were originally situated. In the late '30s, the bracing was "rear shifted" so that the X was closer to the bridge. Probably this was done to better counteract the stress of heavy steel strings. Braces stayed rear-shifted until modern times where a buyer is now offered a variety of placements. Rear shifted bracing on 000-size guitars began with serial number 71470 in 1938. For Dreadnoughts the shift took place in mid 1939.

Reverse tuners: Worm gear is below main gear. Would indicate tuners from the 1800's.

Gut strings: Originally made of cat or goat "gut", these strings have a softer, classical sound (and exert far less tension) than steel strings. Nylon is the common substitute now. Martin built their guitars for gut strings until the mid-1920's. Most modern players use/want steel string guitars, so gut string guitars are generally less valuable, since there is a far smaller audience for that sound.

Slotted bridge pins: On post war instruments, instead of ramping the bridge, slotted pins were used. This meant less work for the factory. The difference in tone between slotted/non-slotted pins and ramped/non ramped bridge is fairly marginal, but everything matters some, and all the little things add up.

Ramping: Slotting the bridge behind the saddle so that the strings have a more gradual entry into the guitar body. This is often combined with bridge pins that don't have slots, making for maximum contact/fit and best transmission of vibration.

Through saddle or "open" saddle: See "Drop-in Saddle" above.

Slotted headstock:

Ebonized: Cheaper wood dyed black to look like ebony. Very common on fingerboards on lesser brands. Never on Martins... sometimes on Gibsons. When cracked, it can be very unstable and hard to repair.

Friction tuners or pegs: Pegs that run straight through a solid guitar, banjo or uke headstock and that are slightly conical so that they "grab" in the holes in the headstock. The pegs hold the strings in tune but the cheaper ones can slip easily and can be imprecise and difficult to work with.

MASTERTONE: A Gibson trademark mostly associated with banjos and used to indicate the upper level line that included a tone ring in the construction. Also the Mastertone name was put on lower-end instruments that were not marketed under the Gibson name. Gibson had many "brand" names like this. Kalamazzo and Recording King are others.

Mustache bridge:

ice cream cone heel:

Celluloid

Intonation:

Nut

Fingerboard radius

chipboard case

arched top case,

double X brace.

tucked bridgeplate

The Golden Era: For me, this was the period when Martin instruments were at their best; 1924-1945. Some people put a finer point on it and say 1929-1939. This has to do with materials, bracing, workmanship and construction.

Pre-war: instruments made before America's entry into WWII, in 1941.

popsicle brace

f-holes

archtop

thinline

MOTS: "Mother Of Toilet Seat." One of my favorite descriptive terms. It's plastic meant to look like pearl.

clownpuke

volute or neck dart: Before Martin necks were made from one piece of mahogany, they were made of spanish cedar and were two pieces. The neck shaft and peg head were separate pieces glued together and held by the volute. Since the early 1900's the volute has been vestigial only and is found on style 28 and above Martin guitars.

flush frets

truss rod: Patented by Gibson this adjustable metal rod inside the neck can be used to straighten most curves that develop in the neck. Truss rods do not affect the neck angle, they affect the neck straightness.

ebony rod: Wood rod used to stiffen the neck in Martin guitars and to help keep it straight under string tension. First used in the '20s, this was changed to a non-adjustable steel rod in 1934. During WWII, and in the early '50s, shortages of steel necessitated a return to the ebony rod. Martin didn't start using an adjustable metal truss rod until the 1980s. A strong magnet can help determine if a guitar has a metal rod.

X-brace

Ladder bracing

Fan bracing

Tone bars

finger brace

heel cap

pin bridge tie bridge

bridge reset

zero fret

headstock wings

herringbone

rosette

lining

quarter-sawn:

cleat:

kerfing

pores

grain runout

center seam

hide glue

french polish shellac

Chris Knutsen: Built highly distinctive stringed instruments from the late 1800s through the 1920's. To me, Knutsen was the Salvador Dali of luthiery. He was an eccentric who took chances, and also an entrepreneur who had an eye for trends and the ability to shift his focus to whatever style instrument would sell. Many of his guitar designs had original features that were the first of their kind, and for the time (or ANY time) were highly creative. All were hand made without a factory or molds, so each instrument is one-of-a-kind, yet all are immediately identifiable. The total number of instruments he built (350-400) is a range that makes them rare and potentially highly collectable -- If you really want one, they are out there. There are books on Knutsen and detailed websites, so there is a recognized history and provenance, which is important in terms of collectability. Knutsen basically came up with the gold standard design for the symphony harp guitar (a design whose potential was realized by Dyer/the Larson Bros., under Knutsen's name), and the hollow neck lap steel (Knutsen likely taught Weissenborn how to build them.) The great Micheal Hedges played a black, teardrop-body Knutsen harp guitar (with a replaced headstock) to great effect, so there is at least some "celebrity" player who used a Knutsen. Construction quality was not to Martin standards and could be somewhat crude (or, commonly, crude AND sublime within the same instrument.) Builds were "consistently inconsistent" but always functional, often X-braced and of quality materials. Many Knutsen builds are now 100 years old, with the wood being far older than that. Finishes were all hand-varnished. For more on Knutsen, I'd highly recommend Jonathan Kellerman's fantastic book: With Strings Attached, where he devotes as many of the coffee table-quality photos and stories to Knutsen as he does to Martin and Gibson.

Ted McCarty

Herman Weissenborn

Frank Henry Martin: From 1888 until 1945 Frank Henry Martin guided the company through its Golden Era. He took back control of sales from the outside distributor that the company had used for years, introduced the 000 size, style 45's, Dreadnoughts, the shift to steel strings, and the 14-fret neck. He also guided the company through the ukulele, mandolin and Hawaiian booms.

Orville Gibson:

John Deichman

Mike Longworth

Larson Brothers

Leo Fender

Paul Bigsby

Consalvi: Perhaps the best pearl engraver who ever lived. Worked for Fairbanks Banjos, roughly 1902-1906. He also did many early Cole banjos after 1890 or 1891 as well as some Bay State, Howe-Orme and Vega instruments.

Washburn

Oliver Ditson

John Dopyera: In 1925, Dopyera was asked by vaudeville promoter George Beauchamp to create a guitar that could be heard over other instruments in an orchestra. Dopyera invented a guitar with three aluminum "speaker" cones mounted beneath the bridge. This guitar, now called the Tricone, was loud, rich and metallic. Dopyera and his brothers Rudy and Emil w/Beauchamp and others, founded the National String Instrument Corporation to manufacture this new "resophonic" guitar, which was sold mainly to players of Hawaiian music and jazz. Most often the guitars were played with a slide (also known as a "steel".) After a few years and a falling out with National, the three brothers left the corporation and started a new company, Dobro (The name was derived from the "Do" in Dopyera and "bro" from Brothers.) Dobros were single-cone instruments with a different bridge arrangement than that of National instruments. After Dobro won a lawsuit brought by National, National was dissolved and the two companies were eventually combined.

Coordinator rods: One of Gibson's developments for attaching the neck to the banjo rim; two brass rods that attached to two screws in the heel of the banjo neck. The rods secured the neck to the rim and provided a means for correcting the neck angle & "action."

Flange: On banjos with resonator backs, the flange fills the space between the pot and the front edge of the resonator, which has a much wider diameter than the banjo pot.

Lloyd Loar: Loar was not an instrument builder. He was a musician who had an intense interest in musical acoustics, At Gibson, he guided the design and development, including the 'Master Model" instruments and 'Mastertone" banjos. Loar was highly influenced by the work of the great violin makers and sought to incorporate their building practices into Gibson's fretted instruments. His major contribution was the introduction of tap tuning. This process ensured the correct stiffness of the soundboards, backboards, and tone bars by tuning them to specific notes. Realizing that stiffness and pitch were inextricably related, tap tuning ensured reliable and repeatable construction from instrument to instrument. Further, the size of the f-holes was adjusted to tune the air chamber to a specific note. Tap tuning was difficult in a manufacturing environment and Gibson dropped it after Loar's departure in December,1924. The Loar era at Gibson, when he personally signed instrument labels, was from 1922-1924.

Tone Ring: or "tone chamber" on a banjo is a cast metal ring that sits on top of the wood rim to add rigidity and mass to the "pot"(circular wooden banjo body) and to enhance the vibrations of the head. There are many designs of tonering and one must look inside the banjo, right next to the head, to see/photograph it. On older Fairbanks/Vega banjos, the most well known rings were the Tubaphone and Whyte Laydie. On Gibson banjos there are the Archtop, Ballbearing, 40-hole and Flat head tone rings. Older and cheaper banjos might have a "spun over" pot, where the nickel plated metal on the outside of the pot overlaps the pot edge and the head sits on that metal.

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