Wolf Kater :: Custom made musical instruments Wolf Kater :: Custom made musical instruments
Wolf Kater :: Custom made musical instruments
Technical Information

My task as your luthier has two main objectives: to maximize the personality of the instrument and make it as user-friendly and trouble-free as possible. These twin goals affect every decision throughout the instrument's design and construction, sometimes requiring departing from the norm as conventional lutherie has adopted many practices and design features originally dictated by mass production considerations.

String instruments are in a perpetual state of controlled collapse—the art of the luthier is to strike a balance between lightness, resonance and inherent strength sufficient to resist the perpetual load put on the structural system by the strings, climactic changes and general wear and tear. A never-ending dynamic. Museum showcases are full of beautiful display instruments, virtually untouched, that were commissioned by wealthy patrons to hang on the wall and be admired, much as a painting. The real instruments that were played can be found undisplayed on storage shelves, usually dirty, warped and bearing the scars of their intense usage, sometimes centuries long. These battered relics tell the real story of how closely their builders pushed the envelope.

NECK— The great challenge for me as a guitar builder was to marry an electric guitar through-neck with an acoustic body. This placed the glued joint on a horizontal plane within the extended neck-block and dispensed with the heel entirely. The fingerboard, backed throughout its 24 fret length by neck wood, remains deadly straight right up into the top treble, where conventional fall-away in the tongue section normally ruins both action and intonation. At the end of the fingerboard, protruding classical-style into the sound hole, is a suspended bracket that supports a magnetic pick-up—in essence creating an electric guitar neck with pickup installed into an acoustic body. The neck-block and bracing are appropriately designed to transfer the torsional loads; the Achille's Heel of this system and the cause of so many gruesome collapsed guitars. Neck stability is maximized by book-matched laminates mirror-cut from the centre of the same plank. Glued together usually with a contrasting tapered centre-strip related to the body wood or binding, any inherent stresses cancel each other out—the result is an absolutely stable neck and capable of being profiled to the wishes of the client.

TRUSS ROD— The truss rod is an aluminum over/under type, running the full unsupported neck length, adjustable through a broached barrel-nut at the head-stock end. It is light, extremely powerful, bears evenly throughout the neck length and can be easily pulled out should problems occur. So far they've been completely trouble-free.

FINGERBOARD— My preferred woods for the fingerboard are ebony and rosewood. Ebony has better wear characteristics, can be polished to a deep sheen but tends to be sensitive to humidity. Rosewood is very stable in all climates but being softer can become grooved from metal string wear. Fingerboards can be unbound (exposed fret ends) or bound (covered fret ends and a smooth edge), usually with thin strips cut from the fingerboard sides before it is slotted and then glued on, closing the fret slots and creating an invisible seam. My normal arched fingerboard radius is 16", 20" or flat is available as well.

FRETS— I will fret the board with whatever wire you prefer. Personally as a player I like jumbo frets, but many clients prefer mediums especially if they capo a lot which tends to pull the tuning sharp with high frets. In all cases frets are nickel-silver, and pressed in. They require next to no filing so all crowns are consistent and accurate.

TUNERS— The choice of tuning machines is largely dictated by you. I personally prefer the slower ratios , 16:1, 18:1, in the all-metal models, although some of them tend to be heavy. Twelve-strings require the minis to keep the headstock within normal size and weight parameters.

DOTS— Essentially there are two choices here, mother-of-pearl or abalone for both top and side dots. I like a graduated size for the top dots, starting with 5mm. diam., then 4mm. diam. on the first octave, then 3mm. diam. on the top half. Which material is dictated by the inlay ring on the top; mother-of-pearl has better reflective qualities in dim situations. This leads me to a very special request to install LEDs (Light Emitting Diodes), dots that light up, on a custom guitar. See ELECTRONICS

ELECTRONICS— One of the major hurdles created by installing a magnetic pickup in an acoustic guitar was the grounding of the strings to eliminate humming. This is achieved by a carbon-fibre saddle whose conductivity closes the ground side of the circuit. The magnetic pickup, suspended from underside the neck and adjustable in both axes, can be anything you wish, although the Golden Age middle pickup is my preferred choice. Tone and volume are adjustable through pots set slightly above the upper bout into the side—a 1/4" end-pin jack is installed in the tail block. A piezzo pickup can be added as well, fed into the circuit through a 3-way selector switch. Magnetic pickups can access all the external accessories created for electric guitars, are feed-back free and do not transmit action noise. The sound needs to be heard to be believed.

LEDs (Light Emitting Diodes) are available as substitutes for neck dots, both frontal and on the side. Front dots are 5mm. diam., side dots are 2mm. diam. Colours available are yellow, amber, red, green and blue, the latter ice-clear when not lit. Batteries are hidden in a false neck heel compartment accessible through a sliding ebony cap on the bottom of the heel. A rotary selector switch set with the pick-up controls gives three light intensities. The effect is, quite simply, amazing.

BODY— Although infinite variations are available, the Dreadnaught body profile is still the staple of steel string guitars. Its long history is a testament to the tone qualities that it produces—singing trebles with boomy golden basses, ideally suited for amplification. My body depths vary considerably, from 3" slim-lines to 5" jumbos, the norm being mid-way. By far the majority are pointed cut-aways to allow access to that magic upper octave. Other styles have also been built, going from a small O format and a mid-size as well, both with Florentine cutaways.

BRACING— Choosing not to re-invent the wheel, I tend to stick with standard X bracing for steel-string guitars, although in a somewhat modified format; to accommodate both the compressive loading of the neck block and the wide bridge foot-print. This aspect becomes critical with the high string loads of the slide guitars. All main braces are mortised into the solid liners, and are tapered in height to pendentive parabolic curves—a standard centuries-old practice in the violin family.

LINERS— Kerfed liners are a production feature to avoid the cost of steaming solid liners. Their horizontal foot-print is wide to impart extra stability to counteract the weakness of the kerfing and allow deep corner grooves for layered binding. Bent solid liners are absolutely "de rigueur" in the violin family. Once installed they form an incredibly strong and light laminate with the sides—exactly what is needed. The use of bent solid liners leaves me a great deal of freedom to design and build the exact type of body shape that your instrument requires.

BINDING— These thin strips of wood that wrap around the upper and lower body corners not only reinforce the exposed edges, but also clarify the tone of the instrument. Due to the width of the bent liners only one binding strip is installed—out of a wood that has the natural resilience to resist inevitable bangs and bumps but also contrasts with the body woods. The same binding wood becomes the centre-strip of the back and usually also the centre neck laminate creating a pleasing esthetic continuity, heightened by a continuous taper from tail to head-stock.

HEAD-STOCK VENEER— this feature is purely decorative, usually book-matched to heighten some spectacular grain figuration and accented by the inlayed mother-of-pearl or abalone (depending on the inlay ring) WOLF head logo.

INLAY— The original purpose of inlay rings around the sound-hole was to stop any cracks from going beyond them into the top, much like the edge purfling in the violin family. Of course luthiers were quick to use this area to show off some marquetry skills and customize their work. I essentially try to stay away from decoration for decoration's sake, preferring instead the elegant deep resonance of form and function expressed through the natural inherent beauty of the materials. My normal inlay would be two concentric rings of mirrored strips of black and white purfling, since "compromised" by the development of laminated panels that allow 5mm. wide arc segments of mother-of-pearl or abalone to be inlayed into a shimmering ring between them. The result is quite spectacular.

Pickguard— The tear-drop black Pickguard is a personal signature, being profiled and polished ebony permanently bonded to the top. It peaks in a 2mm. thick "ridge" that runs concentric with the sound-hole just where a pick might strike, and then tapers from the point at the top to paper-thinness at the edges. The slide has two Pickguards, creating a mirror-image black butterly, that forms the edges of the sound hole as well to resist tearing from thumb and finger picks.

BRIDGE— The bridge of my guitars are also a unique feature. The foot-print is noticeably wide producing a large glue area. They tend NOT to come off. The wings taper down for lightness and resonance. The pin surface curves down as well creating positive string down-bearing on the saddle, a critical detail for tone production. I prefer generic plastic bridge-pins as they are grooved, softer than the bridge wood, will bend rather than break and are easily available.

WOOD— This is a huge category. Let me state right off that I am not dogmatic about any species providing it has the structural and acoustic properties that will not impede the quality of the instrument. Every type of cut has its pros and cons; quartered wood tends to fracture easily due to the short grain structure, tangential wood is far more forgiving but can move in climactic changes. I am not interested in further denuding our suffering planet of live-giving trees. Furthermore I can categorically state that any tree, regardless of intent, cut until the middle of the last century was old-growth wood due to the ample supply and profit margin of milling these huge often centuries-old giants. As a small-volume custom builder I LOVE the idea of using recycled wood. It can be found in demolished buildings as floor-boards and studs—pine, spruce, hemlock,etc. Weathered barn beams reveal centuries old BC fir deep orange with age. If Grandma's old battered-up walnut kitchen table is getting in your way it would make a lovely guitar. Located on the Canadian side of the Adirondacks, local woods are also available—rock maple, black walnut, apple (headstock veneer), cherry , birch, etc. I have extensive re-sawing and thicknessing facilities, and prefer to intuitively select the wood in raw, bulk format and process it myself. This becomes especially important for matched sets of instruments. Of course exotic tone-woods can be ordered as well. The choice is yours.

SPECIES

Tops— sitka spruce, Engelmann spruce, European alpine spruce,old pine, West Coat Cedar

Tone: spruce tends to reinforce upper partials producing a silvery tone with long sustain that blends well for chords and finger picking. Its inherent long-fibre tensile strength along with the tonal aspects lends itself well for the higher-loaded slide guitars. Pine and cedar are softer and more supple, bringing out the fundamentals, producing rich mellow basses and clear singing trebles, more suited for solo voice and melodic work, especially important in classical guitars. Spruce blends while cedar promotes individual strings.

Backs and Sides— Indian rosewood, African mahogany, figured maple, black walnut, or whatever your heart desires.

Tone: rosewood produces a characteristic boomy sound, mahogany a warmer mellower tone. Maple, always used for flamenco guitars and the entire violin family, speaks very quickly and projects well with high clarity of sound and long singing trebles, a true soloist's assertive instrument. Maple is THE wood for mandolins bringing out the bright clear sustain of the doubled strings. Walnut tends to be somewhat between rosewood and mahogany, with a clear warm sound.

Neck— rock maple, curly maple, African mahogany, cherry

Tone: My ultimate favorite neck wood is hard rock maple, book-matched with a centre-stripe. In my decades of lutherie (here I include harpsichords) I have found that the quicker BOTH ends of the string speak to each other the clearer the sound and better the sustain. The neck wood acts as a primary conduit for the vibrations to the sound-box. Although some builders claim otherwise, my instruments seem inordinately affected by the neck wood. Maple invariably produces a bright clear sound that speaks very quickly with a maximum of sustain. The price is top-end weight, especially with an ebony fingerboard. Any mahogany-necked guitar I have built (and mahogany is an excellent wood for stability and weight), still book-matched with centre-stripe, has a "woodier" sound, somewhat more submissive than the electricity a maple neck produces. Cherry gives a warm, singing tone with a lot of sustain.

Binding— rosewood, maple, ebony, purpleheart, walnut, cherry, etc.

Function: the primary consideration of the binding material is the mechanical qualities of the wood—hardness, grain structure, allowing for bending and subsequent finishing and aesthetic qualities. Usually it contrasts visually with the back and sides—also forming the centre stripe of the back and tail-end—maple with walnut, purpleheart with mahogany, ebony with maple, cherry with walnut. I've also done maple with mahogany, walnut with rosewood. They're all spectacular.

Bracing— spruce, B.C. Fir, old hemlock

Neck and Tail Block— African mahogany

Bridge Plate— African Mahogany

Liners— Yellow Birch

Back Graft— African mahogany

Fingerboard and Bridge— ebony, rosewood

FINISH

Hand-Rubbed French Polish: creates a deep satin lustre that responds to how and where the instrument is handled. The gum that is transferred through the alcohol medium into the wood pores never really dries. It is the thinnest of finishes (excluding oil), and, not wanting to venture onto violin varnish thin ice, probably the most compatible from a mechanical musical aspect. It is very sensitive to moisture, degrading through wear and solvents, but has the advantage of being "revitalized" by a vigorous rub-down of a very lightly alcoholized cloth.

Nitro-Cellulose Lacquer: I spray eight coats of varying dilution after an initial sealing coat of hand-rubbed shellac. This is followed by wet-sanding and then sequential hand buffing stages, right up to a gleaming mirror polish should you want it. I don't care for the over-buffed dipped-in-plastic look, even though some makers seem to be using it now. I like the wood grain features to be expressed in the finish. I do not use wood fillers; to me they are detrimental to the natural resonance of the wood. Eight coats of lacquer seems to strike a good balance between a deep mirror finish and avoiding the mechanical properties of thicker lacquer coats, never mind the acoustic detriments of wrapping the guitar in a layer of cellulose. The hand-buffed finish imparts a sensuous silky feel to the instrument. Lacquer resists water and some solvents, and can be touched-up and buffed-out fairly easily. Due to its water resistance I feel it is the preferred finish for necks even if the body is French polished.