Guitars, religion, evidence, and beliefs

Beliefs about characteristics and generalizations of acoustic guitars, and their associated construction techniques and materials, seems to me to be a lot like religion. As an atheist this is weird for me to think about, but we (guitar players) make a lot of leaps of faith based on scant evidence (what we scientists call an "N of one"), what others have told us, and what makes "reasonable sense" to us as individuals. How much of what we believe, prefer, and hear in our instruments is based in tradition, expectations, superstition, illusory correlations, and what we read in books/magazines and on the internet?

Another interesting parallel between acoustic guitar players and religion, although somewhat of a sidenote to this discussion, is that we are inherently conservative; it takes a long time to get us guitar players to change the standards of what is perceived as "normal" or preferable. For example, I'm really interested in seeing how the necessary future use of sustainable "alternatives" tonewoods is embraced by players/consumers. While I love the idea of walnut and cherry guitars that are made from timbers locally and responsibly harvested, given the choice, I'd still take my tried-and-true Honduran mahogany!

I really have great respect and envy for those few folks who have played hundreds and thousand of vintage and new guitars, and for those who build instruments (i.e., and do "experiments" to learn about acoustic properties of materials and construction techniques); those people with lots of data to base their beliefs on. Unfortunately, that's not me (yet?).

Keeping these reservations in mind, here are my guitar beliefs; much like religion, they are based on a small sample size, what people I respect think, and what "makes reasonable sense" given my basic knowledge of physics and lutherie. Some of these beliefs are probably totally irrational, and like religion, we could get into endless and unwinnable debates about all of these points:*

*However, unlike religion, the below points could all be tested experimentally,
and I'd happily change my mind in the face of good evidence.

• Lots of little things add up to a good sounding guitar. There are many "ingredients" that can be slightly changed, and these are the things that, in sum, create the unique tonal signatures of individual instruments and general characteristics of different acoustic guitar brands.
• I believe that hide glue positively impacts the sound of a guitar compared to titebond or other commonly used adhesives, which have more "flex" to them.
• I don't believe that, as a broad statement, lighter guitars sound better than heavier guitars (and I'm not talking about lightness of soundboard/bracing; that's another issue, and much less debatable). In terms if the thickness and stiffness of the sides/back of the instrument, I wonder if this impacts the projection of the sound outward versus feeling more vibrations as a player. I do, however, prefer the feeling of playing a light weight acoustic guitar, but that's probably more due to ergonomics.

Bourgeois neck (from pantheonguitars.com)

• Bolt-on vs. dovetailed necks: I believe that both can be excellent sounding, but that the type of neck joint probably does impact the tonal qualities of a guitar (although I can't say how). I like Collings (bolt-on) and I like Martin (dovetail). But bolt-on does add a bit a weight. I love, in principle, the design of bolt-on necks that don't glue the fingerboard to the top of the guitar (i.e., Taylor's NT neck and similar designs used by Bourgeois, my friend David Cavins, and like we did at the Vermont Instruments School of Lutherie) due to the relative ease of maintenance. I'm sure it colors the sound somehow, and it certainly does impact the overall weight of the instrument.
• Image source: fretnotguitarrepair.comWith the commercial success of Martin's "Authentic" series, which employs non-adjustable T-bar truss rods in many models (and non-adjustable ebony in others), there's been a renewed discussion in the relative merits of adjustable vs. non-adjustable truss rods. Like with neck joints, my guess is that there is a sonic difference, but this is one place I'd rather err on the side of modernity...I'll take adjustable over not if given the choice, especially if I'm buying a used guitar (like I tend to do).
• I don't have enough personal experience with Brazilian rosewood to make statements about it's merits compared to Indian or other rosewoods. But I believe that the use of good Brazilian (i.e., quarter-sawn) is confounded with a lot of other variables that I do think are important (i.e., the use of hide glue, T-bar truss rods, age of the wood, and break-in time for vintage guitars). I'd love to spend some time with some guitar sporting various rosewoods that are otherwise as identical as possible.
• I do believe that herringbone purfling (or other similar decorative details around the top, like pearl inlay) could have a small impact on the sound, due to the wider channel being routed into the top right where it's connecting to the sides (maybe more flex = a bit more bass? just thinking theoretically, here).

Herringbone Martin (image from folkwaysmusic.com...lots of nice guitars on their website!)

• I have heard a similar argument about sunburst tops: that the extra pigment that is applied to certain areas ever-so-slightly changes the mass of the top in those areas, which changes the sound. This seems far-fetched to me. In my opinion, if you do want to make the claim that sunbursts sound different/better (and I'm not a all convinced about this claim, although I love a good sunburst), what makes more sense is thinking about the stack of cosmetically "flawed" wood that could not be used if not for the shaded top...That there's lots of great sounding wood to choose from if you ignore cosmetics, and sunbursts allow luthiers to pick tops based on tonal properties only without having to balance the look of the top in their selection.
• I think there is probably significant overlap in the distribution of Sitka vs. Adirondack tops (i.e., normal curves that overlap), but that there are some characteristic differences between them on average. But that "different" does not globally mean "better."
• I suspect that the labels of "European," "German," "Italian" etc. spruce that are used are not particularly useful, because they refer to where the wood came from, not a particular species. That's not to say they don't sound and look different that your typical Sitka top, but that it's not so clear, across makers, what the consistent tonal properties of these woods are.
• In theory I like idea of Madagascar rosewood as an alternative to Brazilian, but I'm uncomfortable with it due to the socio-political and environmental concerns associated with its harvest (more about this topic here and here). For my own piece of mind, along with all the reasons to buy vintage, if I wanted a rosewood guitar, I'd pony up the dough and get a '50s-era D-28 or '45-55 000-21 or 000-28, and not one of the re-issues or custom models that many manufactures have rolled out recently.

• That wood, as a material that is/was alive, continues to change both due to aging and playing (i.e., the "opening up" that players described is a function of at least two processes that impact the structure of the wood itself).
• Related to the above point: I believe that part, but not all, of the "opening up" process is psychological-- that we become more familiar with the sound of a guitar over time, and that is perceived as more pleasing. Yes, remember that I'm a social psychologist, and that we call this the "mere exposure effect."
• One of my biggest "turn-offs" are the pixelated pickguards that Martin used (still uses?) on some of their guitars, like my 2002 D-18GE. I've since replaced mine with a "tor-tis" Dalmatian pickguard, which is admittedly a non-traditional choice for an -18-style guitar.

Ick! (from http://www.acousticguitarforum.com/forums/showthread.php?t=266220)

I like mahogany

Image from: en.wikipedia.org/wiki/MahoganyThe two most common traditional tonewoods for the back/sides of guitars are mahogany and rosewood (with nods to maple, koa, walnut, etc). Typically, rosewood was the more premium and prized of the two; for example, Martin's flagship models like the D-28 and D-45 are rosewood, compared to the "entry-level" D-18. I've gone through my share of guitars, and I expect to go through many more, and I'm coming to realize that I'm a mahogany guy.

Two koa guitars have come and gone (Taylor 414K and Larrivée parlour in koa), three rosewood guitars are in new homes (1978 Larrivée L-11, Taylor 420R, Collings OM2HA), and a maple guitar (1977 Taylor 915) has moved on. Of course, a fair share of mahogany guitars have been traded/sold away (1995 Larrivée LS-05, 1990 Lowden S7c, 1976 Guild D-40SB, a Collings D1VSB, a 12-string Takamine N-10, Guild 12-string....I think it was an F-212 or similar) as well, but all of the guitars that are still around, except for one, are mahogany.

(read more about these guitars, and others, in my in-progress personal guitar history: Part 1 | Part 2)

I'm no good at describing tone, but there's something about the warmth and clarity of mahogany suit me. That doesn't mean I've totally sworn off other tonewoods, but if I had to wager on it, the next one will be mahogany!

Maybe next time we'll talk about sitka vs. adirondack spruce tops...Hint: I like both.

Day 12 - Snow on April Fool’s Day and major catastrophe averted, just barely

Day 12: Not so many pictures today, because I was too busy troubleshooting to take many shots (and since the results of some of the work don’t look that interesting or impressive, despite our time and effort!). It was a beautiful day; we got about 4 inches of snow, but it's also warm enough that the roads look okay.

It was a long day. I went in a little early to do some minor work on my neck and truss rod that had been setting overnight, and most of the crew was already there. Once everyone arrived, and after spending some time cleaning up the body with our good friend the metal scraper, we started a task that seemingly would be easy: cutting the channel for the ebony end strip wedge and then inlaying the piece. This was surprisingly challenging for everyone, and we basically didn’t finish that up until around lunch (I had to cut my lunch short to come back and finish it up before the afternoon tasks began).

After lunch George showed us how to route the “ledge” for the binding (the dark wood edge around the top and back of the guitar. Routing the back is actually pretty tricky since it doesn’t sit perfectly perpendicular to the sides. Although I had a good handle on what and how we were suppose to do it, somehow my cut ended up being about 50% too deep, and it was dangerously close to being a structural as well as cosmetic issue. This is a BIG problem, because now my nice ebony bindings won't sit flush to the surface of the back and I've cut very deeply into my linings, which provide the connection between the back and the sides. And to make matters worse, this happened on the front too! It’s unclear if it was user error or an equipment manfunction with the router with the bit slipping down as I worked; in my defense, when George replaced the bit, the router began to behave. But at this point, it’s a bit too late. What do you do with your router cut is too deep? I figured I was screwed and would have to start my guitar over!

But George had a clever solution that in some ways even makes my guitar fancier than I had planned. He suggested making a new set of oversided bindings that had a piece of purfling attached to make them taller (purfling is a strip of veneered wood in alternating colors). In my case, I’m essentially adding a white/black/white racing stripe to my binding that will show on the side of the guitar (the other students’ guitars won’t be this fancy!). The only drawback to this solution is that now my bindings are rosewood, the same as my back/side wood, so other than the purfling, they don’t really stand out from the back/sides like the ebony would have. We didn’t have any ebony binding material big enough for the size of my oversided binding cut, so I made my own set of bindings with the orphaned rosewood side whose mate had cracked a few days earlier. I’m happy that nice piece of rosewood will make it onto the guitar! And it was interesting to be able to make bindings and glue the purfling to it (I learned to do a few things that the other students didn’t).

While this is an elegant solution to the problem, I still have some other nicks and cuts that were too deep from the router. This definitely saved the day, but my guitar will proudly display some scars from today’s mishaps. It should be noted that only one out of the five of us made it through the back binding without any problems. This is definitely a hazard stage.

Given our “issues” this afternoon, we were running late. So we took an hour for dinner and then reconvened. After dinner, George bent the new bindings I had cut (on the side bender), and I rerouted my back and top for these new “superbindings.” 

The last thing to do today (to keep us on schedule) was glue the bindings onto the body. This is actually pretty time consuming, as you have to do a dry run to determine the length of the bindings so you know how much to trim off. It’s a two person job, as the body is strapped onto your board and bound with tight rope to hold the bindings in place while the glue dries. I have to give a shoutout to my classmate Matt who is a true superstar for staying late with my dad and I, even though he was done with his work for the day. We couldn’t have finished without him.

In at 7:30am, home at 11:30pm; 30 minutes for lunch, and an hour for dinner. Whew, that was a long one.

Well, I know now that my guitar won’t be cosmetically perfect. I knew that it was highly unlikely it would make it through the three weeks without any cosmetic blemishes, but until you get that first battle scar, you still hold out the hope for perfection. Now that I’ve made peace with it, I can relax a bit and enjoy the rest of the process without being so anxious.

Day 4 - My fingers smell really great!

Day 4: Yesterday we joined two pieces of bookmatched wood into a single piece for the back of the guitar, letting it dry over night. This morning we continued working with the back, cleaning it, removing excess glue that had squeezed out, and working the thickness down to 110/1000" with our friend the metal scraper. In the second most scary operation of the day, we used the band saw to rough cut the back to the shape of the guitar (leaving about 1/4 - 1/2" all around the outline of the body).

We also continued working with the headstock, cutting it down to its final shape (except down near the transition area to the neck). The most anxiety-provoking operation to date was when we drilled the tuner holes. This is a pretty bold task, and there aren’t any easy (or at least unsightly) “undos” if you mess it up. With a bit of luck, mine seemed to go okay.

My headstock

The headstock for my dad's classical guitar

After lunch we chose wood for the sides, to match the back. I got a nice set of straight-grained rosewood that has a similar coloration to the back. Since the sides (as opposed to the back) fit through the thickness sander we didn’t have to manually scrape/plane them down to the proper thickness. We did have to clean them up a bit, but mine looked pretty good to start with. By the way, rosewood smells great! My hands are currently stained purple, but at least they are really sweet smelling. You’re probably wondering “who goes around sniffing their fingertips?” Well, if you haven’t spent two days working with rosewood, don’t laugh.

The design for the neck that George employs is really clever; from what I can tell, it’s similar to the Taylor “NT” design. I’m sure I’ll talk more about it later when when connect the neck and body, but today we worked on the heel area, which will include the hardware for the bolt-on hardware. It’s a three piece neck: headstock, neck shaft (for lack of a better term), and a stacked heel. Today we drilled the heel for a brass shaft that receives the bolts to attach the neck. Somehow I messed this up and drilled my hole slight off vertical by about 1/16”. That might not sound like a lot, but it could have been a serious problem if we hadn’t caught and corrected it. It was my first screw up, and hopefully (but probably not) the last! Finally, we glued the heel to the neck, and left it to dry overnight. 

Started working at 8:00am, left the workshop at 6:45pm.

My commute to and from "work" each day