Making Guitars with a Physics Mind | Curtin University
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>>Yeah thanks very much Jim. Thanks everybody for
coming along today and everybody watching
on the web over there. I guess I’ll let the guitar
do the talking for a start. [ Playing guitar ] [ Applause ] Okay we’re going to over
it in a little while. And there was a reason we played
that and we’re going to talk about the projection and
such of these guitars. So, that there is one of
the latest and greatest of the ones I’ve made. For those of you who’ve known me
a while you know this is pretty much what I do. It’s a great privilege to be
able to talk about guitars in front of some of my
colleagues that shout me down quite often because I’m
always talking about them, living them, breathing them. Thanks Mark. So, today’s talk is titled, “Making Guitars with
a Physics Mind.” And it was really interesting
putting this presentation together, the realisation I
guess that I’ve come to find out about myself and the
sort of things that I do when I’m making guitars. I’ve seemed to absorbed a
lot of stuff through my skin and not able to sort of quantify
or talk about the principles that I’m discovering
and trying to apply in the way I make these things. And a great example of that
is if I ask the audience here, what is it like to
see the colour red? And you really can’t
put that into words. But, I guess with a physics
mind oh yeah, of course, colours have different
wavelengths and red has a particular
wavelength that it reflects off objects
and therefore we see red. It still doesn’t answer that
question, what do we feel or see when we see the colour red? It’s really hard
to describe that. And so what I’ve discovered in putting this presentation
together is the physics has allowed me a language
now to describe some of the things that I’m doing. So, that’s a very
important point. It’s not like I pull apart the
guitar and quantify every part of it, tune everything to
certain resonant frequencies and thinking this is
a great way of going and then put it back together. I actually make the guitars
really based on intuition and I guess empirical
knowledge that I’ve gained from previous manufacturers who
share their knowledge via books or internets and
things like that. And once I’ve absorbed that and know what I’m doing I can
then quantify what I’m actually really doing in physics terms. So, that’s a fairly
important distinction that I’m not just simply
making things by formulas. That’s my cave there. That’s where you can find
me between six o’clock and eight o’clock every morning
of the week and a lot of times on evenings and weekends
as well. I’ll talk about string
vibrations because after all
that’s what we used to put the energy
into a guitar body. If we just had a string on its
own it won’t make much sound at all in that’s directly
related to the amount of air that it’ll move. The string’s a fairly
thin thing. It can’t move much air
so we don’t hear much. A guitar isn’t an
amplifier of the sound. That’s a really bad term to use. It certainly doesn’t do that. In fact, the guitar is a real
waster of the energy budget that you put into it
with the strings’ energy. It really does waste
that energy. But, we try as best as
possible as guitar makers to make the most
efficient use of the energy that you have got there and hopefully not too
much of that is wasted. So, in broad terms this
is just an introduction. The guitar will resonate at a
whole spectrum of frequencies and the whole of the
guitar will vibrate. As a player on a really well
made handmade instrument you’ll feel the neck moving. You’ll feel the back moving. The whole of that guitar is
actually in motion at the time. Another thing that happens
as well is it goes in and out like a bellows and so
it’s like an air pump. And so the sound also emanates
from the sound hole as well. So, it’s radiating from
the surfaces of the guitar and it’s also coming
out of the hole there. [ Silence ] Some basic physics here,
how the strings vibrate. This does lead onto
other aspects. You’re probably very familiar
with things like fundamentals, first overtones, second
overtones and third overtones. And this is something I’ll
be talking about later. And we can actually force
those modes on a guitar. If I was to go halfway
between the guitar here and pluck the string
right in at centre, funnily enough those two
dots have been put on there for the player to know that. Have a listen to the sound,
having a lot of buzzing. I can’t stop that because I’m
really exciting the string at its middle here. It’s a very round tone. If I pluck the string right at the back now what I’m doing
actually is I’m exciting first, second, third and higher
overtones to the string sound. So, that would sound like this,
compared with something up here. So, you can immediately
see there’s a difference in the way you play the guitar. And of course, some players
might even strum the guitar halfway along the neck for
particular sounds and effects as opposed to further back here. So, the player themselves
actually influence quite a bit what the guitar will sound like,
in fact an extraordinary amount. You don’t just get
a fundamental. You don’t just get
a first overtone. You get a whole mix of those. And so if we just took for
instance the first overtone and fourth that would
be a resultant waveform and algebraic addition
of those two. And of course, there’s a long
series of these harmonics and depending on the
type of manufacturer of the string depends
on what kind of harmonics you might
expect on that string and also the weight of that. It’s the harmonic
series that’s responsible for the unique sound quality
of different instruments. And did I bring it along? I just invite everybody at the
moment to indulge me just to– it’s too late now, because
you’ve probably seen at the front what I’ve got. If you can just close your
eyes for a minute I just want to play a note on a
particular instrument and see if you can tell me what kind of
instrument’s making this tone. [ Silence ] [ Music ] By the way, it’s not a
strangled cat at all is it? Okay so without even
seeing that instrument– hopefully those at the
back never saw that. You can tell instantly with
that kind of harmonic spectrum that thing is a violin. Instantly you know that. If we look at a guitar where does all this
transfer of energy happen? It happens at the
place called the bridge and also the saddle is that little white
piece sitting in there. And high quality instruments
will make that out of bone. And so, it’s the
bridge and the saddle that essentially are the
energy transferring components of the guitar where the
first bit of energy comes from the string and goes
into the guitar body itself. They tug at that bridge with
their unique harmonic spectra. That’s not to say the
guitar’s going to vibrate at that unique harmonic
spectra at all. It’s just that’s what’s
available in its energy budget to then be distributed around
the guitar in whatever way that particular guitar
will respond. [ Silence ] Okay so I’ll just– we’ll
go back a few steps now and I’ll work back up to the
slide that we just showed. Wood is the engineering
material you use. And wood is always on the move. It’s a very, very humid day
today and I had to retune all of these instruments
because they move around. Wood will absorb the
moisture in the atmosphere and similarly it will dry out. And so the parts of the
guitar will actually distort with these different humidities. When you go to Bunnings have
a look at the top plank there, plank number one that’s
nice and buckled and bowed. Strangely enough Bunnings have
quite a number of those planks in jarrah and things
like pine for sale. What the wood does is
it actually cups away from the centre of the tree. So, if you ever see something– a wood bending like
that on the bottom of the radius you know that’s
the bit that was closest to the core of the tree
and the reason being that the wood will
shrink primarily between its growth rings. The kind of wood that
you want to make a guitar out of is the plank indicated
by number two over there. That plank there is what’s
known as quarter sawn wood. If we were to slice that log
into quarters and then take one of the– a board off the face
of the quarter, so we’d slice it into quarters down this way
then we’ve taken a board off one of the quarters. The only that piece of wood
can move now is in and out. It can’t flex up
or down and bow. It only can go in and
out with moisture. So, that’s a reasonably
stable bit of wood. I’ve brought along a few bits of
wood just to show what I mean. This is a bit I’ve
bought from Bunnings. Isn’t that lovely clear timber? Not really, knots
all over the place. But, you can’t really expect
much else out of this. This is pine wood. And what I’ve– when I go
purchase wood I do look very carefully at the
ends of the grains. And just here and it’s very hard
to see, is the core of the tree. This is the centre here. And out here are the growth
rings radiating out from that. So, this particular piece of
wood even though I bought it as a throwaway piece for some
of the things I was doing, I made sure it was at
least quarter sawn. So, I went through the
stacks of wood and got a bit that okay it has a few knots
on, but at least this is going to stay relatively flat for me. I think I’ll– yeah in a minute. We’ll just show you
some other wood. This is the kind of wood that
you hunt through wood stacks for as a guitar maker. You can see that I can’t
really see any discernible ingrain here. It’s very hard to
know what’s going on. And usually if I go to
these wood yards I’ll ask if I can saw a little piece off
the end or bring my plane along and just plane the ends so
that I can have a look here. And this particular piece
of wood even though no one in their right mind would pay
21 dollars for something that’s so rotten is an excellent
piece of guitar wood. We’ll see that shortly. And for me, this heartens me. I know this was a fallen tree that I’ve now reclaimed
from the forest. So, we’re not just tearing
up tropical hard forests, hardwoods there for that piece. [ Silence ] Why do you get such
poor cuts in wood? Of course, it’s got to
be sawn for economics. So, you don’t want to go wastefully
sawing wood in quarters. It’s a very wasteful
way to do things. And they have come up
with various schemes. I’ve just illustrated some
here for cutting these woods and trying to maximise the, I
guess the yield from the wood. And if you look through all of those pictures you could
probably see quite a few planks and all those different
cutting methods that would yield suitable
wood for guitar making. So, you do spend a lot of time
hunting through stacks of wood, annoying these wood
keepers and going through their stack again
and again and again. As well as being quarter sawn,
it’s an interesting phenomena of trees that aren’t
always straight grained. What we mean by straight grained
is that the tree has just grown up with no twists in it. This is a reasonably
rare phenomena. I’ve got two straight trees
out in the front of our house. They’re both weeping
peppermints. One is ramrod straight,
no problem at all. And the other has an
extraordinary twist on it. So, these were two trees
grown at exactly the same– planted at the same time, grown
in the same location, same soil, same watering and yet they have
such different characteristics. Why they do this is they
actually follow the Sun. So, in the southern hemisphere
here a tree that’s looking at a northern facing
Sun will follow that Sun and track it through the day. Oh it disappears. Oh here it is again. And it’ll follow and track
that and actually grow a twist in an anti-clockwise fashion. Guess what happens in the northern hemisphere,
the opposite. And why are tropical
hardwoods sometimes so valuable and stable? It’s because they twist
one way and then another. And so they’ll just twist back
and forward and work their way up and be very, very
straight grained for a long distance
up their trunks. So, as best as possible if you
can, you’ll actually cut wood for guitars out of
split billets. So, someone’s cleaved it with an
ax that’s followed the natural split line and then you resaw
the board to follow those lines and that will yield
very, very stable wood. Wood used for guitars ideally
have a very high stiffness to weight ratio and
that’s why I’ve hung onto these two bits
of wood here. So, here’s our Bunnings pine. We’re a student. We want to make a guitar, so
we’ll buy some cheaper wood and see what it might
sound like. So, if I grab the wood, usually
about a third down its length and just give it a nice rap with my fist you can
usually see the sort of tones it might produce. That’s quite subdued. I didn’t get that
tone this morning. That’s not bad. And then we’ll grab
our piece of rosewood. I’m trying a similar
thing to that. And this will rattle around. There’s lots of rot in this one. The sustain in that’s a lot
more even though as I say that there’s a lot of
rattling around there. So, I go around the wood yards
not only planning their bits of wood, sawing off the ends
and looking at the end grain, but I go around there bashing
them with my fists as well. What I am listening for is things like,
you hear that rattle. I’m listening for cracks
also in the billets of wood. We don’t want to have any
hidden cracks in there. But, the amount of sustain in that wood would tell me this
will make a great guitar back and side set. The wood that’s illustrated
over there in the picture’s been
all sawn up by me now, but this is all wood
I’ve selected for back and side sets using
exactly that principle. So, I’ve gone to the wood shows
as it turned out in Perth, purchased those just by
bashing them and seeing if they were resonant or not. So, rather than sticking to
traditional timbers I go out and just look for physical
properties of the timber. I’m not particularly interested in reputations of
historic woods. So, if you want to
find stiffness to weight ratios this
is how you can start to quantify some
of these things. You basically look at
the density of the wood and its modulus of elasticity. And I’ve illustrated these
four woods in particular because they are the premium
and premier woods used in the guitar building industry. Spruce, whether its Sitka spruce
or Engelmann spruce or all sorts of subspecies, Alpine spruce
from Europe is a very, very good soundboard material. And far and away, although
the numbers don’t suggest far and away, it is the
best stiffness to weight ratio you could
ever get in the wood family. So, it’s just like balsa wood. It’s extremely soft. Trust me, you have a little
sand grit or grain on your bench when you’re working it and put
it down on top and it’ll indent into that very nicely. So, it’s a very soft wood,
but extraordinarily stiff and extremely resonant. So, it’s used for the
soundboards for pianos, for soundboards for violins and
soundboards for a whole host of musical instruments. A good second– a very popular
timber is Western Red Cedar. We actually have an
example of some here. This is a cedar soundboard here. It’s been manufactured
at the moment. This just has a more
subdued colour. Not as bright white. And this is imparts quite a
lot of warmth to the guitar. It’s not as stiff as the spruce. And so the bass notes here are– it’s easy to get a good
bass sound out of something like Western Red Cedar. So, that’s usually used for
lower tension instruments. You wouldn’t put that in a
high tension instrument at all. And back and sides woods are
the two bottom ones here. Mahogany nowadays, Brazilian
mahogany is site certified, so it’s an endangered species. It’s no longer able
to be exported from Brazil and South America. Whatever’s around is around now. I was very fortunate
recently to purchase some. I didn’t– it wasn’t very large, but I’ve made some necks
recently out of this timber. Very nice timber to work and you
can see why it was so revered, but unfortunately
so heavily forested, logged and it’s pretty
much all gone now. But, that’s a very,
very good timber to use. And there’s a number of mahogany
variants that are very good, African mahogany and some of
the Asian species are very good. But, this is the old
Brazilian version here and you can see it’s stiffness
to weight ratio is quite high. The premium wood by far for back
and side material is rosewood and in particular would
be Brazilian rosewood. That was site certified in 1972. So it’s pretty rare to
find a guitar nowadays or to find that wood. If you do they’re
actually cutting it out of old tree stumps. And so the sort of grain,
the nice straight grain that follow the split
line sort of rules, they’re out the window. What they’re relying on there is
that people will buy something that you can’t get anymore. And there’s a lot of mystique
associated with that wood. But, personally I would never
make a guitar out of it. It would be way too risky. As an example, here’s
a very similar timber. I’ve had this for
years and I wanted to make a guitar out of it. And this was a set
of sides I made. And this is the sort of
thing you might expect out of Brazilian rosewood. It’s– it looks reasonably
straight and clear grained, but it’s certainly not. And this thing is that cranking. You couldn’t bend this
thing with any sort of luck. And I’ve just put this aside
as a bit of a bad loss. So, it was– that was a shame. I had a big board of it all cut
up and I’ve still got it all cut up and it’s going
to remain cut up, so not made into guitars at all. Okay guitar anatomy;
what’s inside a guitar? Someone recently was very
surprised when I told them that what you see on the outside
of the guitar really isn’t much to do with what makes
them produce the sound. And when they poke their head
inside the guitar they were astounded to see the
amount of wood work that goes on inside there. And to be honest, what’s under the hood is the most
important part of the guitar. Here’s one– here’s a guitar
I haven’t prepared earlier because it’s still in pieces. Bob Coleman down in the back’s about to become very intimately
acquainted with this guitar. This is his guitar. So, here’s the internal
structure here that I’ve been working
on for him. These are the struts or
the braces and we’ll go over their function in a minute. And there’s a few little
hacks and chisel marks. It hasn’t quite been
finished yet. But, this is a guitar top that I’m slowing
carving away the braces to get a nice tap tone on it. Doesn’t sound very
much to you guys, but last weekend this
was extremely stiff because the braces
weren’t carved and it’s slowly opening up. I’ve got to now decide
how much wood to take away from this before it’s
opened up enough. And you’ll see shortly if
I open it too much it’ll actually break. Here’s the back of the guitar. These braces haven’t
been shaped. They’re still in their
rectangular form. And even so, don’t know what
that truck’s doing out there. You can still get a reasonable
tap tone from something like that that still
hasn’t been carved. Okay apparently we’re okay. Oh there we are,
very good Glenn. Thank you very much
for your assistance. So, we’re going in. So, there’s the struts
you see along the back. Have a look how I’ve
tucked those in under those linings there. So, those back braces are
actually coupled to the sides of the guitar and
held quite firmly. There’s the backblock. The big piece you
put the strapping to. There’s another one
tucked in over there. Here’s another one. Oh nice woodwork. Don, very good. The biggest thing with
all of the little cuts, the bit I’m coming really close
to now is called curthed lining. We’ll see a slide of that later. And that’s actually quite a
critical part of the guitar. Every one of those cuts
believe it or not is almost cut through that piece of
wood, but not quite. And it’s all done by hand. So, it’s been a very enjoyable
experience making curthe lining. And I think Bob Ross here
has had a turn at that and would have to agree that
that’s just fantastic fun. If we just back up
a bit it’s going– I might have to do
a bit of bending. He’s up. We can just
see the tops of some of those soundboard braces. Oh there’s another
scheme for making sure that they’re anchored
quite nicely and this is the way
we do it on the tops. We actually stick one of those
little curthe lining blocks on top of the brace to hold
it in there quite firmly. It’s an important point
of the guitar as well, how thick that little
bit of brace is that goes into those linings in there. And I think if we back, back–
no we’re not going to see that. No. I thought we might be able
to see the strings coming in. Okay, so there’s a little
bit of a different way to look in the guitar. Oh if this works I’ll be amazed. [ Tapping sounds ] [ Silence ] Fantastic, smooth as. Okay, here’s one I
did prepare earlier. What I do when I make guitars like these things,
this is a cutaway. But, in particular it’s a
Venetian cutaway rather than– I don’t know why they call
it a Venetian cutaway. A Florentine cutaway has
a smooth flowing curve that you bend into it. These supposedly
are harder to make and I guess I have to concur. They are fairly difficult
to get right and make everything
look nice and crisp. And what I’ve done when– I usually make the guitar
as a solid guitar first and actually hack into the
side and cut that part out. And here that allowed me– you
can just see the bottom edge down there of where
I’ve cut it out. That allowed me to poke a camera
in there and get quite artistic. So, you can see the internal
structures of that one there. This is about to be
strung up and working. So, those braces there are
at the correct thickness and weights and resonance
and everything that I wanted about them. The finish has also
been put on as well. So, I’ll refinish after I’ve
put the cutaway in there. So, I can judge– I could have
stuck my hand in after this, after cutting it and
actually adjust it or taken some wood away from
those braces if I had chosen to. So, it does allow a little
bit of luxury that way. Here’s another look at them
when the backs are not on. So, this is the soundboard
bracing. This is specifically for
steel string guitars now. It’s about 700 Newton’s
of tension. So, about the standard
physics person, that’s 70 kilograms standing on
a rope, hanging off that bridge for the life of the guitar. So, it just gives
you an appreciation of how much force is on the
guitar, on the guitar top. And it turns out you don’t
even need those braces. You can make a guitar
without the braces whatsoever. So, that’s quite a surprise
I’m sure for a lot of people. What would it sound like? Horrible. What would
it last like? Probably a month or two before
it would collapse in on itself. So, it wouldn’t hold
up to long-term tension and it wouldn’t sound
very good at all. Why is that? Well, most importantly on
the right of the image there, braces increase the
stability of the top. That’s very important. But, most importantly
they control the modes of vibration of the top. And this is something that
certainly I’ve learned since my previous talk here
in the physics department that that’s really the
main purpose of braces and brace schemes is
to control the modes or the way the top will vibrate. Yeah sure, it also has
the secondary function of keeping them held up
over a long-term tension. But, it’s really the modes of vibration that’s
very, very important. What am I talking about modes? This is a bit of a go at
trying to have a graphic to show what modes are. And so if you can imagine red
being out perhaps and blue being in this is the type
of oscillation that the monopole
mode is on the guitar. So, that’s in and out type of
bellows movement and this is where we get the sound
coming out of the sound hole, sort of helm hole;
it’s resonator style. The monopole mode in
steel string guitars because they’re made of jangly
steel is a very important one to get right. What we’re trying to do in steel
string construction is increase the bass response. And if you make the monopole
large, a big monopole where the whole thing can
move in and out as a complete and total unit, then you can
increase the bass response and get a nice rich bass
response on the guitar. So, the monopole is
certainly something that I’m constantly
striving towards increasing. There’s two other main types. This is the cross dipole mode where you’ve actually
got the bridge teetering on itself going backwards
and forwards. And this is extremely
important in nylon and classical string guitars. This is the mode that they
primarily are interested in. Nylon strung guitars
have great bass response. The thing they struggle
for is treble response. And so this mode here
gives great treble response and also actually as it
turns out aids in projection. If I play a guitar a
long way from somebody and they can hear it
very clear, then you know that we’ve got the cross
dipole mode very active on that particular guitar. These aren’t exclusive
of each other just as the harmonic spectra of
frequencies weren’t exclusive. We don’t just get
the fundamental mode. We get a whole mixture of these
modes on any one guitar top. And then the final one
is the long dipole mode. This one’s a bit
difficult to get going because of the way you’ve
orientated the wood. You’ve put a lot of
stiffness in that area. And so the long dipole mode
where the bridge teeters back and forward on itself is a
hard one to try and enhance. If you’re trying to
enhance that one you tend to weaken the structure
a little bit and over a long-term the
guitar will fall apart. So, that’s not going
to be a very good one. But, that one is
prevalent and is used. So remember, there’s
a mix of all of those, but just like we
had the fundamental in the first overtone we’ve
also got similarly fundamentals and first overtones of these– of the dipole modes,
not of the monopole. So, we can also get the top
breaking up into two area– with two nodes or three
nodes or four nodes, etc. And so actually
the movement of the top on a guitar is actually
quite chaotic. It’s a very chaotic
thing indeed. And remembering that
this is the sort of bracing scheme we’ve got. So, it’s not a homogenous plate. We’ve got braces placed in
very specific places here to enhance very specific modes. So, we’ll just have a quick look at nylon string soundboard
bracing. And if you remember, what
they want is the cross dipole. They want the bridge
to rock backward and forward on each other. Look at all the bracing schemes. They all brace in
that long fashion. They all want the bridge; they
want to enhance that bridge to move backwards and forwards. Interestingly you might not
intuitively know that down in the bottom right hand side
is a guy who lives in Esperance, and he has this lattice
brace arrangement. He has probably some of
the more innovative ideas on classical guitars. But, his bracing system as well
very much enhances that dipole and he’s very aware
of that as well. So, it’s not as intuitive
on his style of bracing, but that’s what he’s doing. So, that’s the realm of
classical guitar building on nylon strung guitars. That’s not my realm. My realm is steel
string construction and very specific kinds
of steel strings as well. This is the bracing pattern– it’s not the only bracing
pattern you can use. But, this is the bracing pattern that I base everything
that I do on. It’s known as the X
brace pattern mostly because of two main braces
along there, the two main X’s. The good thing about
this bracing system in steel string guitars
is it really does tie the whole structure. So, to get that monopole mode
going it’s very easy to do. The thing you see on the
top of the guitars here, the brown thing, is the most
important brace on the guitar. It’s the only one that’s
on the outside too. But, this bridge here
actually ties those legs of that X brace together
by its exact placement. So, you can see that
on the diagram. There’s a bridge plate and
there’s a little tiny outline of the bridge itself there. And if you were making a gate or
some sort of a structure at home and you had two cross pieces of
wood wouldn’t it be advantageous to stick something across to
tie those things together. So, it’s able to tie
that together and get that monopole mode
going really nicely. But, the good thing about the X
brace is we can open and close up the X, not by much,
by very minute amounts and we can actually increase
the amount of long dipole or cross dipole modes
that occur on there. And we have auxiliary braces. They’re just called
finger braces, although these are
called soundboard braces. I just call them finger
braces that come off here. And they’re also
important as well as the lower transverse braces
in just helping control some of the spectra that we see. If we have a look
at this guitar, this is actually a
small body guitar. So, we’ll just go back
to that soundboard. And it’s a very lightweight
cedar top that can’t handle
much string tension. And what I’ve done here is
modify it a little bit what we might see over on
the slide over there. So, I’ve eliminated a second
finger brace from here. I don’t want to stiffen
this top up at all. And I’ve only got one
transverse brace and look at the orientation I’ve put
rather than having it hang right down the base of the
guitar down here. So, what I’m trying to
do as much as possible with this guitar, it’s a
small body and I’m going to fighting getting
a good bass tone. So, I’m trying to open up the top a little
bit more artificially by removing any weight down here
so that the thing can get a bit of a long dipole, but hopefully
a really good monopole movement. So, hopefully I’ve tied the
structure together really nicely with the arrangement
of braces there. So, the rest of voicing
this top, as it’s known, is just removing just removing
a little bit extra wood. I’m almost there now, until
I can get a really pleasing tap tone. And although this is not fixed
at the sides like it would be in a guitar this gives
you a quantifiable way of knowing have you
reached your target tone. Interestingly with
braces the buzzword in braces is let’s get a guitar
that has scalloped braces. And so many guitar companies
offer scalloped braces. What happened there was in a factory setting the guys
would put the guitar together slightly overbuilt, a little bit
heavier than it needed to be. They would string it up and
go this guitar’s a bit dead. They’d reach in the sound
hole with their planes and they would plane a
little bit of the braces and they would just weaken those
braces up and string it up again and try it again until
they got it right. And so by slavishly
copying what people said– saw when they opened
up the guitars and saw these braces
were scalloped. It’s false. You don’t need to
scallop braces at all. What you should be doing
is getting very skilled at getting a very
nice slim taper on the braces in
the first place. So, I’ve yet to have any
of the guitars I’ve made where I’ve thought gee, I really
need to get my hand in there and start to carve away
some of these braces. So, that was in a
factory setting where basically they assume
all components are the same. So, some guitars clearly
won’t be the same as others. [ Silence ] Going back delving into the
physics why do I make the braces or I just know that you
need to make them taller than they are instead of
really squat fat ones. Basic physics can tell you. If you look at the brace
on the left hand side if we make it twice as wide
we get twice the stiffness. But, there’s a squared rule
if we make it twice as high. Sorry it’s a cube rule. Pick me up on that
would you hey? It’s a cube rule. So, we get eight
times the stiffness. So, when I’m mucking around
now removing a little bit of wood here I can do a
lot of damage very quickly. And one thing in guitar making
I’ve realised over the years in making many guitars is
you can’t put the wood back on again. And so when you’re at this
almost target thickness here it’s very much a slow
process of removing a bit of wood and testing it again. You don’t really want to try
and put that wood back on. It’s a really hard thing. I’ve had one guitar in
the history of making where I’ve basically run this
hole through my thickness sander and taken all the braces
off again and started again. So, I went a little bit too far
on that particular one so, yeah. So, we like high braces and
the reason is we get a lot of stiffness. And the same happens with the
thicknesses at the tops as well. So, if we make the top twice as thick it will have
quite a lot more stiffness than if we make it only a
little bit stiff, a bit thicker. Domes, tops and backs
are a little bit of a current trend
in instruments. I’ve actually got a
mysterious instrument that I had under here. This is a violin
kit I put together. I wouldn’t say I made. I just glued the components
together that I bought. And it’s well-known
in the violin world that they carve a dome into
their instruments for strength. So, these guys don’t
have to worry too much about the internal
bracing and structures. They don’t have complicated
bracing schemes here. What they have is just a single
tone bar run down the middle and not just controls
some of the modes of vibration on a violin. The back is un-strutted. So, it’s just carved
out of maple and the top is carved
out of spruce. So, this is a well-known of
getting larger instruments like violas and double basses to contain the stress here
that’s put on by the bridge. So, it’s a very strong way
of building instruments. The way you can do in a steel
string sense is in part a bit of a dome to your instruments. And this is the one
I played first off and is a good example of that. And it might be a
bit difficult to see, but built into this
guitar has been a radius. And I’m sorry to use the units,
but it’s a 40 foot radius. And in the back of the
guitar has been built in a radius 28 feet. So, you do the math if you
like the metric system. And this has been
done specifically to increase the stiffnesses
of the woods. If I can increase the
stiffness of the top of guitars I can remove a lot
of the wood that I’m using in the bracing structure
purely as a structural element. I can then concentrate
on using the braces as more controlling
in the mode element. So, they’re just simple
lightweight things that are almost fixing the top in certain positions
in that case. So, earlier constructions I’ve
made and still do a little bit, things like this guy here. That’s a true flat
string– a flat top guitar. So, that has a completely
flat top on it. But, as it turns out you tend
to dome the backs as part of the manufacturing process. So, it’s possible to make
guitars with flat tops as well. They sound just as good. It’s just that I have to
be mindful now that it has to be a bit more structural
in my bracing system rather than looking at the
sound that I’m getting out of the instrument. [ Silence ] Okay oh I just wanted
to– how do I do it? How do I put a dome
into instruments? Here’s Bob Coleman’s back
there and this has a dome put in it already like this. I have a 40– sorry, for this
particular one its 28 foot radius dish that it’s coated
completely in sandpaper. And each of these braces
I’ve put it on the dish where it will sit on the guitar
and sand the dome into that. And then when these are glued
I actually press this bottom, the bottom of the
guitar onto the dome dish and have some sticks– it’s
known as a Go-Bar deck, sticks that sit down
and press the brace onto there while it’s glued. And then when I finally
get to stage– you saw an open guitar
before without the back, I’ll actually turn the back
upside down on my sandpaper and sand in the dome
into that as well. So, when this is glued onto
it it’s pulled completely into a dome in all dimensions. So, that’s how we do that. And the tops are done
in exactly the same way. It’s just that the dome in
those is a lot more subtle. But, those at the front can
certainly see this thing’s teetering on quite a radius. So, I’m able to now lighten
up those braces probably more than I normally would
have been able to. Seeing the unseen, these
images are being pinched from the University of
New South Wales website. Thank you very much for those. And this is using
Chladni patterns. So, we throw a bit of sand
on top of the guitar top and where it collects is a node
point where there’s no movement. And you can start to investigate
what is the frequency response of your guitar top? This is done by a lot
of manufacturers as part of their manufacturing process. I’m personally not
interested in that at all, but it’s a very interesting
exercise if you do look at the response of a guitar top. Note also, this is a free top. It’s not being fixed to
the sides of a guitar yet. So, obviously that would
be a completely different response altogether. Seventy seven hertz, this is around the base E
frequency of a guitar. And this one is quite
low and got a little bit of that monopole activity
and as well as some of that crossbow pole
activity, which is a good thing. As the frequency gets increased
you can start to see more and more complex patterns. The first few seem to
stay about the same and obviously the
soundboard breaking up in all sorts of weird ways. Remember the bracing system’s
not symmetrical underneath and that’s controlling a lot
of what you’re seeing here. About there I think, I
think it’s a bit lower is that frequency, the high
E string on a guitar. So, that’s what the top’s doing and vibrating similar
to that I guess. And as you keep sweeping through
these frequencies you can see the tops breaking up into more and more areas where
there’s modes. It’s a pretty crazy
one isn’t it? Look at that. Okay so that’s what
the guitar top I guess in some ways is doing. It’s like the string
breaking up into higher and higher modes
of those dipoles. As the frequency gets higher, the frequency that’s
driving them. So, we talked a little bit
before about curthe lining. We had a little bit
of a look at them on the probescope
inside the guitar. Here’s the guitar with the back
off and those linings exposed. I was told this by
a guy in America. I went to Santa Cruz
Guitar Company and the president was very,
very kind and gave Glenn Lawson and myself a personal
tour of his factory. He sat down at the end of that and I guess had a quick brain
dump of some of his philosophy to me and this is the
one that resonates and has absolutely
stuck with me ever since as being a true thing. He used basswood for his
linings of the guitar. And I asked him why? And he said, “Well, basswood has
no preferred grain direction.” You can’t really cleave
or split basswood. It’s a very interesting
wood that way. And he said, “If
you use the basswood for the linings you’ll actually
isolate the top and the back from the sides of
the instrument.” So, you should get minimum
vibration of the sides, but the back and the front
will act more like a drum. And he suggested I try and
concentrate on tuning those back and top plates to each other so that they’ll actually
enhance what each other does. And I’ve certainly found
and by playing his guitars that is a very, very true thing. The majority of manufacturers
still use mahogany linings. They couple the sides and so
the energy budget you’ve put in with the strings is a
bit lossy around the sides. Guitar players appreciate that
a lot because they can get some of the sound that they’re
producing radiating to them instead of going
out and being wasted on their audience, alright. What would you want
to do that for? And this concept’s been
taking a lot further nowadays that people are cutting sound
ports into the top sides of the guitar so the player
themselves can hear that music. To me that’s a little bit
odd and I certainly don’t go for those types of things. It’s very much defacing a
lovely looking instrument and I would never put a sound
port in my guitars at all. So, the basswoods lining
here, their function is to isolate the vibrations
at the top. So, the vibrations can
only get to the back now through the interaction of
the airspace in between rather than through the
sides primarily. So, the role of the back
very, very important. The back is a little bit like– imagine an athlete
on trampoline. They can start boinging away
and what they do with their legs to get the maximum jump
is very much in harmony with the resonance
of the trampoline. But, if you’ve seen these
Olympic people once they’ve done their time or their amount of tricks they can stop
themselves instantly by putting their legs at a
different resonant frequency and just stop instantly. This is exactly the function
of a back on a guitar. So, the top will be
driving, being driven by the strings vibrating
away happily, nicely isolated by the basswood linings. And if the back is in sync
with that motion it will keep that motion going and enhance
the sustain of the instrument. And this is something
for those– possibly there’s a
few guitar players around here today
that own a guitar. You can test this for yourself. So, here’s a back,
Queensland maple. It’s nice to promote
our local species. You can tap those– these things and get a sense of
its resonance. That’s one way to test the back. But, a really good way is
to play the guitar with it against your ample
girth if you want and then play it a little
bit further away and see if there’s any difference
in the sound. And probably a nicer
way to do that– let me just hook
my leg up somehow, is if I just tap the
top rather than play it. So, I’ll tap it without–
against my body and with. This guitar maker
knows what he’s doing. He’s made that back
really a part of the sound and that’s an important point. If someone wants a guitar
that they want to strum in say a rock setting, a rock
band, they’ll put a strap on this thing and
they’ll be standing up and be playing it like that. So, they’re missing out
on all those frequencies. So, if I’m designing
a guitar for a player like that I won’t bother
too much about the back. The back might be
aesthetically pleasing, but it’s certainly not going
to help and enhance the sound. So, the difference in playing
with it against me and away so we just get a lot rounder
tone and much more muted. And you can test a number
of guitars with that. So, here’s a mahogany back. Mahog– this is African mahogany
so it’s a bit of a substitute for the normal mahogany. Once again a great report. Fantastic and you can try a
similar thing with this guitar. So, I’ll just do the tap. [ Tapping sounds ] And take note of that name. This guy really does know
what he’s doing doesn’t he. Alright and the last wood here, this one’s probably
the most striking. This is– in sound as
well as looks I guess. This is Tasmanian
Blackwood, which also occurs on the Australian mainland. This is actually fiddle
back so that’s quite fancy. But, that has a very,
very good tap tone, extraordinarily good
stiffness to weight so it makes a great
back material. And similarly if we just
tap that one virtually dead without it, this
particular guitar. And this one has very much been
designed with that in mind. So, this is what we’d call
a finger style guitar. This is one that’s
meant to be played on the knee away from the body. For something and I don’t really
have a good example of that, but I guess the best example I
have would probably be this one here with Queensland
maple back and sides. This is what I call
the rib tickler. So, the guy would be standing up
and having it against their body as they play the guitar. [ Playing guitar ] [ Silence ] Okay bracing patterns in
backs, a little boring. What we’re trying to do is
enhance the long dipole. And so primarily, these are the
bracing schemes that prevail. I used to slavishly copy
what we see on old guitars and put four braces across
here, but this is one of the small body models and
I realised you didn’t need as much stiffness in these. And so I’ve now gone to
a three brace system. And these will be carved away
just like I do to the top braces to try and get the most
resonance I can out of the back so it’s part of the
guitar sound. So, apart from looks on a guitar
back it’s very much a part of the sound as the top is. Scale length, there’s
not much variation in scale lengths of guitars. Historic guitars– why
did I bring this along? Historic guitars were
these kind of things. It isn’t a lute. It’s actually an oud from the
Middle East, but it’s very, very similar to a lute and
it’s the only thing I’ve got to illustrate this. This was what was used in the
olden days, the old times. That was strung with gut strings and they have a particular
kind of bridge here. The bridge is actually
technically very boring. It was not much thought
put into that. There was a rule of
thumb that you put it– I think it was one
ninth the distance of the whole top along here. This particular one
certainly isn’t that, but that’s not a great place
to put the bridge at all if you want maximum monopole
activity on a guitar body or any musical instrument. So, these things are
a quiet instrument. They were meant to be played
in small rooms, ensembles, in very, very quiet settings. So, this is a really
inefficient machine, very, very inefficient,
strung with gut. And the scale lengths in
these were quite short. So, they’re a very quiet
instrument for a reason. And as modern times went on
and we got to raucous bars and things and people wanted to
be heard the scale length sort of standardised and I have gone
metric, although I can’t think of that in my brain,
61 and 66 centimetres. It’s– the most common scale is
the 25.4 inch as standardised by the Martin Guitar
Company in America. The steel string
guitar is primarily an American instrument. It was born over there. And the shorter scale guitar
24.9 inches is commonly used and Gibson Guitar Company quite
often uses those shorter guitar skills as well. What would the difference be? A musician would know instantly. If strung with exactly the same
strings a long guitar is going to have more string tension. Because it’s got more
string tension the middle of the string’s going to
vibrate and buzz on the frets. And so that’s going to have to
have a little bit more clearance between the fret board so
the action or the height of the strings is going to have to be a little bit higher
above the soundboard. There’s going to be a lot less
energy to move the soundboard. Just lightly strum that
thing and you’ll get a lot of energy put into
the soundboard from the longer string. Definitely has a more
resonant sound and by that I guess I’m talking about more fundamental
in the string itself. It’s going to be stronger
and therefore it’s going to have a better bass response
than a short scale guitar. I did bring a short
scale guitar along. My daughters are very lucky. When they were five
they got a guitar each and this is my first
daughter’s guitar. This is an extremely short scale
guitar because she’s a very, very short scale person
she was five, alright. I mean she’s grown up and
this is a bit of small thing. But short scale guitars
lack a lot of bass response. Not much bass response. But, what they do have
is a really sweet treble. And back to the basses,
which are very weak again. There’s another reason and you’ll see shortly why this
has a fairly weak bass response. But, that’s what a short
scale guitar is like. It’s very tiny. There’s no doubt about that, but
you won’t get treble sounding like that on a normal size
guitar with a normal scale. Okay we’ll get something
with a longer scale now. There’s rhyme and reason why I
brought everything along today I think. So, this is a tambura
from northern India. Quite a long scale length
you’d have to admit. And the good thing
about this is rather than getting a bass guitar,
which is obviously strung with big thick rope strings
played by Neanderthal types. This one’s a little more
subtle with very thin strings. And this is used a backing for
the vocalist in Indian music. And with very little energy the
strings just keep going forever, quite nice to annoy
your spouse with. This has been a– look
forward to her trips to Sydney so I can play this thing. And so, tiny amounts
of energy in here in actually a very
inefficient sound box. The thing is a pumpkin, right. I’ve got a pumpkin and I’ve
stuck a big heavy piece of rosewood on with a big
heavy stiff arch on it and I’ve just pressed the bridge
against it in violin style here. So, it’s an extremely
inefficient generator of sound. But still, with a long
string you’re still able to get these lovely sustaining
notes out of the thing. Feel free to sing
along if you want to. Okay getting to the
last few points now. Intonation is a critical
aspect of making guitars. If you don’t get this
right your musician’s going to throw the guitar
back at you and say, “What did you make this
piece of rubbish for?” This is another classic for
slavishly copying designs, which you might get from perhaps
nowadays Chinese factories. But, historically perhaps
Korean and then before that Japanese factories just
simply grabbing a guitar from the west, copying every
part of its design and trying to sell that out to the public. They didn’t know why the
intonation was an issue. They didn’t know why we have on this bridge here a
little slant on the saddle. I’m not sure if that’s
perceptual in that picture. But, thicker strings
are far stiffer than the thinner strings. And on a guitar the thinner
string is at the bottom and they progressively
get thicker as you go up to the bass strings. And so they all flex
a different amount. The nice slinky thin strings
they can pretty much vibrate along their ends
as they’re fixed. But, if you get a heavy bass
string and try and fix it at the two ends it doesn’t
actually vibrate along its whole length. It can’t because of
the stiffness inherent in the material the very, very ends of the string
are actually held quite stiffly there. And progressively
that relaxes as you go into the centre of the string. So, there’s dead
points in the string that are actually what you would
think be actively vibrating, they’re not vibrating at all. And as you progressively go to thicker strings this
becomes more of a problem. And so rather than slavishly
copying the designs that you see on historic guitars you should
be measuring these things. And so we start to slant the
saddle on the bridge here by a very precise amount and
go even further than that that you would carve the shape
of this piece of bone on there to accommodate different
gages or styles of strings so that they would
intonate correctly. And that’s quite important
that we get that right that the guitar would intonate. The way it’s done it’s
not rocket science. You get a tuner out. You play a note and you
play the octave of the note and see if they’re the same. And the octave should
be the same as the original fundamental note
and an easy way for you guys to hear that, I guess, is
playing open chord down here and then play the same
open chord up here. It’s very much in sync and in
harmony with those open strings. We can hear that. Once again, what can I say? This guy has got the
right idea there. So, he’s got the intonation
right on that particular guitar. And that’s not done by ear. I’m no– I’m not trained
to hear tones by ear. I do that with a strobe tuner. And that’s a big part of I
guess the dollars I’ve made over the years is in
setting up peoples’ guitars from cheap copies and
turning them into something that actually works musically. So, that’s a very
common thing to do. Most importantly the bridge– we’re getting now to the final
aspects of all of these things. This is just– the importance
of this can’t be understated. It really is the thing
that connects the strings to the whole guitar body
and so its height, weight, type of wood, amount of flex
are very, very important to the overall tone
of the guitar and how that then interacts with
the rest of the guitar. It is the most important brace and luckily for us
we can see it. It’s on the outside. The best place to put
the bridge is right in the centre of the guitar. If you put it in the
centre you’re going to get good monopole action. You’re going to get the
thing going in and out. And we can illustrate that with
a little windup toy box here. Does anyone have a
birthday today at all or had one this week at all? Alright I’ve just got
a little song for you. This goes out to you. [ Music ] Okay so that’s the
mechanism itself. It doesn’t make any–
much sound at all. I put it inside this box. It makes a little
bit more sound. But, what about if we stuck
it on the bridge of a guitar that has its back
supported up and we stuck it where the bridge location was? Wow, fantastic. [ Music ] Hip, hip. We could
also try sticking this on the edge of the guitar. Why don’t I stick
the bridge over here? Wow this guy’s got a
nice resonant guitar. It’s supposed to be
quite tinny and trebly. Nowhere probably as resonant
as we’d find in the– right in the centre
here in the bridge, so it’s an obvious
place to put the bridge. And its placement is
quite critical to getting that monopole mode
going on a guitar. Here’s a few guitars I’ve made and one we just played
earlier the short scale guitar, look where I’ve put the bridge. And I told you there
would be something about why the bass frequency of this particular
guitar is not great. This instrument was
constrained by its player who had tiny little hands. And they have to be able to
put their hands around here and actually physically
be able to hold it. And I can’t stretch the
neck right out there, which would then pull the
bridge into the correct position because then the neck would
fall forward on the thing. So, the whole design
of this guitar I knew from the outset wasn’t going to
be the most efficient design, but it was something
that they could at least play and
get started on. If only she would. The next one along– I’m
not sure if we brought that. Yeah we did. The next one along was the
next daughter’s guitar. The first one of course,
complains that hers was smaller. This one’s bigger and
better apparently. And the bridge placement
here is wrong again. It’s completely wrong to get
the best bass sound out of that. It’s not bad, but it’s
not very resonant compared to the larger body guitars
with the bridge in the centre. This again was constrained
by the player. If I stretch that neck out by another two frets then
the guitar would fall forward and she’s not strong enough
to play a guitar like that. But, I do have– every guitar
for me is a point on the graph. And we can see the one on
the right hand side was made for a friend last
year for his daughter. I very quickly realised it
wasn’t for his daughter at all because he had asked
for a full width neck, which she wouldn’t
be able to play. It was for him. So, it was a great excuse to get
another guitar under the radar of his wife and built pretty
much to what he wanted. So, this then allowed me to
do another point on the graph. What about if I stretch
this by another two frets and had the body join here,
exactly the same body shape. And exactly the same body shape
is our friend Bob Coleman’s guitar is made as. And this is how Bob’s
guitar is going to be made. So, his bridge is going
to be put in the centre by pulling this whole
scale up a little bit and stretching the neck
out of the body and then that will place the bridge where
it should be for great sound. Ah I think it’s that one. The bridge and saddle
is how the loading of the strings gets dumped
on down to the soundboard. So, I can’t really
quantify what you do here. It’s a feel that I’ve got. And it’s a feel that I’ve
got overt making a number of instruments, which
really is the way you start to get a handle on how these
parameters affect the tone of the guitar. And you can tell if you
had a really high saddle. Some people do this. They put a really
high saddle on. It dumps a lot of force on the
guitar and makes it very loud for usually a short
period of time. And over the months the strain
on that will eventually bow and buckle the soundboard down. Another trick and a
trick that the people who slavishly copy guitars
onto where of and don’t put on their guitars is there
is a little relief slot cut so that the string here can
come down without having that saddle up too high. And you should cut these little
relief slots in very accurately and specifically to what
you’ve known works before. And that’s another way of
dumping a little bit more forced down onto the guitar top without
having the bridge and saddle to high down or to
high up, sorry. Finally, the finish is
just about the finish. When you put all these
together you then spray it to protect the wood
against knocks, beer or whatever you might be
getting onto the instrument. But, also you’re protecting it
against rapid moisture changes. That’s the worst thing
you could ever do wood. How stressful was I bringing
this collection over here today? It couldn’t stay in my car
at all so it had to go back into the office and back
out into the car again. Modern lacquers have got to be
applied as thin as possible. Factory guitars like durable
instruments then spray a great big thick coating right over
the top of their instruments and kill all of that
wonderful tone off. They’re quite happy to do that. The old traditional shellacs and French polish has an
extraordinarily thin finish and that is the best one
you could ever possibly use. I don’t use it because
it basically is very, very– it’s easy to wear. It– alcohol will dissolve it. Not that you ever do spill
alcohol on these things. But, alcohol will
dissolve and even heat on that thing will
affect the shellac so really it’s not a
great modern finish. And so my lacquers I
use are as thin as I can to still get a nice
polish onto the guitar. Okay thank you very much. I hope you enjoyed that. Sorry about the gratuitous
advertising. But, I do have cards up here
and you’re welcome later to come and look at the instruments. Could I ask please if you could
just ask me first before you play any of these things? A lot of these aren’t–
haven’t been sold yet and some are belonging
to people. So, if you could respect
that that would be great. [ Applause ]>>You do have time to answer–>>Well, do you have time? Absolutely I do.>>About five minutes.>>Make it snappy. Yes?>>What adhesive do you use?>>What adhesive? I use aliphatic resin and also
some of the joints actually, on the guitar for future and I
look ahead, need to be repaired. And so, I’ll use
animal hide glue, the old traditional animal hide. And that’s a very,
very strong glue.>>[inaudible]>>Yeah that’s right, yeah. And both those glues are
stronger than the wood itself. Yep?>>I was just interested in the
effect of age on instruments. I know there’s been
a great debate about whether it’s true or not. I just wanted your take on that.>>Ah well, it’s– it is true. There’s a product came out
this year in fact that sits over your strings and has an
oscillating electromagnetic field in it. So, when you’re not playing
your guitar it sits there and sort of plays it for you. And it’s well known that that
will break in a new guitar. So, that’s a product
specifically aimed at luthiers to get a guitar to break in and so old guitars
absolutely have a go. It’s really hard
to get these things to be 80 years old right now. So, the best thing is to
sell them and play the hell out of the things be
the best way to do that. Yep?>>[inaudible] of
resonating guitars.>>That’s right.>>So, how– what is that– what’s that promotion,
the monopole?>>No. I thought an idea to
promote something with it. This was actually my
very first guitar I made. And I guess the reason I
made that was all I had to do was get the
bridge location in the right spot
for the scale length. There’s no– the
frets are in there, but they’re not actually played because this is played
with a slide. And so I guess I was
thinking this might illustrate that you can use other
things other than wood as a vibrating device as well. So, this uses a very thin
aluminium diaphragm underneath this heavy chrome cover here. Yep? Sorry I didn’t
play that one earlier. Yeah?>>Have you really tried
making necks with frets, different spacing like
for different frequencies?>>Ah–>>Experimented, no?>>Ah that’s– yeah I did. That’s what I did with this guy. So, you can pretty much choose
any frequency you want to out of this guy because
we’re using a slide. So, we can use halftones,
quarter tones and all that style of thing. With fretting no we don’t. Usually we fret an
instrument so that it’s in the diatonic Western
scale so not as yet.>>I have a naive question.>>Naive question. I like them.>>I suppose wood is
central to the guitar itself. What about electric guitars? Do you need wood?>>Yeah indeed, an
electric guitar, typically three pieces of wood. Some people might correct me. There might be four
if they’re capped with a particular
exotic species. They have the body wood, the
neck wood and then the wood that would clamp on top of the
neck would be the fret board. So, they have very minimum wood. But yeah, the type of wood in the body does definitely
change the character of the guitar.>>I’ve seen electric
guitars made from plastics.>>You can as well, but
they have a particular tone and quite a nasally
tone to them. Whereas the nice woods are
older or even the basswood that I talked about earlier
make really good guitar bodies as well. And mahogany’s a nice one too. So, it’s the same
basic principles apply. We’re talking about
the dark side here of electric guitar making. So, I have forayed
into the dark side, but only as personal
instruments for myself.>>Anymore, yeah?>>Ming.>>This is the last question.>>What’s the use
in the cutaway? Is that just an aesthetic
thing or is that–>>No. The thing about playing in the modern styles
is people want to have access to
the frets up here. Why would you bother
fretting up there if you can’t get your
little mitts up into there? And so the idea being
you put a cutaway there and obviously you can see that would facilitate your hand
going right up to the top there.>>Does that compromise
the acoustics by?>>This part of the guitar
top if we have a bit of a tap around then we go
down to the bridge. You can see this is
quite an inactive spot. But, what it does do is
it reduces the air volume and the air volume usually around this area
here is responsible for that helm hold resonation. So, it doesn’t really
affect it that much, but I notice it does
have a slight effect. But, certainly not
enough to say I don’t want to have a cutaway
because of that. It’s really more
aesthetic I guess and access to these frets up here. Yep.>>Okay thank you
all for turning out.>>[Inaudible]>>Yep. [ Applause ] [ Music ] [ Silence ]

100 thoughts on “Making Guitars with a Physics Mind | Curtin University

  1. A good acoustic instrument teacher will instruct to never mute the instrument (allowing shirt sleeves or other to contact). This applies mostly to the top, but also the back of the instrument can resonate as well.
    Humidity is a major factor – drier resonates better than humid.

  2. Terrible guitar playing there at the intro but I guess he was nervous and the guitar wasn't tuned up. Otherwise an interesting lecture on guitar building.

  3. It has always fascinated me when things are taken down to sheer fundamental building blocks. I loved the wood bashings. 😀 Seen a lot of guitars but never saw an inside of one.

  4. This video contains a TON of good info. Mr. Howman explains everything clearly. It is too bad that his nerves prevented an effortless presentation; the poor guy was sweating so much. He even had a bit of foam at the corners of his mouth. If this otherwise excellent presenter could have taken a valium before the talk, it might have gone much easier for him. Still, I applaud his effort and appreciate his techniques.

  5. Aaaaaaaaah. I recently bought a 3/4 size classical. I instantly noted how loud of a treble sound it produced. Glad he was able to explain that.

  6. And hat exactly solution you offer? 🙂 Do you have produced guitar that sound better than Martin?? 🙂 Because first guitar that you test in the beginning sounding very bad (probably strings not tuned well).

  7. Was this an example of a bad sounding guitar at the beginning? I’m still watching the video so I’m not sure if he is going to touch on that but I thought it sounded bad

  8. great video! One of the key take aways was the physical properties of the soundboard playing a role. A particular species may be known for its qualities but those properties can be found in woods not necessarily known to be reputable. so the take away was, go with the properties of the piece you have. That being said, how could one do a quick specific gravity or modulus of elasticity calculation when you have a wood selection in front of you?

  9. i don't want someone who can't play or tune guitars to go ahead and explain how they are made and then build one for me…

  10. I'm a big side sound port fan. Certainly not on a upper end or vintage instrument, but it's an old and fine idea IMHO.

  11. not to mock his playing skills………but Blackbird was so very out of tune……..& it also sounded quite "blunt"……..almost no sustain nor projection(as if it had a rubber saddle or something)……..that guitar sounds much worse then my 69$ casual kicker(which via luck just happens to be as "good" as most of the $250-$500 acoustics I've owned)……I've also had $1200 – $3000 Martins & Taylors etc…& I've learned long ago that price is NOT necessarily directly related to quality(though it usually is for the most part)……perhaps the recording quality affected the tone(somewhat)…….but the 1st & simplest physics related item just has to be tuning.

  12. Many thanks for your lessons. It was very instructive for me. Especially your information about the bracing and how the tone arises and how to influence it. Many Thanks from Germany, Duisburg in the ruhr area.

  13. Wonderful video thanks for sharing. I have a question if you would be so kind. Can you do a video on voicing the sound board and share your techniques? I noted the tapping and the music box. I use a tuning fork to get an idea but only have one fork in "A". From a physics perspective would you recommend all 8 notes to get a feel for resonance or is that a little over the top? I have only built a few guitars and I am now exploring voicing from a scientific perspective and would love your input.

    Also have you given any thought to chambering the body or know of anyone who has? What I am thinking is Dr. Bose's approach to speakers.

    But anyway this was really really thoughtful and provocative talk on the subject thank you from the bottom of my heart.

  14. Great video Dominic. You should ignore the Trolls. Lots of useful information in a short presentation. What are you using for the finish on these guitars?

  15. Thank you Mr Lecturer, at least I would know how to choose my next guitar, and it wont be those made in cheap factories in china or Indon… etc

  16. Either the guitar sucks, or you are a terrible player. Since I don't make guitars, and much less play them, I can't judge…lol I do however can hear, and have a very well tuned hearing sense. Please! Don't play the guitar anymore. Stop!

  17. Oh my sweet baby Jesus. Don't ever start your seminars with you playing. I would have walked out laughing.

  18. Well if you want to make a guitar using physics you will not make it with wood. I have made many out of magnesium and solved the problems of making guitars out of metal and wood. Luthiers cant do it because they are not machinists and machinists cant do it because they are not Luthiers.

  19. This man has gone his whole life being told that he was a good guitarist by his friends and family, only to become suicidal after reading the comment section

  20. Kindof lost me within the first half minute there. The guitar sounds terrible and you can't play it. Not very inspiring. I'll just assume you are better at physics then at music and go on with my day.

  21. sooo…it occurs to me a very simple way to avoid the tradeoff between a certain top resistance and freedom of movement, why not use a tailpiece?

  22. I thought the opening playing was a goof to show how shitty he sounded with that guitar. Thought he would then pick up a different, beautifully made guitar and play it beautifully. Christ, that guy shouldn't go anywhere near a guitar!

  23. 19:49+ Don't mean to be rude, as I very much appreciate the lecture, but you're mixing up Venetian and Florentine cutaways. Venetian is the rounded cutaway. Florentine is sharp. Gibson pretty much coined the terms starting back with their fancy florentine style mandolins with sharp cutaways way back. Then before WWII, they started making archtop guitars with rounded cutaways that they originally marketed as "premier." Later they began referring to the design as "Venetian." There were plenty of other companies who offered cutaways of course, but Gibson supposedly is credited for coining the terms that everybody uses today. Thanks for your lecture, Got to learn a few cool things I didn't know before!

  24. Why is he using the term "monopole" action? Isn't that dipole action? BTW, if you want the bridge in the center of the body, then just extend the large end of the body. Duh?

  25. Sir, your effort is to be praised. Are you familiar with soundboard crown? Tension on the topside and compression on the underside, with specific downbearing at the saddle by the strings. These are physics on pianos as well as guitars. this is a finely balanced equilibrium at different sections on the bridges to achieve desired resulting tonal projection ( usually more down pressure in the high treble section to achieve a balanced volume at the loss of sustain but a 2-inch long, thin wire needs to be as loud as the 7-foot bass string. less downbearing equals more sustain, but you give up dynamics. hope my 2 cents helps ps. the 70 kgs is lateral tension. not to be confused with downbearing. on an average piano lateral tension is about 20 tons, while downbearing is about 6 lbs. per string. ( about 225 strings per piano )

  26. uuuhhh physics please? Just watched an hour long video of a gentleman and the struggles of how to replicate the manufacturing process of a guitar from one's garage. I'd wager that if we took a physics approach to this process we'd see a physical difference in design rather than an imitation. Sounds like he forced the little bit of physics he spoke of into the presentation as the delivery was very awkward and ambiguouis

  27. Wonderful lecture- full of information and presented in a concise and easily understood style. You cleared up many points for me about guitar construction and performance, especially the critical importance of the bridge. Thanks for posting.

  28. The info is extremely good for luthiers 🙂

    The reason the intro sounds so bad is is because it's only partly picked up by his lapel mic. If he was playing into a proper mic, it would have been more even. As far as tuning, that could be an artifact of video speed, etc. Way to many influences to cancel out in an inexpensively made video in a glossy classroom setting. Do it all over in a sound studio correctly mic'd, and most folks would not have the gripes …

  29. There was so much buzzing on the strings that it made me think he was a beginner trying to pull of a hard riff. The guitar sounded like crap because of it. He obviously knows what he's talking about, but if he's going to play he needs a bit more practice.

  30. Okay, I thought that abomination of an example of what this guy is capable of, as both a builder and a player, was a joke. As in literally a joke. I kept expecting for him to pick up the guitar, quickly remedy the intonation and sound by removing whatever tone choking device he had put on the guitar and once again play Blackbird, this time having it ring out pure and beautiful. But that never happened. It wasn't a joke. I am speechless! That was literally the worst sounding acoustic guitar I have ever heard bar none. His playing was on par of that of a double amputee who still had his legs. And this is the guy who Curtin University is using as the expert for this seminar? I would question every decision this university has ever made. If I attended this University I would de-enroll myself. If I had paid for an intuition for one of my offspring I would sue to get my money back based on fraud through ineptitude. This whole thing is a jaw-dropping study of incompetence! I am flabbergasted! Absolutely, 100% flabbergasted!

  31. I would love to know what you think of Taylor's new V Bracing. I will consider this in my upcoming build

  32. I hope it was his playing that was atrocious and not his guitar, because there is no way anybody would buy one!!

  33. Liked everything he said except a tree following the sun as though it twists each day. What a load of rubbish. I dare anyone to watch a tree and tell me if the tree, any tree does this.

  34. at least bring along a proper guitar player to demonstrate your machines if you can't play, there's a reason you never saw Bob Moog trying to play Keith Emerson licks on a MiniMoog, yet no one would argue Bob knew how to make incredible sounding synths.

  35. This idea of side ports allowing the player to better hear the guitar themselves seems counter to the known action of the port in a Helmholtz resonator. According to the known behaviour of a Helmholtz resonator, air only flows back and forth through the port at the resonant frequency, so the only aspect of the sound that this augments for the player is the low end around the main resonant frequency of the body and top.

  36. That guitar needed quite a bit of work to sort out its lousy intonation and fret buzzes. Other than that… very interesting.

  37. Let the guitar do the talking!? I will have to take a pause before watching the rest of this! How someone who is clearly tone deaf give a presentation, on the intricate and complex process of soundboards and guitar making, and expect to be taken seriously when that is his intro? I will give him the benefit of the doubt but honestly fella, spend $15 on a tuner and save yourself the criticism! Even better, edit the video to remove the first 38 seconds.

  38. Why not replace the side boards with some dampening material…some sort of styrofoam for maximum transfer of energy to the top & rear boards ?

  39. You have got to be kidding me. Seriously… the medium is the message, and in this case the message is: If you can't tune your guitar or play it well, and you demonstrate this right off the bat… are people going to take the rest of your presentation seriously? Or even watch it? I know I won't, and I'm seriously studying guitar making, so I won't even know what valuable tips I'm missing because of that awful first minute of guitar torture and the inept butchery of a fine tune.

  40. This guy must have some balls to start off a guitar related presentation by sucking to this extent on a simple tune. Respect.

  41. Here we go again. Folklore masquerading as science. The Nobel prize awaits the first person who can scientifically show a guitar construction method superior to the last 60 years of guitar design.

  42. i have ten guitars at the moment and i've owned about thirty in the last few years, my pride and joy being a '66 gibson J45, what you said about vibration going through the back to the player, and sound holes that are cut into the sides makes sense, i also have a martin OOOX1, spruce top but HPL back and sides, basically laminate, i think it's the best guitar i've ever touched, the sound is clean, the bass growls and the trebles ring, but what makes it a complete experience is that the back passes the vibration to the player, so you get to feel the guitar as well as hear it (i play fingerstyle pretty exclusively). i've been looking at (not playing) composite and carbon fiber guitars and i think the same might be true of them, mcpherson and composite acoustics guitars sound a whole lot better than some solid wood.

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