archtop cutaway styles
j bonny
thanks
jeff
Martin Bick
That's basically true and I'm assuming you are referrining to a
D'Angelico (or copy) New Yorker. The Florintine style cutaway is
pointed and the Venetian is rounded. FWIW, in an acoustic archtop or
flat-top guitar luthiers generally agree that the rounded cutaway is a
better design, sonically speaking.
Martin
W. Sugai
this is not obvious to me. what's the reasoning behind this?
Martin Bick
It has something to do with the rounded cutaway facilitating the flow
of air within the guitar versus a trapping effect with the pointed
cutaway.
If you're that curious, I suggest you do a search of the acoustic
newsgroup where several reputable luthiers, including makers of
archtops, post regularly. This topic has been discussed ad-nauseum
there.
Martin
Paul Buerk
hose" analogy. I wonder if it's one of those things that's more imagined
than real. In any case, I hope the trapped air doesn't cause the body to
explode spontaneously.
Martin Bick wrote in message <38fcddba...@news.inetworld.net>...
Dick Schneiders
>
>-Howard
Not to me!! I much prefer the appearance of the sharp Florentine cutaways.
They maintain the normal lines of the upper bout of the guitar. The rounded
cutaways look like somebody simply chopped off part of the instrument.
Dick Schneiders
Stan Gosnell
>>pointed and the Venetian is rounded. FWIW, in an acoustic archtop or
>>flat-top guitar luthiers generally agree that the rounded cutaway is a
>>better design, sonically speaking.
>
>
>this is not obvious to me. what's the reasoning behind this?
IMO, it's because of angles. The rounded cutaway reflects sound
energy back toward the center of the guitar much more than the pounted
cutaway, which tends to reflect the energy back upon itself & to a
dead end, which does nothing to help the sound, & possibly something
to worsen it. The function of the sides is basically to reflect
sound, plus hold the back, which also reflects sound.
---
Regards,
Stan
David Hajicek
You are right in saying that a plane sound wave would be reflected by
the pointed cut-away in a manner to spread out the sound energy. But it
is not obvious that guitars generate an internal sound wave with the
right plane to be affected by this. Also, it is somewhat desirable to
minimize specific resonance frequencies, so this could actually be a
benefit (either style would do this). In the end, it is probably really
hard to hear a difference, if at all.
If things were this fussy, you would have to worry about reflections off
the bracings and the end blocks and harmonic spacing, etc.
Go for the look you like.
Dave H.
Dennis O'Neill
wrote:
>On 18 Apr 2000 16:47:50 GMT, wsu...@eskimo.com (W. Sugai) wrote:
>
>>>[Florentine is] pointed and the Venetian is rounded. ...
>>> [assertion that luthiers think Venetian cutaways are superior
>>>from a sound perspective] ...
>>
>>... what's the reasoning behind this?
>
>IMO, it's because of angles. The rounded cutaway reflects sound
>energy back toward the center of the guitar ... [while the pointed] ...
> tends to reflect the energy back upon itself ...
> The function of the sides is basically to reflect
>sound, plus hold the back, which also reflects sound.
Looked at a violin, cello, or viola lately? There are lots of sharp
corners. I don't know what the interior construction looks like.
I was always under the impression that the sides and back serve mostly
to enclose a volume of air and thus help control the resonant
frequency of the instrument, much like a bass reflex speaker cabinet.
The soundholes act like the port of a bass reflex speaker cabinet, as
part of the resonant-frequency controlling function. Since most of
the sound of a stringed instrument comes off the top, not out the
soundhole(s), any soundwaves travelling inside the box would have at
most a secondary effect on the tone of the instrument. Any effect the
shape of the cutaway would have will be overwhelmed by other
characteristics of the instrument.
Think about what happens to the top of a guitar when it's excited by
string motion. It's a little different between an archtop and a
flattop. In an archtop, the increase and decrease in tension of the
vibrating string pushes the top down or relaxes and lets the top start
to return to its rest state. The motion of the top is not that of a
spherical section because of its shape and because it's constrained by
being attached to the sides, so the motion will be quite complex,
particularly when many frequencies of energy are put into it by
several strings vibrating at once. From the outside, the pressure
waves (sound) coming off the top just expand into the surrounding air.
On the inside, the pressure front will impinge on the back of the
instrument and get reflected in many different directions according to
the local shape of the back (cf. Snell's Law, which says that the
angle of reflection with respect to the perpendicular to the
reflecting surface equals the angle of incidence, and then throws in
some complications based on the speed of sound in the transmitting and
reflecting media, etc.). Then constructive and destructive
interferences will occur, diffractions will occur based on the
geometry, some energy will travel through the wood to be emitted
somewhere else, and blah-de-blah. It will get very messy very
quickly.
I would guess that the reason most handmade archtops have rounded
cutaways is that they're a bit harder to make due to lots of tight
compound curves having to be put into the wood by bending, and so are
a higher perceived value. To some people, they look better. Luthiers
generally do not have much knowledge of physics (some do, but most
don't) and didn't engineer the cutaways with fine details of acoustics
in mind. They designed them with access to frets in mind. The shape
of the violin (recall the points mentioned earlier) evolved as an
accomodation to bowing techniques.
Bottom line, in a guitar the shape of the cutaway is mostly a fashion
question. If you're concerned about the sonic effects, flout the
guitar fashion police and get a guitar without a cutaway.
Stan Gosnell
<haj...@skypoint.com> wrote:
>Stan:
>You are right in saying that a plane sound wave would be reflected by
>the pointed cut-away in a manner to spread out the sound energy. But it
>is not obvious that guitars generate an internal sound wave with the
>right plane to be affected by this. Also, it is somewhat desirable to
>minimize specific resonance frequencies, so this could actually be a
>benefit (either style would do this). In the end, it is probably really
>hard to hear a difference, if at all.
I agree that the difference would be pretty small. Lots of other
factors are more important. The original poster was asking about
general opinions, & what I said seems to me to be the general opinion.
I'm not sure I agree with it. IMHO, the look makes more difference
than the sound, so go with what looks best to you. If the sound is
that important, no cutaway might sound better, but I'm not completely
convinced of that, either.
---
Regards,
Stan