Try this- Pp. 29 - 32:
http://dspace.mit.edu/bitstream/handle/1721.1/61924/707340180.pdf?sequence=1
Also of some interest-
http://hyperphysics.phy-astr.gsu.edu/hbase/waves/cavity.html#c4
http://newt.phys.unsw.edu.au/jw/Helmholtz.html
On 11/30/2014 11:55 PM, Martyn Hodgson wrote:
In his interesting response, I had understood Martin was asking for a
measured scientific explanation rather than a list of anecdotal (and
necessarily subjective) observations: "I invite all you proper
physicists out there to explain why!". I'd be interested to read
anything you have along these lines.
MH
__________________________________________________________________
From: David Tayler <vidan...@sbcglobal.net>
To: BENJAMIN NARVEY <luthi...@gmail.com>
Cc: "lute@cs.dartmouth.edu" <lute@cs.dartmouth.edu>
Sent: Sunday, 30 November 2014, 19:13
Subject: [LUTE] Re: Single versus triple roses
This is a very interesting question, and also one that has been
debated
in the construction of harpsichords.
I have a few, very simple observations.
First of all, and most importantly, Andy is absolutely correct that
if
you use a measurement micaI recommend the DPA 4007aand analyze the
sound coming out of the sound hole (or holes), the sound is vastly
different. The classic mistake when recording lute, guitar, cello,
harpsichord, etc, is to place the mic too close to the soundhole,
because of the extreme difference in the sound. You can also make a
tube out of paper, roll it up and listen like a coelenterate. Using
the
same mic, you will also see that the bridge is the other hot spot.
Let's take a little detour here and mention that in almost all
recordings of lute, the frequency pattern is skewed so the left
channel
sounds different than the right, and that's because the sound is
fundamentally different from the rose and the bridge, causing big
imaging problems (which can be fixed using the lute centering trick,
subject of another post).
I can also go on record as saying that if you take a cheap lute and
remove the rose and put a different one in, it will change the sound.
Also, the surface area of the actual holes (not the size of the rose
but the amount of space in the rose) makes a difference. If you add a
vent hole to the bass, well, it changes the sound. They knew this
back
whenever.
Lastly, the rose and the lute form a strategic sound system. You
can't
teak one without tweaking the other. And that's because the size of
the
rose affects the resonance and flexibility of the soundboard on the
rose bar amplification nodeaa sub-hotspot that runs usually through
the
middle of the rose, edge to edge but mainly in the middle (the center
of the rose or rose pattern, in most cases).
If you make a BIG single rose that has the same open surface area as
a
triple, generally speaking it will sound more open, and if too big
will
make the lute yawn. But it all depends on the way the sound board
interacts with the tension resulting from the roseaa really big rose
bends easier, unless heavily barred (another factor).
My feeling is that the most open sound comes from a large, single
rose
with narrower weaving, but you can achieve almost the same sound with
a
triple. And, again speaking very generally, if you want a more open
sound, have the rose made a bit larger, bearing in mind that the lute
may yawn. A lute that has a naturally stiff top may benefit from the
added flexibility of a single rose, because the top of the triple is
inherently stifferamore soundboard, less rose. Obviously, the shape
of
the bowl comes into play as the sound board may be wider at the top
of
the rose with a more barge-like bowl. It could also be that players
in
the renaissance and baroque preferred a more covered sound. After
all,
there are no recorders made nowadays with historical windways, the
builders just widen them.
It's up to the builder to find the sweet spot for an instrument, and
it's up to the player to work with the builder to push the limits.
dt
_______________________________________________________________________
From: BENJAMIN NARVEY <[1]luthi...@gmail.com>
To: Martin Shepherd <[2]mar...@luteshop.co.uk>
Cc: "[3]lute@cs.dartmouth.edu" <[4]lute@cs.dartmouth.edu>
Sent: Sunday, November 30, 2014 4:45 AM
Subject: [LUTE] Re: Single versus triple roses
Dear All,
Thanks so much for all your thoughts into the single/triple rose
conundrum. It is obviously so hard to know just how this aspect
changes
the tonal colours of lutes. It is also very difficult to test just
how
this one aspect alters things given that every lute is different,
even
if it is the same model from the same maker.
I will continue to do some intuitive and highly unscientific tests!
Best wishes,
Benjamin
On Sunday, 23 November 2014, Martin Shepherd
<[1][1][5]mar...@luteshop.co.uk>
wrote:
I fear there is a natural tendency to think of the rose as the
hole
that "lets the sound out", but I think this is a case where
intuitive physics lets us down.A The size of the opening affects
the natural resonant frequency of the body, with a smaller
opening
giving a lower frequency.
But I invite all you proper physicists out there to explain why!
A more complex issue, but one which is related in that it also
involves a mismatch between intuitive physics and the real thing:
many people seem to believe that the lute soundboard should be
flexible to "allow it to vibrate", and that the more flexible it
is
the better the bass response.A In fact I think - please
contradict
me if I'm wrong - that the frequencies which we are interested in
are far too high to be aided by a floppy soundboard, which is
more
likely to have a damping effect.A As far as I can see, a
relatively
rigid soundboard is going to produce a more sustained sound.A
The
most important factor is the mass, which must be kept as small as
possible so it can be activated by a small input of energy -
hence
the rather thin soundboards (supported by many bars to retain
sufficient rigidity) required by lutes.
Martin
On 23/11/2014 16:07, BENJAMIN NARVEY wrote:
A A Dear All,
A A Just wondering if any of you (especially the makers out
there)
have
A A thoughts about the projection of single versus triple
roses.
A A I have had many lutes/theorboes with both single and triple
roses over
A A the years, and I have always felt that triple roses helped
make more
A A sound, and that single roses made possibly more focussed,
but
more
A A "woody", interior, sounds. Perhaps I am wrong?A
A A All thoughts welcome.
A A All best,
A A And thanks,
A A Benjamin
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