I agree with Guy that one certainly wouldn't want an instrument to
resonate loudly at one particular frequency (and not so much at others).
And there is certainly more involved in sound production than the RF
of the chamber (and I'm certainly no Physicist).
That said, I went through a couple of my mandolinos that are
supposedly close copies of real instruments. From what I can tell,
the copy of the tiny Cutler-Challen Strad has an RF pitched at "a"
while a somewhat larger early-18th-century model has an RF a fourth
lower at "e" (A-415 reference pitch for both). These are two very
different instruments with one being at least 1/3 larger in body
volume.
I find it intesting that both "a" and "e" are open (and often-used)
strings in the middle range of the instrument (where it seems to need
the most support for good tone production). These tiny instruments
need all the vibrational help that they can get and "tuning the instrument
to itself" so that at least one course sits near the natural RF seems to
help.
Eric
(man of anti-gravitas :-))
ps - Here's a page that explains cavity frequencies. To find the volume
of your lute, just fill it with water and then pour out it into a
measuring
container of some sort ( :-) :-) :-) ... ):
http://hyperphysics.phy-astr.gsu.edu/hbase/waves/cavity.html#c1
guy_and_liz Smith wrote:
>You really wouldn't want an instrument to be strongly resonant at a
>particular frequency. I think that they did at least some things to
>distribute the frequency response over a wide range. Something I picked up
>from Grant Tomlinson's class this summer: in theory, the braces under the
>top are perpendicular to the centerline and evenly spaced. That degree of
>symmetry would tend to favor the fundamental vibration modes of the top. In
>actual practice (from Grant's extensive study of historical lutes), the
>braces on historical instruments depart somewhat from both regular spacing
>and perpendicularity. From what I understand of acoustics, this should serve
>to spread out the frequency response of the top, and make it less responsive
>to any particular frequency and more uniform over the whole range of
>frequencies (the other physicists can chime in if they have a better
>understanding of this issue).
>
>FWIW, I'm a little puzzled by the emphasis on the resonant frequency of the
>interior of the instrument. I rather suspect that such a resonance is at
>most a secondary factor, the primary one being the elastic properties of the
>top. If it was mainly about the geometry of the bowl, I doubt that luthiers
>would spend so much money on tonewood, nor would they go through the sort of
>elaborate tuning process that Bob Lundberg describes in his book.
>
>Guy
>
>
>----- Original Message -----
>From: "Eric Liefeld" <[EMAIL PROTECTED]>
>To: "Ed Durbrow" <[EMAIL PROTECTED]>
>Cc: "lute list" <[EMAIL PROTECTED]>
>Sent: Sunday, January 18, 2004 12:34 PM
>Subject: Re: Electronic tuners
>
>
>
>
>>Hi Ed,
>>
>>My understanding is that the resonant frequency of a volume (such as a
>>lute or guitar) is a function of both the volume, and the size of the
>>sound
>>hole. So yes, in theory, a luthier could adjust the frequency somewhat
>>by varying the size of the rose... though all the frilly bits might make
>>this
>>a bit tough to do predictably.
>>
>> From a practical perspective, I'd be interested in knowing if any
>>luthiers
>>actually do this "tuning".
>>
>>Eric
>>
>>
>>
>>>James,
>>> This is amazing. I tried this on my Baroque guitar. I merely muted
>>>the strings with my hand. It clearly resonates at d and f. This is
>>>good, I like Dm. :-) On my Ren lutes, it wasn't as pronounced and
>>>seemed to be a wider Q factor (width). My B lute resonates at A low
>>>pitch. This is truly facinating.
>>>
>>>
>>>
>>>
>>>
>>>>The difference is amazing. If you're not the sort to be convinced,
>>>>as I am, by the physics, the sound will decide it--as it should.
>>>>The resonance of the instrument will be greatly magnified, as will
>>>>the volume, and even the clarity of the plucked notes and their
>>>>overtones. I have done it with two 64cm lutes, one responded at E
>>>>and the other at F. They are much the richer for it--totally
>>>>different instruments. They stand up very well to a voice they
>>>>accompany, without being overwhelmed. The harmonic synergy between
>>>>the voice and lute (if it's you singing) is palpable.
>>>>
>>>>
>>>>
>>>>
>>>I'm wondering if this is something easy or difficult for a luther to
>>>control. Do they design instruments to resonate at certain pitches?
>>>If there is too much resonance doesn't that give an uneven response?
>>>Who wants to be trying to play something evenly and one note suddenly
>>>jump out? I haven't noticed that problem on my B guitar, but it is
>>>pretty much a tank of an instrument anyway.
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>
>
>
>
