Lute soundboard analysis

[sebastiaan56]

Heads up for the lute dudes,


youtu.be/

and


youtu.be/

from the Mandolin Cafe forum http://www.mandolincafe.com/forum/showt ... d-analysis

[kiwigeo]

Thanks Seb,

Interesting stuff. Id like to know exactly where the speaker is positioned relative to the bridge....its not obvious from the video.

[Puff]

Would love to see this sort of thing done comparing completed instrument tops with and without soundholes.

[kiwigeo]

Would love to see this sort of thing done comparing completed instrument tops with and without soundholes.

Would probably be significant for a lute top as around the rose the top gets down to around 1.3mm thickness...it's paper thin. Tuning of lute tops is done mainly through positioning and trimming of the J brace and the two treble braces after of the bridge....the actual procedure as described in Lundbergs book is fascinating.

[matthew]

I don't think the position of the speaker is very important. A resonant frequency is an inherent property of the object; provided you can induce enough vibration through volume or position, the thing will resonate at certain key mode frequencies irrespective of where the energy is coming from.

[kiwigeo]

I don't think the position of the speaker is very important. A resonant frequency is an inherent property of the object; provided you can induce enough vibration through volume or position, the thing will resonate at certain key mode frequencies.

You maybe right but on a lute the bridge is right at the rear of the soundboard...ie there's no lower bout area behind the bridge like on a guitar or a bass.

[Puff]

"Would probably be significant for a lute top as around the rose the top gets down to around 1.3mm thickness...it's paper thin."
Martin did you mean "significant" or "insignificant"?

[duh Padma]

Videos of sound board freek ~ wencie response with out any audio...must be for the deaf...just gotta love it.


duh Padma

[Puff]

Padma -respect. My point was to see from these people what they might get without putting a bloody great void/soundhole in the middle of the belly. Right in the firing line so to speak.

[matthew]

@puff - I don't think it would make all that much difference with all the bracing on there.

@padmuh - you like the sound of white noise?

[kiwigeo]

"Would probably be significant for a lute top as around the rose the top gets down to around 1.3mm thickness...it's paper thin."
Martin did you mean "significant" or "insignificant"?

Significant.....the lute rose is structurally a weak part of the soundboard despite the small braces that run underneath it.

[Puff]

Thanks Martin.

[matthew]

But what do you mean by "significant"?

[kiwigeo]

But what do you mean by "significant"?

What I'm pointing out is that a sound hole on a guitar top is just that...a hole. On a lute it's a hole(s) but it's also a significantly thinner and flimsier part of the soundboard...even taking the tiny braces behind the rose into the equation. Not many guitar tops would get down to 1.3mm/0.05" thickness. The thickest part of my lute top is around the bridge but even then it's only 1.7mm/0.07".

[duh Padma]

Puff ~ Matthew, every once in a while me gets a tad glib, please, pay no attention.

duh Padma

[Puff]

Attention where it is due sunshine. Respect is the backbone for all things. If I did blessings I would add that Padma

[TKAY]

All is new and nothing is new!!!

Ernst Chladni D.1827. was working on vibrations in plates MANY years ago.There was also work I think in the 60's on violin plates to achieve a particular sound.
As always it is all in the interpretation.

If you mount a belly on a speaker (8") or so in diameter, horizontally with rubber blocks in between,cover with cling wrap,(to keep it clean), drive the speaker with a particular Hz,and sprinkle fine dust/filings/glitter on the top, patterns corresponding th the frequency will appear.
What help is it?
I would not have any idea!! I have only seen the results, but it sure looks interesting!

Regards Tom.

[DarwinStrings]

What help is it?

Knowing that this question was rhetorical I will still answer it. It can be very helpful for shaping the struts on a free plate to get the ring and a half mode functioning well and at the frequency of your choice. I think it is a good question to put to Alan Carruth or just read what he has to say on the subject and he answers it anyway.

Jim

[matthew]

What help is it?

It is an accurate way of measuring the flexibility of the plate, in a number of dimensions.

What use that information is to a luthier depends on the luthier. At the least, I believe it can help produce consistency between different instruments.

This is some of the fun I have had:


youtu.be/

[kiwigeo]

All is new and nothing is new!!!

Ernst Chladni D.1827. was working on vibrations in plates MANY years ago.There was also work I think in the 60's on violin plates to achieve a particular sound.
As always it is all in the interpretation.

If you mount a belly on a speaker (8") or so in diameter, horizontally with rubber blocks in between,cover with cling wrap,(to keep it clean), drive the speaker with a particular Hz,and sprinkle fine dust/filings/glitter on the top, patterns corresponding th the frequency will appear.
What help is it?
I would not have any idea!! I have only seen the results, but it sure looks interesting!

Regards Tom.

Chadni patterns tell you which parts of the soundboard are moving (nodes) and which are not (antinodes). A laser interferometer will tell you _how_ the soundboard is moving...ie you can see monopole, dipoles etc.

[Dominic]

Martin, In the Allen Carruth dvd the position of the speaker does not matter as long as it is close enough to excite the plate. What Allen spends time getting right is the placement of the little foam block the top sits on. If the modes are not forming he moves the blocks around until he judges they are neutral in their influence. And he just holds the speaker over the plates until the modes form in the glitter.
It is very loud.
Dom

[matthew]

on my bass tops, the most responsive patterns are when the bass is balanced on a foam block at the bridge position, not at the edges.

@Martin, once you can see the nodes it is not hard to infer how the top is moving. However, you are limited to the simpler modes at the lower frequencies. But you can clearly see monopole , dipole and tripoles, as good as any laser study!

http://guitars.morrisonprairie.com/test ... -modes.pdf

[kiwigeo]

@Martin, once you can see the nodes it is not hard to infer how the top is moving. However, you are limited to the simpler modes at the lower frequencies. But you can clearly see monopole , dipole and tripoles, as good as any laser study!

All taken on board thankyou Matthew

[TKAY]

My original comments were said slightly "tongue in cheek" from one who has seen a little information but understood less!
Thanks for all the comments which filled in a few gaps in my knowlege.
But I guess that is what the forums are all about.
Regards Tom