Understanding wood

WantzChas

http://www.warmoth.com/Bass/Options/WoodDescriptions.aspx

I found this to explain everything a bit. Anyone else have something to add?

AlanRatcliffe

http://www.ratcliffe.co.za/articles/bodywoods.shtml for a bit more depth

aja

Very nice articles!

Has concrete research ever been done that correlates the characteristics of the wood (stiffness/density etc..) in terms of material properties to resonant frequencies and such?

I am thinking about doing something like this for my final year project investigation. Not sure yet

Gearhead

aja wrote Has concrete research ever been done that correlates the characteristics of the wood?

Read David C. Hurd, Left-Brain Lutherie, ISBN 0-9760883-0-4
This oke goes so far as to take a reference from the one piece of wood of a known guitar and modify geometry of a guitar-to-be-built from measuring the properties from the wood it is to be made of. Even while using the same type of wood... ???

I could think of a more interesting mechatronics topic (been in robotics for a decade) but would like to find time to really study this stuff.

aja

Gearhead wrote
I could think of a more interesting mechatronics topic (been in robotics for a decade) but would like to find time to really study this stuff.

Thats crazy!

Yeah I was thinking of doing something like an anti-feedback controller for acoustics or something like that for my design project.
We should keep in touch then! I might come ask your advice when it comes to this stuff. I am still coming to terms with Zero order hold concepts. My brain gets confused when filters and saturators and such come into play. I am also starting to understand things like feedforward and forward control in conjunction with will state feedback. Strange stuff though...

Gearhead

Guitar analogy for zero order stuff: you try to tune a string to a stepwise changing given note. Since you first have to listen, hear the difference, make some decisions on how to turn your tuner knobbies you're always late. Since the tuning takes some time as well you will wind up with a continuously varying pitch. (This is what a DAC followed by an amp will do)
Typical real life problem for mechatronics systems is in the above example, if you would be on time you would not hear any difference so there would be nothing to make you decide to turn your tuner. There is no perfect follower.

Guitar analogy for feedforward: while bending a note your fingers already know the feel of that particular string at that point on the neck so they bend it close to where it needs to be and you do the corrections on that by ear.

aja

Gearhead wrote Guitar analogy for zero order stuff: you try to tune a string to a stepwise changing given note. Since you first have to listen, hear the difference, make some decisions on how to turn your tuner knobbies you're always late. Since the tuning takes some time as well you will wind up with a continuously varying pitch. (This is what a DAC followed by an amp will do)
Typical real life problem for mechatronics systems is in the above example, if you would be on time you would not hear any difference so there would be nothing to make you decide to turn your tuner. There is no perfect follower.

Guitar analogy for feedforward: while bending a note your fingers already know the feel of that particular string at that point on the neck so they bend it close to where it needs to be and you do the corrections on that by ear.

That is a brilliant way of looking at it! Makes a lot of sense! Thanks man, I appreciate it ?

AlanRatcliffe

Off topic, but if I'm not mistaken, that's a close description of how the pitch to MIDI converters in guitar synths work. Most of the time they are playing catch-up because the pitch recognition needs at least one full cycle of the wave to identify the pitch and send the MIDI note on, which becomes a noticable delay with lower notes (because of the longer wavelength).

Some all-in one guitar synths (notably the Roland GR-30 and GR-33) trigger an unpitched attack while they are waiting for the correct pitch to be identified, and then trigger the pitched sustain and decay.

You might also like the Axon "Neural Net" stuff - not a neural net at all, but a nifty way of identifying the pitch of the note by using the delay in the reflections along the string from the fretted note to the picking position.

aja

Thanks for the tip, Alan. Very interesting reading material awaits me for the weekend ?

AlanRatcliffe

Do a patent search on Szalay and you'll get some great stuff - Andras Szalay invented the Axon tech and sold it to Blue Chip. He also did a lot of work for Shadow's MIDI guitar system.