Join Date: Dec 2000
Location: Het rijk van Nijmegen, the Netherlands
Re: Technical Genius Required !
Unfortunately I haven't read anything in this thread that's even remote to the physics that actually determine this type of behaviour.
The basic thing you need to know is that the string/spring-tremblock system will have a resonance frequency much lower than the strings:
somewhere around 5Hz, where the lowest string frequency is ~80Hz.
Any interaction between these two is mostly unwanted, as they will cause tuning/intonation problems first and foremost.
This interaction is what we know as trem warble or flutter and can be used as an effect (notably Vai, but also Petrucci) As it is imposed as a low frequency modulation (say 5Hz) on the regular note, it can best be compared to a heavy chorus effect that quickly fades. It also bleeds off string vibrational energy. But at the same time, exciting the trem arm to get flutter will put some energy in the system so the note can be sustained by sharply hitting the trem arm repeatedly.
Adding more mass to the trem block will lower this flutter frequency, but not by much: doubling the mass will only reduce the frequency by less than 30%.
Adding extra springs will increase the flutter frequency: going from three to five trem springs will move flutter up by 30%.
Neither one makes enough of a difference considering the distance between flutter and string frequencies.
Sometimes you will find another unwanted warble effect at much higher frequencies (>250Hz), which would be the springs themselves vibrating. This effect is almost independent of spring numbers or trem block mass. Most people try to avoid this effect with some cotton wool inside the trem springs (while still allowing flutter).
1) you cannot easily change the mass of the trem, but you can rotate the whammy bar. Pointing it down (or up), means it will have very low rotational interia, pointing it back (or forward) increases inertia, if the trem bushings are tight enough, you may notice this. Loose bushings will dampen flutter.
2) a heavy trem will affect tuning, when the guitar is not perfectly vertical. Tune it flat on your lap, and it wil be out of tune standing up.
3) higher mass anywhere will mean:
-lower resonance frequencies (-30% for every +100% increase in mass)
-any damping effects are relatively smaller,
-higher forces are necessary for similar movements.
-Since many damping forces are proportionate to movements, smaller movements might mean less damping.
4) a very light trem block still works: the Allan Holdsworth signature Ibanez had a machined Aluminium trem, three times lighter than brass or zink.
Last edited by eviltwin; 08-06-2009 at 07:19 AM.