nethanpaul wrote: ↑Tue May 21, 2024 1:41 am
Raising your bridge can definitely help with sustain on your 64 Jag! A higher bridge increases the string break angle over the saddle, transferring more vibration into the body.
If more string vibrations were transferred into the body, that would mean
loss of string vibrations from the strings - so not seen by the pickups. That is, the exact
opposite of sustain. That's the Conservation of Energy Law as it applies to guitars.
That this specious notion of "transfer of vibrations to the body" as a "good" thing is not uncommon amongst guitarists is seemingly a result of a science-challenged 'echo chamber' of famous players, guitar journalists*, and guitar manufacturers - promulgating notions about how guitars work that often contravene the laws of physics. You don't need to fully understand guitar physics to play, write about, or build great guitars ... but you do need that understanding to talk as if you do and actually know what you're talking about. Unfortunately people feel their solid body guitars vibrating and jump to completely wrong conclusions about what that small vibration magnitude actually means. It's lucky that they're wrong about body vibrations, because their guitars would have very poor sustain if they were right.
*Zollner quotes an assertion from the echo chamber about solid-body guitars - in this case a German guitar journalist - in the early part of section 7.5 in his book ...
"The largest portion of the string vibration should be transmitted to the body. Indeed, if the latter is supplied with uninhibited vibration energy, a maximum in tone and sustain develops.[Gitarre&Bass 12/05]"
Zollner, M. (2014). Neck and body of the guitar. Ch 7 in: Physics of the Electric Guitar.
https://www.gitec-forum-eng.de/the-book/
That journalist is talking complete and utter physics nonsense.
I've held off on saying anything in this thread before now because the precise physics of how bridge height/break angle affects string vibrations is complex - it evades easy answers. If you want to see that, read ch7 of the Zollner's above-cited "Physics of the Electric Guitar" (free to download). Mainly section 7.5 Reflection and Absorption at Bridge and Nut.
We
do know that sustain is maintained by anything that
avoids the loss of string vibrations going to vibrate
other parts of the guitar - the bridge, the neck, the body, the trem, etc. We also know that those losses are small in solid-body electric guitars. Almost all string vibrations are reflected back up the string when they reach the bridge. All direct measurements of real guitars over the last several decades show that - bridge admittance, neck admittance, direct string vibration measurements, direct sustain measurements, direct neck and body vibration measurements. etc. That is, measurements of different physical phenomena - on different guitars, by different people, in different labs - that all point to the same conclusions. That's
why sustain is generally good in most solid-body electric guitars (and some of the reasons why it can vary have more to do with pickups and signal chains). See in particular the independent work of Fleischer, Zollner, and Pate.
The sustain-enhancing effect that one
might have expected to see would be that increased bridge height/break angle increases the reflection of string vibrations back to the string. That is, presenting greater mechanical impedance to string vibrations, causing more of them to be reflected back up the string, and thus maintaining sustain. As opposed to allowing some vibrations to pass over the bridge into the 'residual' string length behind the bridge, and some to pass into the bridge.
But it doesn't quite pan out that simply when direct measurements are done (see Zollner section 7.5). An increase in break angle actually reduces the proportion of the string's initial transverse wave reflection; but there is also an increasing transformation from transversal to longitudinal energy with break angle, that considerably complicates the picture. As I said, no easy answers.
As I indicated earlier, reflection back up the string is still the predominant fate of
almost all string vibrations reaching the bridge. Otherwise sustain would be very poor. So we are not talking about a significant detriment to sustain of adjusting a bridge in the 'wrong' way or an enhancement with the 'right' way. Whatever those adjustments might be.