Re: If an electric guitar is acoustically louder, does this translate through pickups
I've been doing some thinking about this. Let's focus on string vibrations. This is what an electric guitar pickup is 'seeing' and converting to signal, so should be all we care about when discussing loudness and sustain of an electric guitar.
1. A plucked string held between two anchor points vibrates. As it vibrates it loses small amounts of energy from friction with the air (nothing we can do about that, few guitarists are able to play in a vacuum).
2. When a string is plucked, it vibrates. But there's a maximum amplitude that a string can vibrate, and the gauge (mass) of the string and the pitch it's tuned to determines this. Heavier strings will sustain for longer (check the sustain of the low E on a bass vs the high E on an electric guitar). Energy initially enters the system from the plucking action, so the heavier string must therefore be able to accept/store more energy before maxing out.
3. If the two anchor points holding the string are deform-able and not completely rigid, these deformations will absorb energy from the vibrating string. A steel guitar neck will sustain longer and louder than a guitar neck made of rubber. The wood that a neck is made of, the inclusion of a truss rod, the stability of the joint used to hold the headstock (if any) all contribute to the rigidity of a guitar neck and thus to the anchoring of one of the points . . . so will have an impact on sustain.
4. Sound is mechanical energy lost from the vibration of a string via radiant waves. A plucked string will produce some sound as it vibrates though the air, but this is usually pretty minimal. An acoustic guitar works to make loud noise by robbing some of the energy from the string to vibrate the flat top (through the bridge). The top of the acoustic guitar then vibrates a large quantity of air and we hear a loud, resonant sound. (Heavy strings on an acoustic guitar produce less sustain than lighter strings on an acoustic guitar because the heavier strings vibrate the bridge and the top of the guitar more, which causes chaotic vibration at the anchor points. This vibration slows the string down more quickly.)
From point 4 I think that it's clear that production of (any) sound is evidence of energy leaving the vibrating string system. Therefore the louder that an electric guitar is acoustically, the more vibration will be robbed from the string sounding and the less signal a pickup will 'see'. An acoustically quiet guitar is not losing sound energy and thus is more likely to be efficiently transmitting your music to the speaker.
The only real exception to this would be when playing a guitar at high volumes. A guitar that is acoustically loud is more likely to feedback. The top resonates sympathetically with the noise coming from the speakers, which causes a positive feedback loop - body resonating causes strings to resonate, which causes the pickup to get more signal, which causes the speaker to produce more signal. That's why a hollow jazzbox or semi-hollow guitar will howl like a banshee when you plug it into a Metal Zone where a Les Paul will be comparatively well-behaved. An acoustically loud guitar gives you this feedback effect at lower volumes than an acoustically dead guitar.
There's one other thing to consider. Point 3 indicates the necessity of minimal deformation from the anchor points (bridge and nut, or bridge and fret for fretted chords). We've all played/heard dead sounding guitar bodies that aren't acoustically resonant. There are a variety of ways that a body/neck system can rob energy from a vibrating string without making much sound:
- The bridge could deform slightly absorbing energy
- The body or neck could be softer/mushier, absorbing this energy
- The nut or fret could be improperly seated, and give slightly to absorb some energy
You might hear this energy being absorbed (probably as a kind of buzz), or it might be largely released as heat. I think the latter accounts for 'dead' sounding guitars . . . where they're set up properly and play OK, but don't seem to give much back to the amp. A guitar that's dead sounding for this reason will impact what you hear when plugged in.
The reason I think that this is a contentious question is that there are two 'right' answers:
If you want to optimize signal from an electric guitar, an acoustically quiet guitar is probably a good place to start looking. The guitar should be acoustically quiet, but the strings should feel like they ring for a long time. If you are often playing at high volume on the edge of feedback, you might find that an acoustically loud guitar is the best place to start looking (and might be drawn towards unpotted or even slightly microphonic pickups). This type of guitar will get you to that 'edge of feedback' point more easily, which you can use to manipulate and more than make up for the loss of volume/sustain due to sound vibrations.
And we should all stay the hell away from acoustically quiet guitars without much sustain.
NOTE - This response ignores the benefits of energy loss. This is not always a bad thing. None of us are used to hearing a pure signal - so some energy loss in the mids, lows, or highs may well reduce sustain and signal to the amp . . . but will also give a guitar it's characteristic sound. Loss of highs might make a strat sound particularly sweet, loss of low mids might cause an LP to cut through better than others. I still think that an acoustically quiet guitar without much sustain is likely to suck though.
