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Good Vibrations: Repair and Beyond With Chris Brandt

In my last article I posed a leading question to the readers…

A magnetic pickup on an electric bass (or guitar) can not hear wood resonance yet if you plug it in and stand back and listen you CAN hear wood resonance. How does the pickup do it?

Jonathon M. sent a great answer and it opens up a rich way of better understanding the electric bass. He shared:

“In short, the resonance of the wood dictates how the strings vibrate. The resonant characteristics of the wood cause some frequencies to dampen (zero) and others to resonate (pole). The magnetic pickups only react to the magnetic field vibrations caused by the strings, which is entirely determined by the “pole/zero” characteristics of the wood (and the neck joint, bridge mass/material, nut material, etc.). There’s plenty more physics behind the sound of any instrument, but that’s beyond the scope of this question. Thanks for the great question!”

Jonathon’s answer gets to the idea that there is a circulation between the energy in vibrating strings and the energy in the vibration of all the rest of the bass. This continuous circulation of energy shapes the tonal properties arising from the body, neck, bridge, and other parts as well, but it also sets up the flex characteristics principally of the neck. These flex characteristics can effect how low the action can be adjusted and it varies from bass to bass, even on instruments which appear to be identical.  Same model, same wood, same everything, yet they aren’t the same and each has to be adjusted for its own best performance.

The electric bass is a system of great complexity and nuance and over the next few articles I’ll discuss some of these subtle and interesting factors. You could say that the vibration in a bass circulates with all of the other vibration in a bass and this  accounts for its complexity. It is a sophisticated system. But all of this complexity is balanced by an elegant simplicity as well. The energy (vibration or resonance) flowing back and forth between the body and strings is totaled up within the string vibration. Here you can think of the strings as a delivery system for carrying the resonance from the body and neck to the pickups. Strings do a lot of multi-tasking, and I’ll discuss this in a future article. The complexity within the cross-resonating body might be comparable to the ripple patterns from raindrops on the surface of a pond but this doesn’t bother the strings a bit. They are happy with all of it and the strings pass this energy to the pickups which are like the front door to the rest of the system. This sophisticated system makes for elegance and simplicity and there is tremendous complexity as well.

Here’s what’s cool. Once the pickup comes into the picture, we cross into a historic revolution within the development of stringed instruments. You see, we now have the emergence of an entirely new pathway to get sound to the human ear! By now we’ve all grown up with electric instruments so it is easy to take them for granted, but if you think about the slow development of musical instruments over many centuries you can begin to see how revolutionary this new technology really is. The power of a bass is no longer confined by the acoustic limitations of the pre-electric instrument and the physical capacity of the person playing it.  There are enormous new tonal possibilities and it revolutionizes what is now possible in terms of range extension.  This business of range is particularly important for the bass because dropping down into low registers has always been hard to do acoustically. This is a big subject and I’ll discuss it more in a future article.

But beyond all this, there is an even more revolutionary effect and it might not necessarily seem obvious. You see, the sound or energy produced by an amplifier becomes a second source of the energy which enters the bass. The first source of energy is the bass player playing the strings but the second source of energy is the sound from the speakers inundating the bass itself. It re-circulates energy back into the bass almost as a form of arco, arco in the sense that a violin bow can indefinitely keep a flow of energy going into the violin. So I think of the energy from amplification as an intrinsic component of the electric bass itself and this “second” source of energy is why an electric bass feels as if it physically comes to life when it is plugged in. This too creates something new in the history of stringed instruments.

Knowledge is power and this is the key to appreciating how fantastic the electric bass really is. I hope that interested bass players will find it helpful to picture how energy moves through out the bass and that this now gets us ready to start talking about all sorts of practical questions having to do with set ups and adjustments, repairs and modifications, differences in construction and much else as well. If you have a few questions about repairs or set ups go ahead and send them my way and we’ll get started.

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