The world of electric bass has evolved in many more directions than that of electric guitars. The number of strings, the scale length, the string spacing, even the wood selection now come in radically different varieties to suit different players needs. Ordering a fully custom bass can be a daunting experience, as every aspect of the instrument can be individualized. On this page I will offer my thoughts on some of the more commonly considered design elements.
One of the most important details on a bass, the scale length affects both the playability and tone of the instrument. I don't know the rationale behind Leo Fender choosing 34" as the original electric bass scale length, but it has remained the standard for eighty years. Along the way, however, other makers were quick to offer shorter variations, and in more recent decades going longer has become quite normal. In general, the longer the scale length, the more focused on the fundamental frequency the string becomes. Extra long scales are very useful in making the lowest notes retain their clarity, but the more complex harmonic range can be lacking. Going with an extra short scale will actually produce a deeper, warmer sounding bass, with a more musical sounding upper range. The use of multiscale fretboards is typically done to get the best of both worlds; clarity in the low range, sweetness in the high range.
A typical example of when using multiscale is useful. With eleven strings, the huge range in string gauge necessitates different tuned lengths.
An example of a more complex construction, an ash/wengee neck-thru is capped with a walnut tone block, then sandwiched within two mahogany body wings, all of this topped with a facing.
There are three common construction methods- neck-thru, set-neck, and bolt-on. All refer to the union of the body and neck of the bass. They each affect the tone, though it is less the joinery method and more about the ratio of woods that has the most tonal impact. Generally speaking, bolt-on and set-neck will produce a punchier sound than neck-thru, which offers a more piano-like sound. This is because the bolt-on and set-neck leave much more of the soft body wood mass on the instrument, while the neck-thru will have a much higher ratio of the dense neck woods. This effect can be modified by some degree with the selection of non-traditional woods to change the density ratio overall. For example, using a very dense body wood like hard ash or maple on a bolt-on bass will offer similar response to a neck-thru design.
There are three widely used types of finishes on electric basses. The most minimal is some variation of tung oil. The lack of a thick coating offers less protection from abuse and wear, but offers the advantage of allowing the woods to resonate to their fullest potential. Urethane is the most widely used, and offers great protection and beauty. Nitrocellulose still has a place as the original finish used on vintage instruments, and offers moderate protection with good resonance.
An exmple of a tung oil/varnish finish, in this case on a figured walnut topped body with bloodwood accents and a birdseye maple fingerboard.
An example of an urethane finish. In this case a turquoise burst is applied to a Douglas fir carved top, while the rest of the bass is left natural.
An example of a more complex layout, this bass starts with a passive single pickup and adds a Roland MIDI control system.
An example of keeping it simple, one passive pickup connected to one volume. I've been wiring my personal basses this way for years.
The world of electronics has definitely evolved in basses through the years. Active EQ preamps, buffered piezos, and on-board MIDI controls have become commonplace, sometimes all on the same instrument. Something that I think players should always consider is determining what is necessary, as opposed to doing what is expected. The on-board EQ preamp is a less sophisticated version of the EQ that exists on most amp set-ups. It can be very helpful if adjusting the tone while performing is needed, but otherwise is redundant.
There are endless possibilities when designing the body shape. With a bass guitar, the main focus is typically on achieving balance for ease of playing, whether standing or sitting. Custom body shapes do add a small surcharge. Here are some standard shapes that I have used through the years that do not add to the price.