The two main types of double bass cases are include soft and hard cases. Cases sometimes are hybrids, however, having elements of both hard and soft styles. The level of protection varies with each type of case, as do mechanisms for transportation.
Double bass cases may be made from cloth and foam, with nylon versions being popular. These are soft cases that are designed to be very light. This facilitates daily movement of the double bass, so players also call these versions "gig bags." It also helps when storing the bass in a smaller space, as the case is not as bulky. The foam is designed to protect against dings and scratches.
Hard cases are the other type of double bass cases. These versions usually are made of a synthetic material such as plastic, carbon fiber, or fiberglass. These materials are not as heavy and, in many cases, are more durable than other options such as wood. For instance, some cases are made from Kevlar®, the same material in bulletproof vests. The inside of the cases are a soft material such as chenille or velvet that will not scratch the instrument, with some cases having removable linings so that a bassist may put a bass already in a soft case within the hard case.
When comparing the two types of double bass cases, the level of protection is a major difference. Soft cases have foam that is usually 1 to 2 inches (2.54 to 5.084 cm) thick, but the foam is not sufficient enough to save the instrument from major damage. Players use these cases primarily for storing the instrument at home, school or music shops as a result. Hard cases for doubles, by comparison, take up more space but are better for travel, particularly if the player must let others such as airport workers who might not have music training handle the bass.
Another way soft and hard double bass cases differ is that hard cases, due to their added size and heavier weight, usually have rollers on the bottom. The rollers allow the bass player to move the case and the enclosed instrument without lifting, reducing physical strain. Some soft cases provide this option as well, but it's not as common. Soft double bass cases may have shoulder straps instead.
Although most double bass cases can fall clearly into a hard and soft category, some cases combine elements of both. For instance, some cases have a firm shell that, although padded, is much thinner than usual, more like a basic guitar case might be. The outside of the hard shell has an outer nylon covering. These hybrid cases provide slightly better protection than soft cases but still are not recommended for intensive travel.
All but the most basic cases for double basses include at least one pouch for accessories and music. This matters because it is safest to transport the bass using two hands; bassists cannot easily carry both their accessories and music in addition to the instrument. Although these pouches add convenience, they can make it slightly harder or time consuming to pass through security networks.
In general, hard cases are more expensive than soft ones. They also last longer. Of course, this depends on the exact materials from which the manufacturer constructs the case. Bassists may opt to have more than one type of case, depending on how they use their bass.