The Roland Bolt 30/60/100 was the only line of tube guitar amplifiers produced by Roland. The amplifier was launched in the market in 1979 when the Roland company was trying to pursue the success of
the Mesa Boogie Mark amplifiers.
Properly speaking these are hybrid amplifiers, the pre-amp being built with solid-state circuitry. The built-in solid-state distortion channel gives a somewhat harsh sound, and is best bypassed.
Aside from the overdrive circuit, the amp contains a spring reverb, and provision for external effects loops and switches.
The Bolt was produced until 1984: Roland made a decision at that time to focus production on solid state amplifiers
such as their very successful Jazz Chorus. In recent years the interest in this range of amplifiers has increased, owing to their good tone, and affordability
in comparison with other classic amplifiers.
Both combo (amp/speaker) and 'head' versions of these amplifiers were produced. The combo amplifiers are often
found (as in the illustrated example) with replacement speaker drivers, the original having failed under stress, as the Roland unit was only just beyond the constraints of the amplifier output.