Gibson previously produced amplifiers in Kalamazoo, MI from the mid-1930s-1967, and various other locations including Chicago, IL from 1968 through the mid-1970s.
Distributed by the Gibson Guitar Corporation in Nashville, TN.
Other companies started building amps for Gibson, and by 1968 a new line of tube amplifiers with some familiar old names were released.
These lasted only a short time through 1969, when only various solid-state models were available.
A great resource to date a vintage guitar amp is to check out the Blue Book Of Guitar Amplifiers.
Gibson amplifiers have become known amongst guitarists for their warm, consistent sound and reliability.
Some things are very obvious such as non-original or reconed speakers, non-original transformers, replaced pots, re-tweed, re-tolex, re-grill, etc.
Amplifiers currently produced since the early 1990s.Other sources to date your amp may include serial numbers and overall look and visual components on the amp as well.For example, the logo on the amp or materials used during a certain time period of production.Guitar amplifier dating by serial numbers - How To Date A Guitar Amp or Bass Amp By Serial Number.There are a number of resources available online to help you to date your guitar amplifier or bass amp.
Many of these resources refer to source-date-codes located on pots or speakers within your amplifier.