Over the course of the 70s, the Japanese output improved dramatically, and in many ways these early 70s models are a low point for the brand. These new Epiphones were based on existing Matsumoku guitars, sharing body shapes, and hardware, but the Epiphone line was somewhat upgraded, with inlaid logos and a 2x2 peghead configuration. The Matsumoku factory had been producing guitars for export for some time, but the 1820 bass (alongside a number of guitar models and the 5120 electric acoustic bass) were the first Epiphone models to be made there.
By the end of the 1960s, a decision had been made to move Epiphone guitar production from the USA (at the Kalamazoo plant where Gibson guitars were made), to Matsumoto in Japan, creating a line of guitars and basses significantly less expensive than the USA-built models (actually less than half the price).