There is a definite lack of information concerning these basses, so thought I’d contribute to the pool of information. From what I can gather, these were made in Sverdlovsk, USSR - offered as an alternative to the original bass model (Ural 510L) to remedy the neck/body balance problem by utilizing the body of the Ural 650 guitar.
The Ural basses are pretty frequently put down for their purportedly terrible sound, but i am not seeing that here at all. frequencies are round and full, bass is responsive to different picking styles (and to where on the string it is plucked), volume is more than adequate, and the switching system offers a wide palette of frequencies. i would liken the neck pickup’s tone to a vintage 4001. very unique, full sound - nothing else sounds quite like it.
I’m not gonna sit here and tell you the build quality is great, or that it is an excellent player. it most certainly is not. It is heavy and bluntly assembled. The engineering is bizarre. The whole thing seems