SV83 is an inexpensive but highly linear low power output tube similar to EL84.
SV83 tube has higher conductance than EL84 (15K vs 11K), but the screen grid (g2) of SV83 cannot take as much voltage (200V vs 300V) as EL84. Because of this, SV83 is not a direct replacement for an EL84.
SV83 tube has many fans, and there are great sounding amps such as Decware Zen that are designed with SV83 tubes. SV83 tubes are often used in DIY designs as well.
Svetlana SV83 tube is a Russian 6n15n, also known as (6p15p)[https://www.tubesforamps.com/products/el84-6bq5-sv83/russian-6n15n-eb-matched-pair]. Although SV83 is branded as Svetlana, most 6p15p were made at the Xpo-pul factory in Saratov where the Sovtek tubes are built.
There have been cases where 6p14p was labeled as SV83. You will receive only the 6n15n version, we make stock only the correct SV83 tubes.
If you are looking to replace your SV83 tubes, we have tested and matched SV83 sets ready to ship in stock. We match SV83 on both Ip and Gm using a custom test setup.