Mr. Bernstrom is known in many circles as being one of the most knowledgeable in tubes and tube circuits in Sweden. He has amassed over 30,000 tubes in his collection, more than 15,000 are audio types. Sentec had many successful products including the kit series SE77 preamplifier, PA77 amplifier, and SP77 speaker's. This series of products was often considered the "Swedish Dynaco." In the late 1970's Mr. Bernstrom brought to market the SC8 preamp, PA8 amplifier and and TU8 FM tuner. These were available as kits and pre-built products which were extremely popular in Sweden throughout the 1980's.

In 1978 Mr. Bernstrom brought to market one of the very first Mosfet amplifiers, the 120w mono amplifier named the ACM1. These were considered by many the best amps of the time. In the late 80's with the shrinking Hi-Fi market in Sweden the budget series 9 was released which included the PP9 phono preamp, the DiAna digital to analog converter, SC9 preamp and PA9 power amp.

By the end of the 1990's Mr. Bernstrom decided to go back to his former interest in vacuum tube design. He studied and learned tube audio transformer design and designed and wound his own transformers for the power amp M30 30 watt EL34 amplifiers using 5751 and 6189 tubes along with a passive preamp.

In 2002 Mr. Bernstrom decided to sell his manufacturing facility and retire. His plans for retirement include making small production of his favorite tube projects he thought about and collected during the years. The series starts off with the EQ10 78RPM phono equalizer.