The OA2 used in the First Sound is different from the one used in the Joule Electra. The Joule Electra will take any domestic OA2, but the First Sound needs one designed for the Russian military that can handle a 3ma current draw. These are getting hard to find. The domestic OA2 will either crack or burst when used in the First Sound.
What are OA2 tubes and why are there more gear
using them?
I have a First Sound Presence Deluxe preamplifier which I bought used. This preamp as well as the JOULE ELECTRA use the OA2 tubes. What sort of tubes are these? When where they made and why are they not more prevalent in other preamp except in a handful of them such as the JOULE and the LAMMs, as well as the First Sound gear? What particular sound do these produce that make them appealing or unappealing for designers to incorporate them in their designs? Is there a designation that is different than the 0A2 that I am not aware off?
I have a First Sound Presence Deluxe preamplifier which I bought used. This preamp as well as the JOULE ELECTRA use the OA2 tubes. What sort of tubes are these? When where they made and why are they not more prevalent in other preamp except in a handful of them such as the JOULE and the LAMMs, as well as the First Sound gear? What particular sound do these produce that make them appealing or unappealing for designers to incorporate them in their designs? Is there a designation that is different than the 0A2 that I am not aware off?