Art Audio only sells Grade A Tubes from Sophia Electric in matched pairs or quads.
Note: S.E.T. Princess 300B tube models are proprietary products of Sophia Electric Inc. Due to popularity of these Princess 300B products, there are many look alike (or early ST model) in the market trying to get a share of success from those who can be easily switched.
We have been selling this S.E.T. Princess 300B carbon plate tube as rigid plate 300B tube since April, 2006. So far the feedbacks from users are very positive. It has totally different sonic characters compared to the ever popular S.E.T. Princess 300B mesh plate model. Much like carbon composite Allen Bradley resistors in a single ended amplifier, this carbon plate 300B does have its carbon flavor and charm.
These tubes usually ship within 2-4 business days.