Want to smooth out your Twin Jet? This is the Gold Pin Option Retube Kit for the Bogner Uberschall Twin Jet. The preamp section uses six Gold Pin ECC83S's with one balanced for the phase inverter in V6. The default power tubes are a matched quad of the JJ Electronic KT88's but you can configure this kit to use the JJ 6550's by clicking on the "Customize" button.
These are adjustable bias amps and all you need to check and adjust the bias is a Multimeter to use with the test points.