Looking for more warmth and definition? This is the Standard Retube Kit for the Engl Invader E642 and E642/2 Amps. The preamp section uses four ECC83S's with one balanced for the phase inverter in V8. The default power tubes are a matched quad of the JJ Electronic E34L's but you can configure this kit to use the JJ EL34II's, EL34’s, KT77’s or the Big Bottle 6CA7’s by clicking on the "Customize" button.
These are adjustable bias amps and all you need to check and adjust the bias is a bias probe and a Multimeter, or our all-in-one Eurotubes "Pro One" bias probe that reads both the plate current and the plate voltage simultaneously. These are available under the "Related Products" tab.
You can use our Generic bias video for reference which we did on a Marshall 800 and the procedure is the same.