Want all the gain you can get? This is the High Gain Option Retube Kit for the Engl Retro Tube 50 E762 Heads and Retro Tube 50 E768 Combo Amps. The preamp section uses four handpicked High Gain ECC83S's with one balanced for the phase inverter in V4. The default power tubes are a matched pair 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. The video below explains the difference between bias probe types.