Want all the gain you can get? This is the High Gain Option Retube Kit for the Vox AC100CPH. 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 quad of the JJ Electronic E34L’s but you can configure this kit to use the JJ EL34II's, EL34’s, KT77’s or 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 Multimeter if you use the factory test points. The E34L's, EL34's, KT77's and 6CA7's all bias the same.