The Fender AB165 Bassman is a great guitar and bass amp, but for guitar it sounds a bit dark, muddy and lacks the high end chime that prior Bassman models where famous for. The driver circuit mod converts the AB165 circuit to sound very similar to older tweed Bassmans like the famous 59' model. After the mod you will have a great sounding guitar amp that takes pedals very well. Great amp for Blues, Blues Rock, Classic Rock, Country, Funk etc. The mods are simple and if you don't like them it's easy to convert back to the original circuit.