BT-45R has a clean channel and a overdrive channel. The 3 band EQ and SPRING REVERB make the tone more warm and more suitable for many performance styles. About the overdrive effect it added a SHARP button to add the power of the GAIN and let you get a more power overdrive tone. BT-45 standard is a 10” specialized speaker. As the nominal power is enough so we leave a outside speaker jack to convenience your performances. You can connect a 12” speaker no less than 4ohm.