Vintage Bass Octave upgrades the warm analog sub-bass vibes of a classic circuit with superior tracking, cleaner headroom and the versatility that modern players demand. Delivering an impressive range of smooth, musical sounds all in the space saving MXR mini housing. The voice is rich and throaty, and it comes in two forms - one octave down and two octaves down. Each can be dialed in separately from the 2 volume controls, plus a Dry volume control to dial in your clean signal, you can concoct just the right blend for your rig. For extra clarity and definition, use the Mid switch to boost your clean signal's mid range at 800Hz by +6dB. Want even more boost? Remove the bottom plate and adjust the internal trim pot to kick it up as high as +13dB. Finally, this pedal comes equipped with Constant Headroom Technology , a custom circuit that provides clean, crystal clear headroom by producing 18 volts from a 9 volt power source. True hardwire bypass. Cannot be powered by a battery. Supplied with 9 volt AC adaptor (ECB003).