In the words of EarthQuaker Devices:

The Depths is our take on the classic optical vibe circuit. Now you can swab the decks with the same lush, pulsating, three-dimensional swirling sound you know and love, with some modern accouterments for all you land-lubbers out there. The Depths is optimized for use with all kinds of instruments, pickups, and to play well with dirt, so nobodys left waiting on shore. If its got a output, plug it in and get deep!

Controls:

• Voice: Dials in the overall sound. Turn it clockwise for a fuller sound with
• more lows, bring it back for a thinner, more midrange focused tone.
• Throb: This controls the low end pulse. It may not be immediately evident on
• the bridge pickup, but switch to the neck or add some dirt and it comes
• alive. All the way up for more throb, dial it back for less. Works best
• when the Voice is set to a warmer tone.
• Intensity: This controls how subtle or intense the overall effect is. Counter
• clockwise from noon are the more subtle, classic sounds. Clockwise from
• noon are the more drastic and intense sounds.
• Rate: Controls the speed of the effect.
• Counterclockwise for slow, clockwise for fast.
• Level: Controls the volume of the effect. Unity is around 1 Oclock, everything above that is boost.