Sony ULT TOWER 9AC Party Speaker Black (SRS-ULT900AC)Powerful ULT POWER SOUND Powerful sound and bigger bass for better parties The prominent ULT button gives you access to two exciting bass modes. Powerful bass to feel the beat and get you dancing, or deep bass boost for low frequency sound that will make your heart tremble. Hit the button. Feel the bass. Press the ULT button to enjoy the powerful sound of ULT1 and ULT2. Select ULT1 for deeper, lower frequency bass. Select ULT2 for powerful, punchy