LOW EQ is a shelving filter that provides 12 dB of boost and cut below 100Hz.
HIGH EQ is a shelving filter that provides 12 dB of boost and cut above 10kHz.
VOLUME is a master volume control used to adjust the overall volume of the signal at the
Use the POWER switch to turn the UP4000 Series on and off.
The 
The OVERLOAD indicator lights when the amplifier is operating in overload, a condition generally caused by a problem on the speaker line. When the amplifier is switched on, the OVERLOAD light comes on for a few seconds. This is normal and does not indicate a problem.
The SIGNAL indicator lights when a signal is present at the POWER OUTPUTS.
The PEAK indicator lights when the output signal is approaching clipping.
The ON indicator lights when the UP4000 is turned on and ready for operation.
POWER INPUT provides a means to connect an external 24 VDC power supply or battery as an alternative or backup power source. The UP4000 Series seamlessly switches to the backup supply if there's an AC power loss. When both AC power and 24 VDC power are connected, the DC power is switched off.
The D.C. FUSE protects the DC power input to the amplifier circuit. Replace with the same type fuse only.
POWER OUTPUTS are 
UP4061, UP4121, UP4161 specifications
The Mackie UP4161, UP4121, and UP4061 are part of Mackie's extensive range of professional audio products, designed primarily for live sound reinforcement and studio applications. These high-performance units hold a reputation for their reliability, robustness, and superior sound quality, which is essential in professional audio environments.The Mackie UP4161 is a 16-channel mic preamp featuring high-headroom, low-noise performance, and an impressive dynamic range. With its onboard 96kHz/24-bit A/D converters, the UP4161 ensures that audio is captured with exceptional clarity and detail. The presence of individual channel gain control and a -20dB pad provides versatility, allowing users to manage a wide array of sound sources, from soft vocals to loud instruments. Additionally, the device integrates seamlessly with various Digital Audio Workstations (DAWs), making it an ideal choice for recording studios.
The UP4121, on the other hand, is tailored for applications requiring fewer channels without compromising quality. This 12-channel preamp shares many features with the UP4161, including the robust 96kHz/24-bit A/D conversion technology. The UP4121 is equipped with advanced metering for each channel, ensuring that audio levels are monitored accurately, preventing clipping and distortion. Its lightweight design enhances portability, making it suitable for both studio and live settings.
Finally, the UP4061 rounds out the lineup with its 6-channel configuration, perfect for smaller productions or personal use. Despite its compact size, the UP4061 does not skimp on features, offering similar performance specifications that are consistent with its larger counterparts. It utilizes high-performance analog circuitry and delivers rich tonal quality, making it suitable for both powered speakers and passive monitors.
All three models feature Ultra-low noise, which minimizes self-noise, ensuring that recordings are clean and professional. The high-quality components and durable construction mean that these preamps will withstand the rigors of regular use, making them indispensable tools for audio professionals.
In summary, the Mackie UP4161, UP4121, and UP4061 are versatile audio solutions that cater to a variety of needs, from expansive studio recordings to intimate live performances. Their built-in technologies ensure high-quality audio while maintaining excellent usability, solidifying Mackie's standing in the professional audio market.