ETI Sound Systems, INC US-3000, US-4000, US-1800, US-1200 Setting UP Your US-SERIES Amplifier

THE BEAUTY OF POWER US SERIES AMPLIFIERS

in limiter circuitry for improved performance when overloading. The limiter activates at “clipping” when the output voltage reaches the power supply voltage rails. Without limiters, the output voltage will grossly distort if the signal elevates beyond this point. The signal wave form is flattened (“clipped”), producing excessive high frequency distortion not present in the original signal. This makes music sound “dirty” and increases stress on the high frequency transducers, significantly shortening their life span (most loud- speaker manufacturers will not honor warranties if high frequency drivers are “burnt” due to a clipped signal overload). Clip limiters effectively solve this

problem by compressing the signal at clipping. US- Series amplifiers use intelligent clipping circuitry to protect both the loudspeakers and amplifier.

NOTE: US-1200 and US-1800 amplifiers have a built-in limiter circuitry which is constantly activated. The US-3000 and US-4000 amplifiers have an external switch located on the rear panel, which activates and deactivates the clip limiters. B-52 recommends the clip limiter switch on both the US-3000 and US-4000 remain ON. You may choose to turn OFF the limiters when using the US-3000 and US-4000 to power subwoofers.

SETTING UP YOUR US-SERIES AMPLIFIER

CLIP LIMITER: Clipping is the result of an amplifier running into a power supply limitation. The maximum output voltage that any amplifier can produce is limited by its power supply. Attempting to output a voltage level that exceeds the power supply voltage rails results in a flattening effect of the signal causing it to clip. A clipped waveform exhibits severe distor- tions, making it sound harsh. The clip limiter detects this condition and reduces the gain to minimize the amount of overdrive. To preserve as much of the program dynamics as possi- ble, the limiter reduces the average program level until the peaks barely clip. Each channel has its own clip limiter and you can switch it ON or OFF (only on US-3000 and US-4000). The clip limiter allows brief clipping which is not detectable to the ear. It activates when a clip condition repeats, to avoid prolonged distortion. When driving full-range speakers, clip limiting reduces the high frequency distortion caused by low frequency overload. It also protects higher frequency drivers from excess overdrive and harsh clipping harmonics.

NOTE: You may want to keep the limiters OFF when connecting the US-3000 and US-4000 to power subwoofers.

HPF (High-Pass Filter): High Pass Filters (HPF) are also known as low-cut filters. HPFs on the US-Series amplifiers cut off signals below 50Hz. As a result, bass reproduction is optimized, since ultra-low frequencies, which most speakers cannot reproduce anyway, are eliminated and more power becomes available for the reproduction of the remainder of the music signal.

NOTE: You should set the filters to best suit the frequency response of your speakers as some speakers are particularly sensitive to over-excursion. The 50Hz filters on the US-Series amplifiers work well with most full-range speakers.

NOTE: For most subwoofers and in studio applications keep the HPF in the OFF position.

B-52 US Series Professional Power Amplifiers - Instruction Manual 15