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CONTROLS and OPERATION:
The Gain Control directly adjusts the input amplifiers giving you control over the dynamic range of
your source. You get a 45dB range of control when using the XLR input and a 25dB range when
using the ¼" input. Set the control counterclockwise to minimum gain when connecting the inputs.
The Gain Switch gives you an additional 20dB of gain between the input stage and the tube to bring
up very low-level signals and allow you to drive the tube harder.
The Impedance Switch works with the balanced XLR input only. Input impedance is 4.7k Ohms in the
high position. This position should be used for most microphones and line level signals to minimize
any loading effects on the source. The low position sets the input impedance to 600 Ohms. This
position terminates the signal with known low impedance that can flatten and clean up the frequency
response of some vintage equipment including ribbon microphones, and various transformer coupled
outputs. By doing this at the input you reduce the need for added equalization and the response to
percussive audio dynamics is tightened in many cases.
The Filter Switch rolls off the response to signals lower than 40Hz. This helps to cut out low fre-
quency rumble, wind noise, and all types of low frequency energy before it is amplified. When re-
cording, this allows you to get more gain before clipping the preamp, recorder, or computer and in a
live situation you get more gain before clipping your amp.
The Phantom Power Switch applies +48 Volt phantom power to the XLR input jack for powering your
microphone, if needed. It is slow at turning on and off and is current limited to protect sensitive micro-
phones and reduce pops. Ideally, when connecting a microphone that requires phantom power, you
should first turn down gain, next connect the microphone, next switch on the phantom power, and
finally bring gain back up to the desired level. This minimizes pops in your system and stress on the
microphone.
The Limit Switch engages a fast attack FET limiter at the tube stage. This helps to prevent clipping or
overload of any equipment following the preamp. When engaged it limits the maximum signal on the
meter to 0dB and maximum output at the XLR output to +6dBu if the Output control is up full. When
recording this lets you get the hottest signal before clipping into your computer or recorder. It can limit
peaks of over 20dB but should normally be used to protect on overshoots and musical peaks for best
results.
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