Universal Audio, Inc. www.uaudio.com PO Box 3800 Santa Cruz, CA 95063-3818 (831) 466-3737 voice (831) 466-3775 fax www.uaudio.
The 2108 Microphone Preamplifier Thank you for purchasing the 2108 Dual Channel Microphone Preamplifier. The 2108 was inspired by the 1108 line amp developed by Universal Audio in the early sixties. The original 1108 was the “father of the 1176 limiter”. The classic sound of the legendary 1176 starts with the line amp / output transformer of the 1108. In fact, the 1176 was born as a result of my father’s (Bill Putnam Senior) desire to create a remote controlled pre amp.
IMPORTANT SAFETY INSTRUCTIONS Before using this unit, be sure to carefully read the applicable items of these operating instructions and safety suggestions. Afterwards keep them handy for future reference. Take special care to follow the warnings indicated on the unit itself. as well as in the operating instructions. Water and Moisture – Do not use the unit near any source of water or in excessively moist environments.
Notice This manual provides general information, preparation for use, installation and operating instructions for the Universal Audio 2108 Microphone Preamplifier. The information contained in this manual is subject to change without notice. Universal Audio, Inc. makes no warranties of any kind with regard to this manual, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose. Universal Audio, Inc.
Table of Contents The 2108 Microphone Preamplifier............................................................................... ii 2108 Specifications .................................................................................................... 1 Operating Instructions ................................................................................................. 2 Front Panel ...................................................................................................... 2 Gain ...........
2108 Specifications Microphone Input Impedance Selectable, 1 kΩ or 4 kΩ Hi-Z Input Impedance Selectable, 58 kΩ or 2 MΩ Maximum Microphone Input Level +8 dBu Maximum Output Level +26 dBm Recommended Minimum Load 600 Ω Frequency Response 20 Hz to 20 kHz ± .5dB Maximum Gain 65 dB Signal-to-Noise -165 dB EIN @ 65 dB Gain Power Requirements DC-30 Power Supply & 2108 DC Power Cable Dimensions 1U rack, 11.5” deep Weight 10.85 lbs.
Operating Instructions The 2108 is a two-channel, solid state microphone / instrument preamplifier. Each channel has two gain stages operating in a class A single-ended configuration. Variable negative feedback is applied to both of these stages to control gain and “color”. Balanced inputs and outputs are transformer coupled. 2108 Front Panel The front panel has two identical channels (Figure ) each with an eleven position detented Gain control that doubles as an input selector.
Level The Level knob is the master volume control. It determines the amount of signal from the preamplifier gain stage sent to the output stage. The cleanest signal is attained by setting the Level knob between 7 and 10 on the scale, then turning the Gain knob until the desired level is attained. Altering the Gain, Z-in Switch, and Output controls together provides many useful tonal variations. The numeric values on the front panel for the Level control denote magnatude and are NOT specific dB values.
Output Input (Signal) The Signal Output Input push button selects which amp stage the Signal indicator is monitoring. When the button is pushed in, the light will indicate signal strength measured at the input of the final amp stage. When the button is out, the light will indicate signal strength at the output of the 2108. Button In. It is useful to push this button in and monitor the input while adjusting the Gain control. This can help determine how hard you want to drive the first stage.
Input/Output Connectors Standard XLR input and output connectors are provided on the rear panel. Pin 2 is wired positive (hot) on the MIC INPUTS. Pin 2 is positive on the LINE OUTPUT when the front panel Polarity switch (Rev ø) is in the normal out position. Pin 3 is positive on the LINE OUTPUT when the front panel Polarity switch is pushed in (selecting the reverse phase condition). DC Power Input Connect the 2108 to the DC-30 Power Supply box using the supplied 2108 DC Power Cable.
Voltage Selector The 2108 can operate at 120 V or 240 V. To change the mode, unplug the AC power cord from the DC-30 Power Supply. Remove the top cover. Looking down on the unit, locate the round Power Transformer at the front of the unit. Unplug the transformer connector with the larger wires and reconnect it to the appropriate headed as shown in Figure 4. This figure shows the unit configured for 240 volt operation.
History Bill Putnam Sr. was awarded the 2000 Technical Achievement Grammy for his multiple contributions to the recording industry including the design of the modular console. Highly regarded as a recording engineer, studio designer, and inventor, Putnam was a favorite of Frank Sinatra, Nat King Cole, Ray Charles, Duke Ellington, Ella Fitzgerald and many other musical icons.
