Chameleon Labs Model 581 Discrete Class AB Microphone Preamplifier Module Owner’s Manual 704 228th Avenue NE, # 826 Sammamish, WA 98074 206-264-7602 www.chameleonlabs.
Your Model 581 microphone preamplifier card has a transformer balanced input with a gain range of +25dB to +80dB. The Model 581 has been carefully constructed and individually tested for quality. It utilizes class ‘AB’ circuitry. This unit is made with 100% discrete components and was fabricated to precisely match vintage counterparts manufactured in the early 70’s. The Chameleon Labs Model 581 is based on high audio performance design techniques.
Features of the Model 581: • Fully balanced transformer mic input which can be upgraded to a vintage Carnhill® unit; • Transformer balanced output; • 300 Ohms or 1.2K Ohms mic input impedance selectable on the front panel; • 48VDC phantom power selector on the front panel; • 12 position Grayhill® gold contact rotary gain switch for Mic gain section; • LED illuminated push buttons for visual confirmation • Output level control functions as a fader when going straight to D.A.W.
Front Panel Controls: General rule: When the button is pressed in, the feature is selected and the LED illuminates. 48V ButtonThis button supplies +48V (Phantom Power) to the microphone circuit. 1.2K/300 ΩThis button selects the microphone input impedance to either 300Ω or 1,200Ω. Ø ButtonThis button shifts the phase of the unit 180°. DI ButtonThis button connects the DI jack to the gain stage of the unit. GainThis selector switch controls the gain of the preamplifier circuit.
Installing the Preamplifier Card The Chameleon Labs Model 581 has been designed to be powered by an API® compliant powered chassis. Consult the chassis’ product manual for further information. The card can also be powered by the Chameleon Labs CPS501 powered chassis.
First time users Set up of the Model 581 1- Select 40 dB on the Gain control. Turn the Output control fully counter clockwise. Make certain that the DI, 48V and Phase buttons are all out. 2- If the microphone requires Phantom Power, press in the 48V button. The normal position for the 1.2K/300Ω button is 1.2K, this matches most professional microphones used today. If you have microphones that require a lower impedance you may select 300Ω.
Technical Specifications Microphone Input Impedance: 300Ω or 1,200Ω Microphone Amplifier Gain: +25 dB to +80 dB in 5 dB steps. Output Impedance: 100Ω Noise: -115.5 dB Maximum Output: +26 dB into 600Ω Frequency Response: 20Hz – 20 kHz +/- 1 dB. Dimensions and Weight Weight: 2 pound 8 ounces Dimensions: Width – 1.5”, Height – 5.25” Depth to Rear of Mounting Surface: 5.938” =/- 0.
Warranty and Liability Your Chameleon Labs product is warranted to the original owner for a period of one year. Chameleon Labs guarantees this product to be free from electrical and mechanical defects and will repair or replace defective components, or replace the unit at Chameleon Lab's option. Should service be required for your Chameleon Labs product, please contact the manufacturer. Service is provided for products beyond the warranty period.
