Parasound A21PLUSB - User Manual

5 Unpacking Your A 21+ & Placement Guidelines Unpacking Your A 21+ Carefully remove your A 21+ from its shipping carton and locate the enclosed accessories: • AC power cord • A 12V trigger wire for auto turn on. It has a mono 3.5 mm mini plug at each end. • Rack mount ears While you are unpackin...

8 Rack Mounting Your Parasound A 21+ To mount the A 21+ into a 19" wide equipment rack, you must first attach its two “L” shaped rack mount brackets (included). W ith its four feet removed, the A 21+ chassis and front panel height occupies four rack spaces (7" or 176 mm). When mounting equip...

9 Audio Input Connections Always disconnect the AC cord to your A 21+ before making or changing any input, output or trigger wire connections. Inserting or removing an input or output cable while the A 21+ is turned on can result in a blast of sound that can damage your loudspeakers. Balanced XLR In...

11 Turn On Options The setting of the rear panel Turn On Options switch determines how the amplifier turns on and off. Setting the Turn On Options switch to Audio or 12 V disables the A 21+’s front panel Power button. There are three positions for this switch: Manual: When the Turn On Options switch...

12 Front Panel Operation On-Off Button Push once to turn on the A 21+. W hen the A 21+ is turned on the dim blue glow around the On-Off button will become brighter and the two blue channel indicators will illuminate. Push the button again to turn off the A 21+. The front panel On-Off button will be ...

13 Technically Speaking Balanced and Unbalanced Lines Recording and broadcast studios use balanced connections exclusively because of their inherent ability to reject noise and hum, thus assuring the best sound. Certain high quality preamplifiers and surround controllers built for residential use ut...

14 Parasound A 21+ Design Overview Circuit Designed by John Curl Parasound design consultant John Curl has been a legend among audiophiles and electronic engineers for decades. He pioneered measurements to correlate musical accuracy with the materials used in parts, worked with world-class touring c...

17 Problems and Remedies Unit will not turn on • Check the setting of the Turn On Options switch. (The front panel On-Off button will be disabled if this switch is set to Audio or 12 V) • If using Audio Turn on, try increasing the sensitivity of the audio trigger by turning the audio threshold knob ...

18 Are You Having Difficulty? Repair or Service Call your Parasound dealer first. If the dealer can’t help you with your problem we encourage you to call Parasound’s Technical Service Department at 415-397-7100 , Monday - Friday, 8am - 4pm Pacific Time. We can suggest other diagnostic tests you can ...

20 Total Gain 29 dB Input Sensitivity for 28.28 V Output into 8 Ω Unbalanced: 1 V Balanced: 1 V per leg S/N Ratio > 115 dB, input shorted, IHF A-weighted > 110 dB, input shorted, unweighted Damping Factor > 1100 at 20 Hz DC Trigger Requirements +9 Vdc to +12 Vdc, 5 mA Audio Trigger Requirem...