Page 4 - PLACEMENT GUIDELINES FOR YOUR A 51; Keep it away from heat sources such as air ducts or radiators.; Rack Mounting Your Parasound A 51; allows 1; To attach the rack mount brackets:
PLACEMENT GUIDELINES FOR YOUR A 51 Power amplifiers are usually heavier and generate more heat than other components. To avoiddamage to the A 51 or other equipment and to reduce risk of fire, you must follow these guidelines: • A cable with a 2.5 mm sub-mini plug on each end (provided). • Place the ...
Page 5 - Balanced - Unbalanced Input; To Connect; Balanced Ch 1 input; YOU SHOULD KNOW
CONNECTING A SURROUND CONTROLLER TO THE BALANCED INPUTS ON YOUR A 51 Left and Right Balanced Input Jacks Balanced connections will give you the best sound. If your surround controller has balanced XLR output jacks, we recommend that you connect them to these inputs. Refer to the Balancedand Unbalanc...
Page 6 - Ch 1-5 Unbalanced Inputs; Five shielded interconnect cables with RCA plugs; Before Connecting; Plug one end of the cable into the; Unbalanced Ch 1 Input jack; Repeat steps 1 and 2 for
CONNECTING A SURROUND CONTROLLER TO THE UNBALANCED INPUTS ON YOUR A 51 Ch 1-5 Unbalanced Inputs Use these inputs if your surround controller doesn’t have balanced output connectors or if yousimply prefer to use unbalanced connections. What You’ll Need: • Five shielded interconnect cables with RCA pl...
Page 7 - CONNECTING YOUR SPEAKERS TO THE A 51; Technically Speaking; section for information about bare wire termination.; When selecting speaker wire, follow these guidelines:
CONNECTING YOUR SPEAKERS TO THE A 51 Speaker Terminals The A 51 speaker terminals accept speaker wires with banana plugs or bare ends. Refer to Bare WireSpeaker Termination in the Technically Speaking section for information about bare wire termination. What You’ll Need: • Five lengths of AWG 16 or ...
Page 8 - MANUAL AND AUTOMATIC TURN ON-OFF OPTIONS
MANUAL AND AUTOMATIC TURN ON-OFF OPTIONS You can manually turn the A 51 on and off with its front panel On-Off button. It can also be triggeredto turn on and off automatically when your preamplifier, surround controller, or system controller isturned on and off. Manual On-Off from the Front Panel If...
Page 9 - Input
CONNECTING AN EXTERNAL DC SOURCE FOR AUTOMATIC TURN ON-OFF To automatically turn on and off the A 51 with an external DC voltage, choose the DC Triggeringoption by moving the Auto Turn On switch on the rear panel to its lower 12 V position. What You’ll Need: • A cable with a 2.5 mm sub-mini plug on ...
Page 10 - UNDERSTANDING THE INDICATORS ON THE A 51; AC Present Indication; Troubleshooting Guide
UNDERSTANDING THE INDICATORS ON THE A 51 a AC Present Indication When the A 51 is plugged into a live AC outlet, a soft blue halo glows behind its On-Offbutton and its red “P” Badge glows faintly. These indicate that the unit is plugged into a liveAC outlet, even when it is turned off. b On, Off and...
Page 11 - CONNECTING THE A 51 AC POWER CORD; AC Power Connections; Remove power to all the components in your audio system.; Plug the male end of the AC cord to an AC outlet or power strip.
CONNECTING THE A 51 AC POWER CORD AC Power Connections We recommend that you plug your A 51 into the same AC wall outlet or power strip that pow-ers your other audio components, especially the preamplifier or system controller. Having all the audio components on the same power circuit helps prevent ...
Page 12 - MAINTAINING YOUR A 51; Main Power Fuse
MAINTAINING YOUR A 51 Your Parasound A 51 power amplifier requires no periodic maintenance and has no user-serviceable parts inside. To avoid the risk of electric shock, do not remove its top cover. The amplifier’s exterior can easily be cleaned with a soft cloth pre-moistened only with a few drops ...
Page 13 - TROUBLESHOOTING GUIDE; No power; TROUBLE
TROUBLESHOOTING GUIDE 11 No power Auto turn on doesn’tfunction with a triggervoltage Auto turn on doesn’tfunction with an audioinput signal A 51 will not turn off whenaudio signal is removed Power on, but no sound On-Off button glows redand channel indicator(s)off Distorted sound Hum and / or buzzth...
Page 14 - SERVICING YOUR A 51; If All Else Fails –Call Us for Help; outer carton only; Important Notice - Shipping the A 51; Use
SERVICING YOUR A 51 If All Else Fails –Call Us for Help Call your Parasound dealer or Parasound’s Technical Service Department toll free at 1-866-770-TECH (8324). We can often solve the problem with simple diagnostic tests you can per- form yourself. If we determine that your A 51 will need further ...
Page 15 - TECHNICALLY SPEAKING; s metal post. Before inserting the
TECHNICALLY SPEAKING 13 Audio Trigger Sensitivity Adjustment The Audio Sensitivity Control sets the threshold of theaudio trigger signal. You can adjust this level from amaximum sensitivity of 50 mV (fully counterclockwise)to a minimum sensitivity of 250 mV (fully clockwise). If you set this control...
Page 16 - TECHNICALLY SPEAKING continued; Use balanced input lines with your Parasound A 51.
TECHNICALLY SPEAKING continued 14 hum (or 50 Hz hum in regions with 50 Hz AC). Theharmonics of these frequencies (120 Hz, 240 Hz, 480Hz or 100 Hz, 200 Hz, 400 Hz) may add buzz in addi-tion to the hum. The ideal of zero voltage ground for all the compo-nents in a system is practically impossible, bec...
Page 17 - PARASOUND A 51 DESIGN OVERVIEW; Each channel
PARASOUND A 51 DESIGN OVERVIEW 15 Circuit Designed by John Curl Parasound design consultant John Curl has been alegend among audiophiles and electronic engineersfor decades. He pioneered measurements to corre-late musical accuracy with the materials used in parts,worked with world-class touring comp...
Page 18 - PARASOUND A 51 DESIGN OVERVIEW continued
PARASOUND A 51 DESIGN OVERVIEW continued 16 The Driver Stage The driver stage provides critical amplification forwhich we employ a complementary matched pair ofMOSFETs selected for their tube-like sonic qualities.MOSFETs tend to generate less odd-order harmonicdistortion than bipolar transistors. Th...
Page 19 - PARASOUND A 51 SPECIFICATIONS; 0 amperes peak per channel
PARASOUND A 51 SPECIFICATIONS Power Output - All Channels Driven 250 watts RMS x 5, continuous, 20 Hz - 20 kHz, 8 Ω 400 watts RMS x 5, continuous, 20 Hz - 20 kHz, 4 Ω Current Capacity 60 amperes peak per channel Slew Rate > 130 volts per microsecond Frequency Response 5 Hz - 100 kHz, +0/-3 dB at ...
