Parasound A 31 manuale d’uso

A 31 Three Channel Amplifier OWNER’S GUIDE[...]

2 Important Safety Instructions The lightning flash with the arrowhead symbol within an e quilateral triangle is intended to alert the user to the presence of “dangerous voltage” inside the product that may constitute a risk of electric shock. The exclamation point within an equilateral triangle is intended to alert the user to the presence of [...]

3 Table of Contents Introduction ................................................. 4 Placement and Ventilation Guidelines .............................. 5 AC Mains Voltage ............................................. 5 Rack Mounting ............................................... 6 Audio Input and Output Connections .............................. [...]

4 INTRODUCTION Thank You for Choosing Parasound Your new Parasound Halo A 31 power amplif ier has been designed with the most advanced, proven class A/AB amplifier technology. The A 31 is built to extremely strict quality and performance standards for which Parasound is renowned. We’re proud to offer you this exceptional audio component that will[...]

5 Unpacking Your A 31 & Placement Guidelines Unpacking Your A 31 Carefully remove your A 31 from its shipping carton and locate the enclosed accessories: • AC power cord • Two trigger wires, one with 3.5 mm mini plugs, one with a 2.5mm and a 3.5mm mini plug While you are unpacking your A 31, inspect it thoroughly for possible shipping damag[...]

6 Rack Mounting Your Parasound A 31 To mount the A 31 into a 19" wide equipment rack, you must first attach its two “L” shaped rack mount brackets (included). With its four feet removed, the A 31 chassis and front panel height occupies four rack spaces (7" or 176 mm). W hen mounting equipment below the A 31, you will also need to allo[...]

7 Audio Connections Alw ays disconnect the AC cord to y our A 31 before making or changing any input, output or trigger w ire connections. Inserting or removing an input or output cable while the A 31 is turned on can result in a blast of sound that can damage your loudspeakers. Make sure there is no strain or tension on any cabl es that could caus[...]

8 Speaker Connections Speaker Terminals The A 31 speaker terminals accept speaker wires with banana plugs, spade connectors or bare wire. Refer to “Bare Wire Speaker E nds” in the Technically Speaking section for information about bare wire termination. Correct Speaker Polarity is Important Polarity refers to + and – connections. Speaker wire[...]

9 Gain Control Settings The Gain control knobs should be left at the 12 o’clock Normal/THX setting for most applications. When a Gain control knob is set to No rmal the gain for that channel is 29. This is the THX Ultra2 Reference Level where 1V input = 28.28V output. (28.28V driving an 8  speaker equals 100 watts.) If you are unsure where to [...]

10 Turn On Options For convenience, there are three wa ys the A 31 can be turned on and off: • Manually , by pressing the On-Off (Power) button on the front panel. • Automatically , when an audio signal is present at any of the audio Input jacks. • Automatically , when a suitable trigger voltage is applied to the 12V input jack. Note: When ei[...]

11 12 Volt Jacks 12V In Jack The A 31 12V input uses a 3.5mm jack (mono). To use the 12V trigger, insert the trigger wire plug into this jack and the plug at the wire’s other end into the AV receiver or preamp’s 12V output jack. We have included a 3.5mm to 3.5mm trigger wire as well as a 3.5mm to 2.5mm trigger wire. Note: If the controller’s [...]

12 Front Panel Operation On-Off Button Push once to turn on the A 31. When the A 31 is turned on the blue glow around the On-Off button will be brighter, the red P badge will glow brighter and then the 3 channel indicators will illuminate blue. Push again to turn off the A 31. The front panel On-Off button will be disabled when the Turn On Options [...]

13 Technically Speaking Balanced and Unbalanced Lines Recording and broadcast studios use bal anced 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 utilize balanced connections with XLR jacks for th[...]

14 1 . Your Cable TV or Satellite receiver box might require a Cable TV ground isolator. 2 . Use balanced input lines with your Pa rasound A 31. (See Balanced and Unbalanced Lines in this section). 3 . When rack mounting, always use the insu lated “shoulder” washers. These break the ground loops caused by metal-to-metal contac t between the rac[...]

15 times and under all conditions. It also reduces in ter-channel crosstalk that can blur the sound and impair the correct sense of where inst ruments, dialogue and effect are positioned. Each channel’s +/- 80 Vdc B+ and B- s upply rails use high-speed rectifier diodes and four enormous 8,200 uF electrolyt ic filter capacitors, chosen fo r their [...]

16 The Output Stage The amplifier’s sonic characteristics are es tablished by its input and driver stages. Now, the sole job of its output stage is to deliver the enormous current and voltage from its power supply to the speakers. Bipolar output transis tors are better than MOSFETS in the output stage because of their higher safe operati ng area [...]

17 Total Protection - Current Overload Specialized current-sensing transistors are connected to the output stages of the A 31 to constantly monitor the current flow through the output transistors. If the current drawn by this stage exceeds a predetermined safe leve l due to a load impedance below 1 ohm or a short circuit at the speaker terminals, t[...]

18 Are You Having Difficulty? Repair or Service Call your Parasound dealer first. If the dealer c an’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 easily perform. If we determine that your A 3[...]

19 Input Sensitivity for 28.28 V Output into 8 Ω Unbalanced: 1 V Balanced: 1 V per leg (Gain controls set to Normal / THX) S/N Ratio > 112 dB, input shorted, IHF A-weighted > 102 dB, input shorted, unweigh Damping Factor > 1100 at 20 Hz DC Trigger Requirements +9 Vdc to +12 Vdc, 2 mA Audio Trigger Requirements 2 mV AC - 10 mV AC XLR Pin [...]

20 Parasound Products, Inc. 2250 McKi nnon Ave, San Francisco, CA 94124 415-397-7100 / Fax 415-397-0144 www.parasound.com[...]