QSC Audio SRA 1222 manual

1 TD-000107-00 rev .A *TD-000107-00* Studio Reference Amplifier User Manual SRA SRA SRA 1222 2422 3622[...]

2 © Copyright 2002, QSC Audio Products, Inc. QSC® is a registered trademark of QSC Audio Products, Inc. “QSC” and the QSC logo are registered with the U.S. Patent and T rademark Office Speakon® is a registered trademark of Neutrik Inc., Lakewood, NJ IMPORT ANT SAFETY INSTRUCTIONS & EXPLANA TION OF SYMBOLS The lightning flash with arrowhe[...]

3 INTRODUCTION General Overview ..........................................................................................4 Illustrations.............................................................................5 UNP ACKING Unpacking and Inspection..................................................................................6 What is Include[...]

4 INTRODUCTION- General Overview Congratulations on your purchase of the SRA (Studio Reference Amplifier)Series power amplifier . T o help you obtain the best results from your purchase, we encourage you to carefully review this manual. With information including connections, configuration and operation, it offers many useful guidelines. Building u[...]

5 INTRODUCTION- Illustrations Front Panel (gain control security cover removed) 1- Power switch 2- Channel 1 gain control 3- Power “on” indicator Rear Panel 1- DataPort connector 2- Channel 1 RCA input connector 3- Channel 2 RCA input connector 4- Channel 1 XLR input connector 5- Channel 2 XLR input connector 6- Mode switches 7- XLR connector p[...]

6 The SRA amplifier is highly durable and carefully packaged. We recommend you inspect the unit carefully after removing it from the packaging, as occasionally there may be damage due to some unfortunate incident during shipment. Report any damage to the shipping carrier . W e recommend saving the carton and packing material in case the unit must b[...]

7 Rack Mounting 1- A #2 size cross point (Phillips) screwdriver . 2- The rack mount ears included with you SRA amplifier . T o attach the rack mounting ears, you will need: Dimensions shown are useful for non-rack mount installations. SETUP- Stand-alone mounting (cont’d.) Continued, top of next page..... Rack mounting the amplifier Rack mounting [...]

8 SETUP- Rack Mounting Dimensions for rack mount installations. Note: Some dimensions are taken from the front surface of the rack rail. Continued, from previous page..... 1- Remove the two screws holding the front panel end cap in place. Use a #2 cross point screwdriver (Phillips). 2- Place the rack mount ear as shown, aligning it so the screws wi[...]

9 SETUP- Supporting the rear of the amplifier If transporting the amplifier in a loaded equipment rack, support the rear of the amplifier using rear rack ears. They are optional and not included with the amplifier . QSC’ s T echnical Services Group has the rear rack ear kits for sale. The rear ear kit mounts two ways (shown below): - using machin[...]

10 SETUP- Removing the Gain Control Security Cover Gain Control Security Cover The amplifier is shipped with its gain controls at their maximum setting of +29 dB and a security cover installed to prevent tampering. T o adjust gain settings, remove the cover . Reinstall the cover to prevent unintentional changes. Removing the Security Cover 1- Using[...]

11 SETUP- Installing the Gain Control Security Cover Installing the Gain Control Security Cover 1- Slide the cover into the front panel recess. Push it fully to the right and against the front panel. Y ou should feel the cover’ s retaining tabs drop into the slot in the front panel. 2- While lightly pressing the right side of the cover against th[...]

12 SETUP- Cooling Requirements The amplifier has a rear -mounted variable-speed fan. Speed is determined by the temperature of the amplifier’ s internal heat sink assembly . Cooling air enters the rear of the amplifier and exhausts from the front vents. If mounting in an enclosure, be certain not to restrict airflow . Do not obstruct cooling air [...]

13 SETUP- AC Power Requirements AC Power V erify operating voltage before plugging amplifier into AC mains. Make sure the AC mains voltage is the same as specified on the serial number plate. Do not use a smaller gauge cord than supplied with the amplifier! 120 V olt models are sup- plied with a #14 A WG cordset. 220 V olt models are supplied with [...]

14 SETUP- Operating Mode Selection Stereo Mode Mode Switches The mode switches are located on the rear panel. The switches are recessed to prevent accidental changes. It is best to set the switches as re- quired before mounting the amplifier in an equipment rack as they may become difficult to access. Change switch positions by sliding the switch l[...]

15 Biamp Applications- Use Stereo Mode Stereo Mode Notes: •T o operate in stereo mode, set switches 4, 5, 6, and 7 to the left position. •Input connections: connect one input to CH1 and the other to CH2. Use the XLR or RCA connectors. •Output connections: using the binding posts or the Speakon connectors, connect CH1 and CH2 outputs to their [...]

16 Parallel Mode SETUP- Operating Mode Selection: Parallel In parallel mode, channel 1 and channel 2 XLR inputs are connected in parallel. Applying an input signal to either XLR input will drive both channels. Each channel still has independent gain control, clip limiting, and output connection, just like stereo mode. Do not use the RCA inputs if o[...]

17 Bridge Mode In bridge mode, both output channels are interconnected into one, higher power output. The result is one output with about 4 times the peak power and about 3 times the sustained power of a single channel. Use CH1’ s gain control, clip limiter , and LF filter . Use channel 1’ s XLR or RCA input. Output connection is different for [...]

18 SETUP- Clip Limiter CLIP LIMITER ON: T o turn the limiter on, slide the switch to the right (Sw .1: Ch.1, Sw .10: Ch.2). CLIP LIMITER OFF: T o turn the limiter off, slide the switch to the left. Clip Limiters The SRA has separate clip limiters for each channel which respond only to actual amplifier clipping. Amplifier clipping generates internal[...]

19 SETUP- Low Frequency Filter Channel 1’ s low frequency filter is operated by switches 2 and 3. Channel 2’ s filter is operated by switches 8 and 9. FIL TER ON: T o turn the filter on, slide the switch to the right (Sw .2: Ch.1, Sw .9: Ch.2). FIL TER OFF: T o turn the filter off, slide the appropriate switch to the left. 20 HERTZ: T o set the[...]

20 Audio Input Connections CONNECTIONS- Inputs, General Information Input connections to the SRA can be made with balanced XLR connectors for all operating modes, or unbalanced RCA connectors for Stereo and Bridge mode. We recommend using the balanced XLR connectors whenever possible. Unbalanced connections are prone to noise and interference picku[...]

21 XLR Connector Pinout CONNECTIONS- Inputs: XLR and RCA Connector Pinouts RCA (phono plug) Connector Pinout Balanced Unbalanced pin 2 pins 1 and 3 Jumper pin 2 pin 1 pin 3 Signal (+) Ground Daisy Chain Example (parallel mode only) All amplifiers being daisy chained must be in parallel mode. Input signal[...]

22 Connecting the Outputs to the Loudspeakers There are two basic speaker connection configurations for the SRA amplifier . Stereo and parallel modes use two separate output connections (two loudspeaker loads). Bridge mode uses one output connection (one loud- speaker load). Use either the binding post or the Speakon output connectors. Each connect[...]

23 CONNECTIONS- Outputs: Binding Posts Using the Binding Posts The binding posts support several connection methods; banana plugs, spade lugs, or direct wire connection. European models do not support the use of banana plugs. If using banana plugs, plug into the binding post directly . If using spade lugs, refer to the diagram, below , for acceptab[...]

24 Stereo and Parallel Mode output connections using binding posts Do not use less than 4-ohm loads in bridge mode! Note polarity of con- nections for bridge mode. Bridge Mode output connec- tions using binding posts CONNECTIONS- Outputs: Binding Posts Connect each set of binding post outputs to its respective loudspeaker . Maintain proper polarity[...]

25 CONNECTIONS- Outputs: Speakon connectors Speakon Outputs The Speakon connectors offer quick, reliable connection and disconnection of the speakers. Although more expensive than banana or spade-lug style speaker cable termination, the speed, convenience, and reliability make Speakon use popular with portable and live sound setups. The Speakons ar[...]

26 CONNECTIONS- Outputs: Speakon connectors Stereo or Parallel Modes Stereo and Parallel modes use one cable for each channel. Each cable con- nects to its respective output connector and speaker . CH1’ s Speakon can be used with a four conductor cable for carrying both outputs. The required signal splitting would take place at the speaker -end o[...]

27 CONNECTIONS- Outputs: Speakon Biamp Application Biamp Operation In biamp, one channel is used for lows, while the other channel is used for highs. It requires the use of signal processing equipment between the source material and the amplifier . Always test the system at the lowest practical power level for proper operation. Biamp-ready loudspea[...]

28 CONNECTIONS- Remote on/off (remote trigger) Remote turn-on and turn-off capability is provided by the remote trigger jacks on the rear panel. Remote trigger can be operated by two methods, 12 V olt DC or contact closure (switch, relay). The IN and OUT jacks can be used interchangeably as they are wired in parallel. The amplifier’ s front panel[...]

29 CONNECTIONS- Remote on/off (remote trigger) 12 VDC T ype 12 V olt DC Remote T rigger For 12 V olt DC remote trigger operation, use a mono (2 terminal) 3.5 mm mini-plug. Do not use a stereo (3 termi- nal) plug. Connect a suitable two- conductor cable to the plug. Connect the tip of the plug to the + (or positive) polarity wire and the sleeve to t[...]

30 CONNECTIONS- Remote on/off (remote trigger) Contact Closure T ype 12 V olt DC Remote T rigger For contact closure remote trigger operation, use stereo (3 terminal) 3.5 mm mini-plug. Do not use a mono (2 termi- nal) plug. Connect a suitable two- conductor cable to the plug. Connect the sleeve of the plug to one wire and the ring to the other wire[...]

31 CONNECTIONS- DataPort DataPort is located on the left side of the rear panel. A typical DataPort application shown with a program- mable QSC DSP-4 signal processor . The PC is required only for programming the DSP-4 and is not required to remain connected. The DataPort is a QSC-specific connection used for interfacing amplifiers, amplifier monit[...]

32 LED indicators. USE- Front Panel Controls and Indicators Gain Controls A gain control adjustment is provided for each channel. The voltage gain of the amplifier (in dB) is marked around each control. Rotating the control clockwise increases the gain applied to the signal. Rotating the control counter - clockwise reduces the gain applied to the s[...]

33 APPLICA TION EXAMPLE- 7.1 Surround 7.1 Surround Application The block diagram, at right, shows how SRA amplifiers might be connected in a 7.1 home theater applica- tion. The connections shown are simplified so as to convey the signal routing scheme. All amplifiers shown are operated in stereo mode. Amplifier inputs can be via the RCA or XLR conn[...]

34 TROUBLESHOOTING The amplifier “cuts-out” when I really crank it up (intermittent operation)- • Make sure the AC power source is rated for the required current! Avoid using extension cords! If required, use only the short est possible 10-gauge heavy-duty extension cords. • If the AC power source is “sagging” (or drooping) under heavy [...]

35 TROUBLESHOOTING I am using the amp for a subwoofer application and it sounds “rubbery”, what’ s up?- • V erify that the Clip Limiters are OFF . Why? The Clip Limiter is set to respond as quickly as possible after clipping is detected. On low frequency material, this may be perceived as a “rubbery” effect. It may be preferable to turn[...]

36 SRA1222 SRA2422 SRA3622 Output Power: (watts per channel, stereo/parallel mode) 8 ohms, 20Hz to 20kHz, 0.03% THD 200 425 725 4 ohms, 20Hz to 20kHz, 0.05% THD 350 725 1100 2 ohms, 1kHz, 1.0% THD 600 1200 1800 Output Power: (watts, bridge mode) 8 ohms, 20Hz to 20kHz, 0.10% THD 750 1550 2400 4 ohms, 20Hz to 20kHz, 0.10% THD 1200 2400 3600 Output ci[...]

37 SPECIFICA TIONS- SRA Series Specifications subject to change without notice! ALL MODELS V oltage gain: 28× (29 dB) Controls: Front- AC switch, Recessed Ch. 1 and Ch. 2 gain knobs Rear - DIP switch (Ch. 1: clip limiter on/off, LF filter on/off, LF filter freq select—20 or 50 Hz; Ch. 2: clip limiter on/off, LF filter on/off, LF filter freq sele[...]

38 Disclaimer QSC Audio Products, Inc. is not liable for any damage to speakers, or any other equipment that is caused by negligence or improper installation and/or use of this amplifier product. QSC Audio Products 3 Y ear Limited Warranty QSC Audio Products, Inc. (“QSC”) guarantees its products to be free from defective material and / or work-[...]

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40 QSC Audio Products, Inc. 1675 MacArthur Boulevard Costa Mesa, California 92626 USA “QSC” and the QSC logo are registered with the U.S. Patent and T rademark Office. ©2002 QSC Audio Products, Inc.[...]