User manual NUMARK SA9500

[. . . ] Owner's Manual SA3000/SA5500/SA9500 Amplifiers ©1997 Numark Industries 2 http://www. numark. com SAFETY FIRST! WARNING - TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK, DO NOT EXPOSE THIS APPLIANCE TO RAIN OR MOISTURE. If water or other liquids are spilled on or into this unit, unplug the power cord immediately from the wall socket (with DRY HANDS) and get a qualified service technician to check it out before using. Keep this unit away from heaters, radiators and other heat producing devices. ONLY A QUALIFIED SERVICE TECHNICIAN SHOULD OPEN THIS UNIT FOR SERVICING. CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN The lightning flash with arrowhead symbol within an equilateral triangle is intended to alert the user to the presence of uninsulated 'dangerous voltage' within the product's enclosure that may be of sufficient magnitude to constitute a risk of electric shock. [. . . ] However, both channels can be configured to drive a single load with a single signal at twice the power. put one speaker of not less than 4 ohms impedance across the red (+) output terminals of the amplifier http://www. numark. com + tip - ring sleeve gnd 7. Balanced Barrier Strip Inputs These connection points provide the best option for permanent or long term installation. Connections should be screwed down tightly to exclude oxygen, and care should be taken to avoid loose strands of wire that may cause short circuits. + - GND - + 8 ©1997 Numark Industries 3. ensure that there is only one input signal connected to channel 1 of the amplifier - channel 2 input must be vacant 4. switch the amplifier to bridged mono (back panel switch) 5. turn the gain down and turn on the amp 6. verify operation at low gain, and then increase power to desired level, ensuring that the gain controls on each channel are set equally. IMPORTANT: NEVER SWITCH BETWEEN STEREO AND BRIDGED MONO OPERATION WHEN THE AMPLIFIER POWER IS ON. Limiter On / Off Switch In cases where a dedicated compressor / limit unit precedes the SA5500, some users may seek to disable the on board limiting. Sliding the switch to the off position removes the limiting from both channels of the amplifier. ©1997 Numark Industries 9 http://www. numark. com Audio Terms Gain This is the factor by which an input signal is amplified (increased) or attenuated (reduced) when passing through an amplifier. Gain is generally measured in decibels (dB) which is a logarithmic ratio of input to output. Unity or zero gain means that the signal comes out at the same level that it went in. With all this gain available, it may seem tempting to turn the amp up to full to get the loudest sound possible. And why is it that smaller amps have roughly the same gain even though they are less powerful?The answer is that an amp can only amplify up to a certain point, which depends on its power rating. Past this point, the output just distorts in what is called clipping. The peaks of the signal are `clipped' as they exceed the limit. max+ Hum and Buzz Hum typically is a lower pitched sound of around 50 or 60Hz, depending on the AC supply. If the hum or buzz is very loud, this is generally caused by bad connections - check cables and plugs for faults. Lifting the Ground In other cases, a ground conflict between the chassis and the circuit ground can induce hum. This happens when a magnetic field induces a small voltage in the casing of the amp, making it slightly different in potential from the circuit ground. This hum sounds more subtle than it would be for a bad connection and is generally ignored. If your environment requires the highest quality sound, it may be eliminated by `lifting the ground'. [. . . ] The combined voltage across the terminals is then twice what it would be between a positive terminal and speaker ground (0 V). This is like two cars driving towards each other at 50mph; the relative speed between the two is actually 100mph. Note that in this way, a load of twice the impedance can be driven at twice the power compared to stereo operation (see specifications). In order to configure your Numark amplifier for bridged mono operation, follow the instructions listed under bridged mono, 10 in each amplifier's description (front half of manual). · · The difference that these factors can make is significant. [. . . ]