of RF interference and plan for them before you begin construction. Know the frequency, transmitter power, etc. You can get this information by calling the station. Remember that many broadcast stations change the antenna coverage pattern and transmitter power at night.

11.Don’t use hardware-store light dimmers.

12.Don’t allow for anything other than micro- phone inputs at stage/altar locations. Supplying line inputs at these locations is an invitation for misuse. Make all sources look like microphones to the console.

13.Balance (or at least impedance balance) all connections that are remote from the console’s immediate location.

14.If you bridge an amplifier, don’t use 1⁄4" phone plugs for speaker connectors.

Grounding

Grounding exists in your audio system for two reasons: product safety and noise reduc- tion. The third wire on the power cord exists for product safety. It provides a low-resistance path back to the electrical service to protect the users of the product from electrical shock. Hopefully, the resistance to ground through the safety ground (third wire) is lower than that through the user/operator to ground. If you re- move this connection (by breaking or cutting the pin off, or by using a ‘ground cheater’), this alternate ground path ceases to exist, which is a safety hazard.

The metal chassis of the product, the ground connections provided by the various connectors, and the shields within your con- necting cables provide a low-potential point for noise signals. The goal is to provide a lower im- pedance path to ground for noise signals than through the signal wiring. Doing so helps minimize hum, buzz, and other extraneous non-audio signals.

Many “authorities” tell you that shields should be connected only at one end. Some- times this can be true, but for most (99%) audio systems, it is unnecessary. If you do ev- erything else correctly, you should be able to connect every component of your audio system using standard, off-the-shelf connecting cables that are available at any music store.

Here are some guidelines:

1.Use balanced lines if at all possible. They provide better immunity to induced noise and ground loops. Remember that you can balance a line by inserting in-line a piece of equipment that has a balanced output.

2.Avoid using three-phase power lines since they are usually used for air conditioning and other heavy power equipment. If using 240VAC single phase with center-ground power, connect all audio equipment to one side of the AC power, and all lighting and other equipment to the other side.

3.Be sure all AC outlet safety grounds are connected to one common point in a star ground arrangement. This common ground point should then tie back to earth ground at the service entrance by one heavy stranded wire, #2 gauge or larger.

4.Don’t cut the third pin off the power cord. Carry some ground-lifter adapters and use them only if you have to plug into an ancient two-wire outlet.

5.Cables that are too long are less likely to pick up hum if you uncoil them in their entirety, and then find a place to stow the excess. Leaving the excess coiled only helps the cable pick up hum more efficiently.

6.If you bundle your cables together, don’t bundle AC wiring and audio wiring to- gether. Bundle them separately.

7.If your sound system insists on humming, you may need to teach it the words.

Optimizing Sound System Levels

In a full-blown (not fully blown) sound system, the signal level can be controlled or adjusted at many different points throughout the signal chain. The best system performance is achieved when the dynamic range of the system is maximized, thus reducing noise and allowing a nominal signal level to be used with maximum headroom. Whatzat!?

Dynamic range is the difference between the noise floor and the maximum undistorted signal level capability of the component. The greater the dynamic range, the better the sig- nal to noise ratio, because the nominal signal level can be set at a higher amplitude and the noise tends to get buried underneath the sig- nal. Headroom is the difference between the maximum undistorted signal level capability of

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Mackie M1200/M1400 owner manual Grounding, Here are some guidelines, Optimizing Sound System Levels

M1200/M1400 specifications

The Mackie M1200 and M1400 are two prominent power amplifiers that have gained recognition for their reliability, performance, and innovative design in the professional audio field. Engineered for both live sound and studio applications, these amplifiers deliver exceptional sound quality and unmatched power, making them a favorite among audio professionals.

One of the standout features of the M1200 and M1400 is their impressive power output. The M1200 boasts a power output of 1200 watts at 4 ohms, while the M1400 takes it a step further with 1400 watts at 4 ohms. This substantial power allows users to drive a wide range of speakers, making them suitable for various settings, from small clubs to large venues and outdoor events. Furthermore, they excel in providing clean, distortion-free sound even at high volumes.

Both models incorporate Mackie's patented Smart Protect DSP technology. This intelligent thermal and signal protection system helps prevent overheating and ensures that the amplifiers operate within safe limits, enhancing longevity and reliability. The DSP also contributes to superior sound quality, maintaining clarity and detail across different frequency ranges.

Another key feature of the M1200 and M1400 is their rugged construction. Designed for the rigors of touring and live performances, these amplifiers feature a sturdy chassis that withstands the challenges of transport and heavy use. Their efficient heatsink design allows for effective cooling, ensuring the amplifiers remain operational even under demanding conditions.

In terms of connectivity, both models are versatile. They offer XLR and TRS inputs, allowing compatibility with a variety of audio sources. The outputs include Neutrik Speakon connections, providing secure and reliable speaker connections. Additionally, the amplifiers have built-in limiters that help to prevent speaker damage by controlling signal levels.

The user-friendly interface of the M1200 and M1400 includes level control knobs, LED indicators for power and signal, and a comprehensive set of output options. This simplicity ensures that audio engineers can quickly adjust settings to cater to specific acoustic environments, making setup and operation seamless.

In conclusion, the Mackie M1200 and M1400 power amplifiers are remarkable for their powerful performance, durability, and advanced technology. Whether for live sound reinforcement or studio applications, these amplifiers continue to set a standard in audio excellence, proving their worth to sound engineers worldwide.