Initial Wiring Considerations

For optimum performance, it is essential for the earthing system to be clean and noise free, as all signals are referenced to this earth. A central point should be decided on for the main earth point system, and all earths should be 'star fed' from this point. It is common electrical practice to `daisy chain' the earths to all electrical outlets but this method is unsuitable for audio installations. The preferred method is to run an individual earth wire from each outlet, back to the system star point to provide a safety earth screen reference for each piece of equipment.A separate earth wire should also be run from each equipment rack and area, to the star point. This may or may not be used depending on circumstances, but it is easier to install in the first place, than later when problems arise.The location of the star point should be a convenient, easily accessible place, preferably at the rear of the console or in the main equipment rack.

Install separate 'clean' and 'dirty' mains outlets, wired individually back to the incoming mains distribution box. Use the 'clean' supply for all audio equipment and the `dirty' supply for all lighting, etc. Never mix the two systems.

If necessary, to provide sufficient isolation from mains borne interference, install an isolating transformer. This should be provided with a Faraday Shield which must be connected with earth.

Never locate the incoming mains distribution box near audio equipment, especially tape recorders, which are very sensitive to electro-magnetic fields.

Ensure that all equipment racks are connected to earth, via a separate wire back to the star point.

Equipment which has unbalanced inputs and outputs may need to be isolated from the rack to prevent earth loops.

Audio Wiring

Having provided all equipment with power and earthing connections, consideration must be given to the method of providing audio interconnection and adequate screening of those interconnections. This must be done in a logical sequence to avoid problems and assist in the localisation of problem equipment.

Connect the FOH or Monitor system to the console and check for any hum, buzz, or RFI. Only when you are satisfied with the quietness of the console and the PA system should you proceed with the next step.

Connect stereo or multitracktape recorders, FX and foldback sends one at a time, checking and isolating any connection which degrades performance.

Connect all other peripheral devices.

Connect all microphone lines.

By following this sequence much time and future trouble will be saved, and the result will be a quiet, stable system.

Shielding

Audio equipment is supplied with a variety of input and output configurations, which must be taken into consideration when deciding where the screen connections should be made. There are three sources of unwanted signal being impressed on the screen, which are as follows:

Extraneous electrostatic or electromagnetic fields.

Noise and interference on the earth line.

Capacitive coupling between the screen and signal wires.

To minimise the adverse affects of the unwanted coupling to the signal wires, it is important that the screen is connected at one end only, i.e. the screen must not carry any signal) current. Any signal) on the wires within the screen will be capacitively coupled to the screen. This current will ultimately be returned to the source of the signal, either directly, if the screen is connected at the signal source end, or indirectly via the earthing system, if the signal is connected at the signal destination end. The indirect connection will cause an increase in high frequency cross-talk, and should be avoided wherever possible.

Therefore, in general, always connect the shield only at the signal source end. In high RF areas, the screen can also be connected to earth via a 0.01 mF capacitor. This will present a short circuit at RF frequencies, thus lowering the effective shield impedance to ground. However, at low audio frequencies the reactance of the capacitor will be sufficiently high not to cause an earth loop problem.

GB4 User Guide

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Harman-Kardon GB4 manual Initial Wiring Considerations, Audio Wiring, Shielding

GB4 specifications

The Harman-Kardon GB4 is a sophisticated outdoor speaker designed to enhance audio experiences in outdoor settings. It stands out for its combination of style, durability, and rich sound quality, making it suitable for both casual listening and more intense audio demands during outdoor gatherings.

One of the key features of the GB4 is its rugged design. Built to withstand the elements, it boasts an IP67 rating, which makes it dust-tight and water-resistant. This means you can confidently use the speaker in various outdoor environments, whether it’s a sunny day at the beach or a rainy evening on the patio. The robust construction is complemented by a sleek exterior, allowing it to blend seamlessly into outdoor decor while also making a statement of elegance.

The sound quality of the Harman-Kardon GB4 is another highlight. With advanced audio technologies, including the use of dual passive radiators, the speaker produces a rich and balanced sound that fills outdoor spaces beautifully. Whether listening to music, podcasts, or enjoying a movie night under the stars, users can expect clear highs, pronounced mids, and deep lows. The speaker's 360-degree sound projection ensures that the audio experience is immersive from every angle.

Connectivity is also a strong point of the GB4. Equipped with Bluetooth technology, it allows for easy pairing with a range of devices, including smartphones, tablets, and laptops. The connection is stable, which means you can roam freely while enjoying your favorite tunes without interruption. Additionally, the GB4 supports voice assistants, making it easy to control your music or access information hands-free.

Another innovative feature is its long battery life. The GB4 can provide hours of uninterrupted playback, making it a great companion for all-day picnics or evening gatherings. When it’s time to recharge, the process is quick and efficient, ensuring you won't be away from your music for long.

Overall, the Harman-Kardon GB4 encapsulates the perfect blend of durability, high-quality sound, and modern connectivity. It adds a touch of sophistication to any outdoor setting while delivering audio performance that meets the demands of music lovers and casual listeners alike. With its stylish design and advanced features, the GB4 represents a significant advancement in portable outdoor speakers, ensuring that wherever you go, your sound follows.