How To Make Land Metal Detector Headphone Operation Cordless - Tutorial, p. 2

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While considering a choice of a Universal Wireless-Headphones System to be used with your metal detector, make sure that this system satisfies all the below-mentioned criteria.

While selecting a proper wireless headphones for your setup, it is important to make sure that the digital wireless headphone system satisfies the following criteria:

1. The system transmits uncompressed audio over a robust 2.4 GHz digital link.

2. The system is based on Kleer technology that provides full lossless audio, a reliable connection, resistance to interference, longest battery life, and do not occupy the bands used by wireless LANs (local area networks).

3. The system does not require any tuning or special set-up - you simply turn it on, plug it into your metal detector and begin searching for treasures.

4. The system can use NiMH rechargeable batteries of AA and/or AAA types and has a charger that can charge the batteries in both the headphones and transmitter simultaneously. A few additional sets of fully charged NiMH batteries will provide for a few days of wireless operation during your long-distance metal detecting trips.

5. Headphones should be circumaural (also known as full-size headphones, over-ear headphones and ear cup headphones), i.e. have comfortable closed around ear cushions to provide comfort during long-hour hunts, adjustable headband for a secure fit and volume controls. But even if you select headphones of a different type like the "ear clip" type, for instance, make sure that the headset does not slide off when you bend over or make moves during target recovery.

6. Portable transmitter must be compact, have a volume control to protect your hearing when "audio overload" occurs (a large target is detected), and be also able to use NiMH rechargeable batteries of either AA or AAA types.

There are many digital wireless headphone systems that incorporate Kleer technology on the market. And, of course, some of them can be successfully used with metal detectors. I had a simple reason to select the Sennheiser Digital Wireless RF (Radio Frequency) Headphone System RS-160 after doing a little research on the web: this was the only system available in my area at the moment. And this system satisfies all the above-mentioned criteria and works well with the Minelab E-Trac metal detector which uses stereo phone jack. If it was mono, I would simply use a stereo-to-mono adapter.

Below are Specifications for Sennheiser Digital Wireless Headphone System RS-160, its headphones and power source:

RS 160 System:

• Modulation: MSK digital
• Carrier frequencies: 2.4 – 2.48 GHz
• Operational Range: approx. 65 feet (20 m) in the open area
• Ambient temperature: 32 °F to 104 °F (0 °C to 40 °C)

HDR 160 headphones:

• Transducer principle: circumaural, closed
• Max. SPL: 106 dB (SPL)
• THD: <0.5% at 1 kHz, 100 dB SPL
• Frequency response: 18 Hz – 21,000 Hz
• Impedance: 32 Ohms*
• Charging time of rechargeable batteries: approx. 16 hours
• Power supply: 2 AAA size NiMH rechargeable batteries, 1.2 V, 800 mAh
• Operating time approx.: 24 hours
• Weight: (without batteries) approx. 226 g

* - even though the HDR-160 headphones' impedance is lower than impedance of most headphones designed for metal detecting, the sound quality does not differ much and is sufficient enough for operation of a "tonal" metal detector such as the Minelab E-Trac.

SSA-4P 5050F power supply unit:

• Multi-country use: four plug-adapters to use with the EU, UK, US and AU wall sockets (electrical outlets)
• Rated input: 100 – 240 V~, 0.2 A, 50 – 60 Hz
• Rated output: 5 V , 500 mA
• Operating temperature range: 32 °F to 104 °F (0 °C to 40 °C)

The headset has both an On/Off button (multi-functional button) and volume controls on the right earcup.

Each ear cup is powered by one AAA battery that is inside and can be easily accessed by turning an ear pad in a direction indicated by an arrow and detaching it from the ear cup.

In comparison with the metal detector's regular corded headphones, for example, Koss UR-30, the Sennheiser HDR-160 headset (without batteries) is lighter (226g against 406g) and has much tighter and comfortable fit. The only disadvantage of the HDR-160 headset is that it is not as water-resistant as the UR-30 or any other headphones that are especially designed for metal detecting.

Because the HDR-160 headset was designed primarily for the INDOOR usage, it must not be exposed to rain or snow. There are two ways to solve this problem: you can either hermetically seal all vital parts of headphones (this time-consuming procedure is out of scope of this tutorial) or simply put your rain jacket's hood up while metal detecting in wet weather. The headset is not too big fit under.

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