BT-Pro™ Using & Applications

The following is a short 'how to approach the BT-Pro DI'. For more information, we invite you to download the manual. (PDF download)

Making Connections

Before making any connections, always ensure your audio system is either turned down or turned off in order to protect more sensitive components from damage caused by loud turn-on or plug-in transients. The BT-Pro uses a USB Mini-B connector and cable for its power requirements. Use the included 'Mini-B to TYPE A' USB cable and connect to a computer, USB hub or the included USB wall charger. You may also use any standard USB wall charger that is included with most phones and tablets, as the BT-Pro will only draw a small amount of current.

BE SURE THAT THE BT-PRO IS TURNED OFF BEFORE CONNECTING THE POWER CABLE to avoid initial intermittent power spikes to the electronics.

IMPORTANT NOTE: Feeding 48V phantom power to the BT-Pro can damage the unit if the protective transformers are not inserted into the signal path. Ensure that you turn off phantom power for the channels connected to the BT-Pro. If only a global phantom power switch is present, then make sure the transformers are inserted!

Connecting the BT-Pro to your audio system is done using two XLR cables. This follows the AES standard with pin-1 (ground), pin-2 (+), and pin-3 (-). These XLRs can be connected to mic or line level inputs.

Once you make the connections, turn up the audio system. It is good practice to always test at a low volume. Due to the analog circuitry in the BT-Pro, it is susceptible to interference in environments that may have high levels of ambient RF energy. To remedy this situation both of the ISO switches may be set to ON (right) and the GROUND LIFT switch set to LIFT (in). This will reduce the level of interference, but in some cases may not totally eliminate the issue.

Headphone output

It is important to note that there is a very loud headphone output built into the BT-Pro that enables professional grade, low sensitivity headphones to be used. Make sure you always set the level completely off (fully counter-clockwise) before using. Adjusting the level control on the BT-Pro will affect both the XLR and headphone output. The headphone amp is not actually intended for listening – it is for testing to ensure the signal is being processed by the BT-Pro and being properly output by the DAC (digital to analog converter). If you do not hear sound in the PA, this lets you know that the problem is likely not the BT-Pro but maybe another connection or that a piece of equipment needs to be checked.

Headphone Safety Warning Caution: Very Loud Amplifier

As with all products capable of producing high Sound Pressure Levels (SPL) users must be very careful to avoid the hearing damage that may occur from prolonged exposure. This is particularly important as it applies to headphones. Prolonged listening at high SPLs will eventually cause tinnitus and can lead to partial or complete loss of hearing. Please be aware of the recommended exposure limits within your legal jurisdiction and follow them very closely. The user agrees that Radial Engineering Ltd. remains harmless from any health effects resulting from the use of this product and the user clearly understands that he or she is entirely responsible for the safe and proper user of this product. Please consult the Radial Limited Warranty for further details.

Bluetooth® pairing

Once the BT-Pro is connected to a power supply, a blue LED on the top of the unit will illuminate. At this point you can turn the RESET/ON switch to the ON position, and the BT-Pro will be available to pair with Bluetooth devices. Check the available devices on your Bluetooth enabled playback source; the BT-Pro should appear in the list as 'Radial Eng'. Once you select the BT-Pro, your plackback device should prompt you for a password. The password is 1246. Once initially paired, the BT-Pro automatically converts the streaming audio to analog for connection to a variety of systems. Your device should automatically reconnect on future sessions, as your smartphone does in your car.

  1. Make sure the BT-Pro volume control is turned fully counter clockwise.
  2. Enable Bluetooth pairing on your Bluetooth enabled device.
  3. Connect your BT-Pro to power, a blue LED on the top of the unit will indicate that it is receiving power.
  4. Turn on the BT-Pro to enable Bluetooth pairing.
  5. Blue and red LED's will alternate showing the BT-Pro is in search mode for pairing.
  6. Your Bluetooth device will identify the BT-Pro as 'Radial Eng' in the Bluetooth devices menu.
  7. Select the BT-Pro in your Bluetooth devices menu.
  8. Your Bluetooth device will then ask for a first time password for the BT-Pro. Type in: 1246.
  9. Once your Bluetooth device has paired with the BT-Pro, the blue LED will flash once every three seconds. When audio is playing, the blue LED will flash three times quickly every three seconds.

Once your Bluetooth device has been paired to the BT-Pro, the BT-Pro will automatically pair to the same Bluetooth device when the BT-Pro is turned back on in range.

Going out of range

If your Bluetooth device loses line of sight or goes out of the range of your BT-Pro (greater than 12 meters), the device playback will pause and the blue LED on the BT-Pro will slowly blink to show the unit is in 'Stand-by' mode. Once the device is back in range, the BT-Pro will automatically reconnect to continue playing back audio from your Bluetooth device. Stand-by mode will not allow another Bluetooth device to pair with the BT-Pro. If your Bluetooth device goes out of range from the BT-Pro for more than two minutes, or if you want to connect a different Bluetooth device for playback, you will need to reset the BT-Pro. This is done by turning the RESET/ON switch off and back to on.

The BT-Pro allows for reception distances of up to 12 meters (40'), which can be significantly extended under ideal conditions. Should you experience interference or signal dropouts, ensure that there is a clear line of sight between the BT-Pro and your Bluetooth device. You can also adjust the angle and placement of the BT-Pro, as this may also affect the reception.

NOTE: If you're using a computer with a USB Bluetooth dongle, some pairing features may not be automatically available. Please refer to your dongle's software manual for instructions on how to activate these features.

Testing and Using

First, set the BT-Pro's LEVEL control to the 7 o'clock (off) position. This will allow you to adjust the output level on the fly. Next, check the status of the MONO SUM switch and LED indicator. For stereo, set the switch to the outward position (LED off). For dual mono operation, set the switch to the inward position (LED on).

It's a good idea to start testing the Bluetooth audio with a sound file you are familiar with. Set your source's output level and the level of the media playback software (if applicable) at 80% or higher for optimal signal to noise. A higher volume from the source will allow the BT-Pro to operate at the lowest noise floor. Keep in mind that various media files will play back at different volume levels depending on your software and how the sound file was recorded.

Slowly raise the output level of the BT-Pro. It is good practice to always test at a low volume to ensure proper connections have been made and all devices in the signal chain are set up correctly and working. This way, should a device not be turned on or a connection not fully made, it will not create a loud transient 'pop' in the PA that could damage a tweeter or annoy your audience. When satisfied, slowly increase the input gain on your mixing console until you reach an appropriate level.