Driveflex Power Amplifiers

Driveflex amplifiers are compact yet powerful, with the performance required to support Fulcrum’s advanced DSP while remaining efficient and easy to deploy. With amplifier control built into Fulcrum One software, Driveflex simplifies design, setup, and monitoring to ensure that every Fulcrum system performs at its highest level. Use of Driveflex amplifiers in a system brings many advantages including the availability of Array Optimization and advanced limiting techniques to your Fulcrum Acoustic loudspeakers.

Links

• Specifications
• Safety & Regulatory
• Driveflex Series Product Manual
• Operation in One Software
• Array Optimization
• Mechanical Drawing (.dwg)

Available Models

Maximum output power per channel for symmetrical loading based on nominal load impedance:

Setup and Operation

The Driveflex Series Product Manual provides detailed instructions for setting up and operating Driveflex amplifiers. We recommend becoming familiar with this information and the recommendations below before integrating a Driveflex amplifier into a system.

The Fulcrum One software platform is used exclusively to configure, control, and monitor Driveflex amplifiers over a standard computer network. Click here to learn more about using Fulcrum One software with Driveflex amplifiers.

Processing and Gain Structure

Driveflex amplifiers are designed to work seamlessly with Fulcrum Acoustic loudspeakers, providing optimal performance and reliability. The integration of Driveflex amplifiers with Fulcrum's advanced DSP technology ensures that every system is fine-tuned for the best possible sound quality.

By default, each Driveflex amplifier is configured with an output stage voltage gain of 32 dB, which is optimized for each Fulcrum loudspeaker processing preset. While this may be changed by the user via a rear panel DIP switch, it is recommended to leave the default gain setting for best performance. When set to this default gain, each Fulcrum loudspeaker preset has been optimized such that the rated maximum power handling for at least one loudspeaker component is reached when the amplifier is driven with an analog input level of +8 dBu (1.95V RMS) using pink noise (with no additional gain adjustments made by the user).

Dante™ digital input levels are calibrated such that a Dante input level of -22 dBFS (true peak) corresponds to an analog input level of +0 dBu (0.775V RMS) using a sine wave test signal (3 dB crest factor).

Standard 8Ω/4Ω Loads

For most Fulcrum loudspeakers, the recommended mode of operation is standard 8Ω or 4Ω operation. In this mode, each amplifier channel drives a single loudspeaker or set of speakers connected to its output terminals with the nominal connected impedance on each channel not less than 4Ω. The amplifier should be selected with sufficient power to drive the loads connected to each channel. Loads should be connected "single-ended" and 70V/100V channels or bridged channel pairs may be mixed in, but no 2Ω loads should be connected at all. Connect wiring as shown:

4-Channel Models	2-Channel Model

Ensure the rear-panel DIP switch for all relevant channels is set to the default lo-Z position (all models) and that the global 2Ω switch is OFF (for models 46, 424 and 232). This is the default setting for all Driveflex amplifiers:

Bridging Outputs

Driveflex amplifier channels may be bridged, which allows for higher power operation by doubling the available output voltage. Bridging should only be used with 8Ω or 4Ω loads and the amplifier DIP switches should be set up matching that of a standard 8Ω/4Ω load. The gain structure of bridged channels is managed to automatically match non-bridged channels. Bridging is controlled in Fulcrum One software by joining channels in the amplifier's properties panel:

Bridged channels should be wired as follows:

4-Channel Models	2-Channel Model

2Ω Loads

Driveflex amplifiers can be configured for 2Ω operation, allowing for lower-impedance loads at the cost of reduced maximum peak voltage. This is primarily useful when coupled with Fulcrum's 2Ω subwoofer models.

When using Driveflex 46, 424 or 232 models in 2Ω mode, the rear-panel global DIP switch must be set to ON. The Driveflex 412 model does not have a 2Ω DIP switch and can support 2Ω loads without any additional configuration.

70/100V Modes

Driveflex amplifiers can be configured for 70V or 100V operation, allowing for long cable runs and multiple loudspeakers to be connected to a single channel. When using 70/100V mode, the rear-panel DIP switch for each relevant channel must be set to the 70V or 100V position and the hardware high-pass filter engaged for that channel. An example 70V channel configuration is shown below:

When using 70/100V modes, it is best to select and pair loudspeakers in Fulcrum One that are explicitly configured for 70V or 100V operation (typically -MT models).