What is "Active Drive"?

Active Drive

Output stage for microphones developed by DPA.

Balancing the output of a microphone can be done with or without a transformer. The transformer provides a perfect balance. However, the impulse response of the microphone signal can be affected by various high-frequency losses and distortion in the transformer due to magnetic reluctance.

To obtain maximum transparency, the transformer may be avoided, but the output circuitry must be designed to retain the best possible balance throughout the frequency range from very low frequencies close to DC and up in the MHz-range. In the active drive design, a circuitry with zero output impedance is implemented. The absolute impedance of the output (pin 2 and 3) is then determined exclusively by the matched output resistors and the resistors by which the phantom power is provided.

It is a straight forward circuitry that provides the headroom needed for very dynamic signals.

Related Articles

DPA-Microphone-University-placeholder.jpg
Tech Talk

IMPEDANCE BALANCING WITH ACTIVE DRIVE VS. TRANSFORMER COUPLED OUTPUT

This article provides knowledge about the design principles of output stages for condenser microphones. Especially the advantages and disadvantages of transformer balancing and “Active drive”.

Read More
About-balanced-and-unbalanced-lines-L-1.jpg
Tech Talk

ABOUT BALANCED AND UNBALANCED LINES

Balanced lines provide better rejection of electromagnetically induced noise. This article explains the difference between signal balanced and impedance balanced lines.

Read More

Be the first to hear about our new products, workshops, events, contests, offers and more.

Subscribe
Loading