LF-3

Low-frequency filter with delay

Status:

Discontinued

Role:

Project Lead Engineer. Responsible for all circuit design, system architecture, layout and coordination with mechanical, Product Development (PD) and New Product Introduction (NPI) teams to assure product meets performance, cost and scheduling targets.

Description:

One of three models in a family of cinema crossover accessories designed for QSC’s DCA Digital Cinema Amplifiers. These products were designed to interface with the Display Port on the rear of the amplifier, replacing the native inputs and drawing its power from the same port. The LF-3 shown here utilizes a 4th order Linkwitz-Riley low pass filter, level shifting and delay.

Innovations:

A truly unique design element is the use of a high order State Variable All Pass filter in the delay circuit. The circuit parameters were painstakingly worked out in Mathcad to realize the desired all pass Bessel transfer function while being parametrically tunable with four equal value resistors. In this way a 4-element, 8-pin SIP resistor network could be used to set the delay. To my knowledge, the design and tuning of a State Variable All Pass in this way was a unique innovation which had not existed previously.

Company

services

product history

Linkedin Instagram Facebook Twitter Google-plus