QA451 Programmable 8/4 Ohm Load

17-Jun-2025: The QA451 is out of stock and has reached end of life due to availability issues with the load resistors. At some point there will be a replacement product. The QA451 and QA451B (collectively referred to as the QA451) are the replacement products for the QA450. The QA451 is designed for high-speed testing of amplifiers. If you are testing at the module level (with modules designed for single supply operation), the QA451 allows the on/off control and current measurement of the supply rail. If you are testing finished amplifiers (eg amplifiers that plug into a wall), then the QA451's programmable loads can enable fast automated testing when combined with the QA40x audio analyzer. The QA451 also offers a 6th order low-pass filter (Fc=67 kHz) to help with testing modern class D amplifiers. The block diagram of the signal chain, from the balanced load inputs to the outputs is shown below. There are three key features performed by the QA451. First, the balanced signal is attenu