Yes, the QA455 is the result of the work started at the first link below. The QA480 notch wasn’t balanced, and using two QA480 notches didn’t give the CMRR that was needed. While the QA480 has really good analog oscillator with 64 dB of atten in 1 dB steps, a modern DAC such as the Topping E70 Velvet can beat most analog oscillators anymore on everything except cost.
The QA455 also has a TX path for cleaning up a the analyzer output before it goes into a modern class D amp. This knocks any 2H down by 33 dB, and hammers the noise beyond 1 kHz (see block diagram at second link). The aim here is to deliver lots of margin for measuring a modern class D amp. And, as the E70 measurements above shown, it’s useful there too.
There are a few changes to the front panel shown below. The input atten on the RX side has 0, 12 and 18 dB atten. This should allow measurement of 400W class D (using external load). There are pushbuttons on the front panel to cycle through all the options.
No idea on date.
