Focus Fidelity Filter Designer

[Confused]

Hi @Confused

Clock drift correction will be in the next release of Impala. It will improve the alignment between the left and right channels at the main listening position. Without the correction, the misalignment is likely to be very small, but including clock drift correction is still an improvement.
Clock drift results from using a DAC (to drive the speakers) and ADC (sampling the microphone signal) with independent clocks. The most typical case is when using a USB microphone. The microphone has a built-in ADC and clock to drive the ADC. This clock is independent of the clock in the DAC. While the clocks will be running at a standard sampling rate, say 48000 S/s, they will not be precisely 48000 S/s. Clock oscillator accuracy is specified in parts per million. If the clock in the microphone is 50ppm fast, it'll be running at 48002.4 S/s.
Similarly, the clock in the DAC may be running slow by some small amount.
I will provide more detail about all this with the next release.

Hi David

This is interesting. I have seen comments elsewhere that USB type microphones can be problematic with respect to clock drift. Notably, Mitch Barnett advocates the use of an analogue microphone with a professional ADC/DAC device that runs from a single clock. Whilst this makes perfect sense from a technical point of view, it does not really work with a Devialet amplifier where the DAC is an integral part of the amp. I guess you could use a decent quality ADC with an analogue microphone to minimise clock drift with a Devialet, but even this would not be perfect. It would also be quite expensive.

So minimising clock drift in Impala is a most welcome update, offering a practical low cost solution to the issue. 

Keep up the good work! It is appreciated.