Focus Fidelity Filter Designer

[Focus Fidelity]

Also please ensure when using the USB connection that you have the Devialet drivers installed, if you don't it'll be using the default windows drivers which work fine for most things but not for Impala.

[markush]

It‘s great to see some new things coming like a MacOS version.
As well as clock drift correction in Impala.

[Confused]

It‘s great to see some new things coming like a MacOS version.
As well as clock drift correction in Impala.

Do you have any details of the clock drift correction planned for Impala? After a very quick search on the 'net I cannot find anything.

I believe that there can be an issue related to the clocks in the built in DACs of USB microphones. Is it related to this, or maybe something else?

[markush]

I am in direct exchange with David but others know too. You might read the last few posts at https://community.roonlabs.com/t/a-guide.../90990/123

It will greatly improve measurements with mics like UMIK etc.

[Focus Fidelity]

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.

[markush]

Hi @Focus Fidelity

thank you very much for the insights. Keeping fingers crossed to see the new release soon and to experience another improvement.
The Focus Fidelity Designer has made such a difference to my sound quality, I cannot imagine ever going back.

Btw: when taking measurements with the UMIK in Impala is there a „recommendation“ what positions to take, meaning what might yield the best data for FFD and creating a filter.

[Focus Fidelity]

Hi @markush ,

Thank you for the feedback, always appreciated.

My recommendations for microphone positions,
The first measurement you will perform is at the main listening position. This position is the “sweet spot” of the listening area where you would typically sit for critical listening. The microphone should be at the height your ears would be.
You should arrange the remaining positions symmetrically around the main listening position with variations in height.
The measurement positions should cover the intended listening area, for example, the width of a sofa.
You can use a tighter spacing between the measurement positions for a single-seat listening arrangement.
There is no exact science to positioning the microphone; however, a total of 8 to 10 measurements will provide enough data.

[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.

[Focus Fidelity]

Hi @Confused

A professional audio ADC/DAC device with a single clock is the best setup. However, almost all users already have a USB microphone and simply want to use the DAC that they already have, so a software solution is required for that hardware combination with its two independent clocks.
The beta version of the clock drift correction in Impala is looking good.

Kind regards,
David

[markush]

Amazing, @Focus Fidelity has released the new version of Impala and Focus Fidelity Designer with the new clock drift feature: https://www.focusfidelity.com/clockdriftcorrection