Thanks for your answer.
VirtinsTech wrote:Adding dither to a signal with an absolute amplitude specified on the signal generator panel may cause inaccuracy in the specified absolute amplitude under certain conditions, e.g. [absolute amplitude] + [dither strength] > full scale and make things on MI complicated.
I understand that.
The level can be somehow approximative then.
That's an acceptable drawback if you consider the benefits though.
VirtinsTech wrote:The best place to add dither in MI is still through multitone configuration where relative amplitude ratio of the original signal and dither can be readily specified.
I'd have no problem with this IF I could make the Multitone without spectral leakage.
VirtinsTech wrote:The Multitone function of the signal generator allows up to 200 tones to be added together in each channel. It would have been impossible to generate such a stereo signal continuously in real time on an ordinary computer if we had not limited the frequency of each tone to integer values.
OK, I didn't consider that point. I understand.
But
this is a MAJOR drawback.
Would it be possible to allow float values with a more limited number of tones (say 40) ?
I don't know how to deal with that, but that would really be a major lock removed for me.
VirtinsTech wrote:Also, it is impossible to avoid spectral leakage for a multitone consisting of more than one component, unless all the frequency components in the multitone are harmonics of a common fundamental frequency.
Strange. (Or maybe I don't understand it ?)
It seems I can create composite signal without spectral leakage for 2 or even 32 tones without them to have to be harmonics of a common fundamental frequency.
That's what Audio Precision does for their 32 tones Multitone, as an example, and they use that characteristic to even retrieve the noise from the bins where they know for sure there can't be any harmonics.
(See
https://www.ap.com/technical-library/using-multitones-in-audio-test/)
![AP Multitone.PNG](./download/file.php?id=272&sid=2c6c43c9abaa6e71950490a04828e956)
- AP Multitone.PNG (19.39 KiB) Viewed 31336 times
VirtinsTech wrote:The WaveFile function of the signal generator does not add dither. It allows the alteration of the original samples through resampling, rescaling, masking, fading, modulating. It is not designed to keep the file bit perfect.
OK, I can live with that.
I can just run the file at the next bit depth level if needed.