I'm seeing some unexpected behavior with the voltage-controlled fractional delay block in SigmaStudio. The processor I'm using is the ADAU1466 with a sample rate of 48kHz. The maximum delay in the block is 36000 samples (750ms at 48kHz).
When setting the input voltage to 0V using a DC source, I'm seeing a delay of roughly 615ms (should be 0ms). When setting the input voltage to 0.0625V (1/16V step size), I'm seeing a delay of roughly 662ms (should be 46.875ms) . Larger step sizes produce the expected delay. For example, 0.125V input produces 93.75ms delay, 0.250V input produces 187.5ms delay and so forth.
Can anyone else confirm this?
I created a small project to test this out. It works by counting up in steps of 1 (in 32.0) and subtracting the delayed value from the original value. I input various values to the delay (including 0, 1/16, 1/4, 1/2, and 1) and each value gave me the expected result.
Can you tell me more about your setup? How are you evaluating the delay block's functionality?