I was trying to make a subtractive-delay crossover (i.e. Lipshitz - Vanderkooy type) in Sigma studio using a Butterworth lowpass, the "Signal Subtract" (from Basic DSP/Arithmetic Operations) and a delay.

The derived highpass wasn't a highpass at all - it was looking like a low-shelf filter. Just as if the subtractor wouldn't subtract but add the signals instead ! I then replaced the subtractor with the "Signal Add" function and the result looked exactly the same ! I.e. my assumption is that the "Signal Subtract" doesn't do what it is supposed to - it does rather add than subtract.

I then inserted a "Signal Invert" before the adder stage - et voila: The crossover worked exactly as it should.

Is there a known problem with the "Signal Subtract" in Sigma Studio 3.4, build 0, Rev 724 ?

Regards

Charles

Hi Charles:

I just checked and I believe you are correct, the substraction calculation of the Transfer function is not correct. It is inverted. You see, the assembly code and the calculation of the transfer function (simulation) are calculated separately. This bug definatively escapted.

This will get solved in the next version of SigmaStudio.

Best regards

Miguel