Voltage Controlled Delay Blocks

lyounkins Question

Feb 24, 2020 00:00

There are two voltage controlled delay blocks in SigmaStudio, one for integer sample delay and another for fractional sample delay.

What are the input formats for both blocks? The integer delay version can be set to samples or ms. Is the input format the same for both settings?

Thanks,
Larry Y.

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DaveThib Reply

Feb 24, 2020 00:00

Hello Larry,

Let's talk about these one at a time.

You did not ask about the standard delay cell. But I will start there.

The standard delay block has the ability to change to milliseconds or samples. This is all done in the GUI and not in the DSP. It is for your convenience. If you watch the capture window as you change the current setting you will see this in action. In the DSP the parameter is always in samples. That is the only way the DSP knows how to time things. So if you enter 100 samples you will see it write a 100 to the DSP. If you change the setting in the GUI to milliseconds, then enter 10ms you will see the number 480 being written to the DSP. This is because the project is setup for 48kHZ and 10ms of samples is 480 samples. So if you are directly writing to the parameter RAM you must always send it the number of samples.

The fractional delay blocks work on a percentage of the total MAX delay time. So the number being input is a real number in the standard format for the DSP. 8.24 or 5.23 depending on the DSP. So if you enter a "100" you get the max delay time. If you enter a "50" you get 50% of the MAX delay time. "10" is 10% of the MAX delay time. The parameter being stored in the DSP is this fixed point number translated to hex. It is sending a number between 1 and 0. So 100% of the delay will be the number 1 being stored in the fixed point format. 50% will store a 0.5 in the DSP parameter. So 0 is no delay.

So that is how the blocks work when you input them from the SigmaStudio GUI.

When you use the voltage controlled versions it is similar.

The multi-tap voltage controlled delay works like the standard delay block. It takes an input that is an integer (HEX) format that is the number of samples. So you must send it a number that is the number of samples in integer format between the MAX and zero.

For the fractional voltage controlled delay, this one takes a number between 0 and 1 and is the percentage of the MAX delay time. So it needs to be a number formatted to the DSP's fixed number format. I tested this using a DC cell and it works perfectly.

(Edit: I just edited this after I realized I had a Duh? moment. So it is fine now)