Hello Brett,

As per the help file both the audio and ext. detector inputs on the dynamic processors accept 'decimal-audio'

I set my schematic as shown in the attached image file.

I hear audio. I expected the audio level to change with the change in volume control slider position. However the o/p level remains constant.

The dynamic processor curve is set to flat as I wanted the o/p to track the volume control settings.

What am I doing wrong here? How would one set-up a dynamic processor to track audio input on its external input pin?

Thanks in advance,

KKSL.

Actually, this is not a correct understanding of how the transfer function works.

The transfer function graph represents the gain applied to the input signal based on the value of the detect signal. The Y axis does

notnecessarily represent the level that the output signal will be. The gain applied for any point on the curve can be calculated as the Y axis value divided the X axis value (in linear, this is division... in logarithmic (dB) scale, it's subtraction).X axis value = Detection signal

Gain = Y axis value / X axis value

Output = Gain * Input

by substitution...

Output = (Y / Detection) * Input

In other words, in the case of external detection, this transfer function is completely independent from the input signal.

So, let's look at some examples.

First, let's think of the case where the curve is linear:

If the detect signal is -60 dB, then the gain applied to the input signal (on the log scale) is the Y axis minus the X axis. So that is (-60 dB) - (-60 dB) = 0 dB. No gain applied. Output signal = Input signal.

If the detect signal is -40 dB, then the gain applied to the input signal is (-40 dB) - (-40 dB) = 0 dB. No gain applied. Output signal = Input signal.

If the detect signal is -20 dB, then the gain applied to the input signal is (-20 dB) - (-20 dB) = 0 dB. No gain applied. Output signal = Input signal.

So, you can see, if the curve is linear, then there will always be 0 dB of gain applied, regardless of what level is on the detection pin. In other words, in the case of a linear, 1:1 curve,

Output = Input.So, let's look at the case where there is a more interesting transfer function:

Here, we are linear up until -40 dB, and start to compress the signal after the detection input exceeds -40 dB.

If the detect signal is -60 dB, then the gain applied to the input signal is (-60 dB) - (-60 dB) = 0 dB. No gain applied. Output signal = Input signal. This is the same as the previous example.

If the detect signal is -40 dB, then the gain applied to the input signal is (-40 dB) - (-40 dB) = 0 dB. No gain applied. Output signal = Input signal. This is the same as the previous example.

If the detect signal is -20 dB, now we have a case where the X value and Y axis are not equal. We calculate the gain by taking Y-X. So, the gain applied to the input signal is (-40 dB) - (-20 dB) = -20 dB. So, the output signal is now equal to the input signal, but with -20 dB of gain applied.

Likewise, if the detection signal is +6 dB, the highest point on the table, then we calculate the output gain as (-40 dB) - (+6 dB) = -46 dB. So, in this case, the output signal is the input signal, but with -46 dB of gain applied.

Now, just think of the case where the input signal = the detection signal. In other words, a dynamics processor without an external input. You still calculate the gain the same way by subtracting Y-X (in log scale) or dividing Y/X (in linear scale). So take a look at the math again:

X = Detection

Gain = Y / X

Output = Gain * Input

by substitution...

Output = (Y / Detection) * Input

However, in this special case, Detection = Input, so...

Output = (Y / Input) * Input

Output = Y

In other words in this special case (and

onlyin this case) when the detection signal equals the input signal, you can think of the X axis as representing the input signal level, and the Y axis representing the output signal level.I hope that all makes sense.