Notch filter mode has much lower level than other filter modes

Brute MatrixBrute
#1

Hi everyone,

maybe this is a total dumb question: The notch mode in the Steiner filter has a much lower level than i.e. the low-pass mode. Especially if the notch is used with a 24 dB slope.

Is this a common behavior of Steiner filters? In my theoretical understanding of the different filter modes, a notch filter - especially with a 24 db slope - should only filter the audio signal in a rather small frequency range. So it is rather surprising to me that the notch lowers the overall output level by so much.

Best regards,
Stephan

#2

Hi everyone,

I did some further testing. I used the init patch with just one sawtooth oscillator running through the Steiner Parker filter. Sawtooth gain was at 100%, the OSC 1 mixer gain and the filter gain was at roundabout 2/3. The filter was completely open, no resonance, and no drive or brute factor activated.

I used this setup for a few recordings in different filter modes to have a better idea of the level differences between the filter modes. This was the result:

  • Low-pass mode, 24 dB slope = -21 dB peak (reference)
  • Notch mode, 24 dB slope = -31 dB peak (10 dB lower than LP)
  • Low-pass mode, 12 dB slope = -21 dB peak (reference)
  • Notch mode, 12 dB slope = -26 dB peak (5 dB lower than LP)

10 dB difference between LP and notch mode at 24 dB slope is quite significant. Has anybody else noticed this difference in levels? Or maybe somebody else can make a short test with a single sawtooth wave on an open Steiner filter. It would be helpful to know if the results of my MatrixBrute are expected and common or something that points to a problem in either the hardware or the calibration. Because in the latter case I would contact the Arturia Support.

Unfortunately, I have no second MatrixBrute at hand for an A/B comparison.

Thanks a lot!

Best regards,
Stephan