Phase and time alignment („Time“)
The settings for the selected channel are displayed in the "Phase, Polarity & Runtime" window in the main menu. Next to the two sliders you can find the display for the phase value in degrees and the delay time, given in centimeters.
The adjustments for phase and delay can be done individually for each channel in the “Main” menu – but we recommend using the “Time” menu that can be accessed by clicking the respective button.
Here you can see the settings of all channels at a glance and do not have to switch back and forth between the individual channels to set the phase and delay.
A clean spatial reproduction of the music is only possible if the time alignment is set properly. For this purpose, the software offers a very sensitive setting option in which the step size depends on the sample rate of the respective device. For products with a 48 kHz sample rate, the step size is 7 mm or 0.02 ms, 96 kHz sample rate leads to 3.5 mm or 0.01 ms and at 192 kHz the step size is halved again.
1. Adjustment of the time alignmentThe software allows to set the time alignment automatically via the "ATM" function and to adjust this manually in two different ways:
In this mode, the distance values between each loudspeaker and the listener's ear are entered, which can easily be determined with a tape measure or folding rule. The program uses these values to automatically calculate the required time delay for all channels.
In this mode the desired value of the time delay has to be entered directly, as far as this is known. This option is rarely used.
With the “Delay Group” function, you have the option of linking the delay settings of several channels. The delay group linking always works relatively – so you have the possibility, for example, to move all left or right speakers of a multi-way system without losing the relative delay differences between tweeter, midrange and woofer of a channel.
2. Adjustment of the phase
The functionality of the “phase” slider depends on the definition of the respective channel in the “IO” menu.
The channels that have been defined as “fullrange” or “low” channels only allow polarity switching between 0 ° (“polarity normal”) and 180 ° (“polarity inverted”).
In contrast to this, the channels that have been selected as subwoofer channels and / or mid / high channels in fully active systems can be switched in polarity as well as adjusted in fine 5.625 ° steps from 0 ° to 354.375 °. Both types of phase adjustment have completely different effects – therefore, familiarize yourself with the functionality in order to be able to use it optimally.
In some use cases it can be helpful to adjust the phase more precisely than just inverting the polarity by 180 °. If you want to combine the subwoofer precisely with the front and rear speakers, the usual polarity switching is often not sufficient.
The phase control with its fine 5.625 ° steps is of great advantage here. The same need may arise in a fully active configuration if you intend to couple a midrange driver at a given crossover frequency with a tweeter. The usual values of 0 ° or 180 ° can produce undesirable peaks or dips in the frequency response due to incorrect phase relation. While the phase control in our products may look simple, it is mandatory to understand in detail how it works.
The phase control is designed as a 2nd order all-pass filter with a variable corner frequency. All-pass filters have no influence on the amplitude of the signal, but only shift its phase depending on the frequency.
If you move the phase control slider, you have no direct influence on the corner frequency of its all-pass filter. The DSP PC-Tool automatically calculates the required corner frequency depending on the setting of the high-pass filter. Only in the case of the subwoofer channel is the crossover frequency of its low-pass filter used as a reference for calculating the phase shift.
In the following example, the high-pass filter was set to 1,008 Hz and the phase shifted by 90 °: The graphic below shows the frequency-dependent phase curve with a phase shift of 90 ° at 1,008 Hz:
Expert advice: If you want to set up a fully active system consisting of a subwoofer, woofer, midrange and tweeter, always start with the phase relation between subwoofer and woofer in the crossover frequency range, followed by the phase relation between woofer and midrange. Finally the phase between midrange and tweeter has to be adjusted. If you don’t follow this order, you’ll get crazy.