An inevitable but unwanted aspect of analogue speaker design is that nothing can be done to control or remove the phase response, that is the time difference between how long it takes for different frequencies to travel through the unit. No matter what is done, we cannot influence the frequency response of speakers without changing their phase response and vice versa. To deliver both linear frequency and phase response together is not possible in the analogue world. However, the introduction of DSPs in recent decades finally gave a potential solution to this problem with the emergence of Finite Impulse Response (FIR) filters, also known as linear phase filters. 

FIR filters allow for control of the phase behaviour in a monitor independent of its frequency response, something that more traditional filters used in DSPs such as Infinite Impulse Response (IIR) filters cannot do. As such, FIR filters make it possible to correct the phase response of a monitor unit, be it a satellite or subwoofer, and align the output of all its frequencies in time, which has made it an essential filter type for DSP-powered monitors today. 

In order to control linear frequency and phase response, FIR filters allow for the storing of parts of the signal until everything is in the timely order needed before sending to the output. The price to be paid for this linear phase response is a delay in the overall signal, with practical numbers between two and 500 milliseconds, depending on various parameters. This is no problem in a pure reproduction chain, but may cause issues in a recording situation which is why FIR filters are best used in specific studio situations. 

The difference in time behaviour FIR filters provide can be measured under specific technical tests and we believe that these technical improvements translate into the listening experience, especially when it comes to the perception of the stereo field and the details it contains.