In a multi-way speaker system, the crossover filters as well as the transducers inevitably introduce phase distortion and consequently also variations of group delay.
The group delays are higher in low frequencies than in high frequencies. Theses create a separation in time between the low and high frequencies which typically gives multi-way speakers a “hollow” sound.
In a limited frequency range, an all-pass filter will allow to alter the phase without influencing the amplitude.
The CPR system is made up of several all-pass filters each acting in a specific range of frequency and together obtaining a Compensated Phase Response. This then provides a constant group delay that is kept to the bare minimum through our entirely analogue technology.
Thanks to the CPR system, the placement of sound in the actual sound space is perfectly accurate. Amongst others, this technology allows designing a surround sound systems with different types of PSI Audio speakers whilst maintaining a perfectly accurate phase response.
PSI Audio speakers are a perfectly trustworthy tool that sound engineer can rely on to design their sound!
Practical advantage of CPR and impact on stereo application:
The human ear is very sensitive to group delay or phase irregularities of sounds. The human brain is very good at detecting these irregularities and processing them in to space related information to position a sound source.
Unfortunately most speaker systems suffer from such irregularities to a certain extend. This is the reason why some speakers produce a wider and deeper room perception and a better or worse sound image.
Such phase irregularities are intentionally used with creative tools like equalizers, compressors, reverbs and delay units when creating a certain sound effects and they are an important part of the creative process of sound engineering.
However, as the speaker system is the reference tool for every sound engineer, they should not add any phase irregularity. If the speakers distort the phase, it will be extremely difficult for any sound engineer to design any specific sounds or to position the sound in space.
As a sound recording process requires several steps (recording, mixing and mastering) and each step is often done by a different person, in a different location and obviously with different speakers. In this process, some corrections may be applied, due to phase irregularities, that may not even be present on the initial recording and thus spoiling it.
The PSI Audio speakers feature the unique CPR system that provides a Compensated Phase Response that removes these phase irregularities. As a result, the stereo image and the projected room are extremely accurate. PSI Audio speakers are therefore a perfectly trustworthy tool that sound engineer can rely on to design their sound.
CPR impact on surround sound applications:
Unfortunately every traditional speaker design has a different phase response and therefore the phase inaccuracy phenomenon tends to get worse in surround sound applications, where the role of room information and positioning becomes a critical.
This is one of the reasons why speaker manufacturers recommend using identical speakers in any surround or multichannel system.
PSI Audio speaker, all equipped with the CPR system, will feature an extremely accurate and superior surround sound image and therefore a much improved working environment.
Another big advantage of the CPR system is that, for the first time, a user can mix different types of speakers (provided they are PSI Audio) in a surround sound system, whilst maintaining perfectly accurate phase response. Not only will the PSI Audio surround system sound impeccably accurate, but it can also introduce significant cost and space savings as the side and rear speakers can be smaller than the front ones.