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PSI Audio CPR technology

  Tuesday 18 December 2018, 12:28
It's not just a phase: PSI Audio uses proprietary CPR technology for perfect phase alignment in monitor speakers

PSI Audio employs the special CPR technology to phase align sonic reproduction in their professional active studio monitors. The Compensated Phase Response uses a number of all-pass filters to account for the delay of low frequencies that generally occurs in speakers. CPR makes sure every signal is reproduced in the most accurate way possible, retaining both its spectral and its temporal structure. Since phase is essential for locating signals in the stereo image, CPR in PSI Audio monitors enables users to precisely place audio in the acoustic space– in addition to the perfectly faithful and natural sound reproduction.

Yverdon-les-Bains, 18th December 2018 –When it comes to optimizing playback systems, people often focus on frequency response as if it was the be-all and end-all of monitoring. While the spectrum is indeed important, other factors equally influence reproduction quality. For example, phase is paramount in accurately playing back sonic signals. Swiss manufacturer PSI Audio developed a technology called Compensated Phase Response (CPR) to guarantee both naturally dynamic transients and the most precise sound image possible.

The importance of phase in monitoring
Phase alignment is often discussed when people talk about multitrack recordings, but rarely mentioned in monitoring. And yet, phase response does have a massive impact on the accuracy of the audio playback. When perceiving sound, phase is a key component in determining the sound's origin and hence its position in the stereo image. Speaker systems generally have a tendency to reproduce high frequencies first, followed by low frequencies, effectively changing the characteristics of the material – especially in short, transient-rich signals. When we represent a snare drum hit, for example, with the sign "TA", where the "T" marks the high frequencies and the "A" the low spectrum, it would be reproduced as "T ... A" with a significant delay on the low frequencies. In PSI Audio speakers, CPR makes sure that the snare comes out as "TA".

The power of analogue
It is possible to phase align signals digitally, but you would have to convert the audio, introducing conversion latency and possible degradation in quality. PSI Audio speakers work with 100 percent analogue technology, completely sidestepping the detriments of digital conversion. Instead of DSP calculations, up to 14 carefully adjusted all-pass filters (in the A25-M) take care of delaying the high frequencies to align them with the low frequencies. The overall delay required for aligning the relevant spectrum is as low as 0.6 milliseconds –equivalent to moving the head back 20 cm from the speakers.

CPR – Compensated Phase Response
The result of CPR in PSI Audio speakers is an incredibly accurate sonic image with precise stereo placement and immaculate transients. The order, in which frequencies reach the listener's ear, is no different from the original, avoiding any kind of colouration or distortion of the source material. The impact of CPR is best to be heard, but can be visualised using a square wave signal. Measuring a typical speaker's output when fed a square wave, the result is anything but square. Put the same signal through a PSI Audio studio monitor and the output is still very much a square wave, due to high and low frequency content retaining their relative positions.

PSI Audio monitors feature CPR exclusively
All active studio monitors from PSI Audio feature Compensated Phase Response CPR for flawless audio reproduction, from the nearfield monitors A14-M, A17-M and A21-M through to three-way midfield unit A25-M and floorstanding mastering reference A215-M. All PSI Audio monitors are handmade, measured and calibrated to perfection in Switzerland.