3D, is it a cross feed?

Here is some information regarding the 3D effect inside our products;

  • The bottom line is that all classic ‘cross-feed’ systems produce, with well-recorded music with a natural rendering of space, what is best described as ‘wide mono,’ but crucially with the perception of sound being outside the head and before the head.
  • While this provides a major relief to individuals that cannot tolerate ‘band in my head,’ what it does not do is to deliver a sound stage with Headphones that approaches well setup speakers.
  • Back in the 1980’s the Radio Television Zentralamt (RFZ) or the Ministry of Radio and TV in East Berlin conducted major research into headphone/speaker replay compatibility to allow a single recording to playback via speakers or headphones while retaining good spatially.
  • Ultimately the German reunification in 1989 ended this program before completion. However, significant progress had been made at that point for matrixes to translate both dummy head recordings to speaker and classical speaker recordings to headphones. The BBC had similar research at the time.
  • In both cases it became clear that existing systems (aka Bauer cross-feed and its variants) were grossly inadequate.
  • What we at AMR / iFi call 3D Holographic Sound is based on this research and further refined, as well as extended to include speaker-based systems.
  • While controlled and shaped feeding of spatial information between channels forms the core of the AMR / iFi 3D Holographic sound system, compared to Bauer cross-feed and its descendents, be it Linkwitz, Headroom or Maier or recent digital implementations by a number of vendors (one which even stole our 3D label), the way and algorithms it is executed to differ quite radically.
  • So we prefer to leave the common ‘cross-feed’ designation strictly to Bauer cross-feed and derivatives and to use ‘3D Holographic’ for our rather radically different approach. And of course we have 3D for Headphones and 3D for speakers (nope, for speakers is also not cross-feed)

Link to our papers: https://ifi-audio.com/tech-notes/#tn-other

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