> that's the main problem with the eigenmike: the higher the order, the > narrower the bandwidth and the higher the lower boundary. which means that an > eigenmike signal set will not usually be downwards-compatible - if you aim > for a correct amplitude response for the full 4th order set, it will sound > duller and duller the more orders you truncate.
Alas, the problem exists even at 1st order which is why Eigenmike is still some way from matching TetraMic for recording music. The relevant paper from Angelo et al is 252-AES-40.pdf which shows their improved software compared to the MH offering. A SPHERICAL MICROPHONE ARRAY FOR SYNTHESIZING VIRTUAL DIRECTIVE MICROPHONES IN LIVE BROADCASTING AND IN POST PRODUCTION - Farina, Capra, Chiesi e Scopece AES 40th Conference, Tokyo oct2010 You'll note poor S/N (especially at LF) & response above 10kHz. _______________ The use of omnis has some advantages (which Eigenmike doesn't take full advantage of) but also severe disadvantages. For Sound Intensity, Angelo has some papers comparing various methods to the time honoured B&K Sound Intensity wand & the new fangled Microflown (??). A properly calibrated soundfield like TetraMic has many PRACTICAL advantages including PRACTICAL accuracy and allows 3D measurement too. One might argue the directivity patterns of TetraMic are not 'perfect' at HF ... but neither are the those for the wands and other methods too. And those for TetraMic are predictable and can be compensated for a measurement application. The B&K wand is practically useless below 100Hz even with the largest spacer cos S/N. Accuracy at HF is limited, even with the smallest spacer. You'll have to dig up Angelo's papers for chapter & verse. I don't think I'm letting the cat out of the bag by revealing at least 1 company is planning a Sound Intensity instrument based on TetraMic. ________________ While trying to dig up that paper, I came across some typical Angelo gems. In ... RECORDING, SIMULATION AND REPRODUCTION OF SPATIAL SOUNDFIELDS BY PCM SPATIAL SAMPLING - Farina et al International Seminar on Virtual Acoustics VALENCIA, November 24-25, 2011 .. he calls the system at Casa della Musica, Parma as a '.. much worst playback system ..' preferring the duodecahedral (maybe even higher order) system of Nelson & Fazi at ISVR. ... the shape of things to come ... thought the wife might have something to say about the furnishings. 8>D _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
