Hello Dave, Not so strange a question... more a fun question!
I'd suggest using the Blumlein Difference Technique. (I'm speaking off the top of my head here, so you'll have to experiment with the below suggestions...) 1st, set the omnis up in the 'standard' Soundfield mic tetrahedral arrangement, spaced about 15-18cm apart. Use the A-format matrix to get W, X, Y, Z channels. Then apply BDT to the X, Y, Z. I'd also suggest using a crossover, so that HFs are time delays. In LF, below the cutoff you've chosen (400Hz or so), you get something resembling standard B-format. Above that, you get something else. I think it is probably best to use a crossover to preserve HFs as time delays. (HF image is aliased all over the place!!) I've tried this with synthetic signals--and the results are as you'd expect. We need to have LFs in the signal to pull the image to the intended incidence angles. BDT (for stereo) with natural soundfields can sound flattering in less than ideal rooms--my guess is that the described approach may sound "flattering" for B-format in similar circumstances. Also--I'd look to control the image aliasing by following the BDT with dominance. I've never tried this with real signals, just with synthetic. And... haziness can be good--if that is what you're looking for. Have a look at Gerzon's paper on BDT: M A Gerzon, “Applications of Blumlein Shuffling to Stereo Microphone Techniques”. J Audio Engineering Society, vol 42, no.6, 435 – 453 (1994 June) My best, Jo On 20 Jun 2011, at 11:54 am, Dave Malham wrote: > > May seem a strange question, but anyone ever had any experience of > building/using a soundfield type mic using omni's? I have been asked by one > of the artists featured on The Morning Line if there's anything he could do > with his collection of 4 DPA's (4060-bm's). Not something I'd ever really > though about before, but as Angelo's B format hydrophone uses omni's ... > (http://www.angelofarina.it/Public/UAM-2011/) > > Dave > > -- > These are my own views and may or may not be shared by my employer > /*********************************************************************/ > /* Dave Malham http://music.york.ac.uk/staff/research/dave-malham/ */ > /* Music Research Centre */ > /* Department of Music "http://music.york.ac.uk/"; */ > /* The University of York Phone 01904 432448 */ > /* Heslington Fax 01904 432450 */ > /* York YO10 5DD */ > /* UK 'Ambisonics - Component Imaging for Audio' */ > /* "http://www.york.ac.uk/inst/mustech/3d_audio/"; */ > /*********************************************************************/ > > _______________________________________________ > Sursound mailing list > [email protected] > https://mail.music.vt.edu/mailman/listinfo/sursound -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://mail.music.vt.edu/mailman/private/sursound/attachments/20110620/c314c55d/attachment.html> _______________________________________________ Sursound mailing list [email protected] https://mail.music.vt.edu/mailman/listinfo/sursound
