Re: [Sursound] Fwd: Bass Problem in crosstalk cancellation
On 13/06/2011 03:44, Marc Lavallée wrote: I made an A/B/C switch to listen between direct stereo, BACCH and the new DW filters; both filters are cancelling well, but BACCH is less coloured. Not EYCv2L-44.wav, I assume. It must be a high $,$$$ version you have! I am curious how you manage to switch layouts. Also, there's plenty of bass coming out of the BACCH filter, more than with normal stereo. That can happen.. http://dl.dropbox.com/u/20268768/EYCv2L-44.png Ignore ear traces which depend on the model used. ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Fwd: Bass Problem in crosstalk cancellation
On 13 Jun 2011, at 09:30, Dave Malham wrote: On 12/06/2011 00:34, Robert Greene wrote: Yes that is it! Incidentally, I would like to add a (nonmathematical) point. I think dipoles are more or less a disaster for Ambisonics Bass is one thing, but what dipoles mostly do is bounce sound off the back walls(unless you were using them as subwoofers only) in a way that creates spaciousness, so beloved of stereo loving audiophlies, but that blurs the actual spatial information. In the past we had a horizontal array (they were actually hung from the ceiling!) of four Quad Electrostatics. They could work well but at other times the image was completely messed up by the reflections from the walls of the rear radiation. This was all very material dependent. Panning directions could reverse, spurious height changes could happen and so on...beautiful speakers, but... I agree re the Quads' in-room bass. I have two pairs of them (ESL63's) on stands in a rectangle 30cm off the floor at 1/7th of the way along each diagonal in a 4.8m x 3.55m room. But I am currently limited to ambi super-stereo and UHJ and have dropped the bass to the 'statics by 3.5dB (at 20Hz, about -1dB at 200Hz), making up the level with a mono sub half way along a wall on the room's long axis. These 'statics also tend to rattle at moderately high bass levels anyway, so the bass cut helps reduce this considerably. My room dimensions tend to boost bass by around 5dB (1/3rd octave) from about 200Hz downwards. The sub's low pass is set at 45Hz (-6dB) for music, at 85Hz for TV, with its output set using a dB meter. Not ideal but works fairly well with the material I listen to, mainly Nimbus UHJ classical and a lot of studio recorded alternative/rock stereo stuff. Ambi and super-stereo imaging is really good at least over the upper bass to low treble range. I'd like to be able to add at least another sub eventually. And then there's that suck-out, at around 200Hz in my case, from the electrostatic's floor reflection... Ho hum. Maybe Quad could be persuaded to make a narrower range ESL that could be put higher off the floor as well. Well maybe not but it's a thought. ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Fwd: Bass Problem in crosstalk cancellation
Robert Greene wrote: The point I am trying to make is that there are ALWAYS higher frequency components, except for the eternal om that started before time began and that will continue into all eternity.(No offense I hope to believers in the religious content here). Only that type of signal can be without higher frequency components. Something that start and ends as nothing Au le contraire! Without being a specialist in Indian music, I would expect that om contains LOADS of overtunes, because a mere sine wave sounds inherently un-Indian! :-D Best, Stefan ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Fwd: Bass Problem in crosstalk cancellation
Stefan Schreiber wrote: Robert Greene wrote: The point I am trying to make is that there are ALWAYS higher frequency components, except for the eternal om that started before time began and that will continue into all eternity.(No offense I hope to believers in the religious content here). Only that type of signal can be without higher frequency components. Something that start and ends as nothing Au le contraire! Without being a specialist in Indian music, I would expect that om contains LOADS of overtunes, because a mere sine wave sounds inherently un-Indian! :-D Best, Stefan Sorry, of course overtones. On the other hand, the term overtune would seem to be a good trade mark... Best, Stefan ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Fwd: Bass Problem in crosstalk cancellation
On 13/06/2011 18:30, Stefan Schreiber wrote: Robert Greene wrote: The point I am trying to make is that there are ALWAYS higher frequency components, except for the eternal om that started before time began and that will continue into all eternity.(No offense I hope to believers in the religious content here). Only that type of signal can be without higher frequency components. Something that start and ends as nothing Au le contraire! Without being a specialist in Indian music, I would expect that om contains LOADS of overtunes, because a mere sine wave sounds inherently un-Indian! :-D Hmm, well, the dynamic range of the universe may very likely be infinitely large, but [un]fortunately our mortal ears are not, so that startup transient from years back has decidedly faded into the expanse of the numinous, and is no longer apparent to the casual listener. Very gratifying, nevertheless, to find scientific theory so deeply at one with the mysticism of the unstruck sound. Everything we hear is indeed an illusion, while everything we cannot hear is the true reality. I struck a note on one of my singing bowls a few days ago. My ears can no longer detect its tone, but the above theory assures me that it is assuredly still singing, and moreover its Cosmic Vibrational Energy thus raised will never stop. I do not always manage to persuade people of this, but at last I have an irrefutable scientific basis for it with which not even Mr Dawkins could possibly argue! Richard Dobson ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
Re: [Sursound] Fwd: Bass Problem in crosstalk cancellation
13/06/11 02:55, « Fons Adriaensen » f...@linuxaudio.org : There is no reason why an XTC system should remove center bass signals, and as far as I know none of them do this. I suspect you are confusing 'out-of-phase' and 'difference'. [[Profanity warning: the following contains crude and probably inexact mathematics.]] In fact, I was still referring to the BACCH paper: the out-of-phase response seems to be defined as the magnitude of the difference between what is (commonly) called H1(w) and H2(w), h1 being the diagonal term for the symetrical XTC matrix and h2 the contradiagonal term. And the in-phase response is simply magnitude( H1(w)+H2(w) ). Still in the same paper, you see that the overall envelope spectrum is defined as the maximum between in-phase response and out-of-phase response. The trick is to minimize that envelope spectrum excursion so that it stays below a certain value, hence achieving the low XTC coloration Marc could hear in his A-B-C listening test. Anyway, I must admit I had no opportunity to hear that particular filter, but still: the in-phase response, in the low frequencies, is way below other levels (see figure 2 for the stereo-dipole cas: -10dB for unregularized filter). The well knows inversion techniques (Farina, etc) state that: H1 = Hi * (Hi^2 - Hc^2)^-1 H2 = - Hc * (Hi^2 - Hc^2)^-1 where Hi is the ipsilateral response (eg. left speaker - left ear) and Hc is the contralateral response (eg. left speaker - right ear) For such a signal, the difference L-R is very small. Reproducing it correctly using normally spaced stereo speakers (which requires amplitude differences instead, this recreates the original signals at the ears) means you need high gain for this L-R signal. To reproduce it (and create an off-center bass) using closely spaced speakers and crosstalk cancellation requires even more. But none of this means that a mono (center) bass would be removed. If we have a mono bass sound panned to the center, we'll eventually have Hi ~= Hc so the inversion leads to infinite values for H1 and H2 in the low frequencies, unless one uses regularization. This is my local (personal!) explanation for the XTC bass problem, but I may be wrong. But back to that Massive Attack bass line: if we use something like E=1 (full regularization, which means no XTC) in the low frequencies, when you pan a mono bass sound to the center, both loudspeakers will emit the same signal = (h1 + h2) (*) bass = (hi - hc) (*) bass = . = 0 (*) bass. Hence: no more bass. Yet most XTC filters often sound more bassy than they should. So, I'm wrong, but I don't know why (yet). Thanks, Best, FM ___ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound
