2008/5/29 Rich Caloggero <<a href="mailto:rjc@mit.edu">rjc@mit.edu</a>>:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
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<div>So I take it that 100 us</div>
<div><font size="2" face="Arial">is 100 microseconds (the suggested delay for
speakers placed 3 meters apart)?</font></div></div></blockquote><div><br>Yes, ěs = microsecond == .001::ms<br><br>I don't feel like doing math on the speed of sound right now but I do think that I keep hearing that with this technique you are supposed to keep the speakers close together and at 60° or something pointing outwards.<br>
</div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div bgcolor="#ffffff"><div><font size="2" face="Arial"> Sampling rate is aprox. 40k so 1 sample every
250 microseconds?</font></div></div></blockquote><div><br>I think you are off;<br><<<(samp / ms) * 1000>>>;<br><br>gets me 22.675737. Unless I'm confused (again!) that means 22.7 microseconds per sample.<br>
<br></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div bgcolor="#ffffff"><div><font size="2" face="Arial"> So from what your saying, this means you'd need to
interpelate 250 times per sample?</font></div></div></blockquote><div><br>I think it's more like 23 but yes. You'd have to do that in the case that you'd have a interpolating delay Ugen with feedback built in, something I don't think we have.<br>
<br>I'd put a few in series without feedback to get around this as you're likely using a amount of feedback that makes a impulse drop below the noise floor of your listening environment after a few iterations anyway.<br>
</div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div bgcolor="#ffffff"><div><font size="2" face="Arial"> Now that I think about it (outch this
math stuff makes my brain hurt), what does it even mean to hae a delay smaller
than the time between samples?</font></div>
<div> </div></div></blockquote><div><br>Well, obviously there is nothing "between" digital values... but the values represent a continuous wave so we can interpolate in the hope of figuring out what the value between two samples would be if it were there.<br>
<br>Let's say we are a delay line and right now we are getting a value of .2 at our input and we know that a sample ago it was .1 ok? Assuming linear interpolation (for convenience sake) we could then say that half a sample ago we had a input of .15 We never actually saw that input, of cource, but we could still output .15 and pretend we got this half a sample ago as our unput. We'd still be able to calculate one such value every time the VM "ticked" us which is once per sample. I don't really see any big problem here, it's not harder then a delay of length 100000.5 samples and nobody frowns at those, I think.<br>
</div></div><br>If we'd be expected to do feedback we'd have a problem because that would mean multiple passes to calculate a single sample.... Which is why I'd lean towards faking it and putting a few delaylines in series.<br>
<br>I hope that helps. Actually I hope it was correct at all; I'm no certified DSP guru...<br><br>Yours,<br>Kas.<br>