Parrot Posted July 5, 2003 Share Posted July 5, 2003 Griffinator: I haven't ever timed them myself, but electrons through speaker wire travel at speeds approaching the speed of light. They don't lumber along at the speed of sound through the air : ) Quote Link to comment Share on other sites More sharing options...
Deang Posted July 5, 2003 Share Posted July 5, 2003 Just so I'm clear on this -- during playback, the signal was played through both channels, with one channel being 5ms behind the other one. If that's true, then Craig was right -- because that's exactly what reverb is. It is an echo -- which is basically what you did. I fail to see how this translates into phase cancelation. In electronics, 5ms is an eternity. You would need 50 miles of cable on one side, and 5 inches of cable on the other. Quote Link to comment Share on other sites More sharing options...
BEC Posted July 5, 2003 Share Posted July 5, 2003 About 900 miles of wire will give you a 5 ms delay. Bob Quote Link to comment Share on other sites More sharing options...
justin_tx_16 Posted July 5, 2003 Share Posted July 5, 2003 You've got mail. Do you want me to reformat them?... Email me. Quote Link to comment Share on other sites More sharing options...
AnalOg Posted July 5, 2003 Share Posted July 5, 2003 The first is flat in a bad way, no solid beginning and end to notes, blah. Second has well rounded notes, fuller,more body like its coming from a tube amp. Tom Quote Link to comment Share on other sites More sharing options...
Griffinator Posted July 5, 2003 Author Share Posted July 5, 2003 ---------------- On 7/5/2003 6:18:36 PM DeanG wrote: Just so I'm clear on this -- during playback, the signal was played through both channels, with one channel being 5ms behind the other one. If that's true, then Craig was right -- because that's exactly what reverb is. It is an echo -- which is basically what you did. I fail to see how this translates into phase cancelation. In electronics, 5ms is an eternity. You would need 50 miles of cable on one side, and 5 inches of cable on the other. ---------------- OK, let's re-explain the test. On the second sample (the original), left and right were the same. It was essentially a mono signal. On the first sample, I delayed the left channel 5ms. This is not the same as a reverb. A reverb is a decaying echo. There was no change in amplitude, only in the timing of the two channels. The phase cancellation is an anomaly that occurs when the identical signal is passed out-of-phase from one channel to the other - this is why the second waveform seemed to be louder, even though the amplitude was exactly the same. The two waveforms (left and right) partially cancelled each other out because of the delay. Here's a frequency graph of the original waveform: Here's a frequency graph of the altered waveform (5ms delay on the left channel) Here's another of the same waveform, only this time the left channel was only delayed 1ms. Notice that, although we are a lot closer to the original, there is still a substantial difference in amplitude between the first and the altered versions. And finally one more shot with the left channel delayed .5ms - this time we're just about back in line with the original waveform, so the difference is probably negligble in terms of what you hear. Quote Link to comment Share on other sites More sharing options...
Marvel Posted July 5, 2003 Share Posted July 5, 2003 Reverb has two basic components -- the first being the delay, or time from the original signal., which indicates the size of the room. A longer delay means a bigger room. The second is the amount of repeats, partly indicating the hardness of the reflecting surfaces )stone, drywall, carpet, and the rate of decrease in the reflections gives us the reverb sound. Marvel Quote Link to comment Share on other sites More sharing options...
Strabo Posted July 5, 2003 Share Posted July 5, 2003 ---------------- On 7/5/2003 6:18:59 PM BEC wrote: About 900 miles of wire will give you a 5 ms delay. Bob ---------------- I originally believed that speaker wire lengths would have an effect. Then this thread came alone and actually made me to do math. 5ms at 900 miles is fairly accurate. I used the following. Speed of Light = 299,792,458 meters per second That is traveling roughly 299,792 meters per millisecond. Electricity flows through very expensive Nordost cables at 87-95% the speed of light. So figure 75% for standard cables per their claims. We are now at 224,844 meters per millisecond (299,792*.75). There are 1,600 meters in a mile so that translates to 140 miles per millisecond. 5 milliseconds = 700 miles give or take depending on the efficiency of the wire. Quote Link to comment Share on other sites More sharing options...
michael hurd Posted July 5, 2003 Share Posted July 5, 2003 Sure speaker wire lengths can have make a difference as resistance goes up as the cable gets longer. A larger cable must then be used in order to prevent a voltage drop or loss in the wire. The amount of capacitance can definately affect the sound as well. By far the most economical change is the sound of your system is to adjust the room and move the speakers until it is optimized, before trying esoteric cables to adjust the sound. As PWK said, adjust your room, not my speakers. Quote Link to comment Share on other sites More sharing options...
Griffinator Posted July 5, 2003 Author Share Posted July 5, 2003 ---------------- On 7/5/2003 9:10:16 PM Marvel wrote: Reverb has two basic components -- the first being the delay, or time from the original signal., which indicates the size of the room. A longer delay means a bigger room. The second is the amount of repeats, partly indicating the hardness of the reflecting surfaces )stone, drywall, carpet, and the rate of decrease in the reflections gives us the reverb sound. Marvel ---------------- Reverb has many components, one of which is "predelay" - time before the reverb starts. That's why what I did to the signal is not "reverb" - it's delay. Quote Link to comment Share on other sites More sharing options...
BEC Posted July 6, 2003 Share Posted July 6, 2003 Try this one. The speed of sound in air is around 1 ft. in 1 ms. Sit 12 ft. from one speaker and 17 ft. from the other. Can you detect that 5 ms. difference? Does it sound like delay or reverb? Bob Quote Link to comment Share on other sites More sharing options...
sunnysal Posted July 6, 2003 Share Posted July 6, 2003 my point was that even if you can hear a 5ms delay (which is what griffinator is trying to help us decide), the results will not tell us to be careful about wire length, wire length is not going to EVER be an issue, due to the speed at which electricity moves through wire, any wire. we are talking thousands of feet here. Nor does it seem to be relevant for driver alignemtn, using the speed of sound in air you are talking a big difference in driver placement to get 5ms differences in arrival, by big I mean too big to address this time alginment stuff, couple of meters...tony Quote Link to comment Share on other sites More sharing options...
Parrot Posted July 6, 2003 Share Posted July 6, 2003 The brain compensates for all kinds of things. One speaker being 5 feet farther away than another shouldn't ruin anyone's day. If you walk around your listening room, does the recording you are listening to sound like 50 separate recordings, changing with each step you take, or does it sound like one recording? Imagine you are at a symphony. Is every violinist equidistant from you? And is every performance ruined if you don't have a center seat? Quote Link to comment Share on other sites More sharing options...
Griffinator Posted July 6, 2003 Author Share Posted July 6, 2003 ---------------- On 7/6/2003 9:23:45 AM sunnysal wrote: my point was that even if you can hear a 5ms delay (which is what griffinator is trying to help us decide), the results will not tell us to be careful about wire length, wire length is not going to EVER be an issue, due to the speed at which electricity moves through wire, any wire. we are talking thousands of feet here. Nor does it seem to be relevant for driver alignemtn, using the speed of sound in air you are talking a big difference in driver placement to get 5ms differences in arrival, by big I mean too big to address this time alginment stuff, couple of meters...tony ---------------- I'll concede the wire length issue. I've never really looked at the numbers there - I was under the impression that even in high-grade wire, the signal was never approaching the speed of light. However, as my graphs show, there is a substantial difference in the frequency response even at 1ms delay. If 1 foot in real space (driver placement) = 1ms delay, it's not hard to create an audible phase issue in your room with misplaced drivers and/or misplaced furniture. Thank you all for participating, and for the math wizards to pop in and correct my misconceptions about signal speed on wire runs... Quote Link to comment Share on other sites More sharing options...
sunnysal Posted July 6, 2003 Share Posted July 6, 2003 yes the 1ms difference was surprising to me, I would love to hear tones with that difference, see if it was detectable. tony Quote Link to comment Share on other sites More sharing options...
Griffinator Posted July 6, 2003 Author Share Posted July 6, 2003 Let's see if Justin will indulge me one more time - I'll link it up. Quote Link to comment Share on other sites More sharing options...
Griffinator Posted July 6, 2003 Author Share Posted July 6, 2003 Here ya go, Sal - let's see what you think... http://www.soundwise.org/klipschubb/griffinator/Test%20wave%201ms.wav Quote Link to comment Share on other sites More sharing options...
ben. Posted July 7, 2003 Share Posted July 7, 2003 It seems to me there is a big misconception around here about what some of us are talking about regarding audibility of delays. Referring to a section of violins to refute the physically proven (through basic wave theory) facts regarding phase cancellation is completely missing the idea. Multiple sources of different sound do have their own reinforcement/cancellation going on, but this is not the context for those issues. .1-7ms delays to identical waveforms WILL ABSOLUTELY cause phase cancellations. They ARE audible. It is a physical certainty. The human brain cannot process delay times this short as seperate events. You will not hear an echo. You will hear crap. If you'd like, see my post in prodj's time-align thread for a more detailed explanation. Quote Link to comment Share on other sites More sharing options...
Parrot Posted July 7, 2003 Share Posted July 7, 2003 bclarke, I would have to know the situation you want me to imagine before I could comment on it. Time alignment typically is an issue with the positions of the tweeter and midrange, and they're obviously not putting out identical waveforms. Quote Link to comment Share on other sites More sharing options...
ben. Posted July 7, 2003 Share Posted July 7, 2003 I haven't (nor has Griffinator-to my knowledge) framed this in the context of speaker time alignment. As many people have correctly and eloquently stated, speaker design is much more complex than simple arrival time issues. I was just trying to make a point that the validity of arguments against speaker time alignment are baseless when the audibility of short delays are used as a point of argument. If these short delays are inaudible, then why do many members of this BB expend so much time and energy controlling early reflections? They hear a difference, usually described as less harshness, more coherence, better intelligibilty of vocals. These are all improvements relating to phase cancelletion issues arising from arrival time discrepencies in the .1-30ms range. Quote Link to comment Share on other sites More sharing options...
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