Home |
Search |
Today's Posts |
#81
|
|||
|
|||
"Phil Allison" writes:
"cirejcon" Phil Allison I don't know what "reverse phase" means, but reversing the polarity is EXACTLY THE SAME as a 180 degree phase shift at ALL frequencies; ** Completely stupid and wrong. Polarity reversal is an instantaneous process - ie there is no time delay. Look, come back after you've taken a basic math class and don't be rude if you don't have any idea what you're talking about. ** To have utterly failed to comprehend the issue - dickhead !!!!! Phase shifting involves time delay between the original and the shifted versions. Polarity reversal does not. They are equivalent, Phil. Let g(t) = -1 * f(t), and let the Fourier transform of f(t) be F(w). Then G(w) = -1 * F(w) = -1 * r(w) * e^{j*phi(w)} = e^{j*pi} * r(w) * e^{j*phi(w)} = r(w) * e^{j*(phi(w) + pi)} In words, multiplying by -1 (polarity reversal) is equivalent to shifting by a constant 180 degress (or pi radians), which is the same as performing a frequency-dependent delay. I know it doesn't seem right because you're not delaying anything in a sense, but this is what the math says. -- % Randy Yates % "And all that I can do %% Fuquay-Varina, NC % is say I'm sorry, %%% 919-577-9882 % that's the way it goes..." %%%% % Getting To The Point', *Balance of Power*, ELO http://home.earthlink.net/~yatescr |
#82
|
|||
|
|||
"Randy Yates" "Phil Allison I don't know what "reverse phase" means, but reversing the polarity is EXACTLY THE SAME as a 180 degree phase shift at ALL frequencies; ** Completely stupid and wrong. Polarity reversal is an instantaneous process - ie there is no time delay. Look, come back after you've taken a basic math class and don't be rude if you don't have any idea what you're talking about. ** To have utterly failed to comprehend the issue - dickhead !!!!! Phase shifting involves time delay between the original and the shifted versions. Polarity reversal does not. They are equivalent, Phil. ** Then produce your *real world* device that performs the 180 degree phase shift at all frequencies ( but is **NOT** a simple polarity reverser) and demonstrate how it has NO time delay. Keep in mind that the "frequency domain" is a fictional place where time does not exist - so it does not exist. ............ Phil |
#83
|
|||
|
|||
Let g(t) = -1 * f(t), and let the Fourier transform of f(t) be F(w).
Then G(w) = -1 * F(w) = -1 * r(w) * e^{j*phi(w)} = e^{j*pi} * r(w) * e^{j*phi(w)} = r(w) * e^{j*(phi(w) + pi)} In words, multiplying by -1 (polarity reversal) is equivalent to shifting by a constant 180 degress (or pi radians), which is the same as performing a frequency-dependent delay. While your math is correct, I think you are misunderstanding. Start with x(t-a) - X(f)*exp(-j*2*pi*f*a) which says that a phase *shift* for a particular frequency in the frequency domain is equivalent to a time *shift* in the time domain. Suppose you had two 60 second sinusoidal pulses of the same frequency, one in the L channel and the other in the R channel and you wanted to shift them 10 degrees out of phase with each other. What would you do? You'd delay one of them and leave the other alone. And if you wanted 180 degrees phase shift you would increase the delay appropriately. Flipping one channel is not the same since the two pulses no longer lilne up in time. What if you wanted 25*2*pi degrees phase shift? Now the pulses really wouldn't line up. Would you leave both channels alone since sin(phi) = sin(phi + 25*2*pi) and call it done ? Joe |
#84
|
|||
|
|||
I don't know about CoolEdit, but in Adobe Audition you simply select /Effects/Filters/Graphic Phase Shifter... . That brings up a dialog with various presets available, two of which are +90 and -90. This is exactly the same with CoolEdit too. But when I applied it, it did not sound the way I expected. Bob "Randy Yates" wrote in message ... "Bob Pit" writes: Hi I am not very familiar with CoolEdit and I want to playback my voice (or any mp3 file) with a 90 degree phase offset between the 2 channels/speakers. It must be easy but how do you do this? Thanks Bob Hi Bob, I don't know about CoolEdit, but in Adobe Audition you simply select /Effects/Filters/Graphic Phase Shifter... . That brings up a dialog with various presets available, two of which are +90 and -90. I found an audible difference on a section of Crosby, Stills, Nash, and Young's old "Our House": www.uspsdata.org/OurHouse90.wav -- % Randy Yates % "Rollin' and riding and slippin' and %% Fuquay-Varina, NC % sliding, it's magic." %%% 919-577-9882 % %%%% % 'Living' Thing', *A New World Record*, ELO http://home.earthlink.net/~yatescr |
#85
|
|||
|
|||
Perhaps this will give you a lead.
- With Cool Edit load the file as a two channel stereo. - Show all the file on your screen. - Select all the right channel - Edit - Cut - Select all the left channel - Edit - Copy - Pinpoint on the right channel screen only at a place where you want to start the signal (Example 0,66 seconds) - Edit - Paste Save the file and listen to it. -- Allen Reny http://www.a-reny.com |
#86
|
|||
|
|||
"Phil Allison" writes:
"Randy Yates" "Phil Allison Phase shifting involves time delay between the original and the shifted versions. Polarity reversal does not. They are equivalent, Phil. ** Then produce your *real world* device that performs the 180 degree phase shift at all frequencies ( but is **NOT** a simple polarity reverser) and demonstrate how it has NO time delay. Since you don't like my definition of phase shift [1], tell me how you define it. [1] Phase shift at frequency f for a continuous-time signal x(t) is the angle in radians of the complex value of the Fourier transform of the signal, X(f). -- Randy Yates Sony Ericsson Mobile Communications Research Triangle Park, NC, USA , 919-472-1124 |
#87
|
|||
|
|||
"Bob Pit" writes:
I don't know about CoolEdit, but in Adobe Audition you simply select /Effects/Filters/Graphic Phase Shifter... . That brings up a dialog with various presets available, two of which are +90 and -90. This is exactly the same with CoolEdit too. But when I applied it, it did not sound the way I expected. Hi Bob, I forgot to mention one detail - in Audition you have an option to apply the shift to both channels, the left channel, or the right channel. I applied it to one channel (forget whether it was left or right). I saw another poster's response that seemed to imply that CoolEdit doesn't have those options explicitly in the Graphic Phase Shifter dialog window. Instead, it performs the phase shift on the selected signal, so you must select just one channel of the stereo pair to get a similar effect. -- Randy Yates Sony Ericsson Mobile Communications Research Triangle Park, NC, USA , 919-472-1124 |
#88
|
|||
|
|||
"Randy Yates" "Phil Allison" Phase shifting involves time delay between the original and the shifted versions. Polarity reversal does not. They are equivalent, Phil. ** Then produce your *real world* device that performs the 180 degree phase shift at all frequencies ( but is **NOT** a simple polarity reverser) and demonstrate how it has NO time delay. Since you don't like my definition of phase shift [1], ** I could not give a **** about your asinine and circular definition - esp. when posted posthumously. The situation is very simple: 1. Your position is that "180 degrees of phase shift at all frequencies " is identical to polarity reversal - OK ? 2. I agree. They are the same. 3. Occam's Razor requires that one must prefer the simplest, complete explanation of a phenomenon - OK ? 4. Ergo, of the two - only phase inversion actually exists. ................ Phil |
#89
|
|||
|
|||
"Phil Allison" writes:
"Randy Yates" "Phil Allison" Phase shifting involves time delay between the original and the shifted versions. Polarity reversal does not. They are equivalent, Phil. ** Then produce your *real world* device that performs the 180 degree phase shift at all frequencies ( but is **NOT** a simple polarity reverser) and demonstrate how it has NO time delay. Since you don't like my definition of phase shift [1], ** I could not give a **** about your asinine and circular definition - esp. when posted posthumously. I propose that the more you use emotion and profanity in a response, the weaker your position on the real issue is. The situation is very simple: 1. Your position is that "180 degrees of phase shift at all frequencies " is identical to polarity reversal - OK ? 2. I agree. They are the same. 3. Occam's Razor requires that one must prefer the simplest, complete explanation of a phenomenon - OK ? 4. Ergo, of the two - only phase inversion actually exists. This is an excluded-middle fallacy (http://en.wikipedia.org/wiki/False_dilemma). You can actually build a circuit that will perform a frequency-dependent delay of 180 degrees. Such a circuit can actually exist. The output of such a circuit will be identical to a simple polarity reversal, but the two implementations are not at all the same. -- Randy Yates Sony Ericsson Mobile Communications Research Triangle Park, NC, USA , 919-472-1124 |
#90
|
|||
|
|||
"Laurence Payne" wrote in
message news On Wed, 16 Mar 2005 00:04:33 +0200, "Bob Pit" wrote: As for the "The modulation on the R channel is about 0.3 sec ahead of the L channel", I cannpt figure how to do it (if it is not already there). If your wave editor has no control over the phase of a LFO signal, you could do this. Split R and L channel as completely separate files. Trim 0.3sec off the front of one file. Apply the modulation to each. Now trim 0.3 sec off the other file and recombine them as stereo. Later, having tried it out: Amazingly, none of the wave editors I have here seem to have a simple LFO function. Audition could probably do it with Convolution. There's certainly a function to create a 1Hz sine wave, with control over the initial phase. There's also an amplitude modulation function in Audition. |
#91
|
|||
|
|||
"Randy Yates" "Phil Allison" Phase shifting involves time delay between the original and the shifted versions. Polarity reversal does not. They are equivalent, Phil. ** Then produce your *real world* device that performs the 180 degree phase shift at all frequencies ( but is **NOT** a simple polarity reverser) and demonstrate how it has NO time delay. Since you don't like my definition of phase shift [1], ** I could not give a **** about your asinine and circular efinition - esp. when posted posthumously. I propose that the more you use emotion and profanity in a response, the weaker your position on the real issue is. ** Opinion presented as fact - ergo no case to answer. The situation is very simple: 1. Your position is that "180 degrees of phase shift at all frequencies " is identical to polarity reversal - OK ? 2. I agree. They are the same. 3. Occam's Razor requires that one must prefer the simplest, complete explanation of a phenomenon - OK ? 4. Ergo, of the two - only phase inversion actually exists. This is an excluded-middle fallacy (http://en.wikipedia.org/wiki/False_dilemma). ** Again, opinion presented as fact - ergo no case to answer. You can actually build a circuit that will perform a frequency-dependent delay of 180 degrees. Such a circuit can actually exist. The output of such a circuit will be identical to a simple polarity reversal, but the two implementations are not at all the same. ** Again, opinion presented as fact - ergo no case to answer. A device that instantaneously reverses signal phase is a polarity inverter. Any mention of phase shift is bunk. ................. Phil |
#92
|
|||
|
|||
"Phil Allison" writes:
[...] A device that instantaneously reverses signal phase is a polarity inverter. Any mention of phase shift is bunk. You are using the term "phase shift." I have defined what I mean by this term. I have shown how a polarity inverter modifies phase shift as I defined it. You have two options if you want to logically refute me: 1) Show that your definition of "phase shift" is not the same as mine. 2) Show that my proof that polarity changes phase shift is flawed. Until then, you are proving nothing but rather blowing hot air. -- Randy Yates Sony Ericsson Mobile Communications Research Triangle Park, NC, USA , 919-472-1124 |
#93
|
|||
|
|||
Phil Allison wrote: "Randy Yates" "Phil Allison I don't know what "reverse phase" means, but reversing the polarity is EXACTLY THE SAME as a 180 degree phase shift at ALL frequencies; ** Completely stupid and wrong. Polarity reversal is an instantaneous process - ie there is no time delay. Look, come back after you've taken a basic math class and don't be rude if you don't have any idea what you're talking about. ** To have utterly failed to comprehend the issue - dickhead !!!!! Phase shifting involves time delay between the original and the shifted versions. Polarity reversal does not. They are equivalent, Phil. ** Then produce your *real world* device that performs the 180 degree phase shift at all frequencies ( but is **NOT** a simple polarity reverser) and demonstrate how it has NO time delay. Now you're just backpedaling. Obviously one is claiming this is a sensible way to globally reverse polarity, only that it is mathematically equivalent. As for a "real world device", the analog device would be - you guessed it - a simple polarity reverser, also known as "180 degrees of phase shift at all frequencies". It would be trivial to do digitially. There would be a delay, but there is always a pipeline delay in digital signal processing, and even analog signal filtering introduces delays of fractional waves; however, since the ear can't distinguish fractions of a wave, this doesn't matter (*please* don't say anything stupid about hearing at this point. You'll only embarrass yourself). Keep in mind that the "frequency domain" is a fictional place where time does not exist - so it does not exist. Just because you don't understand something, doesn't mean it doesn't exist. You do realize that your ear works in frequency space (or are you one of those rare people who can sense the position of their eardrum as a function of time?) You'd better stop. You're just making a fool out of yourself. -jc ........... Phil |
#94
|
|||
|
|||
I forgot to mention one detail - in Audition you have an option to apply the shift to both channels, the left channel, or the right channel. I applied it to one channel (forget whether it was left or right). This is exactly the way I did it in CoolEdit too. The effect was not what I expected. "Randy Yates" wrote in message ... "Bob Pit" writes: I don't know about CoolEdit, but in Adobe Audition you simply select /Effects/Filters/Graphic Phase Shifter... . That brings up a dialog with various presets available, two of which are +90 and -90. This is exactly the same with CoolEdit too. But when I applied it, it did not sound the way I expected. Hi Bob, I forgot to mention one detail - in Audition you have an option to apply the shift to both channels, the left channel, or the right channel. I applied it to one channel (forget whether it was left or right). I saw another poster's response that seemed to imply that CoolEdit doesn't have those options explicitly in the Graphic Phase Shifter dialog window. Instead, it performs the phase shift on the selected signal, so you must select just one channel of the stereo pair to get a similar effect. -- Randy Yates Sony Ericsson Mobile Communications Research Triangle Park, NC, USA , 919-472-1124 |
#95
|
|||
|
|||
You can do the same in CoolEdit with Effects - Delay Effects - Delay.
Bob "Buzz" wrote in message ... Perhaps this will give you a lead. - With Cool Edit load the file as a two channel stereo. - Show all the file on your screen. - Select all the right channel - Edit - Cut - Select all the left channel - Edit - Copy - Pinpoint on the right channel screen only at a place where you want to start the signal (Example 0,66 seconds) - Edit - Paste Save the file and listen to it. -- Allen Reny http://www.a-reny.com |
#96
|
|||
|
|||
"Bob Pit" a écrit dans le message de news: 1110991026.533445@athnrd02...
You can do the same in CoolEdit with Effects - Delay Effects - Delay. Bob ============================================= Yes but that method cuts off the end of one of the channels instead of preserving the whole length of the recording by adding a silence at the end of the non delayed channel. But, if it is not the effect that you are looking for, I am really sorry about the disturbance. -- Allen Reny http://www.a-reny.com |
#97
|
|||
|
|||
"Randy Yates" "Phil Allison" A device that instantaneously reverses signal phase is a polarity inverter. Any mention of phase shift is bunk. You are using the term "phase shift." I have defined what I mean by this term. I have shown how a polarity inverter modifies phase shift as I defined it. ** What a load of arrogant bull****. No-one has the right to re-define matters in what ever artificial way they like. Get ****ed asshole. .......... Phil |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Equalizers | Audio Opinions | |||
Doppler Distortion - Fact or Fiction | Pro Audio | |||
Transient response of actively filtered speakers | Tech | |||
Blindtest question | High End Audio | |||
Negative/Positive Phase Shift in a Transformer | Pro Audio |