Objectivists board room
Jan 14, 2017 at 6:52 PM Post #3,061 of 4,545
I normally consider myself a somewhat smart guy, but in light of the bolded sentence, I feel like a complete idiot. Lol. You guys lost me at sine wave.

 
Being a "smart guy" doesn't mean that you (or anyone else) is born with the understanding of how audio works. It just means you have the capacity to understand, providing we have an appropriate starting point. So, you should definitely NOT "feel like a complete idiot", or, if you do, join the club! Everyone, including all the famous producers, engineers and scientists who invented audio recording technology and the art it contains, were at one time effectively "complete idiots"! All we therefore need to do is ascertain your appropriate starting point and as you're a smart guy, we should be able to quickly progress from there. Have you read this post #3040, specifically point #1? If so and you're still confused, no problem we'll just find an even earlier starting point.
 
Bare in mind that much of the last few pages have been aimed at someone professing to already have a high level of understanding of audio, high enough even to argue with those who do it for a living. It's a shame it got so heated and derailed, to the point that it's made you feel an idiot.
 
BTW, just in case there's any doubt, due to what's been posted previously, there's absolutely no sarcasm intended in this response.
 
G
 
Jan 14, 2017 at 7:02 PM Post #3,062 of 4,545
can I try another answer, yet the same? ^_^
 
a square wave can be seen as a fairly simple signal with a very simple shape, but in the analog domain they are equivalent to an infinite number of sine waves at different frequencies, and the properties of waves make is so that they can all add up to one single signal with the desired shape. (same idea as an impulse response, it's a rather simple and short signal but it contains an infinite number of frequencies, or at least all those that weren't filtered).

while we imagine that turning ON and OFF any circuit is generating square waves, in practice anything having an impact on some frequencies, will have an impact on the shape of the square wave. like even a basic cable will roll off very high frequencies at some point, so instead of transmitting a perfectly identical signal, the high freqs included in the square wave will be rolled off. plus any extra noise is made of yet other frequencies adding up to the final shape of the signal. the time needed to go from 0 to max amplitude is not truly instantaneous but that one is pretty intuitive, electricity doesn't move faster than light ^_^. 
 
 
 
oh, and feeling silly is the best. when I feel like I don't know anything, it's one of those rare moments when I'm actually sure of something.
biggrin.gif

 
Jan 14, 2017 at 7:18 PM Post #3,063 of 4,545
With all due respect castofargh, and despite the fact that nothing you stated was inaccurate, I'm not sure that's an "appropriate starting point". For example, explaining how we can frequency modulate sine waves to approximate an audible square wave will only confuse someone who doesn't yet have a reasonably solid basic concept of what square waves and sine waves actually are. Maybe we should wait for warrior1975's response and ascertain what is the appropriate starting point for him?
 
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Jan 14, 2017 at 7:29 PM Post #3,064 of 4,545
Yes, square waves, impulse response, and sine waves are all just a Fourier Transform away from each other.
 
But the problem with describing these in terms of signal processing math is that it makes no sense if you don't understand signal processing math. 
wink_face.gif

 
It's also completely unnecessary for understanding how signals in a USB cable affect a DAC.
 
Jan 14, 2017 at 8:01 PM Post #3,065 of 4,545
I'm so sad, it's the first time someone suggested that I lack pedagogy, in the last 2 hours. ^_^  (it's horrible because it's true).
 
Jan 14, 2017 at 8:15 PM Post #3,066 of 4,545
  I'm so sad, it's the first time someone suggests that I lack pedagogy, in the last 2 hours. ^_^  (it's horrible because it's true).

 
Don't feel too bad.  I just had a pot of tomato sauce "explode" on me when I went to stir it. (air bubble of something)  Actually, feel worse for my loved ones, as I stripped out of my clothes right there in the kitchen and immediately put my soiled clothes in the wash to avoid any stains.  My youngest will need therapy, I'm told.
 
Jan 14, 2017 at 8:24 PM Post #3,067 of 4,545
   
Don't feel too bad.  I just had a pot of tomato sauce "explode" on me when I went to stir it. (air bubble of something)  Actually, feel worse for my loved ones, as I stripped out of my clothes right there in the kitchen and immediately put my soiled clothes in the wash to avoid any stains.  My youngest will need therapy, I'm told.

Thanks for that.  I didn't need that image in my head.
 
Of the pot, I mean. 
 
Jan 14, 2017 at 8:34 PM Post #3,068 of 4,545
  I'm so sad, it's the first time someone suggests that I lack pedagogy, in the last 2 hours. ^_^  (it's horrible because it's true).

 
I was thinking it was more of just a plain case of being a complete pedanthole.
 
wink_face.gif

 
Jan 14, 2017 at 10:39 PM Post #3,069 of 4,545
For those who don't understand the relationship between sine and square waves: https://i.stack.imgur.com/27HVo.gif
 
Graphically shows how one gets the frequency from a square wave, and what the frequency actually means in terms of signal processing.
 
Jan 15, 2017 at 12:07 AM Post #3,070 of 4,545
  For those who don't understand the relationship between sine and square waves: https://i.stack.imgur.com/27HVo.gif
 
Graphically shows how one gets the frequency from a square wave, and what the frequency actually means in terms of signal processing.


Thanks for that.  I had seen a while ago, and wished I had bookmarked it to show to others.
 
Jan 15, 2017 at 2:15 AM Post #3,071 of 4,545
Not solely focused on audio, but a person I know that is very into psychology just posted an interesting post on Facebook that is somewhat relevant to a previously discussed topic.

 
Jan 15, 2017 at 2:43 AM Post #3,072 of 4,545
Not solely focused on audio, but a person I know that is very into psychology just posted an interesting post on Facebook that is somewhat relevant to a previously discussed topic.


 
That was one of the first things my cognitive psychology textbook from many years ago stated: the authors were asking you to distrust your own mind. It set the tone for the whole section that followed.

It made me think about a period in my own life that I consider to have been filled with good memories. I can remember the things I enjoyed doing, of course, and I can roughly correlate them to a time period and chronological order, but what I have real trouble remembering is all the mundane things that, logically, I would have had to have been doing at the same time. In fact, much of the time would have been devoted to these very things, and yet if I just sit back and let the nostalgia take hold, it's like the entire period was one long unbroken string of awesome. Logically, it's impossible. For instance, I was still in school during most of it (near the end of spring/beginning of summer), and presumably would only have had time to enjoy myself on weekends (or maybe the occasional free evening), and yet I have no memory of school during that period. If I wasn't willing to logically work out things that had to have been taking place concurrently (like school), I would be fully prepared to accept a warped and generally improved overall memory of that period.
 
Clearly my mind is playing tricks, simplifying things, and just generally not getting things right. I've learned not to fully trust anything my mind comes up with unless I can refer to some hard external evidence that what I'm thinking is logical and possible.
 
Jan 15, 2017 at 6:25 AM Post #3,073 of 4,545
Just letting you know - our "friend" Guy Under is actually a formerly banned member. As soon as I know he's seen his PM - his account will be banned.  For those flagging his posts - please don't - there is no longer any need.
 
And please do not reply to this message / post - nor mention his status (it is against forum rules).  I am simply leaving this with you so you are aware.  This ends the matter.
 
Jan 15, 2017 at 8:07 AM Post #3,074 of 4,545
  I'm so sad, it's the first time someone suggests that I lack pedagogy, in the last 2 hours. ^_^  (it's horrible because it's true).

 
Yep, don't feel too bad. My first ever formal lecture (to second year degree students) was a disaster. The official observer had to stop the lecture after 20mins because I'd over-estimated the students' level and they were becoming ever more bored and distracted as they had no idea what I was talking about. The rest of the lecture was an unstructured mess of pure ad libbing as I tried to work out an appropriate level and re-engage them. I overheard some of the students discussing the lecture after it was over ... not my proudest achievement!!
 
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