Electronics Tale, part four (and final)

Started by Mister URL, August 24, 2022, 01:16:43 AM

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Mister URL


If you look at the internal working of a running logic system using an oscilloscope, you see digital signal switching taking place. It is very quick, but luckily, for us, the same electronic advances that allowed the powerful CPU's we have now also allowed much improved test equipment. No human can be expected to see what a CPU is doing but the scope charts time vs. amplitude and puts it on a screen so you can see the microsecond and even nanosecond switching that is taking place. The scope plots time in the horizontal axis and amplitude in the vertical axis. So you see a 'picture' of the real-time pulse as it occurs. This is important because you need a scope to understand the process of converting analog to digital and then back to digital again. It lets you see what is happening.

When you want to convert, say, Frank Sinatra crooning (which is, being natural, all analog) into a nice clean digital form, you need something that takes the analog signal and converts it into a digital representation. This converted data is typically stored in the form of a table of values, with each entry describing one sample of the original signal amplitude. The position within the table indicates the time it occurred. As you might infer, the device used to convert these is called an "Analog-to-Digital" converter, or A/D, as it is usually written.

I could describe the workings or an A/D converter but it is already done. Just Google 'Analog to Digital' and go to the Wikipedia entry and you will find out all you want to know. I will wait here until you return.

Pretty complex, huh? But it works. Just remember resolution and sampling rate. The wider and faster, the better, as far as end result. But you have to be practical. The faster and wider, the more space in memory the conversion requires. Most people would not want a song that lasted three minutes in real time but required 8 gigabytes of space on their hard drive.

The D/A process reverses the operation and changes your table of binary values back into a pseudo audio wave that can feed speakers or earphones and vibrate to produce sound.

This is the Meat of where I was getting: Sorry I had to shovel all that technical stuff into your ravenous maw. Audiophiles claim they can tell the difference between Frank's original croon and the one that is converted to digital and then back to analog to get into their ear hole. They say it loses something. That is why they avoid digital music like CD's, MP3s and such. They go with vinyl LP records or audiotape, which are never converted.

I call hogwash on this. (I originally called another substance, but this is a family forum. I think.)

It is true that no analog to digital to analog conversion will ever be an exact replica of the original; but I maintain that no human or even dog ear can tell the difference at the high end of conversion. I wager that a blind taste test, where the audio expert is blindfolded and has their nose pinched off, would show that they cannot tell the difference between a bite of CD and a bite of vinyl record. Hahahahah. No, I mean a blind ear test.

I believe their claim is based on the unavoidable stair-step shape of the re-created analog. You can see this stair step with an oscilloscope. If you zoom in close enough with your scope, you will see teensy the little steps between samples. But a human ear cannot detect steps that small and fast.

I think what they miss is the noise, the hiss and clang that is unavoidable in analog signals. When you digitize, you clean up. So, you may get what they claim is Franks cracking instead of crooning. You lose the 'oon' and get the 'ack'. And you lose Frank scratching his ass nose and the trumpet player shuffling her feet. Maybe that is what they miss.

Or maybe they are just hipster snobs that always want to do things the contrary way, the Old Way.

So, anyway, that is my electronics story. It's finished now. And thank you for reading.
"...Things I learned in a bobo jungle are things they never taught me in a classroom ..."
― NOT Merle Haggard


It's been interesting and informative.  The two do not always go together.