What defines a digital or analogue circuit?

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samuraipizzacat29
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Re: What defines a digital or analogue circuit?

Post by samuraipizzacat29 » Thu Jun 21, 2012 12:15 am

Thank you!

So, if the wave were not being "interpreted" how would you define it?

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Re: What defines a digital or analogue circuit?

Post by rschnier » Thu Jun 21, 2012 12:28 am

If the wave is being interpreted according to whether it falls into two or more discrete ranges, you're interpreting it digitally. If it's not being interpreted that way, it's analog.

In my high-school physics class we did several computational projects on an analog computer. The core building-block in one of those is a type of circuit called an Integrator. You can solve all kinds of math problems by chaining Integrators together in various ways, for example simulating the path of a ballistic trajectory...in fact, the Norden Bombsight that helped the Allies win World War II was a mechanical analog computer that used gears instead of electronic circuits. Anyway, the "answer" delivered by the analog computer was shown on a voltmeter -- the kind with a physical needle! You looked at the needle's physical position and read it against the scale behind the needle.

Side note, the same Integrator circuit used in analog computers is also at the heart of the vast majority of analog voltage-controlled oscillators. As someone mentioned before, the difference between a VCO and a DCO lies mainly in the mechanism used to periodically reset the Integrator back to "zero" in order for it to start building up voltage again.
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Re: What defines a digital or analogue circuit?

Post by Automatic Gainsay » Thu Jun 21, 2012 3:17 am

:facepalm:

You guys are like a bunch of eggheads watching a couple have sex arguing about whether sex is inspired by pheremones or genetic programming.

Waveforms are graphic representations of actual vibrations. In nature, vibrations are imperfect. In a computer, they are perfect. The difference is often audible.

Whether that difference is relevant is debatable. Dickheads like me care. Dickheads like those who think structure is more important than tone, don't.

Arguing about the math is like defending 12-Tone music on organization alone.
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Re: What defines a digital or analogue circuit?

Post by GuyaGuy » Thu Jun 21, 2012 5:22 am

Automatic Gainsay wrote::facepalm:

You guys are like a bunch of eggheads watching a couple have sex arguing about whether sex is inspired by pheremones or genetic programming.
It's a forum dedicated to old synthesizers. So that shouldn't surprise you.
But you've also just posted your own opinions about it. So welcome to the pheromones vs genetic programming argument!

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Re: What defines a digital or analogue circuit?

Post by Stab Frenzy » Thu Jun 21, 2012 5:30 am

Sorry if we've upset your c00l guy persona Marc, here was I thinking that clearing up the confusion about what is an analogue circuit and what is digital might actually be a relevant and useful thing to know.

This thread has nothing to do with why anything sounds like it does or what's the best thing for whatever, it's explaining what people mean when they're talking about digital oscillators as opposed to DCOs. It's a bit sad that after 25+ years of these synths existing people debate the merits of one or the other without actually understanding what they're talking about, but I guess it's because they skip the 'what am I actually discussing?' stage and jump right ahead to the 'everything digital is rubbish, VCOs are the best BECAUSE THEY'RE ACTUAL REAL THINGS AND DIGITAL THINGS AREN'T REAL' stage.

Perhaps you should have read the thread a bit more thoroughly before offering your 2c. :idea:

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Re: What defines a digital or analogue circuit?

Post by b3groover » Thu Jun 21, 2012 8:21 am

Wait, people argue about s**t they don't understand on the internet? When did this happen?

:)

I think the first line of the wikipedia entry on "digital" explains it rather succinctly:
A digital system[1] is a data technology that uses discrete (discontinuous) values. By contrast, non-digital (or analog) systems represent information using a continuous function. Although digital representations are discrete, the information represented can be either discrete, such as numbers and letters or continuous, such as sounds, images, and other measurements.
http://en.wikipedia.org/wiki/Digital

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Re: What defines a digital or analogue circuit?

Post by nathanscribe » Thu Jun 21, 2012 9:02 am

samuraipizzacat29 wrote:Thank you!
The definition has been given several times before.
So, if the wave were not being "interpreted" how would you define it?
A definition would imply an interpretation.

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Re: What defines a digital or analogue circuit?

Post by clubbedtodeath » Thu Jun 21, 2012 10:43 am

b3groover wrote:Wait, people argue about s**t they don't understand on the internet? When did this happen
:lol:

Nath, Stabs - we salute your patience.

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Re: The VCO vs DCO thread

Post by madtheory » Thu Jun 21, 2012 10:55 am

nathanscribe wrote:The Bits use the same clock IC as the Juno...
Ah right, that might explain why Gordon Reid assumed it was the same circuit in his SOS retro of the Bit.

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Re: What defines a digital or analogue circuit?

Post by Steve Jones » Thu Jun 21, 2012 12:11 pm

Are c**p old Italian organs or Realistic MG-1's digital synths? They use digital dividers to get their note frequencies. Spooky. :shock:
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Re: What defines a digital or analogue circuit?

Post by samuraipizzacat29 » Thu Jun 21, 2012 1:10 pm

nathanscribe wrote:
samuraipizzacat29 wrote:Thank you!
The definition has been given several times before.
So, if the wave were not being "interpreted" how would you define it?
A definition would imply an interpretation.
if you're going to talk down to me, please AT LEAST know why this conversation started and what my starting position was.

to inform you:
meatballfulton wrote:
I think the poly 800 sold for less then a thousand dollars?
$800 MSRP. Of course, it's only partly analog.
samuraipizzacat29 wrote:It's only partly analog? I don't understand...... They're dco's passing through an (only one) analog filter.
stab frenzy wrote:Poly 800 had digital oscs, not DCOs. Also it's paraphonic, not polyphonic.
samuraipizzacat29 wrote:It would appear from the datasheet for the voice ic's that it is CMOS logic tone generators. Therefore, just as "analog" as anything else out there. Also, the Tone generators have direct output. If it were a digital output, it would need D/A converters. the waveforms are made from pulse's stacked on top of each other, hence why they sound different (and/or like butt) compared to other saw waves because they're not really saw waves.
http://www.citylan.it/wiki/images/3/3e/5232.pdf
stab frenzy wrote:In my mind anything that just switches between 0 and 1 is digital.
so from there we talked about the history of cmos and everything else under the sun. My explanations got long-winded, and when I tried my hardest to start basic and build up from there, I still got shot down. As you can see, my first statement included a reference to the definition of what makes digital, digital.
me wrote:If it were a digital output, it would need D/A converters.
Like Stabs said a few posts ago, the purpose of this conversation is for the sake of talking about what's what and how it applies to the thing we find important - making music. this whole conversation could have been avoided if you guys would have accepted an opinion from someone you don't respect. I'm not asking anyone to respect anyone else (I don't respect writing on a wall in an internet forum), but I do ask that if you're going to formulate an opinion to do so only after having done your due diligence to examine the facts. Please, then, share your findings appropriately. if we keep our cool and don't turn it into a witch hunt every time someone presents an opposite opinion, maybe we'll have more upbuilding conversations around here.
i'm not striving for an apology, that's not the purpose of this. You shouldn't have to apologize to random text on a screen. the point is to make sure the text is right.
automatic gainsay wrote:Waveforms are graphic representations of actual vibrations. In nature, vibrations are imperfect. In a computer, they are perfect. The difference is often audible.

Whether that difference is relevant is debatable. Dickheads like me care. Dickheads like those who think structure is more important than tone, don't.
I'm sorry marc, but both of these statements aren't entirely true. Firstly, my oscilloscope is analog, made entirely of discrete components and output through a tube screen (it's old). Therefore, I think it's fair to assess that the electrical impulse that's coming from the probe lead is what's powering the trace that is on the screen. So in a very real sense, the changes in the electrons are manifest on the screen. yes, it's a graphical representation of what's occuring over a given time, but it's not as if there's something lost in translation.
Secondly, the difference is hugely relevant to what all of us do. think about it, we're synthesizing sounds. So if you're building a sound, and the initial building block isn't exactly what you thought, you could be wasting your time. On a playful level it's no big deal, but on a scientific level it's a horrendous impropriety. Like I said in one of my first posts (in the other thread) what manufacturers call a square wave is very usually only similar to a square wave. That's part of the fun, of course :) This isn't relevant to people that grab an instrument because it sounds good and "just play" but none of this thread is so :?
Third, nothing's ever perfect. Ever. It's like saying a ball is round. It's not round. Things are either nearly perfect, or x is more nearly perfect than y. this is why people tend not to like digital, because the waves are more nearly perfect. yet, they're all imperfect in the same ways as defined by the output resolution of the DAC and the quality of the software used to describe the output waveforms. so, they're all more nearly perfect, but (generally) all imperfect in the same or similar ways.

This is all relevant, but it comes down to the end-all be-all that I had originally intended to establish. that is that a nearly perfect "digital" square wave and a nearly perfect "analog" square wave are the exact same thing.

(p.s.: they're not the same thing because something that's digital has to carry information represented by logic states and therefore "can't" be a square wave unless it's used as a clocking mechanism. yet, the statement is meant to be a for all intents and purposes if you made the same wave either way, it would be the same wave, either way.)

I'm glad we didn't get into the physics of electrons in FETs. that would get wonky quick..... :D (edit: but i wish we would have because that would prove there's no possible way to make an oscillation in the digital realm because an oscillation in electricity requires a physical change to take place. If digital is merely logic, that by definition can't produce a physical change.)

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Re: What defines a digital or analogue circuit?

Post by CS_TBL » Thu Jun 21, 2012 1:30 pm

Merely piping in here briefly, got other things to do at the moment. But the imperfection of a digital signal is only relevant when this imperfection can be observed in a neutral/scientific context, rather than emotional love/hate between analogue and digital systems. Since the quality and resolutions of these digital systems increase over time, you may wonder when people will not be able anymore to detect any difference to analogue systems. Similarly with the colors of your PC; 24 bit color means 256 steps for red, green and blue. You could lift these specs upwards, but if your eyes can't detect the difference, then there's no point. The only point would be when there's extreme math being done in this resolution. In extreme situations things may get steppy alright. Question is how often this occurs, and whether internal resolutions could be even higher than the eventual output resolution. Or: often, software audio uses 32bit for its calculations, even when the eventual output is 16bit. In time, we'll be using 192KHz processing out of the box, at 32bit or even 64bit. I wonder whether that resolution would be enough to silence even the biggest worshipers of the "digital sucks" expression!
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Re: What defines a digital or analogue circuit?

Post by rschnier » Thu Jun 21, 2012 2:23 pm

Steve Jones wrote:Are c**p old Italian organs or Realistic MG-1's digital synths? They use digital dividers to get their note frequencies. Spooky. :shock:
Yes, in that case at least the tone generation part is digital. The divider circuit that produces the 12 semitone waves is a series of counters with discrete internal states. The 12 output waves are exactly in lockstep with each other in a repeating cycle.

Not only the organs you mentioned, but also the revered Hammond Novachord's tone generator circuit has digital elements in it, even though it's implemented with tubes/valves! The 12 tones of the "top octave" come from 12 independent oscillators, but the tones of the octave below the top, and the octave below that, and so forth, are produced by digitally dividing the waveform of the octave above it by two. What's really neat is that the designers implemented this frequency division with only a single tube/valve per divider.
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Re: What defines a digital or analogue circuit?

Post by samuraipizzacat29 » Thu Jun 21, 2012 2:40 pm

rschnier wrote:
Steve Jones wrote:Are c**p old Italian organs or Realistic MG-1's digital synths? They use digital dividers to get their note frequencies. Spooky. :shock:
Yes, in that case at least the tone generation part is digital.........hammond novachord has digital elements in it, even though it's implemented with tubes/vales!
I don't understand. This is a contradiction to what you previously wrote. if the divide-down circuit is the direct output (even though these are square waves) how can this be referred to as digital?

is the point that you're comparing/using the leading/trailing edges of a wave to control a flip flop and since this is a function the theory of which is digital in nature (it's a logic operation), that we're calling it a digital operation? Yet, if that's the output that we're hearing, then those waves are analog, no?

I'm asking because I'm genuinely confused now.

If that's what you're saying, then it provides further insight into what we call a DCO, because in that case I think we'd say that everything up to the switching operation is a digital operation. yet, because the switching operation creates a wave that is intended to be disseminated by our ears, that can be considered an analog signal. Even the switch itself is digital, but the output is analog. (just hashing it out in my brain and typing accordingly)

I would have considered the operation itself analog because it's a physical change. But if the operation is digital because you're analyzing a high/low state, then I can understand why that would be true. fun times.....

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Re: What defines a digital or analogue circuit?

Post by tallowwaters » Thu Jun 21, 2012 2:55 pm

samuraipizzacat29 wrote:
nathanscribe wrote:
samuraipizzacat29 wrote:Thank you!
The definition has been given several times before.
So, if the wave were not being "interpreted" how would you define it?
A definition would imply an interpretation.
if you're going to talk down to me, please AT LEAST know why this conversation started and what my starting position was.
It only seems like he is talking down to you because he has been telling you the same thing for the entire thread, which can be a bit frustrating from the point of view of somebody trying to teach, only to have the subject of such teaching seemingly refuse to acknowledge the facts in front of him.

For example:

Person 1: Where is the peanut butter?
Person 2: Top shelf of the pantry.
Person 1: I've already looked in the fridge
Person 2: Uhhh... Okay, now look on the top shelf of the pantry
Person 1: I've looked on the floor in the pantry, not there
Person 2: Dude, top shelf
Person 1: I went into your bedroom and pulled out all of your drawers, still no peanut butter
Person 2: Are you f**k with me?

For what it's worth, I've gleaned enough information about electronics reading Stab/Nath/Meatball's posts to realize that you seemingly have little clue what you are talking about. It's not the end of the world, I've tried bullshitting with people about complex physics and programming languages, but I had enough decency to bow out of the conversation after I had properly belittled myself by spouting phrases that I obviously didn't fully understand.
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