Analog versus digital oscilloscopes

[j57H8I4]

No digital oscilloscope could ever reach the graph quality of an analog oscilloscope. Like no compact disc could ever reach the sound quality of a vinyl disk.

[retrolefty]

No digital oscilloscope could ever reach the graph quality of an analog oscilloscope. Like no compact disc could ever reach the sound quality of a vinilic disk.

 That is one opinion, others might not agree. So, other then trying to raise a brouhaha, what is the purpose of your post?

[j57H8I4]

That is one opinion, others might not agree. So, other then trying to raise a brouhaha, what is the purpose of your post?

That is not an opinion that is a fact. The purpose of my post is to make people aware about this.

Anyway I posted my thread in the wrong section, I should have posted this thread in the "Test Equipment" section.

[ataradov]

quality of a vinyl disk.

Oh, my.

Also, were not you confused how to calculate resistor divider just yesterday? What exactly do you know about test equipment and its quality?

[ataradov]

what is the purpose of your post?

I see a pattern here. Newbie tries electronics. After day 1 it turns out electronics is hard. Newbie gives up and goes full on troll mode.

[j57H8I4]

Oh, my.

Also, were not you confused how to calculate resistor divider just yesterday?

I was, because I do not know electronics.

What exactly do you know about test equipment and its quality?

I exactly know that a digital graph is always approximate, while an analog graph is real.

[ataradov]

I exactly know that a digital graph is always approximate, while an analog graph is real.

You really better stop talking right now, and learn something about oscilloscope design.

It is "smooth" (hence analog), but in many cases it has more linear and non-linear distortions than a digital signal. And with a digital scope you can calibrate that out without problems to a certain extent.

Also, digital scope preserves more fine information about the signal. Phosphor of the display has persistence, so it acts as a low pass filter, so all your high frequencies are gone and not displayed.

[naldo]

Disagree: digital scope is more sensitive to reading gives more details! Here, good night everyone! 

[gildasd]

I want both!

[james_s]

I have both an analog and a digital scope. Each has strengths and weaknesses, and which is best depends on what you are doing. I like the "real" feel of an analog scope, they're great for having a quick look at what's there. A digital scope's ability to trigger and capture is invaluable for transient events though. People get an almost religious faith in one or the other but the reality is that you can have and use both. For a hobbyist, I think you can get a lot more scope for the money with an analog instrument. You generally have to spend a lot more on a DSO because most of the budget models are very limited but once you get to a certain level the disadvantages become less significant. If you want to capture single shot or non-repetitive events though digital wins hands down. For a long time I had a good analog CRO paired with an inexpensive PC based DSO and that gave me a good compromise. Now I have a really good DSO and expect to use my analog scope less but I'm still going to keep it.

I've never seen a digital scope that could come close to the ability of an analog CRO to display vector graphics in XY mode but that is a rather niche application.

I also like and collect vinyl, but I can't say it necessarily sounds any better than a CD to my ears. Good vinyl on decent equipment sounds very good, but better? I don't think my ears are good enough to say. For me it's more about the collecting, finding obscure stuff in thrift stores, and it's a bit of a different experience to cue up a record and play it. I like the album cover art too, modern formats are too small to make good use of that.

[xrunner]

No digital oscilloscope could ever reach the graph quality of an analog oscilloscope.

Well as long as the analog scope CRT doesn't have burn in, and the focus isn't out of adjustment, and the brightness isn't low because of thousands of hours of use ... maybe. 

[james_s]

No digital oscilloscope could ever reach the graph quality of an analog oscilloscope.

Well as long as the analog scope CRT doesn't have burn in, and the focus isn't out of adjustment, and the brightness isn't low because of thousands of hours of use ... maybe. 

To be fair, there are plenty of things that can fail and deteriorate in a digital scope. Let's compare apples to apples here and assume both instruments are in good working order and not worn out or damaged.

[xrunner]

To be fair, there are plenty of things that can fail and deteriorate in a digital scope. Let's compare apples to apples here and assume both instruments are in good working order and not worn out or damaged.

Comparing a digital scope to an analog scope is inherently apples to oranges though ... 

[Dubbie]

This seems to be the most persistent misconception among audio enthusiasts - that analogue == infinite detail, and that the analogue output of a digitized signal looks like a flight of stairs with each sample having infinitely steep risetimes before locking in at a value until the next sample. I wish!

[james_s]

This seems to be the most persistent misconception among audio enthusiasts - that analogue == infinite detail, and that the analogue output of a digitized signal looks like a flight of stairs with each sample having infinitely steep risetimes before locking in at a value until the next sample. I wish!

Well I'm more of a visual person myself, so I guess a reasonable analogy here is comparing a digital video signal displayed on a TFT screen vs an analog video signal on a CRT. I would say that hands down the CRT looks far superior for the same resolution. I've got a 27" Trinitron XBR in my rec room that still looks fantastic despite the fact that you'd never even get a true 640x480 out of analog NTSC. If you could get a 27" 4:3 LCD screen that was only 640x480 it would look horrible in comparison. For SD content I think the old Sony looks nicer than a comparable HDTV upscaling SD content, although 1080p content on a 1080p screen does look better but that's vastly higher resolution.

Could the same apply to audio? I don't know, seems like a reasonable assertion that it could. I could also believe that a subjective matter as music could sound "better" to someone despite being worse in quantifiable metrics simply because it's subjective.

[BrianHG]

This seems to be the most persistent misconception among audio enthusiasts - that analogue == infinite detail, and that the analogue output of a digitized signal looks like a flight of stairs with each sample having infinitely steep risetimes before locking in at a value until the next sample. I wish!

Well I'm more of a visual person myself, so I guess a reasonable analogy here is comparing a digital video signal displayed on a TFT screen vs an analog video signal on a CRT. I would say that hands down the CRT looks far superior for the same resolution. I've got a 27" Trinitron XBR in my rec room that still looks fantastic despite the fact that you'd never even get a true 640x480 out of analog NTSC. If you could get a 27" 4:3 LCD screen that was only 640x480 it would look horrible in comparison. For SD content I think the old Sony looks nicer than a comparable HDTV upscaling SD content, although 1080p content on a 1080p screen does look better but that's vastly higher resolution.

Could the same apply to audio? I don't know, seems like a reasonable assertion that it could. I could also believe that a subjective matter as music could sound "better" to someone despite being worse in quantifiable metrics simply because it's subjective.

Careful, CRT, Sony XBR, had a million:1 contrast ratio & true soft RGB color gamut.  I have a studio color grading grade accurate 21 inch computer CRT with 10 000 000:1 contrast ratio, auto CRT aging compensating electronics to keep perfect color & black level, 2048x1536 at 85hz with a color with obliterates any LCD technology PERIOD.  (Studio grade organic LED tv's with infinity:1 contrast are the only displays I seen which beat it.)  But, it is still being fed from a video card which has a digital source.  So, the problem is your TFT display's color quality limitations, not that the Sony XBR was analog. (Well if you are watching low bit-rate TV from cable of dish or internet, there is nothing I can do to help here) Also, the Sony XBR2 used a digital comb filter to separate the NTSC's luma and chroma signal.  So, even with that TV, the analog source video was first digitally sampled, digitally color luma & chroma separated, then back through an analog dac (an all in 1 IC device), then sent to an old fashioned analog Y/C to RGB decoder (yes, this is absurd, but it is how Sony did things at the time due to technology restraints) and achieved a better picture than the XBR.

[yuzuha]

This seems to be the most persistent misconception among audio enthusiasts - that analogue == infinite detail, and that the analogue output of a digitized signal looks like a flight of stairs with each sample having infinitely steep risetimes before locking in at a value until the next sample. I wish!

Bingo.   Human perception is quantized too, and neuron firing is considerably slower than many digital systems.  Sample fast enough with enough bit depth and digital is just as good as analogue.

[raspberrypi]

what is the purpose of your post?

I see a pattern here. Newbie tries electronics. After day 1 it turns out electronics is hard. Newbie gives up and goes full on troll mode.

Everyone is an expert until the learn a little bit and realize how much they don't know. Yes vinyl sounds better then CD but its not because ones digital vs analogue. I listen to vinyl myself but to get the sound quality you have to spend money on the needle (not to mention pre amp amp and speakers) to get the full effect out. I use an ortophone concord pro ($180USD) on a vestax turn table ($800USD). The turn table makes no difference in sound quality. As long as its spinning at the right speed it has no effect on the signal, you could use a lazy susan spun by hand and it would sound the same. The only reason I have such a top end one is because I do alot of scratching/ mixing and you need a high torque direct drive, very sturdy turn table. If you sample at a high enough rate and have enough bandwidth your ears become the limiting factor. Have you ever heard an SACD on really good speakers and amp? It almost sounds worse because it reveals the limitations of the recording. Sounded really harsh to my ears and I see why the SACDs never caught on; you pay more money for something that sounds better on paper but worse to your ears. Kind of like how tube amps sound better when really they are adding a harmonic that is by definition distortion. Just like your eyes become the limiting factor with a scope.

[james_s]

Careful, CRT, Sony XBR, had a million:1 contrast ratio & true soft RGB color gamut.  I have a studio color grading grade accurate 21 inch computer CRT with 10 000 000:1 contrast ratio, auto CRT aging compensating electronics to keep perfect color & black level, 2048x1536 at 85hz with a color with obliterates any LCD technology PERIOD.  (Studio grade organic LED tv's with infinity:1 contrast are the only displays I seen which beat it.)  But, it is still being fed from a video card which has a digital source.  So, the problem is your TFT display's color quality limitations, not that the Sony XBR was analog. (Well if you are watching low bit-rate TV from cable of dish or internet, there is nothing I can do to help here) Also, the Sony XBR2 used a digital comb filter to separate the NTSC's luma and chroma signal.  So, even with that TV, the analog source video was first digitally sampled, digitally color luma & chroma separated, then back through an analog dac (an all in 1 IC device), then sent to an old fashioned analog Y/C to RGB decoder (yes, this is absurd, but it is how Sony did things at the time due to technology restraints) and achieved a better picture than the XBR.

It's not just the color gamut though. With a low res TFT I can see the grid of pixels, especially if you were to make a 640x480 TFT that was 27", the pixels would look huge. The CRT being analog has approximately round "pixels" that blend smoothly together. It's sharp enough to see the scan lines but the horizontal resolution lacks discrete steps.

Your mention of the contrast ratio reminds me of the absurdly bogus specs on monitors these days. The TFT I have on my PC prominently proclaims 80,000,000:1 contrast, what a joke! It's a decent monitor but in terms of contrast the old Sony CRT I had which was probably rated 1,000:1 absolutely blows the TFT out of the water. Unfortunately it weighed a ton, took up half my desk and was starting to get a little blurry.

[technogeeky]

This thread is nonsense, all the way down, and should be locked. Even good responses given into the teeth of a trolls' query should be sacrificed.

[j57H8I4]

Everyone is an expert until the learn a little bit and realize how much they don't know. Yes vinyl sounds better then CD but its not because ones digital vs analogue. I listen to vinyl myself but to get the sound quality you have to spend money on the needle (not to mention pre amp amp and speakers) to get the full effect out. I use an ortophone concord pro ($180USD) on a vestax turn table ($800USD). The turn table makes no difference in sound quality. As long as its spinning at the right speed it has no effect on the signal, you could use a lazy susan spun by hand and it would sound the same. The only reason I have such a top end one is because I do alot of scratching/ mixing and you need a high torque direct drive, very sturdy turn table. If you sample at a high enough rate and have enough bandwidth your ears become the limiting factor. Have you ever heard an SACD on really good speakers and amp? It almost sounds worse because it reveals the limitations of the recording. Sounded really harsh to my ears and I see why the SACDs never caught on; you pay more money for something that sounds better on paper but worse to your ears. Kind of like how tube amps sound better when really they are adding a harmonic that is by definition distortion. Just like your eyes become the limiting factor with a scope.

A digital equipment takes samples of a wave then calculates the evolution of the wave among its two samples, that means that the digital equipment is inventing the evolution of the wave among its two samples, while the wave among its two samples could be completely different. And this is what happens with digital oscilloscopes and with compact disc players. Analog oscilloscopes, as well as vinyl disc players, do not invent anything, they just return the real wave.

[ataradov]

while the wave among its two samples could be completely different.

So what? Physics and mathematics are such that your equipment does not truthfully reproduce those fast changes.

the real wave.

There is no real wave, it is always limited by the equipment used to observe it. And capabilities of modern digital scopes far surpass capabilities of the analog scopes.

If you don't understand this, then there is nothing can be done here.

[j57H8I4]

There is no real wave, it is always limited by the equipment used to observe it. And capabilities of modern digital scopes far surpass capabilities of the analog scopes.

If you don't understand this, then there is nothing can be done here.

It is impossible that digital equipment can surpass analog equipment ever, because digital equipment will always approximate, analog equipments take and return the full signal, the real signal.

[ataradov]

the real signal.

Limited by the input bandwidth of the scope. In both cases, in digital and analog. Except that digital has much better ability to display that bandwidth limited signal because it does not need to limit it even further because there is no phosphor.


You really don't know what you are talking about, and just look silly.

[daqq]

No digital oscilloscope could ever reach the graph quality of an analog oscilloscope.

BS. Neeeeext!