Thoughts on Rigol DS2000 osciloscopes for audio work?

I know, I know, a digital scope, but hey I already have a couple of analog Tek scopes.

Let me tell you what i find appealing about the DS2000 series: they can go down to 500microV/div which is something not very common on a digital scope and the thing I find most appealing. It can perform FFT which is something very common on digital scopes, but its a thing that an analog scope cant do (at least not your typical one) and I would like to be able to see the frequency spectrum, even if its not a precision dB audio analyer it gives me a good idea. It has an 8 inch color display, etc...

The main thing im interested in is FFT and microvolt/div capability (and price of course)

I was also looking at the Tek TDS2000 series scopes, and they also perform your typical FFT analysis and what not, but they wont go lower than 2mV/div.

They are around the same price for the 100MHz version (which is BW overkill for audio), the Rigol is a couple hundred bucks cheaper, but then again I trust Tektronix with my life.

So yeah, they both have a lot of features I wont be using, but if im buying a digital scope, I wouldnt mind having them.

What do you think, any of you guys use/own one?

I don't know about that, but I'm wandering to buy something, so intrested in this...

I probably would start for something cheaper... was looking at RIGOL DS1052E or something portatil like Hitachi Vc-5460.

Also was looking for those nano scopes, like an iphone... very cheap, but, do they worth? just for having an idea of what's happening... for check my DOAs and things like that.

Any advice?

The Rigol DS1052E wont go down to 500microV/div, its just like the tek scope 2mV/div minimum vertical display which is not very useful if you want to measure stuff like AC ripple coming out of a PSU, unless theres something evidently wrong with the power supply itself.

I have a Tek TDS 2014 and can tell you a couple of things:

i) The 'FFT' feature is absolute pants. There's no proper scaling and I've never been able to find a use for it. I crave a nice standalone FFT, but they're big bucks

ii) My Kenwood 20Mhz analogue scope still sees a lot of use... For signals below 2mV the Tek's near to useless. The refresh rate of the screen isn't great.

In the land of digi scopes, you have to really shell out cash to get accurate portrayals / measurements of low-level signals. That's why, unless your scope cost a five figure sum, you might want to keep an analogue scope handy.

J

Im a bit disapointed to hear that about the Tek. Im not planning on getting rid of my analog scopes,  i wanted to hear some opinions on this digitial one.

user 37518 said:

The Rigol DS1052E wont go down to 500microV/div, its just like the tek scope 2mV/div minimum vertical display which is not very useful if you want to measure stuff like AC ripple coming out of a PSU, unless theres something evidently wrong with the power supply itself.

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This is indeed one of the biggest issues with DS1052E and limits usability. I have a multimeter that measures much more accurately, but it would be much easier to just see it all in one screen. Also the FFT feature is pretty useless. The scale doesn't really show much anything of interest for audio use. DS1052E is one of those "great for the price" scopes. Does a couple of things really well, great UI, fast screen.

By the way it turns out 100MHz is not at all overkill for audio (I modded mine to this bandwidth). I have just discovered this playing with opamps. Very often there are low level oscillations above 50Mhz range.

user 37518 said:

Nice, did you do the firmware mod to bump it to 100MHz? hows that working for you

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Yes, I used the instructions from eevblog forums. Works just like a DS1102E would, a nice $100 saved. As far as they have researched this on eevblog, Rigol makes these two models exactly the same. There's no factory cherry picking involved to make these two different models (something they do with CPU's and GPU's). At least nothing that would show to us end users, just a different firmware. Strange oldschool marketing way of thinking and releasing products with no benefit to anyone really. Rigol even has a direct link to the firmware instructions on their product website.  ???

Also, Rigol is by no means the only cheap China scope manufacturer, just the most famous/common one. There are other players in the field with excellent specs and feature sets. I was actually considering some of them, but Rigol UI (ease of use) weighed more heavily for my use. If you can deal with more UI clicking to move from one feature to another, then there are better choices around.

Check out for example Owon SDS7102V.

There are high frequency oscilations, which in most cases can be considered harmless.

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Is there a new trend to think that stability of a feedback loop is of secondary interest only..? Getting a feedback amplifier stable is, after the basic DC bias conditions, the first and foremost condition to be met. I have yet to see a case where the amplifier showed instability, yet no performance degradation (in particular distortion and noise) in the audio frequency band could be observed.

I can't comment on the quality of the FFTs in digital scopes (I'm using a PicoScope for this, which is reasonably good here), but increasing the sensitivity is easy by adding a simple 100x preamp.

Samuel

Samuel Groner said:

There are high frequency oscilations, which in most cases can be considered harmless.

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Is there a new trend to think that stability of a feedback loop is of secondary interest only..?

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Many (all?) of the famous Golden Pinnae amplifiers I have tested have shown bursts of oscillation on parts of a sine wave when driving real speaker loads.  This behaviour is often dependent on the thermal history of the amplifier too. 

The 'usual' 2uF reactive load tests often don't pick this up.  Now you know why these Golden Pinnae amps sound different.  8)

I was looking at different scope offerings and it seems that they all based on 8bit ADC - which limits sensitivity, resolution etc. Seems to be the case for all scopes from $70 to $2000 or so. I, personally, wanted to see DAC out of band noise floor, but it seems that nothing short of audio precision can do that, which is a little pricey for a humble hobbyist...
:-\

user 37518 said:

I suggested limiting gain BW to prevent high freq oscilation, im just saying that Ive seen several amplifiers exhibit some minor (keyword minor) oscilation on very high frequency (on the MHZ region), and at least to my ears theres not some weird issues going on.

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Dual, both Sam and I take issue with "minor" oscillation.

An audio chain MUST NOT OSCILLATE.  No IFs.  No BUTs.  I won't comment on your ears but in ALL cases where I've seen "minor" MHz region oscillations, the sound has been audibly affected ..  also THD etc.  Its indicative of poor design, layout & testing.

user 37518 said:

I was also looking at the Tek TDS2000 series scopes, and they also perform your typical FFT analysis and what not, but they wont go lower than 2mV/div.

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I own a Tek TDS2024. I agree about the worthlessness of the FFT feature.

Other than that, it's a decent enough little 'scope. I don't know if the newest version (TDS2024B, I think) improves some of the features such as display update and FFT and triggering (who cares about NTSC triggering anymore, anyway!) but it does use a USB stick for data and waveform storage instead of a compact flash card in a $300 add-on.

And I'll throw in with the folks who say you need wide bandwidth to see oscillations and such. And if you're playing with converters you want something that can show you your clocks and data lines.

I think if you're interested in audio-band FFTs, you're best off springing for a Smaart license and using a high-quality soundcard.

Damn the DPO3054 is NICE but pricey.

user 37518 said:

..is just that ive seen that some designs tend to "burp" sometimes high freq. oscillation which at least on my tests, didnt seem to bother me that much

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Dual, if you make stuff for yourself, you are entitled to think this is OK.  I'm not sure where I'm being rude to point out that this is unacceptable to many people including myself.  In my book, if a piece of gear "burps" at HF even 'sometimes', this is very poor design, layout & testing.

If a manufacturer even hints that this is OK, I strongly recommend you don't buy their gear.  Not sure if this is better than a manufacturer who is unaware that his gear behaves like this.  :

user 37518 said:

too much Gearslutz perhaps?

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I avoid Gearslutz. I like my computer monitors without wrenches thrown into them.

-a

Perhaps we need to invent a universal translator that converts what we say and think into something less offensive to younger generations.

I believe Ricardo was trying to express his inability to accept any unstable electrical circuit in a professional audio path.  This is not a matter of subjective taste, but objective design standards.

While modern gear is better about self preservation, it was not unusual for oscillating circuitry to damage tweeters and much more. 

JR

PS; Gearslutz has it's entertainment value, and lots of eyeballs.

JohnRoberts said:

Perhaps we need to invent a universal translator that converts what we say and think into something less offensive to younger generations.

I believe Ricardo was trying to express his inability to accept any unstable electrical circuit in a professional audio path.  This is not a matter of subjective taste, but objective design standards.

While modern gear is better about self preservation, it was not unusual for oscillating circuitry to damage tweeters and much more. 

JR

PS; Gearslutz has it's entertainment value, and lots of eyeballs.

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Naaah John, I've followed your posts, they are great and you always offer a helping hand.

I must add that I find quite amusing those thread in which you and Jim Williams have your arguments  ;D

I have bought a Rigol DS2072 and find it quite decent.  I won't go through all of the features but it is feature rich.  The extra sensitivity is useful and you can limit the input bandwidth to 20MHz to minimize residual noise.  That makes it quite useable even at the 500uV/div setting.  I find it great for general audio work. 

The FFT has limited flexibility and I haven't found a way to adjust the sensitivity for it; It doesn't follow the channel input sensitivity adjustment.  For the FFT function you have a maximum visible range of 80db (10dB per division, 8 divisions) but you would have to adjust the output level of your audio circuit to set the signal to full scale on the screen.  It won't replace a good spectrum analyzer.

It doesn't follow the channel input sensitivity adjustment.

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That's strange. The input sensitivity should be analog (i.e. before the ADC), no..?

Samuel

Slightly OT.. about spectrum analyzers,
I've found some years ago on evilbay an absolute bargain, an Advantest R9211E sold
"we dont know what this is nor if it works", for some 350 eur, shipping and customs taxes included.
Turned out to be perfect and calibrated [apart from a slightly disturbing CRT monitor's 15.75kHz interference peak], and from there I've always used it.
[also, coupled with a white-pink/noise generator via the audio thing under examination has been for me really useful, I like to have some objective measurements and to not trust only my ears].
It arrives only to 100kHz though, so for hi-freq oscillations detection a scope is needed.