If you're used to "real" scopes you'll probably only be frustrated by Rigol and its ilk. I don't know what you consider low end, but I'm mostly pleased with my Tek MDO3000 series scope. Also including a 16-channel logic analyser and 3 GHz spectrum analyser, it's a nice thing to have on the workbench.
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Is DAC ultrasonic/RF output important?
- Thread starter pkane
- Start date
That is one I've been looking at off and on. We can get a pretty good deal through our rep. And yes I am a little worried about some of the bugs and quirks of the inexpensive models, though Rigol seems to have a pretty good rep. I got to play with one briefly when a friend got one but not enough to really dig in.
The ones at work are 30-70 GHz models with lots of memory, SW packages, some with bells and whistles, and all that jazz. We also have a nice VNA and SA (both in the 40+ GHz range so not that great for audio, cut off too high). One of the things that holds me back is waffling between audio-type work and the buried desire to reactivate my ham license and get back into RF stuff at home. The little Digilent kit will probably satisfy my audio needs, but for RF I'll need something more like the MDO3000.
I don't like the interface on my MDO3000 at all. Constantly changing role of A and B knob is madness. In addition, you can get it stuck in modes where the UI response grinds down to a crawl. It also constantly clutters its screen with pop up items. My Agilent/Keysight scope is a joy to use compared to it. I have not used a Rigol but from seeing others use it, I don't see issues with its usability. I use my MDO simply because it is the fastest scope I have (500 Mhz). And has a spectrum analyzer. Otherwise, I prefer to use my other scopes.
I have found people tend to like Tek or Keysight UIs, not both, probably based upon what they use most. I have been using Tek "forever" though we have Keysight's on hand that I have used as well over the years (also LeCroy, Nicolet, few others). I have not used our newer Keysight DSOs enough to tell (my work is pretty much on Tek, but I only use a DSO for setup calibration and debug, not in my actual Rx testing).
How do you legally float the ground?Oh, and a warning (not for you Don, as you know this already), but in case anyone wants to get started with a DSO -- heed the warning about the connection of DUTs to the DSO completing the path to ground! I went through two sets of fuses on the Forte amp until I realized I needed to float the ground
OP
- Thread Starter
- #67
Legally -- you don't
But I also put another 8Ω resistor inline with the ground lead and that fixed the problem also.
OP
- Thread Starter
- #68
One thing that's not obvious is that it has 16K memory onboard, and from what I read, Analog Discovery 2 is limited to 4k FFTs because of this. This makes it a bit less useful as an analyzer. But can't beat the 14 bits ADC at anything close to that price.
It has a "record" mode that can stream data to disk, but the max speed is lower. On my 6 year old Core i5-4250U NUC with a SATA III SSD, I could manage to stream 2 channels at 1 MHz (I tested 2 M samples). It is not as convenient as and much slower (less responsive) than using the tiny onboard buffer.
OP
Reminds me that the Oppo has worse measurements with DSD512 upsampling. Not only noise floor but also spikes.
https://archimago.blogspot.com/2019/03/measurements-look-at-audio-ultra-high.html
Oppo's built-in filter without additional DSD upsampling is obviously cleaner.
Of course with additional software PCM upsampling images are further reduced, but no difference below 20kHz. Even above-average software resamplers can have >150dB stopband attenuation but I suppose perfectionists still prefer 240dB(?) from HQP.
https://archimago.blogspot.com/2019/03/measurements-look-at-audio-ultra-high.html
Oppo's built-in filter without additional DSD upsampling is obviously cleaner.
Of course with additional software PCM upsampling images are further reduced, but no difference below 20kHz. Even above-average software resamplers can have >150dB stopband attenuation but I suppose perfectionists still prefer 240dB(?) from HQP.
Then it must be Forte-specific. IIRC it uses CS4398 but my measurements are from a lower-end CS4382.
Are the idle tones reduced if you drop the amplitude slightly? I'd expect white noise at -4 dBFS to overdrive it now and then. Not that idle tones that low are an audible issue...
dc655321
Major Contributor
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I got an AD2 last year. Great little device. IIRC, one can allocate all the memory to one channel or the other. I've also found the Python bindings to be extremely useful for improvising beyond what can be accomplished in the UI.
By certified isolation transformer before mains cord. One instrument - one transformer.
The red and green lines are two portions of the file and they are unrelated, I just overlaid them in the FFT view. Also the white noise is not clipped. The red line is pure idle noise floor - nothing is being played.
For example, with a -90dBFS 1kHz sine playing, the spectrum changed and looks like this:
Got it, thanks. Years ago intersample clipping inside the modulator produced a similar result in one of my designs. Very different design and application, just curious. - Don
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Much of the spiky output goes away even at -.1 db. You mainly see the really nasty result at 0 dbFS and 22,000 hz to 22,050 hz.Then it must be Forte-specific. IIRC it uses CS4398 but my measurements are from a lower-end CS4382.
restorer-john
Grand Contributor
I've had two Rigols. One is on my bench and if it weren't for the instrument interface functionality and capture straight to the PC, it'd be gone. My old analog scopes are better for what I do. Instant, no delays, no f#$king menus (the Rigol has nine individual menu buttons with sub menus- more than a Michelin 5 star restaurant) and no headscratching moments where you just stare at the thing going "what is wrong with this damn thing?- where is my signal/trace? WTF am I looking at?"
I've never yelled at a test instrument until I bought a Rigol. (you can use that quote)
I wasted an hour yesterday trying to track down a strange signal. Gave up with the DSO, turned on my oldest 20MHz CRO and boom, problem solved in about 30 seconds. Actually going to my storeroom to pull out the old Trios I put away several years ago because I miss them so much.
I second that with a Tek DSO we have in the company. I always use the old Tek 2465 to find signals in our NMR spectrometers. But that's just me. All my younger colleagues hate the 2465 and much prefer the DSO. I guess it's just what you're used to work with, and that in my case the manual of the DSO is not available on the spot.
You can always press the AUTO-SETUP knob on a DSO, it should show you something for a start.
Having my own private DSO at home now (Siglent SDS 1202X-E) I can say that it is actually a joy to use. Of course you have to read the manual (220 pages!) to be able to use its higher functions but it can do so much more than my old Tek465. And you can easily shoot yourself in your foot as I did, of course
. As always one should know the limits of one's measuring equipment. This is true for analog scopes as well. I recall debugging our control software with my boss for several hours because a 300 MHz RF pulse was missing until I realized that the Tek 465 we had at hand is a 100 MHz scope (I was used to a 485 which is 300 MHz) and just could not show 300 MHz
. There was no bug in the software.Similar threads
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