First personal 'scope purchase... - Page 1
Forum section: electronics / testgear

author: allen.gordon
author_rank: Contributor
timestamp: May 04, 2015, 10:29:42 pm
content: Hello All, as you can tell, I'm new to the forum.I have opened a small part-time business and find myself in the market for a scope.I have researched and concluded these 2 methods:1) buy a used analog and get busyor2) buy a new entry-level DSO and get busy...I am a novice in the world of electronics. I only deal with audio electronics, and specifically those that apply to guitar and bass guitar.Even more specific, I only handle and repair TUBE guitar amps, but can see myself getting into tube hi-fi as a hobby in the future.I am not sure what scope features would be best for me, and which ones would be overkill or never used.I AM, however, in the process of reading XY & Z's of 'scopes from Tek.com's learning center in an effort to answer my own questions.If any of you would be willing to offer guidance in this I would be extremely grateful!Digital or Analog?Will 50Mhz scope work, or do I need 100Mhz?Any other features I need, or should avoid?Thank you in advance for your time and attention!

author: allen.gordon
author_rank: Contributor
timestamp: May 04, 2015, 10:31:48 pm
content: I have my eye on a Rigol DS1102E. I can manage that price, but again, their reputation is unknown to me, and I am not sure if it has what I need...

author: bson
author_rank: Unknown
timestamp: May 05, 2015, 01:43:24 am
content: Get a storage scope - digital or otherwise. Few things are useful as capturing an offending signal and then being able to dissect it. For audio, bandwidth is of no concern, and even 1MHz is plenty. What's useful though is an FFT function, and you'll only find that in a digital scope. 4 inputs is nice and lets you check say, the input, transimpedance output, transconductance output, EF input, and EF output all on one screen. Another nice addition is a uCurrent and a differential probe to let you easily scope current (inserting sense resistors and a quality instrument amp at the flip of a switch), for instance to check the behavior of a current source or the output of an input transimpedance stage.

author: nixfu
author_rank: Unknown
timestamp: May 05, 2015, 02:01:15 am
content: >Rigol DS1102EEeek. The old DS1102E is no longer a good purchase or deal anymore.Get the DS1054Z for just a tiny bit more its LIGHT YEARS AHEAD in capabilities and is much much more worth the difference in price between the two.You might want to watch Dave's review of the DS1054Z.https://www.eevblog.com/forum/blog/eevblog-703-rigol-ds1054z-oscilloscope-review-summary/BTW, EEVBlog members get a 6% discount fromhttp://tequipment.neton top of the price on the website:http://www.tequipment.net/Rigol/DS1054Z/Digital-Oscilloscopes/?v=7401So its $399 - 6%. All you have to do is ask for the special code and someone will PM it to you.I purchased my DS1074Z from them, and got very good service. I think there have been untold numbers of Rigol's purchased by members here from them, all with good experiences.

author: aryasridhar
author_rank: Regular Contributor
timestamp: May 05, 2015, 02:31:22 am
content: Quote from: allen.gordon on May 04, 2015, 10:29:42 pmI work on building guitar pedals and amps and for the most part all you need is a good multimeter, a good analog 15-20 Mhz scope is all you would ever need, I would suggest look for a nice analog scope on ebay, you may get a good one for no more than 50-100 bucks and that's all you need really.Also invest a bit on a function generator, all you need to really trace would be the tone, vol, gain pot behavior on the scope and that will more than likely tell you how your amp/pedal is behaving. Check out this video of mine where I do just that for a few pedals that I build.Another handy aspect of a scope would be to troubleshoot an amp or pedal circuit if something does not work well.You may want to get a DSO, if you have desk space issues, else get a nice old analog oscilloscope. I have one and could not be happier, I do not see a need for me to get a DSO at this point, however, I'd like to expand my horizon by getting into other electronic stuff as well than just audio, so maybe will get a DSO in the future, however to start with as an amateur a good analog scope is all you need.and yes the Rigol DS1054Z is a killer scope for the price. If i had to get a DSO today, I would jump at the Rigol, and as someone mentioned 1052E is pretty much obsolete, however if you are getting a very nice deal, it may not hurt to get one IMO.

author: pickle9000
author_rank: Super Contributor
timestamp: May 05, 2015, 03:28:40 am
content: One thing a DSO can give you over an analogue one is the ability to save waveforms, screenshots and setups. If you are working on a particular bit of gear you will be able to save a set of expected signals (in and out) and show levels this will aid in troubleshooting and you may even want to include this printout to your customer as an indication that the unit is working.The DS1054Z is a good bet, even if you don't use all the features many others are using that scope now. If you have a question about it then there are many on this forum alone that can help.The general rule is get the best test equipment you can afford. And for audio stuff a good function generator and a good audio source that can play what your customer provides is also desirable. Ask them for a sample of their music and what they expect, it's pretty basic but involving the customer is always good in the music industry.

author: allen.gordon
author_rank: Contributor
timestamp: May 05, 2015, 03:52:40 am
content: WOW! This forum is AWESOME!!!Thank you so much for the many detailed replies. I understand how basic of a question this was and how much it must get asked.I used the search function after reading the Sticky, but couldn't find specifics on the features I need.I found Dave's youtube page not long after posting this page and learned a GREAT deal. Especially the video on the OC'd ADC's of the Rigol 1052E and the firmware "upgrade."I have had my eye on some older Tek analogs, but they are priced close to the Rigol, and don't include any guarantee of function, much less warranty! I have found some that have functional screens, but "no further testing was conducted." How hard is it to show a pic of a calibration?!? Seriously...I have much information to process, and some links to explore.Thank you each, again!!!Allen

author: poot36
author_rank: Frequent Contributor
timestamp: May 05, 2015, 03:59:21 am
content: Also be aware of the maximum voltage that the scope can handle! Tube amps can have 450V or higher in them and most digital scopes can not handle that voltage unless you get a 100X probe! Be careful!

author: tautech
author_rank: Super Contributor
timestamp: May 05, 2015, 08:09:58 am
content: Quote from: poot36 on May 05, 2015, 03:59:21 am+1Many scopes Analogue and DSO have only 300V rated inputs.There are a good few with 400V inputs however and these models/brands will give you a better safety margin for the higher voltages encountered in valve work.

author: dom0
author_rank: Super Contributor
timestamp: May 05, 2015, 08:42:28 am
content: Quote from: bson on May 05, 2015, 01:43:24 amI beg to differ. With a 1 MHz scope you'll have a hard time seeing oscillations in amplifiers, at least solid state ones. Even the "old and trusty" NE5532 can easily oscillate at 10 MHz (partial oscillations will greatly degrade audio signal quality)... not talking about the current 'avant-garde' op amp generation (LME series etc).>= 20 MHz should be enough however.Two channels are usually enough and with some ingenuity / hassle almost anything can be done with two channels. Four channels are more of a comfort feature, really.You likely won't need a DSO for audio work, although it doesn't hurt (unless the DSO has a crap display). An analog scope with same bandwidth and channels will usually be cheaper, but of course much older and will probably require maintenance at some point.A somewhat decent function generator makes sense, it's usually cheaper to buy one than to build one yourself. You'll primarily want sine (few Hz to a few hundred kHz for audio work) and a clean square wave output with rise and fall times below, say, 1 us. That being said, almost any function generator can do that.

author: nctnico
author_rank: Super Contributor
timestamp: May 05, 2015, 09:40:18 am
content: I wouldn't get an analog scope for audio work. They are useless for showing low frequency signals (unless you can find a boat anchor with storage). Besides the high frequency response you'll also want to know the low frequency response.

author: KJDS
author_rank: Super Contributor
timestamp: May 05, 2015, 09:45:12 am
content: If you're going near tube amps, spend some time finding a good high voltage x100 probe.If you can find a cheap old analog scope locally then pick it up, otherwise the Rigol is the easy way forwards.

author: aryasridhar
author_rank: Regular Contributor
timestamp: May 05, 2015, 12:13:39 pm
content: Quote from: nctnico on May 05, 2015, 09:40:18 amWould you mind elaborating how analog scope would not show low frequency signals and how can one practically benefit from getting a DSO for audio use? It would help me understand better and maybe I will get one too.

author: dom0
author_rank: Super Contributor
timestamp: May 05, 2015, 12:34:35 pm
content: It of course does, with a normal analog scope you'll just see a moving dot/short trace and no standing image. That doesn't keep you from reading the amplitude.

author: john_p_wi
author_rank: Regular Contributor
timestamp: May 05, 2015, 02:32:47 pm
content: I certainly would not say analogs are worthless for audio, as I use a 100 Mhz Leader 516 with a 400v input rating for all of my tube amp audio work. What is obvious is that with analog scopes, not storage, is that when the function generator frequency is knocked down by a decade, say from 1khz to 100 hz, the display is not a constant display of the wave but a flickering display of the wave - but it does show the waveform. About the only downside (besides storage of the wave) of the analogs are the constant adjustment of the time scale to display the wave as the function generator is swept through a range. Most of us guitar amp guys sweep between 440hz and 1000hz, not a huge range.What is more important is the understanding of where to probe, where to connect the ground (why you don't measure across a resistor with a normal probe and the ground the way you would with a DMM), and the difference between the rms display of the DMM and peak-to-peak shown on the scope and of course safety.

author: dom0
author_rank: Super Contributor
timestamp: May 05, 2015, 04:23:48 pm
content: Quote from: john_p_wi on May 05, 2015, 02:32:47 pmHuh? This is actually a way larger issue with DSOs, especially with the Chinese ones which slow down significantly (the Hantek I got goes down from about 2500 wfrm/s to about 1.5 wfrm/s in deep memory mode, the ds1054z hopefully does better than that) with deeper memory. An analog one will just display a wide band at high time base mismatch, but the amplitude will still show correctly. You can't say neither about DSOs, in general.

author: john_p_wi
author_rank: Regular Contributor
timestamp: May 05, 2015, 04:33:50 pm
content: OK, let me rephrase that:About the only downside (besides storage of the wave) of most analogs are that they lack an "Auto" button....Believe me, I love a good, crisp, thin CRT waveform display, that is why I still use one.

author: dom0
author_rank: Super Contributor
timestamp: May 05, 2015, 04:37:56 pm
content: There are scopes where that thing a) works and b) works faster than me turning the knobs? I hit it accidentally once on mine and it took like five seconds to find the 'correct' settings (which were poorly chosen). Never tried it on any other scope.

author: tautech
author_rank: Super Contributor
timestamp: May 05, 2015, 04:42:05 pm
content: Yes, some think the use of "Autoset" is actually using the scope....it really just demonstrates one's inability to use one.

author: zapta
author_rank: Super Contributor
timestamp: May 05, 2015, 06:41:33 pm
content: Quote from: john_p_wi on May 05, 2015, 04:33:50 pmAnd the lack of FFT?

author: bson
author_rank: Unknown
timestamp: May 05, 2015, 06:44:07 pm
content: Quote from: dom0 on May 05, 2015, 08:42:28 amI did a lot of audio hobby stuff in the 80s with an at that time entry-level 2MHz analog scope, and it was absolutely fine. You wouldn't fail to notice 10MHz oscillation. That said, it's a non-issue since any half decent scope today is 50MHz at least. I wouldn't worry about bandwidth at all - at least not for audio.

author: dom0
author_rank: Super Contributor
timestamp: May 05, 2015, 06:52:22 pm
content: Touche, you'd still see the trace thickening.

author: Howardlong
author_rank: Super Contributor
timestamp: May 05, 2015, 07:53:02 pm
content: Quote from: tautech on May 05, 2015, 04:42:05 pmOn the other hand, the "reset to default settings" button/option is used pretty often here on DSOs. There's far less need for such a button on an analogue scope, all the settings are right there in your face.Autoset is somewhat handy for quick recalibration of probes, but if you can't set up the scope with one or two tweaks from default settings to do that, it's probably time to learn how!

author: technix
author_rank: Super Contributor
timestamp: May 05, 2015, 08:14:58 pm
content: Pay a visit to your local college and they may happen to have a few old CRT scopes for sale (or maybe better, waiting to be given away,) and some of them may even be in a very good shape.I got my Luyang YB4325 CRT oscilloscope, 20MHz with digital readouts, from Shanghai Jiaotong University, one of the best universities in my country that is located in my city. That cost me US$60 meanwhile the cheapest Rigol available on Taobao will cost me four times of that.However for basic audio gear repairing that 20MHz CRO is probably more than enough. I don't have a function generator but my Raspberry Pi with Wolfson Audio Card (up to 24bit/192kHz sample) is more than enough to test most of the audiophile grade gear. The only downside of CRO as I know besides the lack of an "auto" button (which is not really a downside) is it cannot do single shot capture and can be useless when debugging digital circuitry. But for that I use my EPM240 eval board with a logic analyser programmed in, not my scope.

author: allen.gordon
author_rank: Contributor
timestamp: May 06, 2015, 08:31:22 pm
content: Thank you each, again, for your replies!I have selected the Rigol DS1054Z for my first personal 'scope.I am currently searching for a decent set of x100 probes to go along with that purchase.Are Cal Test probes durable?What are the implications of buying 150Mhz probes for use on a 50Mhz scope?I am looking specifically athttp://www.tequipment.net/Cal-Test/GE3121/Oscilloscope-High-Voltage-Probes/

author: Lightages
author_rank: Unknown
timestamp: May 06, 2015, 08:44:11 pm
content: The DS1054Z comes with 4 probes and they are OK. Some have had problems with some faulty ones but Rigol will replace them. I would not worry about getting anything different unless you are sure you need them.

author: technix
author_rank: Super Contributor
timestamp: May 06, 2015, 09:00:17 pm
content: Quote from: allen.gordon on May 06, 2015, 08:31:22 pmAs long as the frequency rating of the probe is higher than the scope's you are good to go. My 20MHz scope is matched with a pair of 60MHz probes and they works pretty well.

author: KJDS
author_rank: Super Contributor
timestamp: May 06, 2015, 09:00:33 pm
content: Quote from: Lightages on May 06, 2015, 08:44:11 pmAre the Rigol ones fine for tube voltages?

author: tautech
author_rank: Super Contributor
timestamp: May 06, 2015, 09:18:26 pm
content: Quote from: KJDS on May 06, 2015, 09:00:33 pmAny scope will do elevated voltages, with the correct probes of course.Most 1x, 10x probes max out at ~600V at low frequencies and the safest move is to have at least one 100:1 probe for HV work.Even so be carefull to watch for "de-rating with frequency".

author: allen.gordon
author_rank: Contributor
timestamp: May 13, 2015, 03:46:15 pm
content: Quote from: aryasridhar on May 05, 2015, 02:31:22 amThanks for your input! I enjoyed the demo of the Flex Drive, but couldn't quite hear the bottom video.

author: allen.gordon
author_rank: Contributor
timestamp: May 17, 2015, 01:05:47 am
content: Quote from: nixfu on May 05, 2015, 02:01:15 amCan one of you fine lab rats take a moment of your time to PM this "special code" to me?I'm all set for the purchase of selected test equipment!Thank you, in advance, for your time!!!

author: Muxr
author_rank: Super Contributor
timestamp: May 17, 2015, 01:36:53 am
content: Quote from: john_p_wi on May 05, 2015, 04:33:50 pmI rarely use the Auto feature on my Rigol DS2000 as it often times just gets set for the noise in my signal and not the actual signal I am trying to see.I'd say the biggest advantage over my Analog scope is storage (or the ability to navigate a larger time slice) as you mentioned. The other thing that analog scopes often don't have are all the different measurements, like having the ability to display different measurements, really helps a lot. You pretty much don't have to count your divisions on DSOs. Also things like cursors.Also not having to fiddle with so many settings to acquire a given waveform. On my CRO at least (Hameg 605) you often have to tweak the trace intensity on top of the usual settings.Analog scopes have their advantages as well. The CRT looks cool, the input is instant. You can quickly set your horizontal and vertical settings without turning encoders endlessly.He can probably get by with just a CRO. But at the low prices of some really great DSOs like the Rigol DS1054z he would be getting a ton for stretching his budget just a bit.

author: john_p_wi
author_rank: Regular Contributor
timestamp: May 17, 2015, 03:05:30 am
content: Quote from: allen.gordon on May 17, 2015, 01:05:47 am

author: technix
author_rank: Super Contributor
timestamp: May 17, 2015, 04:11:08 am
content: Quote from: Muxr on May 17, 2015, 01:36:53 amSome CRO does come with digital readouts but you have to navigate the cursors yourself, like my Luyang YB4325 or some GW ones.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: May 17, 2015, 04:51:00 am
content: Quote from: zapta on May 05, 2015, 06:41:33 pmBehold.http://pcbunn.cithep.caltech.edu/jjb/tektronix/tektronix.htmClose enough?

author: allen.gordon
author_rank: Contributor
timestamp: May 17, 2015, 05:14:34 pm
content: Quote from: john_p_wi on May 17, 2015, 03:05:30 am

author: allen.gordon
author_rank: Contributor
timestamp: May 17, 2015, 05:27:15 pm
content: For all of you that suggested an analog scope, I WILL be purchasing an old Tek or HP in the future. At this point, though, I need a scope I know will work accurately out of the box!My official education on electronics is limited to the role of tube amplifiers, however, I have been spending a great deal of time researching into other applications as well.The DS1054Z will allow me to venture outside the world of tube amps.I have placed the order for my scope.Thank you ALL for your feedback\input! I have learned a great deal about many other topics doing research on the different scopes available!

author: dom0
author_rank: Super Contributor
timestamp: May 17, 2015, 05:47:47 pm
content: What I'm wondering about right now if people are actually aware that the bandwidth rating of any probe is referenced to a 50 ? source?! I mean, you do realize that the typical 1xx MHz bandwidth x10 probe has like 15 pF input capacitance(*) which is a lot of capacitance even at medium frequencies. They're called low frequency probes for a reason...(*) Do the math. 1/(2*?*15 pF*50 ?) ~ 200 MHz, neglecting the 10 M? shunted resistance, which is completely irrelevant above a few kHz.

author: miguelvp
author_rank: Super Contributor
timestamp: May 28, 2015, 01:43:05 am
content: Quote from: allen.gordon on May 17, 2015, 05:27:15 pmI didn't have time earlier to bring this point on Analog vs DSOs.For example my DS2000 Rigol claims 50,000 wfrms/s but I noticed that I can only reach up to 48,000 wfrms/s when the memory depth is set to 700 points (minimal selection is 14K points at just 5,000 wfrms/s, so to achieve 48,000 wfrms/s you have to be looking at a 5ns per division and the voltage and other things seem to matter as well).So people have said it before in the forum how Analog scopes are faster in the update time and I kind of always blew it off, but I had some time to play with my Tek 7613 with a 7A26 dual trace plug-in and a 7B53A time base module capturing a 26 MHz clock and hooked the GATE OUT from the back of the Tek to my Rigol to check what the update rate was.GATE is high when capturing and goes low when retracing the sweep.So to my amazement, it's true, that old scope was triggering at 520,000 wfrms/s, loosing only 2 out of 3 screens, so it was showing me 1 out of every 3 waveforms in real time with the Tek time per division set at 50ns.Edit: since the signal was 26 MHz it was capturing 17 cycles (13 would fit on the screen and 4 would be off screen) and it was missing 33 cycles during the retrace for a total of 50 cycles per sweep cycle.So in order to check how fast it could go I did turn the oscillator off and it seems the maximum free running speed with trigger set to auto is 609,190 waveforms per second.Not bad for something designed in 1973, 42 years ago!Still not older than me, for that you have to go back to the Tek 647I haven't play much with other time bases to see how long the sweep delay takes in other modes.But increasing the intensity you can find runts easy.Of course the DS2000 can trigger on a runt but that's besides the point.I guess I'm trying to say that you should get an analog one as well as the digital one you already ordered.Edit: I must be missing something, it surely is not updating the screen at over 500KHz, does it really display all the triggered waveforms?I think it does and that's impressive, I mean i can put 1000 lines and still get 500 Hz output at that time scale in XY form if I was to put a similar signal as a TV raster sweep?

author: Muxr
author_rank: Super Contributor
timestamp: May 28, 2015, 04:59:06 am
content: Yeah the waveforms/s on the Rigols (I have a DS2000 as well) aren't too hot with what you can get with higher end scopes especially your Keysights. The UI can sometimes be sluggish as well. But you get what you pay for I guess. Rigols are hobbyist scopes that punch above their weight. But I do love me some old analog scopes for that speed, I use my old Hameg 605 as the channel expander.