I'm gonna get me an oscilloscope. I'm going to use it to mainly fiddle with home audio equipment, like hifi amps, and perhaps try to fix this and that other electrical appliance.
What should I make sure I've got covered?
Some say 50Mhz is good, others 100Mhz. I've also realized memory depth is important, but what is enough? I see oscilloscopes can easily top the overall price of my hifi system if I'd really want to.
20 MHz is overkill for audio gear, unless you are going to start poking around in digital devices like a streamer or DAC.
You might want to look into some PC based solutions. There's a number of capabilities the old school style oscilloscope may not have built in, which are useful:
Most of the scopes available now are sampling scopes, meaning they A/D signal. Benefit of that is memory function, while drawback is possible aliasing showing false results. I would go for 2 channel, 1Gs/s (most likely half of that when using both channels), 2mV per division vertical resolution and 5ns per division horizontal resolution. Many scopes have built in additional functions like Multimeter, FFT analyzer, Generator etc. I would go for Keysight and pay $600 because of quality, but Hantek might be OK. There are many things that can go wrong with the scope (mostly switches) so if you go with Hantek - investigate. Keysight used to be Agilent, that used to be Hewlet Packard (wonderful scopes). I used Agilent scopes at work. On the other hand it is complicated instrument. Are you willing to learn? How much time you can invest? There are $50 toy scopes that might be adequate for basic functions in audio band.
My company has Keithley Multimeters that are about 50 years old and all of them work fine (are tested every year). That’s quality. On the other hand I won’t be living that long ;)
because ego is rarely a replacement for knowledge, I would also suggest an investment in Williams excellent text;; Analog Electronics - Devices, Circuits and Techniques a decent used copy can be had for $40 ish
Don’t listen to those saying 20MHz is overkill. You want at least 20MHz or higher, so oscillations can be found viewed and rectified, dual trace so you can compare channels, and a decent brand with good quality probes. Other wise you’ll be looking for another one soon after you’ve learnt how to use it. And get a good audio frequency generator as well, they are a must and go hand in hand. Then once you reach Nelson Pass status, a distortion analyzer will be on the cards.
25 years ago when I was a digital design engineer, Tektronix and Lecroy were the big players in scopes. The techs in the lab preferred the Lecroys for scopes and the Teks for signal analyzers, as I recall. I have no idea if that still the case now all these years later, however.
Again, nothing at all wrong with a good scope, but if I was doing this from your starting point, I would suggest you look at something a little more specialized, like this:
I have no financial interest, just that after being in the hobby for a while, I want more audio specific tools the scopes never gave me. In the old days a scope and audio analyzer and signal generator were 3 different pieces of gear, now I’d rather forego that all and have one.
You may also want to go look at Audio Science Review were they use several bits of kit to analyze audio gear, see what they do. Oh, also, if you want to play with tubes, make sure you have gear that has probes for the high voltages. :)
Noise and bandwidth are directly linked in most modern scopes. The higher bandwidth ADCs will also have more dynamic range when used at lower sample rates. This is probably the biggest price differentiator as well, as the cost of the ADC is usually the most significant parts cost of the scope.
I was recently in the market for a scope to use for DIY audio purposes and decided to go for the Siglent SDS1204X-E. This is a 4-channel 200Mhz scope and cost about $750. This might be a little overkill, but offers a lot of nice features including FFT functions for distortion analysis.
I started my career doing electronics design 40+ years ago, but it's been quite a while since I did any hands-on work, or bought a scope for that matter. The capability of the sub $1K scopes is mind-boggling compared to what I used to spend 10X+ that amount on a few decades ago.
100 Mhz should be the minimum, it will be beneficial for viewing parasitic oscillations. FFT analysis is a plus, especially high resolution. Most budget scopes have a math function to do this but the Rhode & Schwarz models have the highest resolution for the dollar. The 100 Mhz RTC1000 model is around $1,200, but you also get a waveform generator, digital volt meter, and component tester. The stuff packed in there would have cost you tens of thousands of dollars not too long ago. The $2,000 RTC2000 model has 10 bit A/D converters for even sharper FFT and waveform viewing.
It's a lot of overkill for what you are trying to do -- and a lot of money for the occasional DIYer -- but if you are interested in diving in to amplifier design or repair, then you'll never outgrow those scopes.
@jaytor , I noticed that Siglent SDS1202X-E, sold and shipped by Amazon for $359 is identical to LeCroy T3DSO1102 sold for $725. I read that LeCroy relabels Siglent scopes. That would suggest that Siglent is a quality brand. Perhaps one day I will get one for myself.
I'm in general intrinsically motivated by the field.
For audio, I want to both fix, repair, improve and maybe build gear. I can't afford most stuff on the market, and I find I much more enjoy working with gear rather than just buying new and selling old gear, which often has led to letdowns and frustration. Improving things via knowledge and parts has been much more rewarding.
I'm considering doing a kit amp (First Watt F5 (might be too high level as of now)), and I'm also wanting a tube preamp. I might venture into design some day, who knows. That is the audio part of it.
I also see basic electronics as a very useful skill, for example repairs. I'm learning basic electronics now. I haven't gotten very far, but I'm learning through Khan Academy and Coursera. I also got recommended getting a scope via an electronics repair book by Michael Jay Geier, saying it was the most used tool when it comes to repairs.
I run a restaurant on a day to day basis, and restaurant gear is not cheap. Fridges, control panels, coffee makers, etc. But they also seem quite simple in construction. I'm hoping to repair a large espresso machine, for example, and also some ventilation stuff. I might not pull that off, but this is how I defend buying a scope, soldering iron, et cetera.
So, I'm wanting to balance both cost and usefulness when I'm getting my first scope. Spend enough to get to a decent scope that fits the areas I want to use it on. I also want to get one right now so that I can actually DO, not just read and read and read. I know learning goes way quicker if you actually practice, which is the point, anyway.
In general I'll now say thank you to all of you; this helps a lot!
Stuff I can get here in Norway from stores, and which kinda match my budget: Siglent SDS1202X-E Uni-T UTD2102CEX Rigol ds1054z
As of now, that is what I can get + afford. I could also consider going up a wee bit if it gets me to a whole other level for not too much more money.
I didn't spend any time looking at the Uni-T, but did consider the Rigol and Siglent. Both are a great value. Keep in mind that with these lower priced scopes (including the SDS1204X-E that I bought), you can only use the full bandwidth if you are using half the channels.
So with the 2-channel, 200Mhz scopes, you're really getting a 1x200Mhz or 2x100Mhz scope. This is because they have a single ADC which is shared between the two channels (or used for a single channel if the second is disabled).
For most audio circuit use, this will probably be adequate, making these scopes quite a bargain.
I was considering an oscilloscope several years ago and during my research came across this guy. First video is his feelings about the cheap PC based USB oscilloscope devices:
The guy is very entertaining and the videos will help you with how these scopes are actually used. I ended up not getting a scope, but in my reviews I was siding towards the Rigol models and would get a step up model, such as the DS2202A. It's only 2 inputs, but a higher 2GS/s sampling rate.
I agree about modern digital scopes are the way to go.
As a no-longer professional, if I had to start all over again as a student I’d look for combo systems though, get all 3 of your needs in terns of signal generation, measurement and observation.
If you are starting into the hobby, you may even do well with NO scope at all. Just use your PC’s sound card for the signal generation, measurements until you’ve learned what the limits are and where you want to go. In the audio spectrum, what a PC can do is amazing (compared to the 1980s), and certainly good enough to work your way through most Op Amp and simple amplifier text books with the right software, some of it free.
Of course, who doesn’t want the best gear possible? But if you are starting... save your money for text books, courses and experimental parts.
Thank you all for the help! I ended up getting a lightly used Rigol 1054z. And yes. You can hack it to unlock 100Mhz, increasing from 50Mhz, more memory (24M) and some advanced features.
If you have a computer, just get the software and a set of USB or Bluetooth oscilloscope probes and you’re all set. Way cheaper than a real electronic ‘scope.
Ground on a scope is normally chassis ground (on all except fully isolated). Careful when you connect ground both for potential for a short and noise you didn't expect.
Even when scope is fully isolated there will be always some very small capacitance between BNC connector ground and the earth ground. Because of that, probing any circuit that is not battery powered can deliver nonexistent noise, even if probe is shorted on the probed circuit ground. It happens because there will be small current between probed circuit ground and scope's ground causing voltage drop on the probe's return. Scope will "see" this voltage drop as a signal (since input is related to BNC connector GND and not the end of the probe GND). It is just in case you wonder why scope shows anything (very small HF noise) when you touch circuit with shorted probe.
Small parasitic capacitance (even few pF) is enough to produce noise. Every scope I've ever used showed small high frequency noise when touching other circuit, even with probe shorted. It becomes a problem only when you need to look at mV level signals at high frequency, otherwise you can just limit bandwidth of the scope (or use two channels and take a difference). I agree that truly differential input should help, but even probe itself has slightly different inductance of both wires. If you don't have this problem - great. Perhaps you have better scope, I ever used.
Yes, there is alway some antenna, but there is a pronounced increase in noise when shorted probe touches the other circuit (shorted with wire loop or two-pin adapter). Battery powered scopes also show this to some extend, because of these tiny capacitances. Few pF becomes only few hundred ohm of reactive impedance at 100MHz frequency.
Most of what I was going to say has already been said here, mostly by @georgehifi. I do a lot of audio electronics, I use a QA401 for measurements (it's truly incredible value for money when you compare it to the other stuff out there) and an uncalibrated, analogue 100MHz Tektronix to 'see' the signal... usually square wave testing for oscillation which I find much easier on an analogue scope. It's worth remembering that although we can't hear higher than 20kHz, an amplifier can oscillate at any frequency in it's bandwidth so high resolution is a must. I've used digital scopes which were useful at the time for the FFT but I don't need that now I have the QA401... if you set it up right you can measure distortion down to about 0.0001% along with all the other measurements you'd expect to run on an amp. Other than a 4 1/2 count Fluke DMM i could get by without any other measurement tools.
I made some searching on oscilloscopes and concluded that non-toy scope starts at about $200. There are three companies wort consideration: Siglent, Rigol (about the same) and Owon or Uni-T at the lower end. Cheapest you can get is Hanmatek exact copy of Owon, but it is unknown brand, scope has two channels but no external trigger (deal breaker) and no test/calibration points (deal breaker as well). This 100MHz Hanmatek would cost about $230 ending up $250 total, including tax. Rigol has special at $299 (free shipping, no tax) on 2-channel scope, that they normally sell for $369. It is DS1202Z-E - a 2 channel 200MHz scope with 1Gs/s. Of course 1Gs/s for 200MHz bandwidth is not enough but still, 200MHz is more transparent, rise time is 1.75ns and the probes are 350MHz. This scope also includes free options worth probably as much as scope itself - Advance triggering, Memory depth upgrade, Real Time Waveform Record/Relay and Serial Bus Analysis. It has only two channels but 4 channel scope is $50 more for 50MHz only. Either scope is good choice, but I used to work with 100MHz 2GS/s two channel Agilent, that was sufficient most of the time. In addition Rigol now gives warranty extension from 3 to 5 years for direct buys (or authorized dealers). I bought this scope and just finished playing with it. It is wonderful, well build instrument on the par with $1k Agilent. It is very intuitive, in spite of tons of options, and has immaculate user's guide in pdf (plus other guides). Of course I don't have to have it, but it was my tool at work and I feel I need to have it (bucket list). Unfortunately the cheapest protective case that makes sense (size and quality) is one made by Rigol that is $58 at Newegg. I bought it as well.
@jaytor 2-channel 200MHz scope is still 200MHz per channel. Sampling rate drops by half but analog amplifiers are still 200MHz. Some scopes (including mentioned Hanmatek) don't even drop sampling rate (dual A/D converter).
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