oscilloscopes for dummies

Discussion in 'Tube Audio' started by invaderzim, Jun 7, 2018.

  1. invaderzim

    invaderzim Active Member

    Messages:
    355
    Location:
    California
    I'm thinking of getting an oscilloscope. I'd like to be able to actually look at the amp output instead of just guessing; but I am bit overwhelmed by the choices and the how-to use them videos always seem to assume a bit more knowledge.

    It would just be for working on my own personal amps so it wouldn't get a lot of use but I would rather not discover next year that for $25 more I could have gotten one that would do what I need then. I'm also nervous about plunking down $300 or more and then accidentally touching the probe to the wrong spot and frying it.

    I've read through a lot of threads on buying cheap new ones or used ones but there are always multiple different models with numbers really close together.

    I've looked at the Analog Discovery 2, which is appealing because it also does the signal generator part; I'm assuming that an oscilloscope isn't of much use without a signal generator. Plus it would take less space to store when not in use.

    I also did a fair amount of reading on the Rigol DS1102E

    If I go the route of a physical scope then what do I look for in a signal generator to go with it?

    I appreciate any suggestions of new or used models to look for as well as any resources for how to use one for people that have zero experience with one.
     
    Last edited: Jun 7, 2018

     

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  2. BinaryMike

    BinaryMike Pelagic EE Subscriber

    Most serious DIYers eventually acquire two or three audio generators, because all of the desired features aren't available in a single design. Function generators are great to start with, because they can sweep over very wide ranges, they go deep into subsonic frequencies for testing amplifier LF stability, and they produce high quality squarewaves. Unfortunately, they have too much distortion for use with a distortion analyzer, or even for testing speakers by ear. Conventional audio oscillators work well for speaker troubleshooting and general amplifier work, but also have too much distortion for measurement purposes. Ultra-low distortion oscillators work well for distortion measurements and are often incorporated into distortion analyzers for that reason, but they tend to be difficult or impossible to use for smoothly sweeping over a range of frequencies because of pushbutton tuning or amplitude stabilization delays.
     
  3. Audiovet

    Audiovet Well-Known Member

    Messages:
    642
    Location:
    Pretoria, South Africa
    As a cheap 'intermediate' solution, I use sharp resonant filters at several frequencies for distortion measurements. One does not need very low distortion at all audio frequencies, only two or three. One can then adjust the signal generator to correspond with whatever filter you are using and go ahead with distortion measurements at that frequency.
     
  4. audiotemp

    audiotemp Active Member

    Messages:
    482
    You can use a laptop or smart phone as a basic function generator, at least to begin (not for distortion measurements).

    This is a useful introduction to scopes.
     
  5. primosounds

    primosounds Parallel single ended EL84 ,EDCOR OPT

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    A nice signal generator is fun to use. I have BK, that has a digital read out. But for audio frequencies it is definitely overkill but still very easy to use making it a worthwhile investment.
     
  6. invaderzim

    invaderzim Active Member

    Messages:
    355
    Location:
    California
    thank you for the replies.

    audiotemp, that was a great PDF, thanks.

    I'm going to keep my eyes out for a used scope locally and see what turns up.
     

     

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  7. pdm4606

    pdm4606 Super Member

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    Scopes and signal generators seem so cheap lately. I have gotten many pieces at low, low prices.
     
  8. captouch

    captouch AK Subscriber Subscriber

    Messages:
    4,308
    Location:
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    Where in CA are you? I've got a free HP 1744A that kind of works, but could use a tune up. No probes (need them for another scope), but has the instruction manual, power cord, etc. You're welcome to it if you're local (bay area) and just want to play around with a scope before you buy one. Or if you rarely use one, this may be fine for you. I was able to compare signals between channels, etc for the basic work I've done.
     
  9. SPL db

    SPL db It's all about the music! Subscriber

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  10. triode17

    triode17 Well-Known Member

    Messages:
    895
    I bought this Rigol last year for my home bench after using one at work before. The are quite good and a real bargain now because its been replaced. I didn't like what they had replaced it with. There is some getting used to it if you haven't used a digital scope before but once you have, its a night and day comparison. It measures many variations of voltage and time. Like rise time and fall time.Phase shift - so tired of figuring it out by degrees/box on the display. Plus, P-P, Max, min.ave, RMS, etc. It can record and store waveforms and it only weights about 8 lbs, so its very portable. Tip: Always use a 10x test probe and you won't damage the inputs with high voltage accidentally. I recommend it.
     
  11. arts

    arts Super Member

    Messages:
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    For around the same price as that Rigol scope,you can find a used all-in-one audio analyzer that will provide far more useful information than any scope ever will in the audio domain.
     

     

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  12. invaderzim

    invaderzim Active Member

    Messages:
    355
    Location:
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    that is a very kind offer. Unfortunately, I'm a bit too far away.

    time for more research.
     
  13. PastorTube

    PastorTube New Member

    Messages:
    39
    Location:
    Wisconsin
    You might want to check to see if any local schools are having sales. Over the years I have gone to some sales at local tech/trade schools who sell old equipment as they replace their labs. Call around it can’t hurt to ask. Also check out local ham fests and ham swap meets (ham = amateur radio).
     
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  14. Dandy

    Dandy Super Member

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    Arts, can you say more? What to look out for?
     
  15. maxhifi

    maxhifi AK Subscriber Subscriber

    Messages:
    2,455
    Location:
    Edmonton Alberta Canada
    For basic troubleshooting and repair of tube amplifiers, basically any working oscilloscope will do, audio is not a very demanding application. If you're just starting out, try and get a deal on a used one, they can be had very cheap but make sure it's in working condition.
     

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