Digital Oscilloscope?

MattNes

Member
2016-01-30 7:48 am
Hey guys,
Im pretty new to this site. So I just wanted to start off with that. I have some questions about Digital Oscilloscopes.
First, let me mention that I do not know how to use an Oscilloscope. I understand the basic idea but thats it. I want a "scope" to use for testing while building various products like...

Tube Stereo Amplifier (Hi-Fi)
Tube Guitar Amp
Analog Reel to Reel.

I own a Tascam TSR-8, 8-track reel to reel and would like to be able to test and calibrate it. I remember that last time I tried to calibrate the machine the manual mentions that I needed a "True RMS" Multimeter.
So, that leads me to the 2nd part. If I go with a new digital "Scope"? Would that be able to do the same thing as a True RMS Multimeter?
Also, if I wanted to align the heads on the R2R I need to check the Azimuth. Im pretty certain that all "Scopes" can do that.
So what brands and model do you recommend?
 
Digital scopes with math/measurement functions can indeed display RMS values, and should exceed 'true RMS' DMM accuracy when the crest factor is more than about 3.

As for recommendations, I'm sure I speak for many fellow old-timers when I say that there's only one scope worthy of the name: Tektronix. I just bought another one -- probably my last. I see that it was made in China, but it reeks of quality just as much as the first Tek scope I bought back in the seventies. And that old analog 475 still does standby duty in my shop.

While I'm pontificating
icon10.gif
, one more point: Scopes let you visualize unseen and misunderstood electrical phenomena in a way that makes them much more than a measurement instrument. Don't cripple yourself by getting a cheap one that's confusing to operate. You could learn a lot by just fooling around -- if it's not painful.
 
Digital scopes with math/measurement functions can indeed display RMS values, and should exceed 'true RMS' DMM accuracy when the crest factor is more than about 3.

As for recommendations, I'm sure I speak for many fellow old-timers when I say that there's only one scope worthy of the name: Tektronix. I just bought another one -- probably my last. I see that it was made in China, but it reeks of quality just as much as the first Tek scope I bought back in the seventies. And that old analog 475 still does standby duty in my shop.

While I'm pontificating
icon10.gif
, one more point: Scopes let you visualize unseen and misunderstood electrical phenomena in a way that makes them much more than a measurement instrument. Don't cripple yourself by getting a cheap one that's confusing to operate. You could learn a lot by just fooling around -- if it's not painful.

I would NOT recommend anything basic level from Tektronix. As much as they were great, they spent the past decade or so barely innovating on their lower tiers (and some would argue some of their upper tiers were ignored too).

Agilent did a much better job spreading their innovation around, even if they did give Rigol the foot-in-the-door they needed to get started on making their own scopes. For those that don't know, Rigol makes the DSO1000 series for Agilent, Agilent basically taught them how to make a solid quality scope.

The Rigol DS1054Z is the max value scope that you can get. It is not perfect but it gives you a highly capable 100Mhz four channel scope with deep memory and decoding (you can easily unlock all of the features using Riglol).

Otherwise, a better quality would be Agilent/Keysight's used store on eBay. They take offers and you can find one that fits your needs well and make an offer on it.
 
On the other hand, how innovative does a scope have to be for a guy to learn how to use a scope, and to work on guitar amps? Just my opinion, but I think older analog scopes are more intuitive, especially for the beginner. I would consider that a multi-thousand dollar digital scope is maybe WAY more scope than the OP needs. A dumb old 35MHz B&K or something is plenty of scope to align and calibrate his TASCAM deck. I was a authorized TASCAM warranty center for thirty years, using exactly that.
 
I just did a quick review of Tek's TBS1000B datasheet, and they're offering a ton of goodies for the money. Model TBS1052B (2 channels, 50MHz) goes for only $495 at Test Equipment Depot, with a 5-year warranty. This looks like the sweet spot to me, but there's a total of six bandwidth/price combinations.

Lets just do a quick comparison on the tek and the rigol DS1054Z


  • Price: Tek: $500, Rigol: $400
  • Number of channels: Tek: 2-channels, Rigol: 4-channels
  • Sampling Rate: Tek: 1Gs/sec, Rigol: 1Gs/sec
  • Memory Depth: Tek: 2.5kpts (unacceptable), Rigol: 12Mpts (24Mpts after hack)
  • Bandwidth: Tek: 50MHz, Rigol: 50MHz (100Mhz after hack)
  • Intensity Gradient aka Digital Phosphor: Tek: It appears no (this is a HUGE feature loss, it appears only on their DPO scopes), Rigol: Yes
  • Waveform Update Rate: Tek: Unlisted but the next model up has only 5k/sec, Rigol: 30k/sec
  • Decoding: Tek: No, Rigol: Yes (RS232, SPI, I2C, UART)
  • Segmented Memory Tek: No, Rigol: Yes
  • Warranty: Tek: 5yrs (very nice!), Rigol: 3 yrs.

The Tek is MUCH closer in comparison to the old Rigol DS1052E which now goes for under $300. That being said, the Rigol's FFT function is known to not be the best. I won't even discuss triggering because that just gets into a numbers game at that point. The Rigol has way more but it also can trigger off decode too. Full disclosure, I don't have a Rigol, I have a LeCroy WaveAce (aka Siglent) which I got for an amazing price.
 
Last edited:
On the other hand, how innovative does a scope have to be for a guy to learn how to use a scope, and to work on guitar amps? Just my opinion, but I think older analog scopes are more intuitive, especially for the beginner. I would consider that a multi-thousand dollar digital scope is maybe WAY more scope than the OP needs. A dumb old 35MHz B&K or something is plenty of scope to align and calibrate his TASCAM deck. I was a authorized TASCAM warranty center for thirty years, using exactly that.

Most digital scopes are way more powerful than their analog counterparts at this point, entry prices are now below $400. The OP asked about digital, I explained digital. I don't disagree that for the uses he listed an analog would suffice for now. That being said, in the future he might find use for the extra features of the digital.
 
Yes, Enzo... I am not looking to get a top of the line, state of the art Scope. I just need something that I can use to calibrate and check guitar amps and possibly a stereo hifi tube amp and the Tascam reel to reel.

Then do what Enzo said, pick up an analog scope for under $100 and you will be more than fine. Unless you believe in the future that you could use the higher capabilities found in a digital scope.
 

MattNes

Member
2016-01-30 7:48 am
What I like about the digital Scopes is that they are brand new and very unlikely to break. But they will cost more.
What I like about the "Used" Analog Scopes is price and it seems that they can do what I need. What I dont like about the "Old" Analog Scopes is that it seems they are as likely to need a refurb as a old Harman Kardon. I dont want to score an old analog scope for 100 bucks and then spend most of the time fixing it.
It is not so much confusing as just a hard decision to make.
 
What I like about the digital Scopes is that they are brand new and very unlikely to break. But they will cost more.
What I like about the "Used" Analog Scopes is price and it seems that they can do what I need. What I dont like about the "Old" Analog Scopes is that it seems they are as likely to need a refurb as a old Harman Kardon. I dont want to score an old analog scope for 100 bucks and then spend most of the time fixing it.
It is not so much confusing as just a hard decision to make.

Those are valid points and the worse part is that you often need a scope to repair a scope. Personally, if you don't feel like going for a very cheap (sub-$100) analog scope, I would save up for something like the Rigol DS1054Z and hack it to enable all of the features. It is a lot more scope than you need, honestly but there are a LOT of benefits to it. You never know where and when you might find things like I2C decoding or 100MHz bandwidth useful.
 

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
Hi MattNes,
What I like about the digital Scopes is that they are brand new and very unlikely to break.
The problem is that they are easy to break. They generally do not withstand the higher voltages you might come into contact with (not literally!). The USB scopes are probably the worst for that. A 5 V maximum input voltage means that with a normal X10 probe, your maximum input voltage is only 50 V peak. That is very low!
What I dont like about the "Old" Analog Scopes is that it seems they are as likely to need a refurb as a old Harman Kardon.
Well, the better 'scopes need less maintenance, but they still need maintenance. Just like everything else as you've pointed out. That is a reality that most don't like. Most of my 'scopes were bought used. I use the one I bought new to fix them (it was a very good 'scope). These days I buy used equipment, but from excellent firms like HP / Agilent / Keysight, Tektronix and others.

Check the ability of any digital scope to show any signals you may run into. An eye pattern from a CD player is one good example. Most digital scopes don't display this well, although that is changing with the new $8K + market. That will eventually filter down to the less expensive products. They aren't there yet.

I keep an analog 'scope on my bench along with a good digital 'scope. For those who want to know, a Tektronix 2465B and an Agilent 54642D. The Agilent does a decent job with an eye pattern, but the analog 'scope is much, much easier to see and use for that job. I do tend to use the Agilent the most, even though the Tek has been with me much longer.

Do try prospective 'scopes before you buy if that is possible.

-Chris
 

nthall

Member
2015-12-15 4:43 am
Either the Rigol 1054z if you want to spend the money, or a used tek 2225 on a budget would be my first choices.

It's even better to have one of each. I still use the analog ones the most out of habit mostly.

I wouldn't buy a cheaper digital, because you are going to want more features down the line.