A Newbe question about scope probes...

[Mbira]

What is the point of having them? I have been using those ones that are just BNC to one black-usually aligator clip-and one red-usually little eazy-hook. They are much cheaper, obviously, but what is the point of having the expensive probes with audio stuff? I'm sure I am missing something, and I'm happy to learn what! I guess maybe it's to not load down an amplifier stage?

Thanks.
joel

 

[CJ]

There fine for 20-20, I use the regualr ones for stuff beyond that, like transformer resonance peaks, where the scope probes can shift the frequency curve.
The mini grabber leads are mucch easier to work with, and do fine for most audio.

 

[NewYorkDave]

X10 probes aren't just for RF; I use them all the time in audio troubleshooting and design, especially with tubes. Sometimes even the 1M input impedance of the scope (shunted by about 20pF plus a few more tens of pF for the coax) is too much of a load on a high-impedance circuit. Coax-with-clips is fine for many things but you should have at least one X10 probe around. Make sure it has a trimmer cap (a little screw adjustment, usually) so you can trim the probe for best square-wave response with your scope. Switchable X1/X10 models, trimmable, can be had for reasonable money. Trust me, you're going to need one someday, probably sooner rather than later.

Here's a nice, basic intro to X10 probes. They talk about it more in the context of looking at digital circuits, but they're also crucial in any high frequency and/or high impedance work, as I mentioned above.

http://www.elexp.com/t_probe.htm

(PS: the "properly compensated" example they show is still a bit more rounded than it should be. The calibrator output should look like a square wave, period).

 

[Mbira]

Thanks guys. So I have calibrated scope probes at my old job for digital stuff doing that method in the article with the square waves, but I have never really used one in my work...I do have one 10K probe here that has had the ground clip removed...NYD, where specifically would you use a 10X probe tip in a tube amp that a regular one wouldn't work? That would be great because then I could see here what the difference is...Thanks.
joel

 

[Brian Roth]

Speaking of scopes....

I was chatting with a friend the other day who was seeking a basic tutorial on analog scopes. I recall seeing a Tektronix article somewhere on the web...something like the "ABC's of Oscilloscopes", but I don't have a copy to send him.

Any suggestions?

Bri

 

[Anonym]

http://www.radioelectronicschool.net/files/downloads/xyzoscilloscopes.pdf

 

[Mbira]

So a specific place in an audio circuit where the 10X would be a good idea...
Would reading off of the plates of powertubes be the main place? I'm trying to think of other areas where 1M input impedance wouldn't be enough.

 

[Mbira]

Would anyone be willing to tell me specifically where in a tube guitar amp that I will want a 10X probe? Is there a place that you always know you need one?

EDIT: Sorry, mediatechnology, I didn't see your last comment. So the "interstage" you are talking about is anywhere in the circuit then?
Thanks.
joel

 

[Mbira]

Thanks :thumb: