Oscope - What Frequency?

Need a scope, what frequency would be a good overall choice? Essentially I'm asking because I'm unsure of what is needed for audio related digital work. Looking for something that would cover future bases.

Looking at Agilent and Tektronix mid tier models.

We'd need more detail about what you expect to do with your scope. 100 MHz is about the lowest frequency I'd put money down for; that's enough to see oscillation of audio-type IC opamps, and allows basic troubleshooting of 25 MHz digital signals.

Samuel

The thing is I'm not sure what I'd be using it for as my current digital background is limited. A better question is perhaps what types of signals are commonly seen in digital work (audio related)? Perhaps in things like a/d converters.

From my own personal experience (growing from "no-idea-what-a-transistor-is" to making a living from electronics design) I'd advise away from buying too much into the future. You might end up with more, and more expensive, equipment than you'll ever need. First let the need (and understanding of the requirements) present itself.

Typical DACs have clock frequencies in the 10-25 MHz range. Some more fancy ones are moving into the 50-100 MHz range though, and a DSP ahead of it might go to 100-400 MHz.

For basic toubleshooting a bandwidth of 4x the clock frequency should suffice. For more advanced situations (e.g. timing issues) you might want 10x. Proper probing of fast signals however might also require more specialized probes (e.g. active ones).

Personally I still consider a well-maintained general purpose analog scope (e.g. Tektronix 465,  2445 or 2465) to be an excellent choice for audio work. It probably covers 99% of your needs.

Samuel

john12ax7 said:

The thing is I'm not sure what I'd be using it for as my current digital background is limited. A better question is perhaps what types of signals are commonly seen in digital work (audio related)? Perhaps in things like a/d converters.

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If you're considering anything digital, 200 MHz analog bandwidth and 1 GHz sampling is a minimum.  ADCs and DACs likely have a 24.576 MHz oscillator, and many micros run at similar frequencies. An SPI bus might run that fast, too. So if you want your clocks and digital signals to have square edges, you need wide bandwidth.

-a

I picked up a 300MHz Tek TDS3034c for a good price.

They are good scopes from what I remember, but the memory seems a little light compared to some other offerings. Is this an issue for digital work?