There are several PC digital oscilloscope apps that allow a soundcard to be utilized as the A/D for the hardware probes that feed signals to the app. The problem is most do not support ASIO, nor sample rate above 44.1 KHz. Which makes them laggy and very limited in usable bandwidth.
The solution below using Cantabile in 192KHz stereo ASIO to host Light Bridge Signalizer (free) (Mayae / Signalizer / Downloads — Bitbucket) vastly outperforms the PC apps I’ve tried. And also outperforms the $50 handheld digital oscilloscopes I tried (except for raw bandwidth). So if you need/want a good oscilloscope for peering into a stompbox circuit or whatever audio gear, this is well worth a look.
Light Bridge Signalizer VST has an excellent two channel oscilloscope (as well as vectorscope and spectrascope). Hosting it in Cantabile Lite provides us with a very decent performing, true dual channel, low frequency oscilloscope suitable for any number of audio frequency tasks with the addition of very little hardware.
Here is a YouTube that shows one way to put together the simple hardware needed, but references a PC app that does not perform very well compared to what is presented above:
Since Signalizer is a true two channel scope, we are able to do A vs B Lissajous display on the Vectorscope, rather impressive! Depending on your soundcard, you might want to add discrete L and R inputs to the Signalizer plugin instance inside Cantabile in order to keep the signals discrete for leveling and routing purposes.
About the only downsides other than the limited bandwidth (even at 192KHz) is that the Y axis is dB only (and even that becomes unknown once the 1M pot is used) and triggering is always on left channel when two channels are used (use routing in Cantabile as a workaround if needed).
Doing this with a dirt cheap Behringer interface works great. Or the onboard sound card in a laptop plus ASIO4All. (lol, no way I use my good A/D for this)
This won’t replace a proper benchtop oscilloscope, but doing it with a small convertible laptop in tablet mode has satisfied need for a small portable low frequency oscilloscope. LOL, just plug in the probe adapter to the laptop, open Cantabile Lite and recall the “oscilloscope” song and I’m good to go!
Need a flexible signal generator good to 20KHz with very clean analog output? Melda Oscillator (in their freebie bundle) run at 192KHz hosted in Cantabile Lite and routed thru your D/A to a wire with probe or clip terminator. Save it in the “oscilloscope” song since this uses only the outputs and the oscilloscope uses only the inputs. This way you have simultaneous access to both. Level can be controlled from the plugin or Cantabile. Or add a 10K pot after the D/A.
Also found a nice Android app called “Function Generator” that has very good functionality.
