# Time domain amplitudes **URL:** \ **Category:** QA40x\ **Created:** [September 25, 2026, 2:49pm UTC](https://forum.quantasylum.com/t/time-domain-amplitudes/2403 "2026-09-25T14:49:35Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Gerrittube](https://avatars.discourse-cdn.com/v4/letter/g/3be4f8/32.png) [@Gerrittube](https://forum.quantasylum.com/u/Gerrittube)\ **Post date:** [September 25, 2026, 2:49pm UTC](https://forum.quantasylum.com/t/time-domain-amplitudes/2403/1 "2026-09-25T14:49:35Z")
When using 2 probes in the time domain (like an oscilloscope) I think it’s quite a lot of work to get this working. I succeeded only partially. On one channel I could get a nice full screen sinewave, but the other signal (in opposite phase) was barely visible because this signal was much weaker. I couldn’t find a way to increase the view on the second channel. And to limit the view to just one sinewave is still a lot of work, for some part with trial and error. So I’m interested how other users use 2 channels so scope different signals. ![IMG_3214](https://canada1.discourse-cdn.com/flex032/uploads/quantasylum/original/2X/2/23fcd57da1e76ae15acd0cf3e4c3ca744fff3033.jpeg) ---
**Author:** ![restorer-john](https://avatars.discourse-cdn.com/v4/letter/r/b5a626/32.png) [@restorer-john](https://forum.quantasylum.com/u/restorer-john)\ **Post date:** [September 28, 2026, 6:10am UTC](https://forum.quantasylum.com/t/time-domain-amplitudes/2403/2 "2026-09-28T06:10:46Z")
If you really need to see two signals with quite different amplitudes on the trace at the same time, you could use scope probes with switchable x1/x10 functions to bring the two traces closer. Set one to x1 and the larger amplitude to x10. Most audio testing we want both (L/R) channels to be virtually identical in level and the internal range/attenuator controls are ganged so they change together. It sounds like you wanted functionality like a 2ch 'scope/DSO with individual V/Div controls for each channel. ---
**Author:** ![Gerrittube](https://avatars.discourse-cdn.com/v4/letter/g/3be4f8/32.png) [@Gerrittube](https://forum.quantasylum.com/u/Gerrittube)\ **Post date:** [September 28, 2026, 12:19pm UTC](https://forum.quantasylum.com/t/time-domain-amplitudes/2403/3 "2026-09-28T12:19:33Z")
In this case I have to see both the input AND the output. And the amplifier has a lot of gain. I use the probes like you suggested, but the difference in signal strenght is still way too high. So yes, I need to find a (better) way to use the QA403 as a 2 channel scope with independent settings for each channel. ---
**Author:** ![MarkZ](https://yyz2.discourse-cdn.com/flex032/user_avatar/forum.quantasylum.com/markz/32/4269_2.png) [@MarkZ](https://forum.quantasylum.com/u/MarkZ)\ **Post date:** [September 28, 2026, 12:50pm UTC](https://forum.quantasylum.com/t/time-domain-amplitudes/2403/4 "2026-09-28T12:50:22Z")
What exactly are you trying to see with the probes? Usually any non-sinusoidal behavior is so low-level that it’s not visible on a scope which is why we use the frequency domain and logarithmic values to ‘see’ signals that are 100dB down from the fundamental. ---
**Author:** ![Gerrittube](https://avatars.discourse-cdn.com/v4/letter/g/3be4f8/32.png) [@Gerrittube](https://forum.quantasylum.com/u/Gerrittube)\ **Post date:** [September 28, 2026, 1:59pm UTC](https://forum.quantasylum.com/t/time-domain-amplitudes/2403/5 "2026-09-28T13:59:29Z")
I’m looking at the time domain to see what the phase does, relative to amplitude and frequency. I don’t see how I could see that in another domain (but I’m open for suggestions of course). ---
**Author:** ![MarkZ](https://yyz2.discourse-cdn.com/flex032/user_avatar/forum.quantasylum.com/markz/32/4269_2.png) [@MarkZ](https://forum.quantasylum.com/u/MarkZ)\ **Post date:** [September 29, 2026, 12:47am UTC](https://forum.quantasylum.com/t/time-domain-amplitudes/2403/6 "2026-09-29T00:47:59Z")
I’m not entirely sure what you mean by ‘see what the phase does’ in a time domain display. If you want to measure the gain (amp/phase) of an amplifier by frequency you could use the QA40xPlot Gain chart which in one chart shows gain and phase vs frequency. I’m pretty sure that the factory app has a way to do that also but I’m not very familiar with the templating on it. Mark ---
**Author:** ![dgo42](https://avatars.discourse-cdn.com/v4/letter/d/90ced4/32.png) [@dgo42](https://forum.quantasylum.com/u/dgo42)\ **Post date:** [September 29, 2026, 3:34am UTC](https://forum.quantasylum.com/t/time-domain-amplitudes/2403/7 "2026-09-29T03:34:56Z")
Why you don’t use Phonalyser? In it you can apply different vertical resolution for both channel not only from fixed values, but also manually entered. ---
**Author:** ![M185](https://avatars.discourse-cdn.com/v4/letter/m/2bfe46/32.png) [@M185](https://forum.quantasylum.com/u/M185)\ **Post date:** [September 30, 2026, 1:02pm UTC](https://forum.quantasylum.com/t/time-domain-amplitudes/2403/8 "2026-09-30T13:02:54Z")
In my test work, I find it very useful to operate QA403 in frequency domain and monitor input and output signals simultaneously with a Rigol 4 channel oscilloscope. Yes, it is an added expense but I find this approach very useful. Cost for a scope suitable for audio frequency analysis is very reasonable. ---
**Author:** ![Gerrittube](https://avatars.discourse-cdn.com/v4/letter/g/3be4f8/32.png) [@Gerrittube](https://forum.quantasylum.com/u/Gerrittube)\ **Post date:** [September 30, 2026, 1:38pm UTC](https://forum.quantasylum.com/t/time-domain-amplitudes/2403/9 "2026-09-30T13:38:11Z")
Hi, Phonalyser works great. I can monitor the waveform of 2 channels (input and output). And I can see the FFT at the same time. This software is super and saves buying an additonal oscilloscope! Note: I could see now that for lower frequencies the phase is nearly perfect between input and output. Around and above 10 kHz. I can see a little phase shift, as expected. I’m glad it can be measured this way.