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Spectrum analyzer that shows difference sum of two signals?
Old 26th April 2019
  #1
Here for the gear
 

Spectrum analyzer that shows difference sum of two signals?

Hi,

Is there a spectrum analyzer that only measure the difference between 2 signals?

So lets say:
signal 1 -15 @ 300hz
signal 2 -20 @ 300hz

Analyzer show -5 @ 300hz

Thanks in advance.
Old 26th April 2019
  #2
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loji's Avatar
Spectra foo

and the MH hardware.

... actually any analyzer will do this you just need to set-up your bussing correctly.
Old 27th April 2019
  #3
Gear Nut
 

Add/Invert by SocaLabs
Old 29th April 2019
  #4
Here for the gear
 

Quote:
Originally Posted by loji View Post
Spectra foo

and the MH hardware.

... actually any analyzer will do this you just need to set-up your bussing correctly.
I am on Windows thus i am not able to try, do you know another option?

Quote:
Originally Posted by TimPani View Post
Add/Invert by SocaLabs
Thanks for your suggestion, i tried the add/invert plugin (although it isn't 100% the tool i am looking for) but it's not working properly i can't route a 2nd signal to it.
Old 29th April 2019
  #5
Gear Head
 
Benoit D's Avatar
 

You can demo DMG Track Meter and see if the Phase Spectrum Analyser can fit your needs.

I think it’s what you’re looking for.
Old 29th April 2019
  #6
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Hermetech Mastering's Avatar
 

Verified Member
Maybe Voxengo Correlometer?
Old 29th April 2019
  #7
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Hi,

on Mac there is analyzer called Aurchitect Aura (before that it was called Audiofile Spectre), which has exactly that feature.
They call this Magnitude Difference Trace (just find it at its manual)
https://aura.aurchitect.com/help/meters/spectral/

It basically shows relative per-band difference between two signals.

On Windows, only FFT analyzer I know, which has that feature, is HOFA IQ-Analyser.
For example you can load it to two different tracks. Instances of analyzer automatically communicate together, so you can easily show two FFT traces overlayed. Then if you enable "diff" checkbox at each trace, you'll see that difference.

If you want to try it, you can for example duplicate track with same material and apply some eq to one of them. This diff trace would basically show curve of applied EQ.

When you want to try it with different material (like your own and reference track), also FFT parameters and integration time can play significant role there.
It's always some kind of compromise and I personally never use those visual aids for any overall mixing or tonal shaping decision.. Individual tracks, checking for issues, technical measurements etc. that is fine. However fitting different program material to some reference curve, it never worked for me.
But of course YMMV.

Quote:
Originally Posted by loji View Post
Spectra foo

and the MH hardware.

... actually any analyzer will do this you just need to set-up your bussing correctly.
It isn't so easy.. because OP apparently wants to visualize relative difference between dB values.
If you add or subtract two signals (as suggested with summing or summing with one source with flipped polarity in front of any FFT analyzer), it doesn't do that.
When signals (periodic, in phase and with same frequency) are summed, then result won't be just simple sum of their individual dB figures. Calculation there won't work like that.

Like if you subtract -20 dBFS sine signal from - 15 signal, to continue with his example, then result won't measure -5, but around -22.1 dBFS.
eg. convert to absolute level from dBs.. eg. 10^(value/20) then sum or subtract those and finally convert back to dB.

Quote:
Originally Posted by Benoit D View Post
You can demo DMG Track Meter and see if the Phase Spectrum Analyser can fit your needs.

I think it’s what you’re looking for.
Quote:
Originally Posted by Hermetech Mastering View Post
Maybe Voxengo Correlometer?
I don't think so.. In both cases it's FFT correlation meter. It's certainly useful for different tasks, but it doesn't shows a per-band level difference between two sources.

Michal
Old 30th April 2019
  #8
Here for the gear
 

Hi Michal,

Thank you for your extensive answer, very kind of you to take your time for us
Anyway i tried your suggestion and.....

I have nothing more to say at the moment besides thank you all for the help.

Old 30th April 2019
  #9
Lives for gear
 

Quote:
Originally Posted by Kamusica View Post
Hi Michal,

Thank you for your extensive answer, very kind of you to take your time for us
Anyway i tried your suggestion and.....

I have nothing more to say at the moment besides thank you all for the help.

Hi Kamusica,
you're very welcome. Glad, it works for you, I recalled that feature from testing of IQ-analyser some time ago.

One further O.T. here..
I could really recommend to check also another HOFA plugin, it's called 4U+ BlindTest, it's one of my most used tools. Free version has some limitations (IIRC you can switch maximum four tracks, which isn't so limiting in practice, but I bought paid version anyway just to support them).

It's great tool for any comparisons and usable not just for blind tests as its name suggests, but also for ITB mastering situations.
You can insert its first instance to unprocessed (source) track and then the second one to end of chain at processing track (that can be likely also aux bus, where you send pre-fader audio from source track).
So that way you can easily switch between source and processed track, without any glitches and you can also enable automatic loudness compensation (typically you lower level of processed track for comparison, this can do it for you pretty much automatically, but you can do also manual adjust level offset).

The plugin essentially mutes inactive audio tracks or adjust its level, if you set it to do so. But everything stays latency compensated and there is also tiny crossfade, when switching, so you won't experience any glitches, which typically happens, when you switch between signals with non-zero amplitude.

Michal
Old 30th April 2019
  #10
Here for the gear
 

Wow Michal, that is really nice (from you and from HOFA)
Btw what a warm welcome...and yes i am registered for over 4 years hahaha

The plugin looks amazing, switching in one (or two) simple click(s) between the source and the signal after the processing chain is a neat little feature and i am sure i will be using that, and with the automatic gain staging it's even better! First i am going to test the free version of course!

Most of the time i compensate the gain manually or i use AB LM from TBProAudio.

Have a nice day!
Old 30th April 2019
  #11
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vze26m98's Avatar
 

The Blue Cat FreqAnalyst Multi does this very well.
Old 3rd May 2019
  #12
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Quote:
Originally Posted by vze26m98 View Post
The Blue Cat FreqAnalyst Multi does this very well.
Thanks, i just did a quick test and imo does a better job then HOFA.
I took a little more time to set it up but that is just a little investment of course!
Glad to have a choice.
Old 3rd May 2019
  #13
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vze26m98's Avatar
 

Hey, you’re welcome!
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