Trace Arithmetic solution sought

[bobkatz]

Hi, John. I'm trying to show the DIFFERENCE in amplitude between using some traps and no traps in my room. I've tried all kinds of trace arithmetic and different displays (including V/V) to no avail. What I'd like to see is, for example, if with the trap at 100 Hz the amplitude is 78 dB SPL but without the trap the amplitude is 80 dB SPL, the resultant graph should show a 2 dB difference. If there isno difference the result should be 0 dB.

 

[John Mulcahy]

That's best done using A/B with magnitude-only responses. To generate magnitude-only responses select only the measurement that is to be converted to magnitude-only (no other measurements selected) and click Average the responses, that will generate a new trace whose name begins "Magn". Repeat that for the other measurement (again making sure it is the only measurement selected). Use A/B on the two magn results.

 

[thothsong]

Just to note, the result can look rather different if you smooth the Magn traces before computing A/B, versus computing A/B and then smoothing that.

 

[sam_adams]

Hi, John. I'm trying to show the DIFFERENCE in amplitude between using some traps and no traps in my room. I've tried all kinds of trace arithmetic and different displays (including V/V) to no avail. What I'd like to see is, for example, if with the trap at 100 Hz the amplitude is 78 dB SPL but without the trap the amplitude is 80 dB SPL, the resultant graph should show a 2 dB difference. If there isno difference the result should be 0 dB.

You might wan to take a look at this question I had for @John Mulcahy a while back. Seems to be the same thing that you are trying to accomplish.

 

[bobkatz]

Thanks for that advice!

 

[pklose]

Are you THE Bob Katz?

 

[ddude003]

Lol... The Cranesong Avocet might be the giveaway...

 

[pklose]

Could be a clue. But I checked other posts. Urls with pics and stuff lead to digido.com. Which is Bob‘s facility. Awesome! Bob‘s book on mastering was a source for my bachelor thesis - some 15 years ago.

 

[TNT]

Would be really nice to have that as a ready made "short cut" in that very menu.. the arithmetic one

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[John Mulcahy]

True, I have added |A| / |B| for the next build.

 

[TNT]

Much obliged!!!

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[TNT]

Is it possible to do the same but for phase?

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PS aiming for a mic calibration / compensation file... maybe there is a better way :-)

 

[John Mulcahy]

Not sure what you mean by that, if you want a result with magnitude and phase use A/B.

 

[TNT]

Coming back to understanding the difference between two measurements.... would it be possible to have a function that makes a as complete diff report as possible by pointing to measure A and measure B and hit "Diff Rep"... as a graphics and perhaps text...

UC: Everything set up, make sweep, make one small change to DUT, new measurement - understand difference.... :-)

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