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But just by that greater absolute width, isn’t the absolute value of noise energy going to be more greatly reduced than in the 1khz case? So maybe ok for logarithmic calculations but not for absolute value calculations of noise.

Ok but does a one octave digital notch in REW or Multitone at 10khz make sense?

So we see spreading at the foot of the fundamental with analog oscillators or analog notch filters but not with dacs. To try to compare results with a consumer adc to an AP it would make sense to use the aes17 digital notch feature in MultitoneAt 1khz that digital notch is not “too” wide but at...

Thx Paul, but with measuring devices like the AP, a real notch filter is being used to remove the fundamental as above and in REW and Multitone, a mathematical calculation is being done. Do you do it the same way as REW, i.e. remove 1 octave around the fundamental?

I understand its purpose, but am trying to understand under what circumstances it is appropriate to use.

I know this is off the debug focus, but is there consensus as to when the aes17 notch should be used? Thx

All the time. I also tried with .05 step and its the same. Says 21 measurements but plots 20.

Another question. At the beginning of this sweep it said it was going to make 11 measurements but only 10 are plotted.

Paul, I was doing a level sweep and got the first plot. Then to check if there was really something going on I plotted a smaller range. why would the first plot rise like that from 1.2 to 1.1? Just a glitch like the first hump?

I don’t understand it but post 2156 was just me switching post 2154 results to 20-24000 as you had suggested. Then I got that weird result in 2156. No idea why that would have happened just switching freq range. Ad you can see playback is still at 0db in both. On the spectrum post pic, I just...

Sorry I meant the pic before that of the sweep in post 2156. It was at 0db output from the dac and so into the cosmos adc about -3db.

Sorry I’m being dense here, but why are you saying fundamental was at the noise floor? It should have been close to 0db for the entire sweep.

The entire graph shows rms level at like -98db. I’m not understanding how that is correct? Also it shows thd+n at 0 instead of a large negative number. Why wouldnt each point in the graph be relative to the fundamental level at that frequency?

also here is the spectrum.

But the graph is showing rms level at -90 something and thd+ n around 0. that doesnt make sense.

how do I interpret this?

Paul, I have a question about the way some measurements appear. I am on 1.0.50. In one case I do a frequency sweep from 20-20000. After trying this several times I end up with a jump at the end to a worse thd+n. When I try it from 19-20k, it is flat. I repeated these a few times.

@IVX sorry I don’t understand what you are referring to.

Thx. I think I follow your adjustments but don't understand why they are happening.

I know you guys figured it out but would you explain it to an ignorant guy like me?