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General A/V / High resolution audio - lowest audio setup?
Last post by Anakunda -
Hiyas, coz I'm quite disappointed that my audio gear otherwise can play from hires sources, but I can't make any difference of it, I'd like to have some idea where lays the perceptible threshold, and also where approximately is the true hi-res entry price level.
I realize that it may be the ears or bad mastering that prevents to hear any difference, but given that ears and record are sufficient, I'd like to have a thought how should the most minimal setup look like, which not only reads high resolution, but also is able to "write" it, ie. it can in real render the added resolution.
Can for example anybody post a sample of concrete setup where he's able to ABX 24bit PCM or DSD audio from standard resolution of the same source? (by standard I mean something like CD standard - 44100Hz/16b).
6
Scientific Discussion / Re: Audio Summing Algorithm
Last post by saratoga -
OK... but how does it happen?

If two signals are 180 degrees out of  phase, then each element is the negative of the other.  If you sum (X + -X) you get zero.

FFT of zero: FREQ 0, AMPL 0, PHASE 0.

The FFT only returns 1 complex number per input representing the amplitude and phase. 

Average of FFTs: FREQ freq, AMPL ampl, PHASE (phase1 + phase2) / 2

Addition and subtraction of complex values works differently than you are assuming:

https://en.wikipedia.org/wiki/Complex_number#Addition_and_subtraction
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Scientific Discussion / Re: Audio Summing Algorithm
Last post by saratoga -
The comment about a true FFT being a linear transform is true -- add an FFT (each) of two signals and the result will be the same as an FFT of the sum of the actual time domain originals.

WHAAAAAT?

https://en.wikipedia.org/wiki/Fourier_transform#Basic_properties

How can be average of FFTs of something be equal to FFT of nothing?

The sum of the FFTs of two waveforms that sum to zero also sums to zero.  That is what linearity means.
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Scientific Discussion / Re: Audio Summing Algorithm
Last post by magicgoose -
The comment about a true FFT being a linear transform is true -- add an FFT (each) of two signals and the result will be the same as an FFT of the sum of the actual time domain originals.

WHAAAAAT?
Let's assume we have a signal and an inverse of it. If we FFT both, we get same freqs and amps, but another phases (which doesn't matter while listening). However if we sum anticorrelated signals, we get NOTHING. LITERALLY NOTHING. FFT OF NOTHING IS NOTHING.
How can be average of FFTs of something be equal to FFT of nothing?
Very easy. If you do it by the definition, that is, not ignoring phase information.
Similar to how an average of 2 numbers may be zero.
10
Scientific Discussion / Re: Audio Summing Algorithm
Last post by ziemek.z -
The comment about a true FFT being a linear transform is true -- add an FFT (each) of two signals and the result will be the same as an FFT of the sum of the actual time domain originals.

WHAAAAAT?
Let's assume we have a signal and an inverse of it. If we FFT both, we get same freqs and amps, but another phases (which doesn't matter while listening). However if we sum anticorrelated signals, we get NOTHING. LITERALLY NOTHING. FFT OF NOTHING IS NOTHING.
How can be average of FFTs of something be equal to FFT of nothing?
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