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1
Scientific Discussion / Re: Audio Summing Algorithm
Last post by jsdyson -
If I get up the energy to play with this stuff, I can probably put together a rough 'FFT' based summer (that is, not an FFT, but power based) to see what forcing the phases to match would sound like.  I suspect the results would at least be grainy sounding (like some of the ABBA recordings due to the abuse of the quadrature/destroying the analytical nature of the signal), but more than likely renders the sound unintelligible.

Actually, I have done something similar before -- by zeroing the phase of a given FFT (magnitudes the same, phase is zeroed -- all the same), and the result was pretty much unintelligble-- it was possible to detect some of the material, but didn't seem to be useful.   At the time, I was playing with an FFT based compressor/expander design, and found that the results were generally not much better than an excellently designed 'linear gain control scheme with well managed attack/decay behavior.'   The FFT approach is certainly helpful for NR, but AFAIK there are better techniques using a complex MDCT, where the blips and bleeps are better managed.

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.

John
2
Audio Hardware / Re: Subwoofer advice needed
Last post by krabapple -
Actually

1) One sub is a bad idea, or a good one for poor performance with stereo music in a real room..

Agreed, if more than one listening seat is involved.   One sub is  likely not the best possible situation with just one seat, but it's likely better than nothing.

Quote
2) If one sub, used below 60hz, nearfield, as in as close as possible, is the best position.

By what metric(s)?


(NB actually determining 'best', objectively, requires in-room measurements)
3
Scientific Discussion / Re: Audio Summing Algorithm
Last post by saratoga -
The FFT does preserve phase.  Furthermore it is linear, so (A+B) and IFFT(FFT(A)+FFT(A)) actually give exactly the same result:

Code: [Select]
>> A = [1 2 3]

A =

     1     2     3

>> B = [2 4 6]

B =

     2     4     6

>> A+B

ans =

     3     6     9

>> ifft(fft(A)+fft(B))

ans =

     3     6     9

Probably the above posts mentioning FFT really mean power spectrum, which would not preserve phase.  However, I do not recommend doing this except in the case where you are specifically trying to avoid beating between two signals (for example, different channels of the same recording). 
4
Audio Hardware / Re: Subwoofer advice needed
Last post by Hubert Watson -
At this moment I have the NAD C388 and B&W CM10 s2 speakers.

They sound fine, but I somehow I like the port on the back closed. This gives the most accurate bassnotes, but at the same time the very lowest end is missing a little bit (I think). Subwoofers just go quite a lot deeper.

I have been looking at fairly affordable subs that have a good match with my main speakers and I narrowed it down to the SVS SB-1000 and the SVS SB-2000. I deliberately opted for a sealed enclosure because I like the sound more.

I'm a bit tight on space and doubt between 2 sb1000 subs or 1 sb-2000. For some reason putting 1 sub in a pure stereo setup sounds wrong to me, but maybe I'm mistaken.

With some creativity I can place the SB-2000 next to my right speaker (corner), but placing 2 sb-1000's is a quite a challenge and also not wife proof I'm afraid..

Would love to hear your opinions. Should I just stick with the single SB-2000 and be happy with it, or should I go the (almost impossible) 2x SB-1000 route or maybe there are even people saying "buy 2 or buy none". I'd love to hear the opinions!

Hello Fairy,
Only one sub is needed. HiFi (audiophile) stores want to sell more than one component for obvious reasons, their profit. Just get one.
5
Audio Hardware / Re: Subwoofer advice needed
Last post by ajinfla -
Actually

1) One sub is a bad idea, or a good one for poor performance with stereo music in a real room..
2) If one sub, used below 60hz, nearfield, as in as close as possible, is the best position.
6
Scientific Discussion / Re: Audio Summing Algorithm
Last post by magicgoose -
So, you see, it's not really so nice to recommend an approach which you didn't even test yourself.
Here are the samples.
A "good" example is missing.
I know. There are none :( I'm looking for software to do FFT- based downmix.

Someone on HA mentioned FFT-based downmix earlier than me: https://hydrogenaud.io/index.php/topic,5747.0.html
I'm not alone!
So, you see, it's not really so nice to recommend an approach which you didn't even test yourself.

Speakers (and rooms) aren't perfect, and the impulse response of a speaker also depends on the position of the listener's ear in space.
If you add different and random EQ and reverb to each channel of each track which you are mixing, you'll surely also hear something even if they were to cancel each other otherwise, unless you are infinitely (un)lucky.
How does it relate to "smart" downmixing?
It counters the argument about speakers "always" leaving "something" even if the stuff you're playing is out of phase.
Speakers aren't perfect, and if you try to emulate these imperfections, the mix in software also won't cancel out everything.
You aren't gonna fool physics.
7
Support - (fb2k) / Many pops and other noise when converting MP3 Files for use in car w/ Compressor
Last post by billqs -
I am having problems finding a good solution to convert my MP3's and FLACs for use in my car. I have tried various compressors and limiters. The two most recent ones I have used George Yohng's W1 Limiter and GComp (both use the George Yohng VST Wrapper, have produced lost of nasty pops after conversion.

My immediate assumption was that the conversion stream was clipping. But I tried out several songs using the compressors and got clean sound in both occasions before I started the conversion.

Is there a way to handle this issue in foobar? I'm using the latest stable version but not the beta.
8
Scientific Discussion / Re: Audio Summing Algorithm
Last post by ziemek.z -
Speakers (and rooms) aren't perfect, and the impulse response of a speaker also depends on the position of the listener's ear in space.
If you add different and random EQ and reverb to each channel of each track which you are mixing, you'll surely also hear something even if they were to cancel each other otherwise, unless you are infinitely (un)lucky.
How does it relate to "smart" downmixing?
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