KVR Audio

wuntoo · Post by **wuntoo** » Wed Feb 10, 2016 12:37 pm

I've been trying to understand how dynamic compression works, everywhere they talk about its behavior over threshold but couldn't find any resource on how it works below threshold. So in analogy to its behaviour above threshold, can someone please take a look and tell if this is correct

for Threshold= t,
Ratio= r:1

for input volume, i, below threshold i.e. i<t

output levels, op, would be = i+ (t-i)/r

Thanks in advance

lobanov · Post by **lobanov** » Wed Feb 10, 2016 1:05 pm

If the input signal is below the threshold, the compressor will not change the signal level.

Edited: below the threshold ratio is 1:1.

wuntoo · Post by **wuntoo** » Wed Feb 10, 2016 1:18 pm

here is wiki definition of dynamic compression

"Dynamic range compression (DRC) or simply compression is an electronic effect unit that reduces the volume of loud sounds or amplifies quiet sounds by narrowing or "compressing" an audio signal's dynamic range."

its states- amplifies the quiet sounds - by which I suppose it means values below threshold. What I am missing? please help

No_Use · Post by **No_Use** » Wed Feb 10, 2016 1:28 pm

That would be upward compression

https://www.youtube.com/watch?v=8z4X8WZv33s

edit:
Maybe I misunderstood.
Are you rather asking what happens below threshold when using downwards compression ?
This I can't answer, sorry.

lobanov · Post by **lobanov** » Wed Feb 10, 2016 1:45 pm

When you compress the signal, it becomes quieter (as the signal above the treshold is compressed) and you can make the overall signal louder. You make louder the compressed part and the uncompressed part together (using the "output" knob, see the video above), compresson create a room for it. So you amplify quiet sounds i.e. sounds below the threshold.

stardustmedia · Post by **stardustmedia** » Wed Feb 10, 2016 2:06 pm

I first read that you were asking for a dynamic compression, similar to a dynamic EQ...

I guess you're talking about compression of dynamics (dynamic range) of a signal. Then the easy answer is: Below threshold, nothing happens to the signal's dynamic range, ratio 1:1. EDIT: Downward and upward compression. That's why there is a threshold.

But then, here we go, the above mentioned easy answer only goes for a hard knee settings. With a soft knee and depending on how soft it is, the compression starts way below the threshold, or just below the threshold.

As far as I know there is no standard on how to calculate that. I think it highly depends on the compression topology and the manufacturers design, and probably some other things too.

PS: A little addendum. Depending on the topology and design even above the threshold, the compression must not react linear. Just to make it even more complicated.

wuntoo · Post by **wuntoo** » Wed Feb 10, 2016 2:09 pm

Thanks for the response guys. I see the video he shows upward and downward compression as two different effects where as in Ableton compressor your high volumes are compressed down while your low volumes are push up, both at same time, so your output in within the range. What I still couldn't get(assuming what I stated is correct lol) how the threshold and ratio values alter the input below threshold.

Also on side note in Ableton and many other compressor there is no such thing as over compression, that you signal above threshold will compressed such that it output is even lesser then threshold value like he showed in video.

stardustmedia · Post by **stardustmedia** » Wed Feb 10, 2016 2:16 pm

wuntoo wrote:Also on side note in Ableton and many other compressor there is no such thing as over compression, that you signal above threshold will compressed such that it output is even lesser then threshold value like he showed in video.

"Over" compression, interesting idea although I wouldn't know when to use that. At least never heard about such a type. Which video shows that?

wuntoo · Post by **wuntoo** » Wed Feb 10, 2016 2:18 pm

stardustmedia wrote:
I guess you're talking about compression of dynamics (dynamic range) of a signal. Then the easy answer is: Below threshold, nothing happens to the signal's dynamic range, ratio 1:1
.

I think that is the case when you are only compressing the signal exceeding certain value, i.e. only reducing the louder volume and not boosting the quite volume but in dynamic range compression it does the both at same time . Here is image of input/output of compressor in ableton, as you can see it is reducing the volume exceeding the threshold(yellow dot) and same the same time increasing volume of quiter sounds, for input of -42 db it returning -30 db.

https://geo-news.beatport.com/en/files/ ... n_main.jpg

wuntoo · Post by **wuntoo** » Wed Feb 10, 2016 2:21 pm

"Over" compression, interesting idea although I wouldn't know when to use that. At least never heard about such a type. Which video shows that?

in the video above at around 3:50.

wuntoo · Post by **wuntoo** » Wed Feb 10, 2016 2:22 pm

"Over" compression, interesting idea although I wouldn't know when to use that. At least never heard about such a type. Which video shows that?

in the video above at around 3:50.

stardustmedia · Post by **stardustmedia** » Wed Feb 10, 2016 2:31 pm

Sounds like upward and downward combined... but why would you want that? Just use a normal compression.

PS: That screen doesn't prove that the Ableton stock compressor does upward and downward at the same time? I bet it only does downward compression since this is the common use (https://www.ableton.com/en/manual/live- ... compressor). The multiband compressor can do upward compression (https://www.ableton.com/en/manual/live- ... d-dynamics)

Will have a look to the video... I'm curious

stardustmedia · Post by **stardustmedia** » Wed Feb 10, 2016 2:34 pm

wuntoo wrote:
"Over" compression, interesting idea although I wouldn't know when to use that. At least never heard about such a type. Which video shows that?
in the video above at around 3:50.

I see, in a multiband compression it makes more sense... didn't even know that it was possible with Pro-MB... have to test that soon.

wuntoo · Post by **wuntoo** » Wed Feb 10, 2016 2:40 pm

stardustmedia wrote: PS: That screen doesn't prove that the Ableton stock compressor does upward and downward at the same time? I bet it only does downward compression since this is the common use (https://www.ableton.com/en/manual/live- ... compressor).

The manual I know only talks of downward compression but if you look at screen or try it yourself in ableton you would see values below threshold getting pushed up in output.

stardustmedia · Post by **stardustmedia** » Wed Feb 10, 2016 4:03 pm

wuntoo wrote:
stardustmedia wrote: PS: That screen doesn't prove that the Ableton stock compressor does upward and downward at the same time? I bet it only does downward compression since this is the common use (https://www.ableton.com/en/manual/live- ... compressor).
The manual I know only talks of downward compression but if you look at screen or try it yourself in ableton you would see values below threshold getting pushed up in output.

I wouldn't necessarily trust the screen. But I don't say you're wrong.

I've seen a couple screens that looked different from what I heard. That's where I try to trust my ears and a little bit the specifications of the gear. If it says there is no upward and I somehow cannot hear it, my first bet is, that the screen is not trustworthy. But you never know

dynamic compression below threshold