About "transparent" compression (1/2)

[manu]

Hello,

Would like to understand what is "transparent" when people are talking about compressors.

from sonolive about DAS2A :

"… few settings for a maximum of transparency …"

here : http://www.planetz.com/forums/viewtopic ... 45&start=0

from musurgio about Kompressor :

"...a constant level of transparent compression..."

here : http://www.planetz.com/forums/viewtopic.php?t=23191

from das website :
http://www.digitalaudiosoft.com/das-comp-test.htm

[manu]

here is the same test with Kompressor to try to understand something
1000 hz at -0.1db from control room ,directly routed to asio2.9db attenuation.

Manu

[voidar]

It's a strange concept, yes.

But if you look at the CW standard compressor FFT:



You see how it differs greatly from the others. The first harmonic is quite loud, which means it distorts the signal greatly.
Compression is distortion, but I guess what qualifies as "transparent" compression is to reduce a signals dynamic with little harmonic generation.

Anyway, strange, as I always felt the standard compressor was a very "clean" one.

Another important point is how something will sound. Not all harmonics are pleasing to the ear.

[Fede]

It would be significant to see FFT diagram of the original signal. (I'm at work so I cannot do anything...)

What are those harmonics?
I guess they are the step response of the time-windowed sine signal, which is limited in time domain. (It should make sense because they seem to be exactly on odd multiples of the fundamental => square wave)

For the little of digital processing I know, at first glance these tests don't tell anything but how much hi pass filtering the compressor applies to the signal.

So, is a compressor supposed to cut hi freqs?
Answer: I don't think so.

Thus the spectrum with higher frequency spikes seems to me the more transparent one could achieve: looking at the graphs the stock cw should be that one.

Cheers
Fede

[manu]

@voidar,"Not all harmonics are pleasing to the ear."For sure !
support (at)das has answered me.Seems to be a particularity of the "compal2" module from sdk and if you set attack to 1ms,those harmonics are attenuated.

@fede,a good and "transparent" compressor don't have to add harmonics but Kompressor sound's good,so,it could be a good choice for who want to get a colored sound

Thanks.

Manu

[Fede]

@fede,a good and "transparent" compressor don't have to add harmonics

yes, indeed, but I think here there isn't any capable of adding them, the harmonics are in the *source* signal imho (...and *always imho* the whole story about transparency is pure marketing )

but Kompressor sound's good,so,it could be a good choice for who want to get a colored sound

the ear rules, transparency isn't always a good thing, I really appreciate Vinco "round" sound, a little darker mosfet-wise

cheers,
Fede

[MCCY]

Could you name the settings of the used compressors?
How did you dial in comparable settings? Wolf's Comp is very complex, so should spit out different diagrams in different modes !?
Don't these effects depend on Attack & Release-times too?
A fast Attack & Release of course do cause distortions& co.
Yes, of course the kind of Attack & co. too.

Some tests for my comps (XLight, Tong, LC1) too ? just to complete the image

[Shroomz~>]

Some tests with dynamic material might also come in handy... It's surely not enough to compare only 1000 Hz sine waves. Ok for certain aspects of a test, but you might need some tests with dynamic material & VERY accurately matched settings to make any sort of sensible comparisons.

[manu]

@Fede:"the whole story about transparency is pure marketing"
I don't think so,and i need a clean compressor.I have learned how to make some test and i will use to use my new knowledge.
here are screenshot ,dry and wet signal:
and i like very much Vinco or others reason than you

[manu]

@MCCY,
A very fast attack is the only way to stop a peak or dirac signal,and Kompressor can do it well in peak mode with the generated harmonics and saturation mesured above.
Here are my settings ( for a second time):

[manu]

Some tests with dynamic material might also come in handy... It's surely not enough to compare only 1000 Hz sine waves. Ok for certain aspects of a test, but you might need some tests with dynamic material & VERY accurately matched settings to make any sort of sensible comparisons.

You are right Shroomz,and i have made some dynamic test too.

[manu]

rms mode :

rms mode is clean but it's not possible to stop a peak or a dirac even with a 4ms look-ahead:

[manu]

We could do thousand of test,but ,there is an important point : you missunderstand this topic.I just wanted to understand well what are "tranparency" and "distortion" in a dynamic signal processing.
Kompressor's price is very cheap and i'm sure,lots of people will buy it for this good reason.

Manuel B

Thanks DAS for your very transparent and very good compressors.

[dawman]

So which one is the best DSP emulation then.

Vinco,Wolf or DAS.

Or should I use hardware routed into Scope , like the local Vegas favorite below?

[manu]

@Scope4live:

as i'm french,i vote for this one :

http://www.aielectronik.fr/

http://www.maomusique.com/topic.asp?TOPIC_ID=5742



Manu

[Shroomz~>]

Thanks DAS for your very transparent and very good compressors.

you forgot to say 'make good music with digital audio soft'

I doesn't take much brain power to figure out the true intentions of this thread.

Shroomz

[MCCY]

@manu

If you set attack & release to a maximum I bet that the standard comp has no such overtones, because it just adjusts volume. Just a guess. Smallest attack (attacks near 0.1ms-1ms) allways causes distortions to the signal. Are we the same opinion here?

If you set the attack low and the release very high you can stop a fast signal and avoid some overtones. There are other strategies to make comps react different, so how can I describe their behaviour with a Test?
Only with complex material. Same opinion there?

Here are my settings ( for a second time):

Yes, you showed the settings of Wolfs comp. But I can't find the settings for the other comps. Where are the settings for vinco, das etc...
& how do I know that you used THE SAME ATTACK, SAME RATIO, SAME RELEASE. I don't know, if das compressor shows it in milliseconds, sorry I didn't dig too deep.

I just miss the settings for ALL devices used in your tests and doubt that they are comparable. So please tell me a third time

Have you ever played bass through vinco with lowest attack? It distorts the signal, because attack is so fast, that it reacts "too" fast, so that a bass-wave with its low frequency and therefore "slow" amplitude-changes causes compression changes. I guess this is what happens to any wave - to a certain degree when working with fast attacks.

So it is really very important to use the same settings on all comps in such a test + it is a must imho making it with audible examples, cause a compressor is not that easy to compare + different settings with their results etc. What, if the numbers they show differ?

What if smallest attack is 0.1 in one and 1.0 in the other?

I will not go too deep in this materia, but, why not discussing these aspects a bit. As allways I can learn much here.

Any chance of doing a test with my Varco, Tong, XLight? Or could you describe me, how to exactly do my own test? I mean which values I have to dial in the compressor to make it react comparible to the others. Yes, I know the values of Wolfs, but what about the other settings?

Martin

[hubird]

Thanks DAS for your very transparent and very good compressors.

I doesn't take much brain power to figure out the true intentions of this thread.
Shroomz

must be due to natural chauvenism
when I originally read that quote me too was surprised...a cooked meal suddenly.

[manu]

@Shroomz and MCCY :

Test are made for who are able to understand.
Here is another screenshot : att set to 10 ms and peak is not stopped of course, and saturation and harmonics ! compal2,not for my use.

Cheers,

Manu

[MCCY]

Is there any problem in giving me all settings, so that a test can be reproduced.

Sorry, but without knowing how vinco & das are set, the test can't be redone by anyone. Yes & till then I'm not able to understand them. Who is, without the settings of all devices? What means 'understanding a test' ? If you did that test to proove transparency you have to work with 1. complex material 2. open cards = tell us all settings of all involved devices , right?