When to use the Compressor Knee?

Just curious... when & for what people choose to use the soft vs hard knee on compression?

Thanks

Morning Deep!

 

You just have to use your ears. There are times on some vocal material when a hard knee can be very distracting, but that same distraction can work for you an a particular snare hit for example. You may find yourself changing it based on where the compressors attack time is set too.

 

No rules. Just go with what you like.

I'll be honest with you, personally I find the knee to be the most subtle parameter in the compressor, unless you're using a rather high ratio. I usually don't bother adjusting it because ... well I'm afraid to say I can't hear much difference. Every other parameter makes such a big difference in sound. Please do note that I'm not saying the setting is useless, it's just another tool, one that I chose not to spend too much time with, most probably because I don't really have any use for it - doesn't mean it's the same for everybody else!

 

On the other hand, if I don't want the same compression ratio on all the ranges of dynamic of a signal, I'm not afraid to use 2 compressors in series. One rather soft for the middle range, and one with a higher ratio for the upper range (higher threshold). That kinda resembles a very soft knee but you have total control over the shape of the compression curve. That's a trick I learned from Blumpy, so you may have heard him describe it at one of our meetings.

Thanks fro the replies guys.

I have been seeing people use the compressor, and saying they want a super fast attack, and then they leave the knee on full.

So I was wondering.

I guess it works differently in Logic's compressor of course, than other brands.

Thanks fro the replies guys.

I have been seeing people use the compressor, and saying they want a super fast attack, and then they leave the knee on full.

So I was wondering.

I guess it works differently in Logic's compressor of course, than other brands.

 

The knee has nothing to do with the attack time.. which is set with the attack parameter. It has to do with the value of the ratio around the threshold level.

Thanks fro the replies guys.

I have been seeing people use the compressor, and saying they want a super fast attack, and then they leave the knee on full.

So I was wondering.

I guess it works differently in Logic's compressor of course, than other brands.

 

The knee has nothing to do with the attack time.. which is set with the attack parameter. It has to do with the value of the ratio around the threshold level.

 

Yea, but they interact together, no?

A slower knee will make the attack setting come in with a slower slope?

Yea, but they interact together, no?

A slower knee will make the attack setting come in with a slower slope?

No, they really are totally independent. The attack setting influences the TIME it takes for your compressor to kick in (I'm sure you knew that part). The knee setting influences the ratio of the compressor around the threshold level, totally independent of time (that's the part a lot of people don't get, and that is very poorly documented in the manuals).

 

Ratio = 6:1, Hard knee:

 

Anything below threshold is not compressed (1:1), anything above threshold is compressed (6:1)

 

Ratio = 6:1, Soft knee:

 

Anything well below threshold is not compressed (1:1)

Anything just below threshold is compressed (2:1)

Anything just above threshold is compressed (4:1)

Anything way above threshold is compressed (6:1)

 

So the ratio is a continuously varying function of the level of the signal.

Oh, I really hesitate to do this but . . . .

 

OK, here it is . . . the compression thread from hell . . . .

 

http://logicprohelp.com/viewtopic.php?t=14667

Ratio = 6:1, Hard knee:

 

Anything below threshold is not compressed (1:1), anything above threshold is compressed (6:1)

 

Ratio = 6:1, Soft knee:

 

Anything well below threshold is not compressed (1:1)

Anything just below threshold is compressed (2:1)

Anything just above threshold is compressed (4:1)

Anything way above threshold is compressed (6:1)

 

So the ratio is a continuously varying function of the level of the signal.

I was just reading this in the lp8 effects manual the other day. I understood it at the time, but it really didn't sink in 'til I read your post. Well put! I guess that's why your the one that writes the books.

Yea, but they interact together, no?

A slower knee will make the attack setting come in with a slower slope?

No, they really are totally independent.

 

I think the main thing people mean when they say that the knee does affect the attack, and the thing i find I hear most when adjusting the knee on a compressor, is the time it take for the compressor to reach it's maximum ratio. I find this quite audible while setting a compressor, when I will often apply a LOT of compression so I can hear the effects of the attack and release time and knee settings.

 

Also its worth bearing in mind that some compressors have different amounts of knee adjustment for instance. URS compressors can have up to 20dB of knee so the difference between hard and soft is pretty noticable, especially when on material with very pronounced transients, like drums.

Usage depends almost completely on the level the sound is recorded at and its consistency. Then what level and consistency of level, or what effect you want the compressors to have.

 

HTH