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Simple concepts need clarification
Old 1st January 2011
  #1
Gear Maniac
 

Simple concepts need clarification

I think I may have been using some terms interchangeably and wanted to clarify things...

Compression vs. limiting -- I thought these things were more or less the same thing, but don't think so anymore. What is the difference between these two?

It seems like compression has to do with the overall waveform while limiting is changing the SPL level. They both make the music louder, but in a different way it seems.

I started to notice that there are a number of notable album releases that aren't loud but compressed. You can play it to a higher SPL level than you normally would from a typical loud recording, but the impact and dynamics still aren't quite where you want them to be.

I've found the Eagles' studio recordings from the '70s weren't loud but still a bit compressed. The Hell Freezes Over album is definitely more dynamic and full sounding. The initial percussion strike on "Hotel California" reminds me why I love this stuff!!

Anita Baker's "Rapture" CD feels compressed, whereas the LP doesn't.

All of this came about playing some vinyl on my buddy's high end setup, and being disappointed with some of the LPs I brought that I thought were great. Red Hot Chili Peppers "Blood Sugar Sex Magik" was not loud but not dynamic either...CD or Vinyl.

Billy Joel's stuff on the other hand was very good...

A compressed non loud record just doesn't seem to make sense.....I don't approve of loud, but I understand why someone would want it.

I want to clarify these concepts, thanks! Happy New Year
Old 1st January 2011
  #2
Deleted #157546
Guest
Quote:
Originally Posted by audioaddict View Post
I think I may have been using some terms interchangeably and wanted to clarify things...

Compression vs. limiting -- I thought these things were more or less the same thing, but don't think so anymore. What is the difference between these two?

It seems like compression has to do with the overall waveform while limiting is changing the SPL level. They both make the music louder, but in a different way it seems.

I started to notice that there are a number of notable album releases that aren't loud but compressed. You can play it to a higher SPL level than you normally would from a typical loud recording, but the impact and dynamics still aren't quite where you want them to be.

I've found the Eagles' studio recordings from the '70s weren't loud but still a bit compressed. The Hell Freezes Over album is definitely more dynamic and full sounding. The initial percussion strike on "Hotel California" reminds me why I love this stuff!!

Anita Baker's "Rapture" CD feels compressed, whereas the LP doesn't.

All of this came about playing some vinyl on my buddy's high end setup, and being disappointed with some of the LPs I brought that I thought were great. Red Hot Chili Peppers "Blood Sugar Sex Magik" was not loud but not dynamic either...CD or Vinyl.

Billy Joel's stuff on the other hand was very good...

A compressed non loud record just doesn't seem to make sense.....I don't approve of loud, but I understand why someone would want it.

I want to clarify these concepts, thanks! Happy New Year

In the simplest sense...Ratio.
Old 1st January 2011
  #3
Gear Maniac
 

Quote:
Originally Posted by jayvo86 View Post
In the simplest sense...Ratio.
Please go on....ratio of what exactly?
Old 1st January 2011
  #4
Moderator
 
narcoman's Avatar
 

Limiting has what you'd say "approaches an infinite ratio ".... of course an impossibility - but anything upwards of 20:1 could be considered limiting.
Old 1st January 2011
  #5
Lives for gear
 

Quote:
Originally Posted by audioaddict View Post
It seems like compression has to do with the overall waveform while limiting is changing the SPL level. They both make the music louder, but in a different way it seems.
This has always confused me, that compression makes things louder...

Maybe i'm just being pedantic but compression to me never seems to inherently make it louder, rather, it can help, but not always, to make it easier to make louder if so desired. compression seems to be used mostly for other things then loudness, of course that could just be me...
Old 1st January 2011
  #6
Moderator
 
narcoman's Avatar
 

Compression doesn't make things louder. the make up gain AFTER compression is what makes things louder. Compression changes the dynamic range (and it's shape).
Old 2nd January 2011
  #7
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jayfrigo's Avatar
 

Verified Member
Both a compressor and a limiter will reduce the dynamic range of a signal, making the difference between the softest and loudest sounds smaller. A compressor reduces the gain of signals above a set threshold by a ratio that may range from a gentle 2:1 or less, to a moderate 4:1, or possibly a more aggressive 8:1. A 4:1 ratio means that any signal that exceeds the threshold will be attenuated to 1/4 of the excess level. Most compressors give you control over the threshold and a choice of compression ratios. They also give you control over the attack and release times, which correspond to how quickly the gain reduction takes effect after the signal exceeds the threshold, and then returns to normal when the signal falls back below the threshold.

The most significant difference with a limiter is that the ratio is higher, resulting in more aggressive gain reduction. Using a ratio of 10:1 or greater is generally considered to be limiting. Ratios of 20:1 and beyond are not uncommon. Other differences typically include faster attack and release times, and a higher threshold. What does this mean in practical terms? A limiter is designed to stay out of the way until the signal level gets very close to overload, and then clamp down fast and hard to prevent the signal from overloading. It limits the maximum allowable level.
Old 2nd January 2011
  #8
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Greg Reierson's Avatar
 

Verified Member
Quote:
Originally Posted by Id Ridden View Post
This has always confused me, that compression makes things louder...
Compressors make sounds smaller. Think of that the next time you reach for one.


GR
Old 2nd January 2011
  #9
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lowland's Avatar
 

Verified Member
Quote:
Originally Posted by Greg Reierson View Post
Compressors make sounds smaller. Think of that the next time you reach for one.
That made me smile! And they bring the noise floor up etc. so you'd better be sure compression really is what's needed before using it, not that that's likely to deter anyone. I dimly remember a Studio Sound magazine article in the 80s which was a comedy glossary of audio terms, where 'compressor' was defined as something like 'device for increasing noise and distortion'.

In track-and-mix I'd personally like to see much more gain riding going on, it's such a useful and transparent tool, relatively underused nowadays in non-classical music from what I can see (and maybe not so much now in classical either) - think about the sustain on the big multi-piano chord at the end of 'Day In The Life' on Sgt. Pepper and why the ability to read scores might be a useful asset for engineers recording or mixing from them.

In mastering I'm still regularly surprised at how much importance many non- MEs seem to place on compression - you'd think I'd have got over it by now! A big fat mastered sound needn't involve any at all, in fact in quite a lot of cases I'd say it's essential to avoid it.
Old 2nd January 2011
  #10
Moderator
 
narcoman's Avatar
 

..... yeah but Sgt Peppers had compressor abuse in the aeons!!
Old 2nd January 2011
  #11
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lowland's Avatar
 

Verified Member
Quote:
Originally Posted by narcoman View Post
..... yeah but Sgt Peppers had compressor abuse in the aeons!!
Certainly there was good creative compression on that record, but artists and production team chose when to use it and when not, were willing to take a different route when necessary and had the knowledge to achieve it. I suppose the point I'm making is that compression for the sake of it is a shame when there are other ways of doing things, and taking the compressor out of circuit can be one of those too.
Old 3rd January 2011
  #12
Gear Addict
 

Here's a link to some information explaining compression and limiting.

http://en.wikipedia.org/wiki/Dynamic_range_compression
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