Limiting

Limiting

Main article: Limiting

Compression and limiting are no different in process, just in degree and in the perceived effect. A limiter is a compressor with a higher ratio, and generally a fast attack time. Most engineers consider a ratio of 10:1 or more as limiting, although there are no set rules.^[7] Engineers sometimes refer to soft and hard limiting which are differences of degree. The "harder" a limiter, the higher its ratio and the faster its attack and release times.

Brick wall limiting has a very high ratio and a very fast attack time. Ideally, this ensures that an audio signal never exceeds the amplitude of the threshold. Ratios of 20:1 all the way up to ∞:1 are considered to be 'brick wall'.^[8] The sonic results of more than momentary and infrequent hard/brick-wall limiting are usually characterized as harsh and unpleasant; thus it is more appropriate as a safety device in live sound and broadcast applications than as a sound-sculpting tool.

Some modern consumer electronics devices incorporate limiters. Sony uses the Automatic Volume Limiter System (AVLS), on some audio products and the PlayStation Portable.

See also: Clipping (audio)

Limiting and Clipping compared. Note that clipping introduces a large amount of distortion whereas Limiting only introduces a small amount while keeping the signal within the threshold.

-Wikipedia

Basic's on compression

Basics

The relationship between input level, output level, and gain reduction in a compressor

In simple terms, a compressor is an automatic volume control. Loud sounds over a certain threshold are reduced in level while quiet sounds remain untreated-- (this is known as downward compression, while the less common upward compression involves making sounds below the threshold louder while the louder passages remain unchanged). In this way it reduces the dynamic range of an audio signal. This may be done for aesthetic reasons, to deal with technical limitations of audio equipment, or to improve audibility of audio in noisy environments.

In a noisy environment, background noise can overpower quiet sounds (such as listening to a car stereo while driving). A comfortable listening level for loud sounds makes the quiet sounds inaudible below the noise; a comfortable listening level for quiet sounds makes the loud sounds too loud. Compression is used in order to make both the soft and loud parts of a sound more tolerable at the same volume setting.

Compression reduces the level of the loud sounds, but not the quiet sounds, thus, the level can be raised to a point where the quiet sounds are more audible without the loud sounds being too loud. Contrast this with the complementary process of an expander, which performs almost the exact opposite function of a compressor, i.e., an expander increases the dynamic range of the audio signal.^[1]

A compressor reduces the gain (level) of an audio signal if its amplitude exceeds a certain threshold. The amount of gain reduction is determined by a ratio. For example, with a ratio of 4:1, when the (time averaged) input level is 4 dB over the threshold, the output signal level will be 1 dB over the threshold. The gain (level) has been reduced by 3 dB. When the input level is 8 dB above the threshold, the output level will be 2 dB; a 6 dB gain reduction.

A more specific example for a 4:1 ratio:

Threshold = −10 dB

Input = −6 dB (4 dB above the threshold)

Output = −9 dB (1 dB above the threshold)

Signal Flow

Guru Speaks on Engineering

How to Eq Using Waves.

Let's talk Preamps..

Let there be no doubt that with the mic pre you pay for sound quality. That is what the whole game is about! But the preamp alone is not wholly responsible for quality, it is just one component. Your a\d converters, the cleanliness of your signal paths, the acoustic properties of your recording room, your choice of microphone and choice of monitors (so you can hear the fine differences) are all critical to quality. Those who want "the best" sound quality might spend $4,000 on preamps, $3500 on converters, $1500 on an audio interface and $5,000 on mics and $3,000 on room treatment. That's $17,000 just to get into the pro ballpark, still far from "the best", and we haven't included the cost of monitors, DAW, software or cables. So my first bit of advice is to scale your choices to your overall budget. In other words...

Face reality. If you are just starting out and have a $1000 budget for everything, you should use the preamps on your mixer or audio interface and choose your mic carefully. Do you have to then settle for crappy sound? No! Let's consider technique. You can get surprising results out of mediocre preamps and typical consumer soundcards by meticulously setting the gain or trim level till its perfect, keeping a clean signal path, training your vocalist to use good microphone techniques and doing what you can to reduce your room reflections. A poorly set level on a great preamp recorded in a nasty reflective room will not sound good. If you want to sound like a pro, work like a pro, and then, after much deliberation, saving money, weighing options, get your preamp. Don't scrimp. Remember I told you several pages back I'll tell you where you can compromise and where you can't? The preamp is a piece of gear where you should not compromise. Get one you are convinced will give you better sound quality.

-Tweak

Want to learn how to Mix with Ryan West?

Elements of Mixing 2 needs your help!!

Bob and I need to reach out to as many people as possible to announce our latest Elements of Mixing workshop event. If you know of anyone who is interested in learning to make better sounding records, let them know! If there's a website that you know of that would post our press release (see below) please let us know. We're really looking forward to this event!

FOR IMMEDIATE RELEASE

Ryan West
Bassy Bob Brockman
elementsofmixing@gmail.com


Elements of Mixing founders Ryan West and Bassy Bob partner with Legacy Recording for Sept. 20th workshop

New York, NY
August 27, 2008

Platinum and Grammy winning mixers Bassy Bob (Biggie Smalls, Christina Aguilera, Babyface, Herbie Hancock) and Ryan West (Just Blaze, Jay-Z, Rihanna, T.I.) have partnered with Legacy Recording (formerly world renowned Right Track and Sound on Sound) to produce the next Elements of Mixing workshop. The event will take place 10am-8pm September 20th, 2008. The Legacy 509 facility is one of the premier film scoring rooms in the US and returning students will find the experience bigger, better and full of useful instruction. Bassy and Ryan will cover all the aspects of the professional mixers' work flow, from balancing to panning, effects, and especially the use of compression to handle multiple bass signals, a key aspect of mixing in todays marketplace. A big topic of the workshop will be the degradation of audio fidelity by the widespread use of mp3 with examples of what happens to sound when it gets compressed, why it truly sucks, and why 24/96 rules. Although there will be an emphasis on Hip Hop and R and B in the presentation, Bassy and Ryan will also be tackling mix sensibilities for Rock, Dance, and Indie. Another special focus will be critical listening exercises and techniques to enhnace that ability. Students that attend the conference will also have an opportunity to have their production and mix work evaluated at the end of the day and will get a chance to see and hear their music from a different perspective.


"The seminar is not intended specifically for engineering students from college but also the independent producer and working engineer who wants his/her presentation mix to bang", said Ryan West. "The Elements of mixing seminar will give you the tools you need to make the mix hit hard and yet hear everything. If we are able to train the next generation of mixers and producers to make great sounding records then I will indeed be fulfilled. We're on a mission", says Bassy.


For more information about the Elements of Mixing seminar go to: Elements of Mixing
or email Elements of Mixing EMAIL
September 20, 2008
10am to 8pm
Legacy 509 Studio A
509 W. 38th St. New York , NY 10018
Registration fee: $249
Lunch will be served.