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Dynamic Processing Part 1: The Gate

The Gate

Horizontal Processor

To put it very simply, a gate is a processor that only allows signals greater than a specified amplitude to be heard and signals less than a specified amplitude to be reduced or silenced. This processor is mainly used as a tool for removing unwanted lower level signals like bleed and noise from a track when the desired sound is not being played. A very common example is with a drum. When you place a microphone on a snare drum, that microphone will predominantly pick up the sound of the snare but it will also pick up the sounds of the other drums and cymbals to a lesser degree.

Snare Top original

As you can see and hear, there is a significant difference between the amplitudes of the snare vs. everything else. This volume difference is one of the main aspects that determine the potential quality of the gate’ process. Before we get into how to use the gate, lets look at the controls.

 Gate Controls

 

Attack – How quickly the gate opens once the signal becomes greater than the threshold.

Hold – How long the gate remains open once the signal becomes greater than the threshold.

Release – How quickly the gate closes once the signal becomes less than the threshold.

Range – How much signal level is allowed through when the gate is closed.

 These are the basic controls that are found on every gate. Some gates have additional controls that give you an added frequency dependant element of control. This process is not triggered by the signal breaching the threshold but more accurately by the amplitude of any frequency range or bandwidth that breaches the threshold. This is very useful when it comes to gating drums because each element of a drum kit has a different main frequency bandwidth. For example, the kick mainly occupies a lower frequency bandwidth than the snare. It is this difference that this feature gives you control over. This control happens through a process called “side chaining” which I will cover in more detail in a later post.

Another way to look at the gate and it’ controls is to look at the envelope that the gate creates and how it interacts with the envelope of the sound that it is applied to.

 Envelope Created by a Gate

It is important to understand that even though the primary purpose of the gate is to remove noise or bleed, it can only remove or affect the noise or bleed that occurs when the gate has not been triggered to open. Any noise or bleed that is present at the same time as the triggering signal will be heard as long as the gate is open. You should think of the gate as an automated volume controller. When the gate closes it is similar to turning the volume knob all the way down or fading the signal out and when the gate opens it is like turning the volume knob back up to its original level or fading the signal in. It is because of this turn up/turn down or fade in/fade out function that I categorize the gate as a horizontal processor. The gate will have the majority of it’ affect on the beginnings and the ends of a desired sound.

Next, lets look at how the gate interacts with the envelope of a snare.

The Gate’ affect on the Snare Envelope

The following diagram represents a snare being gated with the following settings.

Threshold – Set just above the sustain level.

Attack – Set to a fast value of (af) and set to a slow value (as).

Hold – Set to a value of (h) that extends into the snare’ release.

Release – Is shown with two different values, a fast value (rf) and a slow value (rs).

The top diagram shows the original snare envelop in thick black lines and the affect that the gate has on it in red dotted lines.

The bottom diagram shows what the gate is doing to the volume of the snare track.

 By looking at the diagram you can see that anything prior to the snare signal passing above the threshold is fully attenuated including the leading quiet portion of the snare. This is because it is the signal’ crossing of the threshold that triggers the gate to (open) where the speed at which the gate opens is determined by the attack. As you can see this causes a slight change in the natural attack of the snare. For the most part, this is not too big of a deal but if the attack of the gate is set to be too long, the natural attack of the snare will not be heard at all.

The next action to be triggered is for the gate to (close) when the signal passes below the threshold where the speed at which the gate closes is determined by the release. If we were to only have the gate to operate on these two points with very fast attack and decay times then the only thing that we will hear is the red shaded area between the (open) and (close) points. As you can guess, this does not sound anything like the original. You can adjust the release time from this point but since the release is a gradual reduction in amplitude, it will have an affect on the natural sustain of the signal. In order to retain this natural sustain you would need to delay the trigger for the gate to close, this delay is what the hold does.

Every naturally occurring sound will typically have a duration that is longer than it’ initial attack spike or transient. Because of this, it is pretty safe to allow the gate to stay open for a bit even though the signal has passed below the threshold. By keeping the gate open it allows the snare’ sustain to pass through unaltered and forces the gate’ release to be applied during the snare’ natural release where the affects of the processing will be less noticeable.

In the diagram I show two release times both of which are shorter than the natural release of the snare. Typically when gating a snare or a drum in general the goal is to match and retain the signal’ natural release and have control over all other leakage sounds after that. Controlling the leakage is what the range does.

The “range” controls how much of the leakage or bleed signal is heard while the gate is closed. If the range is set to zero, then nothing will be heard when the gate is closed. As you increase the range you will begin to hear more of the bleed signal until the bleed is back to it’ original volume.

 Setting the Gate

General Settings

The first thing that you need to set is where the threshold should be. Start by setting the attack, hold and decay to the fastest settings (lowest value) and set the range to it’ lowest value. This will allow you to only hear the signal that passes above the threshold. 

 Threshold

Try to set the threshold as low as possible, where the gate is only being triggered by snare. If you hear even the slightest tick of anything besides the snare triggering the gate then you need to raise the threshold a little.

Snare Top Threshold set

Attack

Most of the time you wouldn’t have to adjust this parameter to a slower setting but occasionally with a fast attack you will hear a tick every time the gate opens. This happens because there is too rapid of a change in amplitude similar to a bad edit where a waveform doesn’t begin on a zero point.

Hold

When processing percussive instruments it is a good idea to think about the rhythm of the song. With this in mind, try to set the hold to a value that is in time with the rhythm, long enough to contain the sustain but not so long that you hear the natural release of the snare. (I like to think of the sound of a dry 80’s electric snare hit)


Snare Top hold set

Release

With this parameter you are bringing the natural release of the snare back in. Try to set the decay so that the gate closes just before the first hit of the unwanted sound.

Snare Top with Release

Range

At this stage the gated snare can sound a bit unnatural because of the sudden start and abrupt end. By allowing a small amount of bleed to be heard will greatly improve the sound of the snare’ natural release.


Snare Top Range set

Gating Challenge

The gate is such a simple yet highly effective tool. By using a gate to clean up your kicks, snares and toms you can greatly improve the clarity of your drums. Back when I was figuring out how to use the gate, I would experiment by mixing a song without using gates at all and take note of the limitations, challenges and the sound. I would then mix the song again using gates and take notes. What I found was that despite the clarity benefits, there were some songs that sounded better without gating and some that sounded better with and just as I would tell my students, knowing the theory is useless without practical experience, so go forth, experiment and form your own opinion.

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A Little Bit About Studio Etiquette pt 1

When people think of a studio and a recording session the first thing that comes to mind is the image portrayed on TV and in music videos. This image is usually far from the truth. A recording session is not finished after one or two takes and it is far from a party environment. Many studios have equipment worth thousands or even hundreds of thousands of dollars. The most expensive microphone that I have ever used was a $12000 vintage Telefunken U47 and we were very careful around that microphone.

With that in mind, you can understand why studio owners are very cautious about what happens around their equipment so make sure that you respect the environment that you are borrowing. Here are a few thoughts to make your recording experience better.


Essential People

The only people who need to be at a recording session are the people that have a direct influence on the recording:

  •         The musicians
  •         The engineer
  •         The producer

People who probably shouldn’t not be there are:

  •         Talkative and opinionated friends
  •         Girlfriends and significant others

It is fine for them to visit because a recording studio is a cool thing to see but there is work that needs to be done and they can be the cause of unwanted distractions. Some friends even try to take over the producers job.

Talkative and opinionated friends can actually be very beneficial to a session if their opinions are in tune with those of the producer. If not, their presence becomes very detrimental to the process, especially if the friend has no recording experience. Their goal is always to help but they can have a tendency to have a short term, from take to take, perspective and not know or be aware of how one action now can effect a later process such as editing or mixing. I have seen a producer tell a band to get rid of a friend in the studio because the producer got tired of explaining to him that all of his suggestions would mean hours of unnecessary editing later. Imagine that your song is a house under construction where the producer and the engineer serve as the designer and the contractor. One day, a friend with no design or contracting experience wants to take control over the building of your house. Would you let him? 

Girlfriends and significant others can have an effect on a session because their presence can set a certain mood. This can work for or against the recording. Many people don’t want to admit it but they act differently around their partners. You can hear it when they answer the phone or when they are around. Girlfriends and significant others typically change the dynamic of the group simply by just being there which in some cases alters the performance.However, there is a time that I would say that friends and partners should absolutely be there. This is when the mixing is nearing the end and the final tweaks are being made. During this part of the process the guitar player wants to hear more guitar, the singer wants more vocals, the drummer… etc. In this situation it is good to have friends in because they can bring a less biased opinion to the group.

 

Use Constructive Criticism

I have a general rule when it comes to criticism.

 Don’t mention a problem if you don’t have a solution to it.

 Imagine that you are playing a new song and after you play it through, someone tells you that you played it wrong and you should fix it but offers no suggestions on what to do differently. How frustrating and de-motivating is that?

This leads into the next rule in part 2.

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Live Recording at Edgewater Casino

On January 13th 2012 I was asked to do a live recording of a performance that will later be synchronized to video. We did this as a test to see how we could enhance the sound quality to video. I have done live performance recordings before but they were always at the mercy of whoever was running the sound. This led to its own set of problems.

 

Sound guys priorities

 

When someone is doing live sound, they have three priorities;

 

  1. Is the band satisfied with the sound from the monitors?
  2. Is the audience satisfied with the sound from the speakers?
  3. Don’t blow up the gear!

 

Whoever is doing sound that night typically has plenty to deal with and the last thing that he/she wants to do is figure out a way for you to record the band by jacking into his board further adding to his list of potential problems. What usually ends up happening is that you are faced with the following less than ideal options.

 

Using the insert send as a line out

The advantage with this option is that you are able to get an output from all of the channels that are being used allowing for multi-track recording.

The disadvantage to this is that your input levels are at the mercy of whatever the sound guy sets the preamp to. Some signals could end up being quite loud and others very quiet. Another disadvantage is that the inserts are typically located post EQ leaving you with a signal that has been EQed to fit the room and could require some creative mixing in order to get it to sound acceptable later.

This option is only possible if the inserts are not being used. If you were to try this with the inserts in use, you would have to daisy chain your recording I/O’s into the channel insert chain which leaves the sound tech to rely 100% on your computer to NOT CRASH!!!! No sound tech will ever agree to that.

 

Using the auxiliary outs

This option is pretty quick and easy provided that there are one or two aux outs that are not being used, but this option comes with some steep limitations. Most of the time you will get one aux made available to you giving you a mono mix. You will have to set the volume levels of that mix by adjusting the individual channel aux sends while trying to monitor the signal through a pair of headphones. Unfortunately with this option, whatever the levels are that you have recorded is pretty much all that you get. You will be able to EQ, compress and add reverb to the entire track later but you will not have the ability to adjust or treat any of the individual instruments later.

 

Using the buss system

Some consoles have a buss system and many live sound techs use them to group instruments together such as drums, guitars, vocals, etc… You can use the buss outs to record these groups. With this option you are recording the signal post EQ and inserts but unlike the auxiliary out option you will have the ability to EQ, compress and add reverb to the instrument groups instead of the whole track later.

 

Using the direct outs

This option is similar to using the channel insert sends the difference being that the direct outs are located at the end of the channel’ signal chain as opposed to the insert send which is located after the EQ. The difference is that the direct out signal is subject to changes in fader levels. Some live sound techs take a “set it and forget it” approach which is great for the recording but not necessarily the best for the audience and some get right into it and ride the faders which is great for the audience and can be a great benefit to you if he does it well. If it is not done well you will be left with a lot of volume corrections to make when you go to mix.

 

My solution

So after many situations of dealing with this issue in all it’ forms and challenges, when I was asked to record a performance at the Edgewater Casino I had an easy, common sense plan to get a great recording.

 

When you do this kind of recording there are two significant unknown factors;

 

What kind of console are they using?

How knowledgeable is the sound tech with that console?

 

In this case the sound tech was very knowledgeable but the casino just bought a digital console that he had never used and we literally took it out of the box while setting up for the sound check and this was his first experience with a digital console.

 

Because of these factor, I figure that the first and most important thing that I had to do was to make sure that I inconvenience the live sound tech as little as possible and what could be better than not having to connect to or rely on their system at all?! Therefore, the most important part of my set up was a pair of 8 channel microphone splitters. These splitters basically receive 8 microphone inputs each and output 8 transformer isolated mic outs (iso’s) and 8 direct outs. The 8 iso’s then go to the channel mic ins of the house console and the direct outs go to the inputs of my recording rig leaving me and the house engineer to handle our input signals independently and separately. From that point on I treat everything as if it were a multi-track studio recording leaving me the freedom to process everything however I please.

      

Whenever you are involved in a project you should strive to get the best quality that you can and if it involves or affects others then strive to make your involvement as unobtrusive or better yet, as beneficial to their performance as possible. I had a great time doing it and I look forward to working with those guys again in the future.

 

Have fun,

 

Kyhan

ART S8 – 8ch mic splitter

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4 things that will create better instrument separation

 


There is nothing better than capturing a well rehearsed band banging out an awesome performance live off the floor. The energy, interaction and vibe just feels great but what can be a challenge is minimizing the bleed while capturing that performance and the smaller the space is that you are recording in, the more difficult it becomes.

Bleed is, for example, when the sound of the guitar is heard in the drum overheads. You would then say that the guitar is bleeding into the overheads.

Dealing with this problem is actually a lot easier than you would think as long as you keep these 4 things in mind.

1.Distance between instruments
2.Microphone polar pattern
3.Microphone proximity
4.Barriers

Distance
You already know that the further you are away from something the quieter it becomes. In the audio world this is described in the “inverse square law” (http://bit.ly/ahWVVo). It basically says that a sound will decrease by 6db every time you double the distance to the source. In other words, a mic that is 2m or 6′ away from a source will be 6db quieter than a mic that is 1m or 3′ away from the same source.
What it boils down to is that the further you put two instruments apart the less bleed you will get.
The thing to watch out for when increasing the distance between sound sources is that if they are too far apart, whatever little bit of bleed that ends up in the other microphones can be off time and can be off enough to give an unwanted delay effect.

Microphone polar pattern
A microphone’s polar pattern describes the directionality of the microphone. I generally like to keep it simple and say that there are three main polar patterns.

Cardioid, also called unidirectional picks up sounds coming from in front of it and rejects sounds from behind it.

Bidirectional, also called figure of 8 picks up sounds that come from the front and the rear but rejects sounds from the sides.

Omnidirectional picks up sounds from all directions.

You can improve the separation greatly just by taking the pickup and rejection areas of the microphone into consideration. For example, a very common set up for recording a singer playing an acoustic guitar is to use two bidirectional microphones where one is closer to and pointing at the singer’ mouth and the rejection point is pointing at the guitar. The second mic is closer to the guitar with the rejection point pointing at the singer’ mouth.

Microphone proximity
This one is pretty much a given but a valid rule non the less. The closer a microphone is to an instrument or a sound source the more prominent that instrument or sound will be in that microphone.

Barriers
Placing a barrier between a mic and an instrument will obviously have an affect on the intensity level of that instrument in the mic. The question is, where to put the barrier? Answering this question becomes more difficult the more instruments you add to the recording. I tend to think of this in terms of how easy is it to box an instrument in. It is much easier to box a guitar cab in than a drum kit. I also think of it in terms of the spreading of high and low frequencies in a room. (That will be covered in a later blog)
Some instruments have characteristics that can serve as natural barriers that may not immediately come to mind. Trumpets, trombones and closed backed electric guitar amps are quite directional. I typically do not have any separation problems when close micing a horn section and I would often place two guitar cabs back to back and close mic them.

By keeping these 4 things in mind you will be well on your way to great instrument separation and if non of this works, you could always use an electric drum kit and DI everything.
Enjoy and have fun,

Kyhan


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Which is the best microphone to use?

This is a question that I frequently got from my students.

What microphone is best for vocals?

What microphone is best for a snare?

What microphone is best for guitar?

My answer to this question was to go to our microphone cabinet, very obviously pick out some random microphone and say “this one”. At that point they would usually look at me with great disbelief and say “ really?!?”. My question to them was always;

have you ever tried this microphone on x?

Are you familiar with its frequency response and how it sounds?

Sometimes my random selection absolutely sucked and sometime we were pleasantly surprised.

Many times audio engineers, both new and experienced, fall victim to the idea that the more expensive a microphone is the better it will sound. This is the same as saying that a $50 screwdriver will get the screw in better than an identical $10 screwdriver. The job is getting done in both situations. Don’t get me wrong, I love expensive microphones and enjoy using them but the price has nothing to do with my decision to use it or not.

Lets look at the question from this perspective. Most of you know the following fact.

  • Things sound different soloed vs. in the mix.

    This is because all of the frequencies of a sound source are being heard when listened to in solo. Whereas in the mix, some frequencies are not being heard because they are being buried by similar frequencies in other sound sources. This is known as frequency masking.

Part of the reason why we mix is to adjust the frequency balance between sound sources and most of the time the frequency balance of each sound source is quite different at the end of the mixing process vs. before the mixing process. So if you have some or at least one of the instruments recorded already in the form of scratch tracks, you should have the musician or singer play along with that and make your decision based on how well the response of that microphone fits in with everything else.

Sometimes, the only way to get that gritty, dirty, in yo’ face guitar sound is to use the cheap, bashed in karaoke microphone that was lost behind the couch for 2 years. You never know until you try!

Keep experimenting and have fun,

Kyhan

 

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Choosing the perfect set of monitor speakers

What is a good monitor speaker? It is a speaker that simply tells me what is or isn’t present in the sound of my recording. Seems pretty obvious but many times we make the decision of what to buy based more on the price rather than the sound. Even then, some peoples interpretation of the sound is limited to bright/dark and clear/fuzzy. Here are some additional aspects to look for that will help you to find the monitor that is right for you.

Frequency Response
When considering this aspect of a monitor you want it too be flat meaning that the monitor has a fairly even representation of all frequencies. This aspect can vary quite a bit between monitors depending on things such as the size of the bass driver, the tweeter, what they are made of, what the cabinet is made of, etc…

Definition
This has to do mostly with the reproduction of the mid to high frequencies or the speaker’ transient response. The majority of the directional cues are most prominent in this end of the frequency spectrum. Due to that, our perception of where a sound is coming from is dependent on the accuracy of the representation of those frequencies. Here is how you listen for it.
Most places that sell speakers have them set up in a listening room where the spacing between each set is fairly evenly consistent. Try to position yourself so that you form an equilateral triangle between you and the set of monitors you are listening to.
Get the sales person to play your favourite CD or a song that you are very familiar with and listen to each set individually. Try to imagine where the instruments are located in the stereo field. On some monitors, pinpointing the instruments positions will be very clear. Also take note of the stereo image width. You may find out that some monitors sound like their stereo image width sounds either; as wide as the speakers are spaced, narrower or wider.

Depth
This also has to do with the monitors ability to reproduce frequencies that are critical to the directional cues only this time we are focusing on distance or depth of field. Listening for this aspect is similar to listening for definition only that here your focus is on how deep you imagine the stage the band is playing on to be. You will find that some monitors sound like all of the instruments are on a shallow stage with no sense of depth and some will give you a sense of depth and the distance between instruments.

You
Yes, in the end it all comes down to you, your ears and your listening environment. Everyone has differently shaped ears and hears things differently. Monitors that I love, you may hate and neither of us are wrong.
Your listening environment also plays an important role. Even though I advertise on my blogs, I very highly recommend that you take your time and actually go to the store and base your decision on what you hear. Make sure that wherever you go that they will allow you to take the monitors home and return them if you need to. What can and does happen is that a set would sound great in the store but not so good in your environment. It will be pointless if those aspects that you liked in the store don’t transfer to your set up.

Here are my two favorite monitors. I own a pair of KRK Rokit 8 and I have always liked the Dynaudio studio monitor range. The reason why I like these monitors is because I have used and like the sound of them. The projects that I mix can be urban one day and rock the next. What I like about these two sets of monitors is that they both reproduce a frequency balance that extends far enough into the low end for me to get a sense of the sub frequencies. Whether or not you buy them through me,  I recommend that you go down to your local recording store and check them out. Let me know what you think.

Have fun listening and good luck.

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