Line by line mixing musicals and plays has been a passion of mine for many years and I’ve been very lucky to be one of the few musical theatre sound operators able to mix musicals on both an analog board and a digital board, and even though the technology has changed, the style of mixing hasn’t.

It’s this style of mixing that people ask me about the most.

The style I’m talking about is line by line mixing. This is very different from what they do in a recording studio.

Simply put, it’s when the sound operator turns on a mic and off when a line is said.

Line-by-line mixing refers to the real-time adjustment of audio levels, and other parameters during a live performance. It involves adjusting each element of the mix individually as it occurs, allowing the sound engineer to make on-the-fly changes to ensure an optimal and balanced mix.

There are 3 different ways I’ve seen sound engineers or a production engineer mix line by line, but before I get into that, what is the difference between mixing your favourite band and mixing a musical?

Band vs Musical

Audio and music production

Mixing a musical and mixing a band or other audio and music production are different because of 6 main factors. These factors are Vocals, Mics, Dynamic Changes, Delay Time changes, Desk Scene Changes, and Mixing Style.

band vs musical


The difference between mixing your favourite local band and mixing a West End Musical is a musical has more lead singers. A band normally has a lead singer, with the bass player and drummer joining in and a few backing singers for good measure. A musical can also be a sung-through musical where every word is sung, some say Les Mis is the toughest gig in the world because of this. I mixed it for a year and didn’t think so.

A musical could have 40 to 50 singers singing at one time, all singing different lines in the song.

Take a song like “Beat It” by Micheal Jackson. At a MJ concert, Micheal would sing most, if not all of the lead vocals in the song. However, in the musical “Thriller Live”, the vocals could be split between several cast members.

It could look a bit like this:

line by line script


musical theatre mics

Your local band could use the good old Shure SM 58 microphone or a similar radio handheld mic. These are normally on fixed stands in front of them at the front of the stage.

Musicals use hairline, boom, and handhelds microphones dependant on the show. This is because unlike concerts the cast are not fixed in one place and are moving around on and off stage.

Dynamic Changes

In a musical the dynamics of a song can change a number of times, this could be due to dialogue within the song or because the director and sound designers want to create a certain emotion for the audience. These changes could happen a number of times during a song so the operator needs to be able to control these changes on the fly.

A band doesn’t normally have that many dynamic changes, especially in thrash metal, that music just starts loud and stays loud.

Delay Time Changes

In the theatre, singers and actors get everywhere, from the front of the stage to the back of the stage, and even off to the sides, and this can be a time delay nightmare. To cope with that, some designers change the delay time on the singers. But why is this even a problem?

Sound Designers like to get what they call the image right. That means they try to get the singer’s voice to sound like it’s coming out of the singer and not the speaker. Doing this will make the vocals a lot clearer.

This is done with time alignment and what that means is they will delay the sound ever so slightly so the acoustic voice and the amplified voice hit the speaker at the same time.

This can be done via the singer’s desk channel or via a vocal group. The designer could allocate 3 groups for each vocal zone and have different delay times. (see diagram) The operator would watch the actors and change the desk cue when the actors moved from zone to zone.

As I mentioned above, band lead singer is usually fixed at the front of the stage so there isn’t much need to change the delay time of the mic unless they move from the front of the stage.

Mixing line by line delay times

Desk Scene Changes

Musical songs have more desk scene changes than band songs as there are more dialogue bits, time delay changes and reverb changes. A band may have a scene recall for each song in the song set or a list of backing tracks. That could be 15 to 17 cues for an entire show. A musical could have over 300 desk cues and lots of sound effects.

Mix Style

A band mix depends on the band in question and the desk layout. you normally mix a band on the channels pushing all the microphones up at the same time and doing small tweaks for each song.

For a musical, you mix each line as it’s said. This is done on a set of DCA’s (Digitally Controlled Amplifier). DCA’s are also known as VCA’s (Voltage Controlled Amplifier) or CG’s (Control Groups), depending on what desk you use. Mixing this way helps to make the overall mix sound clearer. Over the years I have come across three styles of mixing.

Mixing on mute groups, mixing with automation, and mixing with the faders.

Mutes, Automation or Faders.

Using Mute Groups

Some engineers use the mute groups. This method is a bit harsh and I don’t really consider it as mixing.

The professional audio operator unmutes the mic just before the line is spoken and muted again once the line is said.

This way of mixing could be used on a small show that doesn’t have a sound engineer and uses a stage manager to fire the lighting and sound desks at the same time. This style doesn’t work well as it relies heavily on the actor saying the line at exactly the same level every time.

Using Automation

A similar way of mixing uses an automation system on a modern digital desk. This works well for pre-recorded tracks as the tracks are the same level every show. Again, it doesn’t work that well with real-life actors, only because they aren’t as consistent as recorded tracks.

Using Faders

This is the most common way sound engineers use to mix. The operator pushes or pulls the faders as each line is said to balance the actors or singers. This is great for live shows as the sound engineer has more control and can adjust the volume quickly.

Why are musicals mixed line by line.

boom mic - line by line mixing

As I said, theatrical Sound design can be slightly different to plays, TV or films, as they use hairline microphones or microphones attached to ear hangers also know as head boom mics.

Plays, TV and Films

Plays usually use microphones attached to the front of the stage called float microphones and TV and films use boom microphones which are held over the actors, just out of shot.


In a musical, the microphones that are used are small personal ones that are normally the size of the nail on your little finger. They are normally placed either in the hairline or on a boom as shown.

These microphones are attached to transmitters and are called radio, wireless mics or body packs.

They are normally are fitted before the show and are constantly checked and monitored by a mic runner who would also do any mic swaps.

Large musicals can have as many as 70 radio mics in the production and a scene might have 20 actors saying or singing a line, that means there are 20 mics being used.

Having 20 mics up at the same time would create certain acoustic problems like feed back and would reduce clarity, so mixing every line when it happens helps with reducing these problems.

I recently worked with an American producer who was putting on a brand new show and after the first tech run, they said they had trouble hearing voices and asked why a couple of lines were missed. I explained that the lines were missed because I hadn’t seen the show before and I was a little slow on the fader.

They were confused and asked why were the mics off when the actors were on stage.

I explained and demonstrated as it was an unfamiliar mixing style to them and it blew their minds. They told me that in the last show they had produced, every mic was live and the actors were told not to talk.

What effects line by line mixing?

what is line by line mixing

Stage Direction, Hats, and Desk Processing can all affect how you mix each line.


Where the actors are placed on stage matters. The closer the actors the tighter your mixing has to be.

Sometimes the actors are so close for example, during a fight or love scene, it’s best to use just one mic and adjust it accordingly.

Hats and EQ

When an actor wears a hat, the sound designer may decide that actor needs a different EQ.

This new EQ may now sound great for the actor wearing the hat but not so great for anyone else speaking close to that mic.

Mixing each line separately will help reduce the time the hat mic is live and picking up other actors.

Desk Processing

With the more advanced digital console comes the capability of having a compressor across everything, (which in my opinion isn’t always a good thing.)

That means you can have two singers in a scene singing the same song but at different levels. When they are placed at different ends of the stage this isn’t a problem.

The problem arises when again they are close and “screaming down each other’s mics” as I like to say.

The louder singer could trigger the compressor of the softer singer which could mean the sound engineer loses one of the singers.

To be honest, there isn’t much you can do in the situation other than speaking with the director and actors either to cheat the positions or sing quieter.


The main benefit is because each actor has their own mic and channel, the sound designer can EQ and compress them separately, leading to a smoother and nicer sound.

Another benefit is the sound engineer has more control over each mic and line. This can be really important when you have two or more actors who speak or sing at different levels or if the orchestra is close.

The sound operator can push or pull the faders to balance the actors.

This way will always sound tighter and clearer than leaving all the mics up and hoping for the best which is better for the sound design especially if there is an emotional moment.


The main downside is mixing lines this way depends on the operator’s skill level. When you are new to the show and have to read the script you can make more mistakes and miss more lines.

Also, when you are reading the script, you are not really listening to the show as much as you should, meaning it could be a bit choppy and louder or quieter than the sound designer or producers would like.


In conclusion, mixing a musical is like trying to herd cats, but with microphones and sound effects. But don’t worry, I’ve got this under control. If you want to know how to become a musical theatre sound engineer in 2022, check out my other posts. If you want to be taught how to mix musicals by me then check out Mixing for Musicals course, held over a two-day period at Orbital Sound in south London.

How if you are ready to hear your musical come to life? Contact me and let’s make some beautiful noise together!