Home Recording Studio 101: Audio Signal Flow

In the previous article, we discussed studio equipment and three different examples of home studio setup. In this article, we are going to talk about how to connect studio equipment and signal flow in a home studio.

What is Audio Signal Flow?

In a studio or any listening environment, the path through which sound travels from one end — i.e., input or source of the sound, to another — i.e., output or speakers, is called signal flow. The order in which sound travels through different mediums/equipment is called the signal chain.

The simplest example of audio signal flow would be if a vocalist is singing into a microphone that is connected to a powered speaker. The audio signal flow would be:

1. The acoustic sound coming from the singer's mouth
2. Getting converted into analog/electrical signal by the microphone.
3. This analog signal will travel vial wires.
4. And will be amplified and reproduced by the powered speaker.
5. For the audience to listen/hear.

How Sound Travels In A Studio

In every recording/music studio, sound travels in three mediums or states -

1. Acoustic — Sound travelling with air as its medium.
2. Analog/Electrical — Sound travelling through wires/cables after getting converted to analog voltage or electrical signal.
3. Digital — Sound is processed by digital machines like computers after being converted into machine language or binary.

Humans can only hear acoustic sound waves. But machines process electrical and digital sound signals. So at every step in a studio signal chain, these conversions from acoustic to electrical and digital take place.

Every studio setup will nearly involve all three mediums. Whether you are in a commercial or a home recording studio, all three mediums are used. Some studios might operate using analog tapes and there might be no digital medium, but that is rare in today's era.

The simplest signal flow that takes place in every studio signal chain is: there will be recording devices(microphones) that will be used to capture the sound and convert them into electrical signals. Next, in the signal chain, these electrical signals will be gain staged and made useable using preamps. After that, the electrical signal will get converted into digital signals using Analog to Digital converters(generally built inside the audio interface). Analog to Digital Converter samples the analog signal on each falling or rising edge of the sample clock. In each cycle, the ADC gets the analog signal, measures it, and converts it into a digital value.

The digital signals get processed by computers and DAWs and recorded on storage drives(hard disks).

Once you playback the recorded signal, the recorded file/sample will be accessed from the hard disk, processed by DAW. Converted from Digital to Analog(electrical) by Digital to analog converters(generally inside Audio Interface).

Next, the electrical signal will be sent to the output preamp and adjusted for gain to be made useable by the speakers. Speakers will then reproduce the analog sound acoustically, for us to hear.

This is the audio signal flow in the simplest form.

Actual signal flow in studios is a lot more complex. There are a lot more instruments, effects, mixers, monitors etc. Keep on reading to learn more.

Why Understanding Audio Signal Flow Is Important?

Understanding signal flow is all about understanding the inputs and outputs route. If you understand how signal flows in any setup, it will help you :

1. Understand The Working: — If you understand the signal flow and signal chain of any given audio setup or studio, you will be able to make a wise decision and feel a lot more confident about the workings. Your decision-making as a studio engineer or technician will become a lot better in any given situation:
2. Makes Troubleshooting Easier And Systematic: — There will be times, when you will come across breakdowns like no signal getting recorded, no output etc. If you understand how signal flows in different stages, troubleshooting will become a lot easier, and you will be able to troubleshoot properly. Guesswork goes out if you understand the signal flow.
3. Unlocks More Possibilities: — With a complete understanding of signal flow, you will be able to experiment and mix music a lot better. You can play around with equipment and experiment as per your wish.

Home Studio Signal Chain Breakdown

Now that you understand what signal flow and signal chain are. I am going to break down the signal chain of the three home studio equipment setups that we built in the previous lesson:

Home Recording Studio Signal Flow Setup 1 — The First Basic Setup

This is the very basic setup in which there are no recording devices. You have a setup with just a Computer, DAW and Studio Headphones. So let us understand how the audio signal flows in this setup. This is how the audio signal will flow whenever you play any audio on your computer.

Digital Audio

When you playback any sound inside your computer. The sound is processed in digital form from the computer hard drive using software like a music player or a DAW.

Digital To Analog

The software routes the digital signal to output. But before it can be heard, it needs to be converted.

The digital signal gets converted into analog signal by a Digital to Audio converter, present in the sound card of your computer. The sound card also amplifies the signal accordingly.

Analog To Acoustic Sound

This analog signal travels through the wire of a studio headphone that you connected directly into your computer using a headphone jack.

The small diaphragm of speakers, present inside your headphones, vibrates and reproduce the sound acoustically for the listener.

Home Recording Studio Signal Flow Setup 2 — The Budget Home Studio Setup

In this setup, you will get a better hold of audio signal flow as this setup is a lot more complex than the previous setup, and it involves all the stages from recording to output.

Sound Source

There can be a different type of sound source in a studio. Acoustic sound sources like a vocalist, acoustic guitar, drums, speaker cabinets etc. These sounds produce an acoustic output and are captured using a microphone.

Other sound sources can be Instruments like synthesizers, drum machines, electric guitar, bass guitar etc. These sound sources can produce an electrical signal and can be recorded directly into an audio interface. This is also called DI input or Direct Injection.

Apart from this, other sources that produce a digital signal can be like MIDI keyboards. Digital Instruments, and MIDI Surfaces(Push 2) that produce a digital output. These sources can be connected via an audio interface or directly to a computer.

Before any sound source can be recorded on a computer, it needs to be converted into a digital signal(binary) that the computer understands.

Acoustic To Electrical Signal

Microphones are used to capture acoustic sounds and convert them into electrical signals. The electrical signal then transmits through cables and is transmitted to the audio interface.

Gain staging

A gain stage is a point during an audio signal flow at which the engineer can make adjustments to the audio signal level to make it useable. As the output signal produced by a microphone or an instrument is very low, with the help of preamps they are amplified and made useable(we will learn a lot about signal levels in later modules). The amplified signal is further transmitted and processed.

Preamps can be inbuilt into the audio interface/console, or there can be separate preamps. In this example studio setup, the inbuilt audio interface preamps are used.

Analog To Digital Conversion

The electrical signals after getting gain staged are sampled and converted into digital audio signals. AD(analog to digital) converters inside the audio interface convert the signals to digital.

DAW

The digital signals are then transmitted to the DAW (Digital Audio Workstation) inside the computer and are processed accordingly. Different sound sources are recorded and processed individually on different channels of a DAW. Having a proper session setting is important to process the digital signals properly.

Storage

All the audio recordings done through the DAW are stored on the Hard drive or selected storage media. The recorded sound can be processed and played back after accessing it from the storage.

Different channels are recorded individually and stored as individual files, called stems. Master outputs are stored individually. More about all these in later modules.

Channels

Each channel is processed separately inside a DAW. One can alter sounds with levels, effects, EQ, Dynamics etc. for each channel. The summed output of all the channels is sent to the master fader of the DAW.

The channels can be sent to busses and groups as well, but these are advanced topics and will be discussed in later lessons.

Master Fader

The master fader on a DAW or mixing console controls the overall levels of the summed audio output received from all individual channels. With the master fader, one can control the output levels that are routed to the monitoring system.

Digital to Analog Conversion

After getting summed at the master fader, the audio is routed to the audio interface for digital to analog conversions. DA(Digital to Analog) Convertors built inside the audio interface converts the processed digital audio signal back to analog or electrical signal.

Output Preamps

At the output stage, the signal is again gain staged and made useable to output levels. The signal is processed as an electrical signal at this stage.

Output Monitoring

The output monitoring system i.e studio monitors, headphones etc reproduce the received electrical signal into an acoustic signal.

The acoustic sound with all the processing can now be heard by the listeners.

Home Recording Studio Signal Flow Setup 3 — The Pro Home Studio Setup

In the pro home studio setup, a lot more studio equipment will also get introduced in the signal chain. Here is a diagram explaining the signal flow of an advanced home recording and music production studio setup.

Do All Studios Have The Same Signal Flow?

Every studio will have a different signal flow. Some might have fewer instruments and channels while others might have a lot more, some might have fewer AD to DA conversions other might have more. One studio might have an audio interface as the centre others might have a console. It all depends on how the equipment is structured and how the audio signal flows from input to output.

The main thing to consider while designing your studio signal flow is to have the least number of AD to DA conversions. At each conversion, there is a signal loss.

I hope that now you have a good understanding of audio signal flow and signal chain in-home studio.

In the next lesson, understand everything about recording studio connectors, cables and types.