What are the Different Types of Audio Interfaces?

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What are the Different Types of Audio Interfaces?

An audio interface is a bridge between analogue and digital signals for musical instruments and microphones. It allows a number of different sound sources to be connected to a single computer, and it can blend these sources for the purposes of recording music. Audio interfaces are essential in modern-day music production as they convert analogue signals into digital format in order that a computer can manage the entire recording process for the user.

There are a number of audio interface options and formats available, and selecting the best one depends on exactly what it will be used for. A professional unit will be capable of managing multiple streams at once, and that might include several different instruments, mics, and mixing decks. A top-of-the-range interface will also be able to reduce latency to a minimum; latency is the delay between creating a sound and hearing it after processing through the system.

Why Is a Computer's Own Sound Card Not Appropriate?

Someone who intends to simply record their own voice or the sounds of a single instrument will probably be able to do so with the in-built sound card of any reasonably powerful computer. However, even adding one additional sound source could lead to problems. The average sound card will lack the power and headroom to record music of clarity and quality. A decent sound card will be capable of supporting two different channels of audio at the same time, but even that will be a stretch.

Options to Consider When Purchasing an Audio Interface

The number of inputs and outputs an audio interface has plays a huge role in any system's recording capabilities, but the type of connection will also dictate the recording and playback experience. The most basic of systems will feature only two channels, but there are some professional interfaces that can deal with 18 or more channels at the same time; these systems will usually be very expensive, however. So, a solo artist who only wants to record a voice track and a guitar will only need a system with two channels. A band of five, each with their own instrument and mic, will need a system capable of managing at least 10 channels.



Connecting Microphones

Care must be taken to select an interface that is compatible with the microphones that will be used with it. The majority of interfaces have inputs for three-pin XLR jacks.

Phantom Power?

There are some microphones available that have their own, independent source of power; however, the majority use phantom power which comes from the interface. The best systems will come with a switch that allows the user to turn this power feature on or off.

What are Line-Level Inputs?

Microphones generally deliver sounds that need to be amplified, but that is not necessary in a system that uses line-level inputs. Most high-quality interfaces will contain MIDI is a simple audio language used by computers to communicate with devices that are connected to it. Such a facility will, for example, allow an electronic keyboard's notes to be played via a computer. This can allow the composition of more complicated pieces without the need for extra equipment and musicians.

ADAT Inputs

The ADAT systems allows for the management of up to 8 individual digital channels at the same time.

Direct Monitoring

One of the major problems to be overcome when recording music digitally is latency; this is the time it takes for analogue sounds to be processed by the interface and computer before being played back to the musician via headphones. Excessive latency can make it impossible for musicians to concentrate on their singing or the playing of their instruments. Direct monitoring completely bypasses the digital system to give the musician the analogue feed directly through a headset.

S/PDIF Connectors

Sony/Phillips Digital Interconnect Format(S/PDIF) allow for digital music transfers of the highest quality, and they are ideal for the connection of external effects equipment.

The Different Connections Available




FireWire is a super-fast system which can transfer data to and from several different sources. Some computers will come with in-built FireWire ports.

USB 2.0

The main advantages of a USB music interface are mobility and convenience. Although they aren't the most efficient of connections available, all new computers and laptops have at least one USB port, so interfaces can be swapped between systems very easily. Mobile studios will benefit from USB interfaces, and they are also ideal for DJs who have to continually set up and dismantle their equipment in different venues.

PCI Interfaces

A PCI interface is usually built into a computer, and it communicates directly with the motherboard. The result is a fast and efficient, high-bandwidth connection that minimises latency.

PCI Express

A PCI express interface is the fastest available, and its top speed of around 4,000Mbps makes it the preferred system in professional recording studios.

Other Factors to Consider

Many amateur musicians and DJs will want to expand their system over time, and some interfaces allow that expansion to take place gradually. Some 8-channel interfaces come with ADAT inputs and outputs that can be expanded to 16 with an outboard interface or preamp. Most audio interfaces are sold with their own software packages - known as Digital Audio Workstations. However, not all software supports MIDI, but it is still possible to purchase additional software that provides this facility.

How to Find Audio Interfaces on eBay

The eBay website is the perfect place to shop for audio interfaces as it makes searching and purchasing a simple and quick process. The purchase of sophisticated music recording equipment is a huge investment for most people, so it is important that such a transaction is protected, and that is why eBay's feedback system is so important. Every time someone purchases an item on the site, they get the chance to leave feedback on the service they received and the product they bought. This feedback can be viewed by other potential buyers, and an overall score is displayed. There are also a number of online stores within the site which are hosted by authorised sellers. Buying the latest music interfaces from these stores gives people the peace of mind in knowing that they are dealing with trusted vendors who are experts in their field. Some audio interfaces will be sold as part of a bundle, and that can mean accessories such as mics, headsets, and cables can be picked up as part of the purchasing price.

While many people will choose to use the text-entry box near the top of the homepage to conduct a search, more refined results can be found by using eBay's unique category-based search facility. Any search will begin by clicking the All Categories drop-down menu at the top of the homepage. After the Search icon has been clicked, a list of sub-categories will be presented, and the Musical Instruments Category should be selected. A new page will load which will include a list of further sub-categories on the left of the page. The Pro Audio Equipment link should then be selected, and the Audio/MIDI Interfaces link should be clicked on the subsequent page. At this stage, it will be possible to browse through hundreds of music interfaces and relevant accessories, but selecting the check-box options on the left of the page will narrow the search results further.


The latest laptops and home computers will usually be able to cope with a keyboard or guitar, and it may also be possible to record vocals at the same time. However, expecting any more than that from a standard sound card will be asking for trouble. The main decisions to make when purchasing different music interfaces involve the connection needed and the number of outputs required. The number of sound sources connecting to the interface will dictate how many outputs are necessary. However, choosing the correct connection system will not be so simple. A DJ, for instance, may use a laptop to store and mix music, so a USB connection would provide convenience and mobility. However, a professional recording artist who uses a range of musicians, instruments, and mics will probably need the speed and reliability of a PCIe interface. In many cases, the decision on which type of connection to go for may be taken out of the equation as not all laptops and computers will have FireWire or PCI capabilities. Musicians will have their own preferences when it comes to buying music interfaces, and that will develop over time. The only essential outcome is music of the highest quality, and all the main systems are capable of delivering that.

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