Pro Tools is currently undergoing a transition period for its professional solutions. The legacy hardware HD Accel is now being replaced by HDX, allowing users to choose between different technologies and setups. Simultaneously, the software has been updated to versions 10 and 11, two major updates that now coexist with three types of technologies. In this book we will focus on the latest Pro Tools HD range compared to the legacy HD Accel.
HD Accel
HDX
HD Native
Pro Tools HD 10
Pro Tools 10 (formerly LE) with the full production toolkit (CPTK)
Pro Tools HD 11
Next, we will look at the different possible hardware and software options and discuss how choosing one or the other could affect your workflow. Since we can combine software and hardware in different ways, it is important to compare their strengths and understand their limitations.
Avid currently sells HDX and HD Native solutions but still supports the legacy Accel range. This new range came along with a brand new set of interfaces, replacing the legacy Accel range but still supporting 192 and 96 "blue" interfaces that we will not discuss here. However, it is worth mentioning that they really increased the sound quality of their AD and DA convertors, bringing the Avid HD range to sit among the best sounding interfaces in the market. Let's now have a look at the Avid range of DSP cards.
The audio industry flagship for many years, Pro Tools HD Accel is a DSP-based system using Time Division Multiplexing (TDM) coding. It became very expensive because the user would need to purchase many additional cards to achieve a comfortable amount of processing power. You can have up to seven cards per computer for an HD7. Even if it is now technologically unjustified, its quality and studio presence are still current, and since you can still use it with PT10 (PT11 does not support it anymore), we should discuss it.
Pro Tools HD Accel operates at 24-bit for TDM plugin processing with a 48-bit, fixed-point summing engine. Its DSP chips can run specially coded TDM plugins, but its delay compensation engine is limited to a maximum of 4095 samples. Real Time Audio Suite (RTAS) can also be used with this system, but as I will explain later on, should be used in a particular order alongside TDM ones.
The most basic configuration (HD1) only uses a core card to host the mixer and I/O; it can also provide some TDM processing power. HD2 through HD7 use additional Accel cards to increase the amount of TDM processing as well as track and voice count.
Each card on the system can accommodate 32 inputs and outputs via the Digidesign 192 blue interfaces. As an example, an HD3 system consisting of one core card, two Accel cards, and six Digidesign 192 blue interfaces could accommodate 96 inputs and outputs.
The long-awaited replacement for HD Accel came up as HDX with upgraded Field Programmable Gate Array (FPGA) enabled cards and a new Avid Audio eXtensions plugin format that can run on both native (AAX) and accelerated (AAX-DSP) technologies. According to Avid's press release, a single card is comparable to five times the power of a TDM one, while the summing engine was upgraded to a 64-bit floating point and plugin processing to a 32-bit float for greater precision and headroom. The delay compensation engine was also increased to a maximum of 16,383 samples, enough to run the vast majority of plugins comfortably. For those too hungry for samples, we should use the audio suite instead.
The new AAX plugin format brings a better unification between HD and native systems. Before, RTAS and TDM plugins had to be coded differently, hence the sonic differences between the two. With AAX and AAX-DSP, the code can be ported from one to the other without any change, keeping the same sonic characteristics.
Because of the power increase and change in technology, HDX requires only one type of card. A single HDX will allow for 64 I/O, but its processing capabilities will also bring you enough power to run many AAX-DSP plugins and make most sessions happen entirely on an HDX 1 system.
Pro Tools HD Native, like HDX, runs with a PCIE card but does not offer any processing power. Therefore, it is a light version of HDX that can only handle a maximum of 64 I/O because we cannot combine multiple HD Native cards together like we would with HDX. The chip handles input and output routing, allowing for low latency monitoring and to connect Avid interfaces. All other processing happens on the computer's CPU. It is also interesting to note that we can acquire HD native as an internal PCIE card or Thunderbolt external box.
The Pro Tools range has evolved quite a bit over the years. The most recent change to the Pro Tools software choice is the abandoning of LE versions. Now Pro Tools has three versions—Pro Tools Express, Pro Tools, and Pro Tools HD—each aimed at a different market. The latest release, Version 11, also saw the abandoning of the Complete Production Toolkit, which was a convenient upgrade path to many Pro Tools users who could not afford a full HD license.
It is possible to run an HD license on a native system (no cards) and still benefit from almost all the features. Purchasing the Complete Production Toolkit will also give you HD features from a standard Pro Tools license. Both rely solely on your CPU's processing power but rest assured that you will not loose any quality using another manufacturer's hardware; the summing engine is the same for HDX and all HD Native solutions except when using the latest Pro Tools 11.
Note
You might hear sonic changes, but they will be caused by the change of converters within the audio interface.
Mixing with this setup can work very well if you have a fast enough computer, but low latency monitoring will be limited to output 1 and 2 and will therefore be disabled for surround applications. More on low latency monitoring later in this chapter.
Using an Avid interface will unlock the full capabilities of the software, speeding up the workflow by compensating automatically for hardware inserts as well as allowing low latency monitoring across all I/Os with or without AAX-DSP plugins for added recording or mixing power.
The same rules apply when it comes to limitations using third-party interfaces, but the latest release of Pro Tools is a complete 64-bit rewrite of the application, increasing available system memory and performance. I will concentrate on the audio engine and what it means for us later, but just to give you an idea of how significant this update is, here are the highlights:
A new audio engine (AAE for Avid Audio Engine).
A new video engine (AVE for Avid Video Engine) that can harness the GPU power from your graphics card, freeing up the audio processing power when working with video. This new video engine is the same as Avid's professional video editing solution Media Composer.
New track meters that can be calibrated to many industry standards, including the K-system and also new gain reduction meters with many different settings.
An offline-bouncing feature that can also do multiexport and automatic MP3 creation.
Double the number of undos—64 instead of the previous 32.
A new unified workspace browser.
No more Complete Production Toolkit option for Pro Tools 11 owners; we now have to buy an HD license.
The new audio engine features three main improvements:
Full 64-bit float upgrade for a cleaner signal path, eliminating the need for conversion and therefore retaining maximum signal integrity all the time. This comes with drawbacks as Avid decided to drop all legacy code, including 32-bit plugins such as RTAS but also AAX 32-bit. The plugins will have to be coded either as AAX 64-bit or AAX-DSP 64-bit in order to be recognized by Pro Tools. RTAS, AAX 32-bit, AAX-DSP 32-bit, and AudioSuite 32-bit are no longer supported.
They also added a dynamic plugin-processing feature to maximize the plugin count and free up CPU usage if no audio is going through the plugin. This feature can improve system performance dramatically.
Finally, they allowed for a dual buffer technology, allowing different buffers to be used for armed-enabled tracks inside complex mixing sessions.
Buying Pro Tools HD 11 is therefore a move toward the future and will probably cost you more than just the software as third-party plugin developers will have to update their plugin to the new 64-bit standard. Most updates will come free, but some plugins might also never be ported. Luckily, Pro Tools 11 and Pro Tools 10 can coexist on the same machine; you even get a license for 10 when you buy 11, for backward compatibility.