Studio Pro-Audio

Listening to the future

Wed, 21 Nov 2012 09:53

Pro Tools|HD Native Thunderbolt™ interface

What type of audio system do you use – native or propriety? How similar are they? Do you know how they differ? Greg Bester asks (and answers) all these questions – and more.

If one looks back several years, maybe even a decade or two, there was not a huge amount of evolution in the digital audio workstation market for the majority of the period. At least not on the surface. As the industry slowly marched on, two distinct camps emerged: native systems, such as Cubase, Nuendo, Logicand proprietary systems, such as Pro Tools, Soundscape and Pyramix (DSD). If we strip away all of the specifics, the topologies of these systems are actually quite similar. After all, both are track-based and offer processing, editing and mixing tools to route, mix, and manipulate audio; a ‘virtual’ production studio within a computer. So, given that, what are the differences?

Well, proprietary systems are often exclusively linked to their hardware. In the case of Pro Tools, until recently, one could not operate the software without the hardware counterpart. In addition Pro Tools HD incorporated DSP accelerated cards which ran their TDM plugins to take strain off of the processor, which in turn, ran only the audio engine. The hardware was all connected with proprietary connectors and cables too and this made for a closed system that was not open to hardware from very many third party manufacturers. The upside to this is that quality, reliability and support could be assured and that is why Pro Tools became the de facto industry standard in almost all commercial recording facilities. Native systems, such as Steinberg’s Cubase, rely on the computer’s internal CPU to handle all audio duties, including the audio engine itself and real time processing, such as when using native plugins. This potentially puts a huge amount of strain on the processor but given the ever-escalating rise in the power of personal computing, running a completely native system is becoming more and more feasible.

In addition to native systems being completely software-based and running completely on the CPU, they are also open to a wide variety of compatible third party hardware and software – both free and commercial. This means that you can feasibly use any compatible audio interface of your choosing and have the freedom to choose from a massive and growing selection of free and paid-for plugins. Plus given that third-party DSP cards like Universal Audio’s UAD series are becoming more and more powerful (and affordable) and take processing strain off of the CPU, native systems have seen a rise in recent years and are now competing with Avid’s audio giant, Pro Tools HD.

Given these advancements in technology and the rise of the native system, it is no surprise that Avid chose to go native in 2010. From Pro Tools 9 and onwards, Avid allowed the integration of a wide variety of hardware on standard computer audio transport protocols such as ASIO (PC) and CoreAudio (Mac) into Pro Tools and this did much to broaden its user base. The initial release of the HD Native and later the HDX cards for Pro Tools 10 saw the introduction of the AAX plugin format; up to five times the processing power of a TDM HD system on a single card and the introduction of the Field Programmable Gate Array (FPGA) DSP Chip for processing of audio tracks. Ultra low latency (1.6ms analogue throughput!), input processing and high processing capacity are still the main points of interest for Pro Tools HD systems and despite the fact there are powerful native systems available, Avid continues to lead the field as a studio standard.

Thunderous applause

So what’s next? Well, in a follow on to the Pro Tools HD Native PCI-e card that was released in October 2010, Avid recently released the HD Native Thunderbolt interface, which is basically an HD Native card in an external enclosure that interfaces with a PC or laptop via the brand new Thunderbolt protocol developed by Intel.

These two pieces of hardware enable you to use Pro Tools HD software and any of the Pro Tools HD interfaces without the need for any accelerated DSP cards. It also enables laptop users to harness the power of Pro Tools HD on-the-go. Conceivably, an engineer could use the HD Thunderbolt interface at his / her studio, unplug and then perform a remote recording on his laptop; all cross-translatable between systems. This was not possible in the past. But what is Thunderbolt? Thunderbolt – code named Light Peak – is a new bus expansion interface for personal computing and the next step forward in connecting peripheral devices to a PC.

Originally developed by Intel, it was first brought to the market in collaboration with Apple and was introduced in their MacBook Pro product line on 24 February 2011. It uses the same connector as the Mini DisplayPort (MDP) that most MacBook Pro users are familiar with. Diving deeper into the technology, Thunderbolt combines PCI Express (PCI-e) and DisplayPort into a “serial data interface that can be carried over a single cable”. This means it carries both generic data and display data over a single cable and supports transmission of audio via the DisplayPort protocol, USB-based external audio cards, or through HDMI adapters.

The controller chips multiplex (multiple data streams are combined into one signal over a shared medium) data from these two sources for duplex transmission over a Thunderbolt lane and are then de-multiplexed at the other end by the receiver controller, as seen in Figure 1. A massive 10Gbit/sec data rate per device is possible, which is absolutely huge considering USB 3 comes in at 5Gbit/sec and SATA 3 at 6Gbit/sec. Six devices can be daisy chained together and hot plugging is supported.

Interface the music

As mentioned before, the Pro Tools HD Thunderbolt interface is an HD Native PCI-e card in an external enclosure. Looking at the interface, it is unassuming and indeed, one could be fooled into thinking it’s nothing special. The front façade comprises a single headphone output, a volume knob, and an LED light that indicates whether the interface is connected and engaged. The words ‘HD NATIVE’ are brandished there, along with the Thunderbolt logo, which is fittingly a bolt of thunder superimposed over a circle.

The rear of the interface is almost just as sparse as the front comprising the Thunderbolt port, an external DC power port and two Avid Digi connectors for the connection of Avid HD interfaces. Austere? For sure, but the lack of controls belies its true power because, despite being a ’native’ system, there are a few features which distinguishes this system from others. Firstly, the system is not strictly 100% native. Granted, processing is handled by your computer’s CPU but the audio engine itself is run on the FPGA chip installed on the card itself. This chip provides the low latency performance HD systems are famous for and runs the mixer I/O. The card can run both Core Audio and ASIO drivers, which opens it up to operation with other DAW software such as Logic or Cubase.

However when sticking the Pro Tools domain there is full session cross-compatibility with TDM-based Pro Tools HD systems. RTAS plugin versions will automatically be engaged. The only features that aren’t available in an HD Native system are TDM-only plugins and Avid’s HEAT analogue saturation emulation. So what features does one get with a Pro Tools HD Native system? Well sessions of up to 256 tracks are supported, along with 64 channels of I/O. Tracking is enhanced with ‘set-and-forget direct monitoring’ and the included low latency mode feature. All in all, you get a grand total of 1.6ms analogue throughput latency in this system! This is undoubtedly one of the best latency specs on the market.

AAX and RTAS plugins are supported, plus AGC (Automatic Delay Compensation) on hardware and software inserts. Sessions can be seamlessly shared between Pro Tools|HDX and Pro Tools|HD users without any loss of data and with complete mix translatability. Timecode and video reference synchronisation are also supplied when using the SYNC HD interface. Finally, one of the nicest features for me at least, is the new RAM Disc Cache feature which loads an entire session into physical memory, provided there is enough available. This makes operation of the software ‘snappier’ as there is no loading from the hard drive or streaming over a network.

Breaking into the box

For this review, I was supplied with a brand new i7 quad-core MacBook Pro, the HD Native Thunderbolt interface and an Avid Omni HD interface. The Omni is Avid’s ‘Swiss Army Knife’ interface that offers eight channels of AD/DA on a variety of I/O protocols. There are two microphone preamps included with send and return-style inserts; along with eight analogue line-ins; eight analogue outs (on a DB25 connector); eight digital outputs (also on a DB25 connector in the AES/EBU format); an AES/EBU input on XLR, S/PDIF i/o on RCA; and ADAT optical i/o. There are also ports for a remote, wordclock i/o, and loop sync i/o. However, only eight channels of I/O can be used at any time but you can mix and match inputs to your heart’s content. I found this limiting and a waste of all the connectors at the rear, but we’ll leave it at that.

Set up could not have been simpler. I connected the Omni to the Thunderbolt interface via single Digi cable and plugged the Thunderbolt interface into the MacBook Pro with the supplied Thunderbolt cable. It was identified immediately. After opening Pro Tools all that was left to do was configure the interface via the Playback Engine menu by selecting ‘HD Thunderbolt’.

Supplied with the MacBook Pro was a sample session by Grammy winner Imogen Heap of the song ‘Tidal’. This session is 160 tracks and uses nothing but standard plugins in Pro Tools HD Native. The session played back instantly and without flaws despite the slew of plugins used and a large amount of automation. There was no lag after pressing play and everything felt tactile and fast. The Omni sounded good too, and coupled with the Genelec 8030 system with a Genelec sub, I had connected it to; the resulting sound was clear, precise and full.


I was quite astounded at the sheer power of a system with such a small footprint. With 160 tracks going on and lots of processing taking place, the relatively standard MacBook Pro didn’t even seem to blink an eyelid. This, I assume, is because of the load taken off the processor by the FPGA chip and because of Avid’s RAM Disc Caching, not to mention the sheer speed and efficiency of the Thunderbolt interface.

Just when we all started doubting Avid’s market choices and thought they were about to join the rest of the native droves, they came back to establish why they are the industry leader and distinguished themselves as innovators. ‘Going Native’ did nothing to hurt their reputation, in fact, it probably bolstered it not to mention secured them sectors of the market they were only dabbling in before. Goodbye Pro Tools LE and the restricting nature of closed systems. Hello to the future.

By Greg Bester