It is possible to implement support for use of external hardware processing components within your software DAW. This support is common in music recording and audio post production environments.
When properly implemented, operators have the capability to insert an instance of an external component (or chain) on a DAW audio track just like any other installed third party software plugin.
Besides potential tonal advantages, routing through a specialized external component can be less taxing on the host system’s resources.
1 – Your Interface must have an available output (mono or stereo) for routing audio to an external component. You will also need an available input (again, mono or stereo) to accept the processed audio.
2 – Your DAW must support the routing.
Pro Tools and Logic Pro X
In the Pro Tools I/O settings you must define a set of available (and matching) Interface inputs and outputs for signal routing. In Logic Pro X, there is an I/O routing option plugin included in the Utility plugins group.
Have a look at the routing configuration options for both DAWS:
The upper image displays a Pro Tools Insert Routing matrix. The default audio interface has a total of 8 inputs and outputs available as discrete I/O mono channels. They can remain as such. Alternatively, they can be paired to create four stereo signal paths.
I’ve defined three instances or parent paths of “Aphex” inserts using interface inputs and outputs 3 + 4. My processing chain supports a stereo signal flow or discrete dual mono.
The first Aphex instance is a stereo insert. Clicking the disclosure triangle reveals two associated mono channels that make up the stereo pair. This configuration translates in Pro Tools as a stereo hardware insert or as two discrete mono inserts.
At the bottom of the list I’ve also created two custom mono paths the will pass audio to discrete mono component channels. This alternative solution is unnecessary in this particular configuration. The stereo instance above provides the same level of flexibility with support for mono accessibility. Just be aware of the configuration flexibility.
The lower image displays a Logic Pro X stereo I/O instance as it would appear when inserted on any track. Notice how I am using the same combination of interface channels (3 + 4) to output the signal to external components, and to route the processed audio back into the DAW.
Let’s say you are the proud owner of the very affordable and recommended dbx 266xs Dynamics Processor. You would like to use it to pre-process a discrete channel Skype session in realtime. This dbx Compressor, Limiter, and Gate can function as a dual mono processor. With routing properly configured, you can insert mono instances of the hardware processor on discrete tracks in your DAW session. Simply customize settings for each dbx channel and fire away.
Over the years I’ve accumulated various analog audio processors by Telos, dbx, and Aphex. In the displayed diagram I disclose part of my current configuration with a few active components.
Before I get into the Pro Tools insert path configuration, let me explain the basic signal routing:
• I use a Mackie Onyx 1220i FW Mixer in combination with a Motu Audio Express USB/FW Interface. The Mackie controls a POTS line mix-minus using a Telos Digital Hybrid. The mixer also controls signal routing scenarios and recording on a Marantz CF Recorder. I use the mixer’s Control Room outputs to feed the inputs of a power amplifier to drive my JBL near-field monitors.
• The Motu’s Main Outputs are patched to the mixer. This audio is available on the Control Room outputs. I can easily switch back and forth between the mixer and the interface, designating one or the other as the default I/O.
• The mixer also functions as a secondary gain stage for the mic signal path. Notice how the mic is directly connected to the dbx 286A Voice Processor. It’s balanced line output feeds the channel 1 line input on the Mackie. The balanced Mackie Main Outputs are set to deliver a Mic Level signal. They feed the Mic Level inputs on the Motu interface. These inputs can be linked and routed to a single stereo DAW track. Alternatively I can designate the inputs to deliver discrete mono. This is handy when a second mic is integrated
• The dbx160a is a single channel (mono) compressor. It is connected to the Mackie’s channel 2 insert. I can use this device as a serial processor on mixer channel 2. I can also insert it on the channel that returns a telco caller’s POTS audio back to the mixer. In this scenario I can easily bypass it’s use on an insert and instead connect it in-line.
• All system connections are made with balanced XLR and TRS cables.
Not pictured: Aphex Expressor (mono) Compressor, Aphex 622 Expander/Gate, and Aphex two channel Parametric EQ.
Hardware Chain Insert
Let’s focus on the Pro Tools Insert path, instantiated on a stereo audio track:
The two (pictured) devices that I am currently using for external audio processing are by Aphex: 320a Compellor, and the 720 Dominator II. The 320a Compellor is widely used in radio broadcast facilities. This device can be configured to function as a Leveler, Compressor, or a mixture of both. A Process Balance setting controls the Leveling and Compression weighting. It supports stereo and dual mono processing. The current “D” version supports AES/EBU Digital I/O.
The Dominator II is a 3-band Peak Limiter with adjustable crossovers and zero overshoot. This device is also widely used in broadcast facilities and for live performances. The current 722 version features enhanced broadcast processing support, including Pre-Emphasis and De-Emphasis options.
With the Motu interface designated as the default I/0, it’s 3+4 Line Outputs route audio via insert from a Pro Tools audio track to the Compellor’s inputs. The Compellor’s outputs feed the Dominator II’s inputs. It’s outputs feed the Motu’s Line Inputs, routing the processed audio back to the DAW track where the hardware insert was originally instantiated.
A Skype session would be an obvious use option. In this case I would implement discrete mono hardware processing using two separate insert instances. In fact I can use this configuration when recording any audio source, or as a realtime processing option for output, playback, and streaming.
As far as playback, the Motu interface supports a Mix 1 Return option. In essence I can assign my system’s output into Pro Tools. With Input Monitoring activated, I can route the signal through the external processors and monitor the wet audio. This is a handy feature during playback of poorly produced programs.
Unfortunately Adobe Audition does not support hardware inserts. However there are various ways to integrate your external components in a multitrack session. For example you can assign a track’s output (or outputs) to an available interface output that feeds an external component’s input (or inputs). The processed audio is then routed to available interface inputs. By defining this active interface input as a track input, you essentially route processed audio back into the session.
This signal routing option will work in any DAW. Be aware you run the risk of initiating feedback loops!. To avoid this please make sure the software routing utility for the particular interface is properly configured.
It is easy to integrate your analog gear in your software DAW. Use case scenarios are endless. Of course support and effectiveness will vary across all components and applications. I will say it’s a pretty cool feature, especially when software versions of coveted analog devices simply do not exist.