by Eddie Ciletti


Q: How do the plug-in versions of audio signal processors campare with their namesake hardware? 

A: Dare-2-Compare (D2C) has sample comparisons that may surprise you!  Not only will you hear whether a plug-in is worth its weight in bits, but you'll also learn the techniques to roll your own comparisons (and presets)  You might be surprised to learn that some generic plug-ins can emulate the sexier retro-graphic "plugs." 

When comparing hard and soft processing, the common misconception is that using the "exact same settings" should match the hardware.  At best, that gets you in the ballpark because analog component tolerance - especially of vintage gear - is too wide to be do hardware comparisons.  D2C will show how to roll your own comparison.

First you must consider how many jobs the plug is being asked to do and what degree of resolution can be expected.  We have the luxury of running 24-plus tracks all the time with plugs on every channel.  Obviously one of the programmer's goals is code efficiency, which is not necessarily in the best interest of absolute emulation.   If and when true emulation becomes possible, it might be so processor intensive that, for example, you might only get to run one instance of a Fairchild 670 on the mix buss. 

Simply put, it's easier to make the graphics look like the original than to make them sound like some of the originals.  But that doesn't mean we should toss all our plugs in the trash.  Evren when they don't emulate exactly as claimed, many plugs are useful tools once we figure out what they are good for - just like the analog evaluation process.

That said, the processing that should be happening falls into two categories - emulation of the feature set (EQ or Dynamics Processing) and of the artifacts (desirable distortion).  I would persoally trade all the retro grapics for more sonic options - being able to isolate and run throug the LA-2's tube amplifier or the 1176's input transformer, for example.  But, no one is doing that.

There are, IMHO, four reasons for this - (1) the marketing / programmers think the users are not that intelligent, (2) emulating gear-specific circuitry is not really what's behind the facade (3) it's not possible at this time, (4) why work harder than you have to?  I will admit that even I tend to use stuff that works the first time - most of us do need to work quickly in order to do more tan break even.  That said, the D2C project put me in Tenacious Geek mode - I got sucked into hours of fine tuning plugs to get as close an emulation as possible.

Once you know what to listen for - the trained ear is an excellent evalaution device - you will realize how complex the analysis process is..  Distortion analyzers in the analog and digital doman typically provide one static evalustion facet - sound is obviously so much more complex than that.

Thanks to Zach Ridgeway for pointing out an article by Bob Katz  - about oversampling plugins, in his book, "Mastering Audio - The Art And Science" pages 206 - 208 - as well as an Ohmforce link.  Their plugs all have a "high-quality" button that puts them in oversampling mode.  The Weiss DS1-MK2 also oversamples.  Even if your plug-ins do not have this capability, you can always manually achieve higher resolution by first upsampling - from 44.1 to 88.2, for example - then processing before making a CD master or equivalent.

Thanks also to Dave Hill at Crane Song.  Of the many conversations we'd had, the most recent touched on all of these points.  I can honestly say that those who successfully Dare to Compare will find themselves less affected by hype and hearsay more empowered to do their own reviews.  Please feel free to share your results by sendig files or providing links. 

At the heart of any sonic comparison is the ability to NULL - subtracting one track from another yields the differences.  Mid-Side (also known as Sum + Difference) is another process that takes advantgae of the difference between two channels.

Your job is to tweak until the differences are minimized and the signals come as cose to complete emulation, and therefore cancellation, as possible.  This is accomplished by starting with a RAW, unprocessed track, processing with and capturing the Device Under Test (DUT) and then opening the appropriate plug-in (PLUG).  The DUT can be hardware or software, whatever does the job for you.

Reverse the PLUG polarity and mix with the DUT   At first, there will only be partial cancellation - that's the difference between the original signal and what's being done to it.  In this application, the null technique allows our ears to measure "distortion," or the devation from the exact copy or "linear" amplification. 

Take the following step to maximize cancellation / NULL.

  • Start with an unprocessed (RAW) reference track such as drums, vocal, piano, etc. - process as needed and capture the Device Under Test (DUT).
  • Visually line up the two tracks to be sample accurate.
  • Route the RAW (reference), DUT and process/ plug tracks to the mix buss.
  • Insert the short sample delay / invert plug on all channels
  • Reverse polarity and match levels to find the NULL. Make as much audio disappear as possible.
  • Experiment with sample delay to confirm that timing is not the obstacle.  "Best" is when the high frequencies are minimized.
  • Copy the RAW track and create a new channel strip for it.
  • Mute the original RAW / reference track.
  • Insert sample delay, polarity and processing plugs and again find the NULL
  • Tweak the controls - attack, release and ratio (for a dynamics processor) or the various EQ parameters to further improve the NULL
  • Phase Shift NULL: as caused by intentional and non-intentional frequency altering components (capacitors in analog and latency in the digital domain).  Adjust for max treble cancellation.
  • Amplitude NULL:  When judging by ear, it is essential that the levels be perfectly matched. The null technique is the best way to achieve this.
  • EQ NULL: Digital Domain equalization often requires more than one EQ PLUG to emulate in a "simple" analog equalizer
  • DYNAMICS NULL:  This is the trickiest of all because every tweak requires a new GAIN OFFSET

Take a moment to check out the audio samples (below) and then try to roll your own.  Your audio snippets are also welcome.  You can either point me to your web post or email - please note that I only need about 30 seconds of audio.  Music should preferably have an obvious transistion (verse to chorus, etc.) or obvious pattern change because this will reveal the challenges / flaws.

NEVE 1064 EQ, API 550B EQ, 1176, Alan Smart compressor
Samples provided by Tom Garneau and Adam Krinsky

Samples provided by Peter Bregman and Dusty Miller

Samples provided by Colt Leeb

Samples provided by David Hedding

Samples provided by Colin McArdel