Distressor Dual Comps 

Generally regarded as one of the greatest compressors of all time, the Empirical Labs Inc. (ELI) Distressor is also one of the most popular, having become an essential go to for many studio engineers.   These days the more time you spend engineering at studios the more often you are going to be having the opportunity to use the Distressor, or have the likelihood of stumping up for one of your own.   So we figured that it would be wise to get some extra wisdom from the guy who designed it to help you get the most out of using it, and let you learn some things you might not have known.

We’ve also asked him to discuss the Arousor, the recently released plugin version of the Distressor, but with a few important differences and additions.

And of course, after you have read what Dave has to say, go to our Distressor vs Arousor comparison review page and check that out, or shoot them out against over 120 other compressors on Gearshoot and learn what makes them all so unique.


So, here’s Dave Derr on ELI, the Distressor, the Arousor and life. 


1.               You have a very particular design philosophy.   Your site says you incorporated the word empirical to reinforce that your gear is created from direct experience in the world rather than developed purely theoretically on paper.   That probably means a whole load more time in the design stage testing, comparing, critiquing etc.   Can you outline more about your philosophy and anything you think in that gives your gear its particular characteristics and functions?


You pretty much covered why we chose "Empirical" as part of our company name, right there!  In the best sense of that word, it means fashioned and fine tuned from experience and testing.  In the worst sense, it means good ol' trial and error, without much technical knowledge or consideration behind something.  


We always try to use and test stuff a lot before shipping it.  A product is always tested in house by me and a couple others for a few months at least, then we do Beta testing outside with some industry pros.  We take notes and make any changes we know will improve the product.


I am a huge fan of incremental improvements.  Some of our products are in double digit revision numbers.  Sometimes new technology can eliminate a problem, but man, is it a hassle, expense, and risk to make changes to products that may have been around for well over 10 years.  Our Lil FrEQ could have some heat problems in Europe at 50Hz, especially in a hot rack or outdoor concert.  We kept changing the linear power supply to lower the heat, and now went to a Switching supply, as we could finally make them quiet enough for our standards.  They barely run warm now, are quieter, easier to produce, and lots more reliable.  Many of the re-designs were necessitated because of international regulations, and problems they introduced.


Fortunately, I had many fun years as a musician, and then as a recording engineer, to help guide me with what sounds "good".  That is, I've had to use my ears a lot in my life, and was even a music major in college.  But… I am also a measurement nut.  Oscilloscopes and Audio analyzers are very good friends of mine. Working at Eventide was a blessing for me, and is where I learned to use more advanced test equipment and do critical listening.  It's always interesting what you can hear but cannot see on test equipment, and vice versa, what you can easily measure, but cannot hear.


2.               The Arousor, being the plugin version of the Distressor has a few different aspects that are probably worth identifying for first time users, or people wanting to go from the digital to analog version, or vice versa.   Can you let us know about any of these?   For example - The compression ratio on the Arousor is rated differently to the Distressor (i.e. 6:1 on the Distressor is ‘the same’ as 8:1 on the Arousor)  Can you explain how and why it works this way, what is going on with compression ratios and how it relates to other compressors?


We did not worry about doing a 1:1 Distressor, as it was going to be limiting.  And also, there were things that we could "idealize", or make closer to operating perfectly for a desired result.  The Ratios on the Distressor were all a bit higher than what they measured.  But being a knee compressor, measuring the ratio is not a cut and dry thing, to begin with.  Still, as we wanted to add more ratios to the Arousor, we idealized the ratios closer to our measurements, which also opened up more ratios on the lower end.  Things like 1.5:1 couldn't even be done on the Distressor, great for busses and mastering.  So if you are a Distressor user and have some favorite settings, you just use the next higher ratio on the Arousor, and it is pretty much exact.  So 2:1 on Distressor is 3:1 on the Arousor.  However, 20:1 and Nuke are the same.  It’s a bit arbitrary granted, but the ratios are a little more accurate to actual measurements.


Also, there are some cool non-linear things that happen in the Distressor, but were not adjustable in a direct way.  In the digital domain it became easy to provide discrete control over some Distressor behavior.  For instance, other than selecting one of three Distortion modes, you couldn’t really tweak much saturation in between.  So we made the Soft Clipping section, which gives almost infinite control over the amount of crunch.  We also came up with Attack Modification "AtMod", which happens organically in most analog compressors with radical compression.  "AtMod" was made adjustable so it can even be added at low compression amounts, or conversely, be eliminated completely from extreme compression.


In general, we also increased the ranges of the controls, especially on input and output knobs.  You never know how soft or loud something might be or need to be.



3.               The Distressor tips its hat to a number of classic pieces of gear that are known for their particular harmonic distortion characteristics.   It really seems to captures that authentically and enhances these harmonic distortion elements in its circuitry.   How complex was it to model these types of distortion for the Distressor and Arousor accurately?


It actually wasn't hard to get a good distortion match, as the Distressor uses smooth triode curves that are the most tube-like.  The basic Distressor saturation is predictable mathematically, as simple symmetrical soft clipping produces only Odd Harmonics.  But we spent a bit of time getting the even harmonics to sound right.  Older analog gear usually added some even harmonics from power supply and component variations.  Without giving too much away, the Soft Clipping in the Arousor will evolve far beyond what the Distressor can do, in future revisions.  The Soft Clipper should be quite a tool unto itself, and offer some nifty tonal-shaping, while becoming indistinguishable from analog saturation, both audibly and measurement wise.  The main limitation is it will be a while before Digital systems can pass 200KHz, which the Distressor does quite easily.  But that’s something you can probably only measure, and not hear.



4.               If you could design an ultimate piece of gear to add to your range what might it be? (or equally, what piece of gear would you like to design next?).


We have covered the basic common processors in hardware:  A Compressor, an EQ, A mic Preamp, a soft clipping coloring box, an instrument Preamp…   Perhaps we could do a Converter box in the hardware domain.  In a way, the software domain is still being opened up to non-hardware-modeled processing. We do have a few products already underway but it would be unwise to say much at this time.


There was a Direct Box with a compressor that we designed over a decade ago.  It had a few flaws but people loved the prototypes… and will NOT give them back.  We may revisit that, as it’s been a constant request. The main thing it needed was a better isolated output, and a better mechanical design.  We also made an OPTO Compressor or two, but as with most opto compressors, they could not be made to match within a 1-3dB… so we gave up on it.  We like things extremely consistent.  In fact, we have thrown quite a few products out after being mostly finished.  To date, I think we have designed and built 4 - 5 products that did not make it through early testing, into production. It's painful but it's the right thing to do.



5.               In the creation of the Arousor, did you learn any new things about the Distressor that surprised you or made you decide to make changes for the plugin?


Over the 20 years of Distressor production, I learned quite a bit more about compression, and saturation.  So going into the Arousor I already had some ideas of things we could improve, and features we could introduce.  This was one of the reasons we did not want to do a 1:1 Distressor emulation.  It would be limiting.  Plus there are almost always non-ideal things that happen in real-world hardware, that may bother a designer.  But… you have to be careful not to eliminate "imperfections" that actually add to the charm and magic of a device.  

Designers from the 60's and 70's probably would have loved to make "cleaner" equipment.  But they were recording to tape then, and often the non-linearities of tape swamped out non-linearities of hardware amps and processors.  Now we have this super clean recording medium and quickly found out that people really love the "hair" and "dirt" that can be imparted with vintage-inspired designs… or the quickly disappearing tape recorder.

Most of the differences in the Plug-in were to make things more controllable and ideal… without losing the "good imperfections" in the Distressor.



6.                Aesthetically your gear is also very pleasing and the knobs on the distressor are instantly recognisable.   How do you go about balancing the layout of your gear with regards to usability and the visual aesthetic of it?


Stuff has to be fun and easy to use.  There is nothing more aggravating than fighting with a product, just figuring out what it is doing, or having interactive controls that undo each other, or bad control ranges, or a touchy control there. etc. We try to organize the controls, IE Knobs and Switches and displays, in intuitive places.  


Sometimes our stuff looks crowded because of lots of text and markings.  This helps recall.  We also use big, plain "ugly" text, but it makes it more readable, even in dim light.


The big white knobs, which are custom, took quite a few months to find.  They too make it easy to adjust and recall, with their size and all their markings.  And as you noticed, they are easily recognizable in studios and pictures.


Most stuff can be made to be obvious, and almost subconscious to use… with a good interface.  Alternately, I think we have all used stuff that made great sounds, but was just a fight to learn, and a hassle to use when under the gun.  It just takes a little more thought and time to make something great sounding, and fun to use.


Dave Derr

Empirical Labs



Useful Links -

Gearshoot review and comparison of the ELI Distresor vs the Arousor

Empirical Labs Inc. website Distressor 

Empirical Labs Inc. website Arousor 

Buy the Arousor online - Make Dave’s Day

Find your local Distressor Distributor thanks to Wave Distribution




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