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Correspondence with Williams Sound Inc.

Williams Sound IC-2 Interpreter Control Console
Williams Sound IC-2 Interpreter Control Console

Table of contents

1) S. Jetchick (2013-June-27)
2) Franck-Olivier Fabry (2013-July-2)
4) S. Jetchick (2013-July-3)
5) Appendix: Information for interpreters
6) Appendix: Other devices claiming to protect hearing

1) S. Jetchick (2013-June-27)

-----Original Message-----
From: Stefan Jetchick
Sent: 27 juin 2013 18:24
To: info (add the at sign here) williamssound.com
Subject: Feedback on your IC-2 console

Williams Sound Inc.
10300 Valley View Rd
Eden Prairie, MN 55344

Good day Sirs,

I have some feedback about your "Williams Sound IC-2 Interpreter Control

First, a bit about me. I've been a professional conference interpreter
(English/French) in Quebec City for over a decade. I know precious little
about electronics (I used to be a C++ programmer, so I'm not from the
hardware side). I've unfortunately had to use your IC-2 Console twice already.
But I regularly have the pleasure of using one of your delightful
portable kits (from your web site, it looks like the TGS PRO 737, but I'm
not sure. But it's Williams Sound, and it works like a charm).

My negative feedback about the IC-2 Console concerns a small aspect
of it: the user interface. For the rest, I have either ignorance
(I can't judge of the internals, not being a "double E"), or much
praise (the sound was perfect, the knobs and buttons are lusciously
smooth, the whole thing seems very solidly built, etc).

My main complaint concerns not only your console, but every single
interpretation console I've ever used (over the years, I've seen
at least a half-dozen different kinds from various companies):
there should be an intergrated audio compressor in every
interpretation console.

FMR Audio RNC 1773 Audio Compressor
FMR Audio RNC 1773 Audio Compressor

Every day, I carry to work a small audio compressor, which I connect
between the interpretation console and my headphones. Yes, I shouldn't
have to do that, the same way a fireman shouldn't have to bring his
own fire-resistant clothing, and a policeman shouldn't have to bring
his own gun and handcuffs, etc. But the reality of the market is that
audio-visual companies don't force clients to rent an audio
compressor on top of the rest (booth, console, emitter and receivers, etc.).
So we get our ears banged up.

My small audio compressor is worth a measly 200$. I opened it up
and it's mostly empty. Moreover, only two knobs are used (threshold
and gain, the leftmost and rightmost on the picture above), along with
a row of LEDs so the input volume can be adjusted such that the
compressor just barely starts to nibble on it, when the speaker is
speaking at a normal volume. That way, then the speaker suddenly
screams into his mike, or blows a whistle or a horn into the mike,
or starts banging on it saying "is this turned on?", the compressor
kicks in and protects our ears.

Preventing ruptured eardrums (whistle above, happened to one of
my collegues) is one of the reasons for an audio compressor. Second
is multiplicity of microphones, each with their own volume. Typical
scenario: we adjust our volume for the guest speaker, but someone
goes to a floor mike to ask a question. The floor mike volume is
much lower (or the person asking the question is far from the mike),
so we have to raise our volume to hear the question. Then the
guest speaker suddenly says something (at his own much higher volume),
and we are in pain. With an audio compressor, no problem.

Third reason is just a more regular volume. Most conference speakers
often vary the distance between their mouth and the microphone,
so the volume constantly varies. An audio compressor under the
direct control of the interpreter vastly reduces these variations.
I find myself less tired at the end of the day just because of

Adding the few and inexpensive electronic components of such an audio
compressor to your otherwise excellent IC-2 Console would cheer up
the old black heart of many an interpreter.

A few weeks ago, a new audio-visual company showed up in Quebec City,
with one of your IC-2 Consoles.

I'm screwed, no 1/4 inch mono jack...
I'm screwed, no 1/4 inch mono jack...

Every single interpretation console I had ever worked with had
a 1/4 inch mono jack, OR both a 1/4 inch mono jack AND a 1/8 inch
stereo jack. I had never encountered a console with ONLY a
1/8 inch stereo jack. Can't plug in my compressor. I'm screwed...

To make things worse, the event was some kind of retreat for
bigwigs of a local bank. So of course they had to have fun
and play little skits and mock game shows, etc., all with hand-held
mikes constantly passed around (can you say "varying distances
between mouth and mike"?), and yes, a bicycle horn...

How much would it have cost Williams Sound to respect the
industry standard of providing a 1/4 inch mono jack on their
console? (I'm fine with you providing a 1/8 inch stereo jack,
as long as there is also a 1/4 mono jack).

Yes, I've been to all local electronic stores in Quebec City
and they don't have such a thing as a 1/8 stereo to 1/4 mono

Yes, I've ordered a custom-built cable that now has two input
jacks, one for your console, and one for the rest of the Universe.

No, I'm not recommending you add a 1/4 mono jack to your next
version of the IC-2 Console. I'm recommending you add an
audio compressor.

Now the rest of my negative feedback. To
understand it, you must know that simultaneous interpretation
is a very demanding task, mentally. When you are totally
absorbed, trying to understand some Ph.D. speaking at Mach 2
about his most recent discovery (all this spoken in English
with a thick Chinese accent), while simultaneously translating
in your head and spitting everything back out in French as
fast as you can, what is left for other mundane tasks is remarkably
little. An interpreter often appears to have the I.Q. of
a tea bag while working. Writing or typing while translating
is very difficult, and juggling with the buttons of a
console can be quite confusing. The user-interface of a
translation console should be as user-friendly as possible.

The current IC-2 Console has a few shortcomings in that department,
which could easily be solved with different types of switches.

The switch to change between the left microphone and the right
microphone should not be two push-button switches, but one
horizontal "lever"-type switch. When the lever is to the right,
the right microphone is turned on (and the right mike light
turns on to show it). When the lever is to the left, the left
microphone is on. When the lever is in the middle, both
microphones are off (and both lights also). This is the industry
standard, it's very easy to use, and the process of turning
off one microphone when the other one is turned on is automatic.
Using two push-buttons for this function instead of one "lever"-type
switch is perhaps electronically better (more robust switch? less
cost?), but is suboptimal for the actual end-user.

Another very poor use of push-button switches is to change
between languages (in my case English and French). Push on equals
English, and push off equals French? Or is it the other way
around? No end to the confusion of interpreters (except before
they start to work, when their brains are able to actually
concentrate on the buttons).

Here again, one central "lever"-type switch (but without a middle
"off" position), preferably with some console real estate above
and below it to write "English" and "Français" (or whatever target
languages), would be perfect. Maybe
two little slots to hold two little scraps of paper? Anyway, we
can easily tape scraps of paper indicating the target languages,
but a push-button to select between them is vastly inferior
to a "lever"-type switch. I would orient this switch vertically,
to make it crystal-clear which one controls the microphones,
and which one controls the languages. Horizontal = either the
left or right interpreter is working. Vertical = selects
the target language. Even a tea bag can figure that out!

If you come up with such a console, I think I'll buy one and take
it to work with me! Pretty soon, all the interpreters in
Quebec City will start complaining about all the other
interpretation consoles, and beg all local audio-visual companies
to buy your improved IC-2!

Thank you very much,

Stefan Jetchick

1450 av. des Grands-Pins
Québec, QC
G1S 4J6

Post-Scriptum: I sent this text to my seven collegues in Quebec City
(all professional conference interpreters). Within a few hours, five
had already answered, and all of them were very much in support of
this idea. I'll update this Post-Scriptum with the rest of their reactions.

2) Franck-Olivier Fabry (2013-July-2)

-----Original Message-----
From: Franck-Olivier Fabry
Sent: 2 juillet 2013 13:22
To: stefan.jetchick.1
Cc: 'Daryl Dankert'; 'Kent Peterson'; 'Mark Medcalf'; 'Jean-Marc Langevin';
'Wilf Langevin'; 'Pam Mizuhata'; 'Kathy Callies'
Subject: Williams Sound - Feedback on IC-2 console

Dear Stefan,

We very much appreciate your time and helpful suggestions on ways to
improve the Williams Sound IC-2 Interpreter Console. Your feedback
will help us when redesigning the IC-2 Interpreter Console, or when
conceptualizing similar new consoles in the future.

Your comments regarding the flaws of the current two push-button
switch design is precise. I just thought you'd like to know that we
have received similar objections from language interpretation end-
users and have already started discussing possible redesign options.
The horizontal lever-type switch would certainly be a more user
friendly alternative.

As far as the integrated audio compressor is concerned, I am pleased
to confirm that it's already built in the IC-2 console. Initial
market feedback was that compression settings were used infrequently;
for that reason we decided not to have an external switch for it and
hide the access to the compression settings. Actually, the IC-2
console has 2 hidden features: headphone gain and compression.
Standard default compression is 1:1, but it can be increased to 2:1,
4:1, or 8:1. Standard headphone gain is +6dB, but it can be
incremented to +9dB, +12dB, or +15dB.

Both settings are accessible at power on by holding the mute button.
The other lit buttons on the top of the console will then display the
current settings, which can be adjusted by flipping the feed through
switches on the back of the unit. Since these two features were
already built into the headphone amplifier, we built in a "back door"
to access them for customers who need it. I believe there's a
reference to these hidden settings in the operator manual, and we
have a white paper detailing how to adjust them (see attached). You
might be interested to know that this is actually the first time in 4
years we've heard of a customer asking about audio compression

As for the 1/4" stereo jack, this issue might now be moot point, now
that you won't have to plug in your external audio compressor.
Market research have confirmed that the 1/4" jack is not as
widespread as it used to be and can no longer be considered an AV
industry standard. Most headphones come now equipped with 1/8" or
3.5mm stereo jacks, and 1/8" to 1/4" adapters are readily available.

Hope this reply will prove useful to you. Should you need additional
information, please feel free to call our Technical Sales Support at
800-328-6190. If you call, I suggest you ask for Daryl Dankert or
Kent Peterson specifically.

«Merci» once again for your contribution to the betterment of our

With best regards,

Franck O. Fabry
Vice President of Sales
Williams Sound, LLC
Direct: 952-224-****

Cell: 952-607-****

3) Excerpts from IC-2 User's Manual: Hidden Features

The preceeding e-mail included an MS-Word attachment called "IC-2 Hidden Features.docx". Here are, I think, the relevant excerpts.

IC-2 Hidden Features

The IC-2 has several unadvertised features that customer service, sales, and
repair groups should be aware of. There is a "back door" sequence in the IC-2
code for those features that can be set so that they're available if needed.
This document introduces these features and explains how to set them.
Headphone compression "compresses" the dynamic range of the audio; loud noises
get quieter and soft noises get louder. The higher the ratio, the more the
audio is compressed, and the greater the perceived loudness of the audio. This
feature can help improve intelligibility, but makes the audio sound "flat" and
loses some of the expressiveness of speech.

Reset to Factory Defaults
- Press and hold down all three microphone controls ([Left] Mic[rophone] On,
Mute, and [Right] Mic[rophone] On).
- Power on the IC-2.

To set the headphone compression, have the user:
- Press and hold down the Mute button.
- Power on the IC-2.
- Verify that the current revision of code lights come on.
- While continuing to hold the Mute button, toggle the Norm Feedthrough switch
from off to on.

The default gain setting is 1:1 (no compression), but we can increase that to
2:1, 4:1 or 8:1 (the audio becomes more compressed with each step). After the
steps above, the lights will look like this (compression at 2:1 and gain at

Fig. 1.

Fig. 1.

As you continue to toggle the Relay Out Feedthrough switch, the gain setting
light moves to the left as it increments, then wraps back to its default
(compression = 1:1) at the right.

Fig. 2.

Fig. 2.
[Here, I wish I could add the sound of "Close Encounters
of the Third Kind"!]

4) S. Jetchick (2013-July-3)

-----Original Message-----
From: Stefan Jetchick
Sent: 3 juillet 2013 11:50
To: Franck-Olivier Fabry
Cc: 'Daryl Dankert'; 'Kent Peterson'; 'Mark Medcalf'; 'Jean-Marc
Langevin'; 'Wilf Langevin'; 'Pam Mizuhata'; 'Kathy Callies'
Subject: RE: Williams Sound - Feedback on IC-2 console

Good day Mr. Franck O. Fabry,

First of all, please tell your boss that you deserve a case of
beer, or an extra half-day of paid vacation, or something of the

Many of my interpreter collegues here in Quebec City basically
said: "Nice letter Stefan. Too bad they will never do anything about
it." One experienced interpreter even told me he has sent many
suggestions to interpretation equipment manufacturers over the years,
and never gotten an answer.

Williams Sound answered my letter! That in itself is a big victory
for Williams Sound. So pat yourself on the back for good customer

>> The horizontal lever-type switch would certainly be a more user
>> friendly alternative.

Good, but it's not apparent from your e-mail that you understand
there are **two** problems with those push-button switches:

	- switching between interpreters (activating either the
	left microphone or the right microphone); and

	- switching between target languages (for example, switching
	between English and French).

This requires two lever-type switches (which I suggest
to lay out one horizontally, and one vertically, to clearly
distinguish them).

>> integrated audio compressor is concerned, I am pleased
>> to confirm that it's already built in the IC-2 console.

Well, I can guarantee it wasn't operational when I worked with
your console! My damaged ears can testify!

>> we decided not to have an external switch for it and
>> hide the access to the compression settings.

"Ah yes!" as Agent Maxwell Smart would say, "The good old
invisible feature trick!"


Agent Maxwell Smart.

"No need to carry those big bags of audio compressors, Chief,
I have a tiny weeny invisible compressor right here!"

Seriously, I will now go into rant mode, so please don your
asbestos underpants.

I can see two objections to your claim that the IC-2 already
provides the audio compression feature I'm asking for.

1) It's so well-hidden, nobody knows about it

Remember, I'm an interpreter. I don't supply interpretation
equipment. That's done by another supplier (here in Quebec City
we have www.avwtelav.com, www.vision-av.com, www.concertplus.com,

The sound tech who set everything up on the day my ears were
banged up by your console else is a pro (like all the sound techs
in the audiovisual companies around here), and he knew what an
audio compressor was, and he could see we were getting our ears
banged up, and he tried to help me connect my audio compressor to
the IC-2, etc.

So at the very least, you have a communication problem with
the people who purchase your equipment.

(By the way, as a former C++ programmer, if I had supplied a
user interface to a feature that was as cryptic as the one
described above, complete with "Close Encounters of the Third
Kind" status lights, my manager would have slapped me upside the
head. "The people who will use your feature are normal human
beings with social lives, not bit-twiddling cave-dwelling
engineers like you.")

2) I'm not even sure the IC-2 feature technically works

Warning to interpreters: this letter to Williams Sound was written to explain two things:

(i) how NOT to do audio compression (i.e. how their IC-2 console does it); and

(ii) the right way of doing audio compression.

Do not confuse the two!

Of course, I don't own an IC-2 console, so I can't verify, but
I don't think the feature as described would work. (I
repeat once again, I'm not a sound engineer, so I might be
totally misunderstanding everything.)

Allow me to describe what I think I understand. Audio compression,
as your User Manual above explains, "compresses the dynamic range of
the audio; loud noises get quieter and soft noises get louder."

Let's imagine ordinary, uncompressed sound, like a normal speaker
speaking in a microphone:


Let's turn on the [Williams Sound IC-2] compressor, set at 1:2. The
same sound now looks somewhat like this:


But that doesn't solve our initial problem. For example, this can
happen [with the Williams Sound IC-2], even with compressed sound:


In other words, audio compression is just one factor. The other factor
is the threshold.

What you are saying is that the IC-2 has a "Ratio"
button, second from the left on the audio compressor I use:

FMR Audio RNC 1773 Audio Compressor

But the most important button is the first one on the left: "Threshold".
That button lets me do two things: (i) decide what "normal level of sound"
means; (ii) tell the compressor when to start compressing.

In other words, when you activate the tiny weeny invisible compressor
of the IC-2 console, it compresses all the time, regardless of the
actual level of input sound. What my compressor does is nothing,
most of the time. Most of the time, it doesn't even start to
compress the audio signal!

This has two advantages: as opposed to what your User Manual says, my
sound doesn't "sound flat and lose some of the expressiveness of speech".
Secondly, and most importantly, since I set the threshold to a sound
level that is comfortable to my ears, when a divergence occurs (an
"eardrum damaging excursion" of the audio signal), the audio compressor
kicks in and "crunches" the audio signal. Add to that the fact that my
audio compressor is always set on a ratio of 1:25 (in other words,
much, much better than the puny 1:8 of the IC-2). This means that a
potentially eardrum-damaging event ends up looking like this:


If you don't have a "Threshold" adjustment on your invisible
audio compressor feature, I have no idea how you could get it to
work properly. Every interpreter, with his own ears and his own
headphones (with their own input impedance), has a different
idea of what a "normal volume" is, and the "Threshold" has to be
set barely above that. How could it be hard-wired at the factory?

>> Initial
>> market feedback was that compression settings were used infrequently

Well of course! First, the "compression" supplied by the IC-2
probably doesn't do anything useful for a flesh-and-blood
interpreter. Second, no other manufacturer (although maybe
they have invisible features too!) has an integrated audio
compressor! How could interpreters clamor for something they don't
know about!

As the saying goes, if Henry Ford had listened to ordinary users,
he would have designed a faster horse!

I'm one of the few interpreters in Quebec City that use an audio
compressor. I'm slowly beginning to convince collegues how useful
it is. Two years ago, if I had polled all my collegues about audio
compressors, **zero** would have answered it was important. Now,
after much "evangelizing", they are starting to want it.

>> this is actually the first time in 4
>> years we've heard of a customer asking about audio compression
>> settings.

I hereby officially throw down a challenge to Williams Sound:

Call my boss (www.americainterpretation.com) and ask her to
set up a meeting during a big event (when she will have a large
team of interpreters on site, and large events in Quebec City
usually include a slew of interpreters from Montreal, since we
can't supply them all locally).

Bring an IC-2, and a video camera. I'll bring my FMR Audio
compressor. We'll do a kind of "Pepsi Challenge", to ask
interpreters which sound "tastes" better. We'll have some
clown up at the podium alternate between speaking normally,
blowing a horn or a whistle, or speaking very softly. Then
we'll ask all these professional interpreters to try to
translate. We'll post the results on YouTube.

I'm willing to bet every single interpreter, after
having tasted real audio compression (not the way it's currently
done by the Williams Sound IC-2), will never want
to go back to the bad old days.

And if you bring a new "IC-3" designed the way I'm proposing,
I'm also willing to bet you'll destroy the competition!



5) Appendix: Information for interpreters

Other interpreters have asked me about this "audio compressor" thing, so I'm adding a section for them (not having a better place to put this information):

5.1) Draft clause to add to contracts

WARNING: I'm not a lawyer, and this has not been reviewed by a lawyer. Also note this clause refers to the AIIC website, but I don't know if they yet have the equivalent of my "audio compression for dummies". Of course they are welcome to pilfer anything they might find useful on this web page (with credits, if possible).

Occupational Safety of Interpreters ("audio compression").

The Client will ensure the audio-visual vendor
(i.e. "the AV guy") will install an audio compressor somewhere
on the line before the sound reaches the interpreters, and
that it's properly configured (i.e. set at the correct
"threshold" and "dB reduction ratio") to protect against
excessive sound level divergences (i.e. "painfully loud
noises"). If this is not supplied, the interpreters may
refuse to work.

(Practical compliance advice: Several interpretation
console manufacturers claim their console provides this
feature, but their "compressor/limiter" feature does
not work. It must be a standalone professional-grade
audio compressor. The good news is all self-respecting AV
vendors have crates full of audio compressors in their
warehouses, so it's just a matter of asking for it in your
contract with them. If your "AV guy" or the salesman for
your AV vendor is a bit confused, the AIIC website has
additional information to walk him/her through the process,
so you can just ask the salesman to add some wording
about "...SHALL respect all that AIIC audio compression stuff",
and send them the hyperlink to it. Voilà!)

5.2) An interpreter-supplied audio compressor

Yes, in theory you the conference interpreter should not have to provide an audio compressor. But currently, such is life. Here is a Step-by-Step:

1) Buy an audio compressor. (I purchased the RNC1773 - Really Nice Compressor from FMR Audio, through a (rather randomly selected; I'm not endorsing them) Canadian supplier called Long and McQuade, for about 250$CAN.

2) Tape or glue all buttons except the Threshold. Position the dials as on the picture below:

Proper position of dials on FMR Audio RNC1773 audio compressor.
Proper position of dials on FMR Audio RNC1773 audio compressor.

I've had a lot of success in taping all of them (except the leftmost dial, i.e. the "Threshold".) This means you don't have to fiddle with all those useless dials everytime you install your compressor. If you use transparent tape, you'll even be able to see the little row of lights called "Gain Reduction" (useful to set the threshold).

From left to right:
Threshold: about -10 dB
Ratio: 25:1
Attack: 0.2 msec
Release: 0.05 sec
Gain: 0 dB
Never touch the two buttons ("Super Nice" and "Bypass"). In other words, the little red lights next to them should never be turned on.

3) Maybe buy a cable and some adaptors. Connecting your audio compressor is not rocket science, but you do need some cabling. You can buy a cable and some adaptors at any store that sells audio equipment. (What we used to call "Radio Shack"; just ask any audio technician what stores sell stuff like that, your city will have several.) The store-bought solution is sucky, but it does sort of work, most of the time (I'll explain a better solution later):

- quarter-inch splitter patch cable (i.e. a "Link Audio 1/4 TRS-M to 2x 1/4-inch Mono-M Y-Cable" if you're talking to a pimply teenager in the store).

- something to go from a quarter-inch male mono jack to whatever headphone you use. Normally you'll need both something to change a male 1/4" mono jack into a female, then something to plug your headphones into that 1/4" female mono jack (WARNING! I'm not sure the preceding hyperlink points to the right thing: you need a stereo female 1/8" jack to a mono 1/4" male jack, which is a bit hard to find. When I lend the one you can see on the picture to another interpreter, I always tell them: "If you lose it, you must give me your first-born child!").

Off-the-shelf cable and adaptors.
Off-the-shelf cable and adaptors.

4) A better solution: the custom cable. The advantages of a custom cable are: (i) fewer stupid adaptors to lug around (and lose...); (ii) the cable can be made the correct length so you can leave the compressor in the middle of the interpretation booth table, and just switch your cable around when you change positions, instead of having to drag the whole compressor around; (iii) some interpretation consoles (like the Williams Sound IC-2) require adaptors which are hard to find in stores, but are easy to build if you are making the cable yourself. Here is the schematic (if you get tachycardia looking at this, just ask any pimply teenager; expect to pay about 80$CAN for a cable made by an upscale teenager):

Schematic for custom audio compressor cable.
Schematic for custom audio compressor cable.

Technical notes about the "Williams Sound Console Jack":

- It's a kludge. Ideally, all interpretation consoles would have a 1/4" mono female jack. A few rare ones don't.
- Weird behavior. If the "Williams Sound Console Jack" touches anything metallic, the sound cuts off. So keep that jack taped over unless you actually need it.
- Proper R&D is currently impossible for me. I don't have access to such rare consoles, so I cannot easily test potential solutions. This is important for the next item.
- Sennheiser SDC 8200 ID. I recently discovered another console that doesn't have the proper jack, and my current cable doesn't work with it. I did find an adaptor (1/8" male stereo to 1/4" female mono) that works, but I don't know how it is wired internally (are the tip and the ring connected together, or is one just not connected to anything, or to ground?). So a proper adaptor might work with both the Sennheiser and the WilliamsSound, and obviate the need for the silly "Williams Sound Console Jack".

My custom cable, based on the schematic.
My custom cable, based on the schematic.

5) Plug it in. The actual plugging in is simple. You're trying to protect your eardrums, so the compressor has to become the "middleman" between your headphones and whatever is supplying you the sound. A simple approach is to unplug your headphones from the interpretation console, and plug the "input" of the compressor instead, and then to plug your earphones into the "output" of the compressor:

Compressor with cable.
Compressor with cable.

In the above picture, you can also see the power supply of the compressor (the "little transformer"). I made myself a "runt extension cord" (just a normal extension cord made ridiculously short) which allows you to get electricity for your compressor, but also leaves two slots free (one for your laptop, and one for whatever you had to unplug to find room for your runt extension!). Other interpreters are usually glad you don't clog up the power strip with all your electrical gadgets, so don't underestimate that little "runt extension".

6) Configure the compressor. Since you've already immobilized most of the dials on the compressor, the actual configuration is fairly simple.

Front of taped compressor.
Front of taped compressor.

The idea, as explained above, is to set the threshold so the compressor does nothing most of the time. So you play with two knobs: the volume dial on the interpretation console, and the threshold dial on the compressor. One way of setting them both (unsafe for your eardrums, but easy to explain), is to turn the threshold all the way clockwise (i.e. remove all protection! DANGER!), then adjust your volume normally until you can hear well, then dial the threshold counterclockwise until the compressor starts to "nibble" (i.e. the row of red lights starts to flicker just a little bit on the right end), then turn it back just a tiny bit, until the lights stop flickering. There! Now your sound is uncompressed, but if somebody does something stupid like drop the microphone, your eardrums will be protected.

5.3) Bizarre sporadic failure you'll probably never encounter

There is an obscure technical detail, which most of you can probably safely ignore. I was getting weird sporadic failures (the sound would just stop completely, at apparently random intervals), which I thought were caused by my home-made cable. So I paid (twice...) to have cables made by professionals. But the problem still re-appeared sporadically. I finally traced it down to the "OUT" 1/4" female jack at the back of the compressor (second "hole" from the left in the picture). The compressed signal arrives at that jack on the printed circuit board (PCB), then it's the jack itself that transfers that signal to the leftmost jack, not the PCB! But my "OUT" jack had a slightly loose metal blade for the tip, so that would cut the contact sporadically.

Back of compressor, showing where PCB puts signal.
Back of compressor, showing where PCB puts signal.

All I did was solder a "mickey mouse" wire that takes the signal directly from the PCB and sends it to the "IN" (leftmost) jack. That dumb design mistake by FMR Audio cost me much more in time and aggravation and unnecessary cables than the purchase price of their compressor...

2-cent piece of wire that cost me several hundred dollars.
2-cent piece of wire that cost me several hundred dollars.

A collegue purchased the same compressor more recently and never had a problem, so they might have fixed the PCB masks already. Just keep this in mind if ever your sound cuts sporadically.

5.4) Credits

I knew nothing about audio compressors. It was a local AV tech (Ioann) who taught me what little I know.

6) Appendix: Other devices claiming to protect hearing

On 2019-April-18, a co-worker made me aware of two other potential solutions:

PreservEar passive volume limiter at www.preservear.com.
PreservEar passive volume limiter at www.preservear.com.

LimitEar-FL passive fixed level limiter at www.limitear.com.
LimitEar-FL passive fixed level limiter at www.limitear.com.

I was able to try the PreservEar for a few minutes at work. Maybe it was broken, but despite adjusting the reduction level and observing that the light indicating it was limiting the level did turn on, as I raised the volume past the threshold, I did not notice any audio compression. It did not seem to limit the volume level, the way a real audio compressor does. (Maybe it's just a cheap device that cuts the volume in case of an acoustic shock. That in itself would be a good idea, but if so, I can't even test it! It would be like testing a bullet proof vest by shooting yourself: if it works, you're saved, if not, you're dead!) Anyway, be aware that a side-by-side comparaison gave me the impression the PreservEar was close to useless. Also, despite the device claiming to be limiting the volume, my ears still hurt after a few minutes of testing (with the protection level at its best, I wasn't protected).

I was quite sad about this, since I'd love to replace my stupidly bulky and heavy audio compressor (which on top of that needs to be plugged into a power outlet), with a neat little device that fits in your shirt pocket and that doesn't even require any power source. So what all engineers know has been demonstrated once again: if a solution doesn't actually have to work, you can make it really small and lightweight!

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