Empirical Labs EL-DS User Manual

Model EL-DS

Dynamic High-Frequency “Fixer”

INDEX

Page Item

1 Features & Specs

2 What Is the DerrEsser?
2 The Four Modes of Operation

2 Using for the First Time

3-4 Example Settings
5-6 Recall Sheet

7 Installing and Wiring the Module

7 Troubleshooting
8 Stereo Operation
8 Cables – Fact and Fiction
8 About Empirical Labs

9 User Notes

10 Customer Comments

11 Warranty (Rear Cover)

Empirical Labs - Technology for the Artist

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Features



Possibly the highest performance analog De-esser in existence.

 HF Lim Mode, as well as standard De-Ess – High Frequency limiting with

a tailored soft knee. The Dynamic Section can be used for De-essing or
smooth high frequency softening.

 A “BAD!” Hard Clip Indicator light – This “Bad” Clip LED lets user know

he is within 1dB of hard clipping. It monitors several sections within the
DerrEsser for possible clipping.

 Unity Gain in and out – 6dB of gain availible
 Foolproof operation - it's almost impossible to clip or get a bad sound.
 Industry standard API 500 Series Rack compatible
 True bypass - Know what it's really doing.
 High reliability parts and military grade switches and relays.
 Three year limited warranty.
 Interface and features found nowhere else.
 Hand built and calibrated in USA. Shipping weight 1 Lbs.

Specs

♦ Freq. Response is 3 Hz to 120 kHz (-3dB points).

♦

Dynamic Range - 115 dB from maximum output (.5%THD soft clipping) to minimum

output. Noise floor typically – 93dBu.

♦

Distortion Ranges between .0035% and .01% depending on mode and settings.

♦

DC coupled Input and Outputs
High quality audio caps used internally.

♦

Input Balanced, Output single ended but with balanced impedance. It

♦

can be made differential by moving a jumper on the board.
Input Impedance is 20k Ohm. Output impedance is less than 51 ohms.

♦

♦

D-S Dynamics Time Constants - Attack time is less than 1mS. Release .04 sec, fixed

internally.

♦

Power Consumption – 8 Watts max. 4 Watts Typical

Empirical Labs - Something Old, Something New

What is the DerrEsser?

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The DerrEsser is a multi function dynamic filtering device, in an API 500 series module format. In its
basic “DS” mode, the DerrEsser is an effective, level insensitive de-esser, which is a device that will
adjust the high frequency gain on overly trebly or spiky vocal, or other source. By using a crossover
technique, and dividing the audio up into a high frequency range and a low frequency range, the
DerrEsser can use its Voltage Controlled Amp to turn down comparatively high or harsh high
frequencies in an extremely musical manner. However, unlike other de-essers, the device is not
limited to just de-essing, and allows for multi use of its circuitry. See Below.

The Four Modes of Operation

Besides Bypass, there are essentially four modes of the DerrEsser:

DS Mode – (Bypass Button IN, all other buttons OUT). As a de-esser in the DS mode (HF Limit

OFF), one can set the threshold to tame harsh S’s (sibilants) that result from an overly bright singer
or from EQ’ing to make a vocal sound aggressive and clear. In this mode, the dyamic action is “level
insensitive”, as the detector circuitry compares the High Frequency content to the low frequency
content, overall signal level doesn’t matter at all. When there is enough HF compared to LF, the
threshold is exceeded and the DerrEsser starts to turn down the frequencies above the crossover
point set by the Frequency control on the front panel. Again, great care was taken to ensure this DS
section meets the Empirical Labs reputation for originality and ease of use. We use the latest
technology VCA, specially selected for glitch free, distortion free, and noise free performance. The
time constants were carefully selected and the corner frequency is user adjustable with a high
performance active crossover.

HF LIMIT – (Bypass Button IN, HF LIM IN, all other buttons OUT). In this mode, the DerrEsser

looks at the general level of the High Frequencies only. Think of it as a high frequency compressor.
If there is enough high frequency content to exceed the threshold, then gain reduction occurs. It IS
level sensitive, but responds much more to high frequencies. This mode can also act as a de-esser
but is more of a general high frequency smoothing device.The HF limiter is probably the first
carefully tailored soft knee HF limiter in existence. We believe both the DS and HF LIM modes offer
the highest performance of any similar device.

HIGHPASS – (Bypass Button IN, Listen IN, HP/LP OUT, HF LIM doesn’t matter). By using the

“LISTEN” Function, the user can employ the superb filter circuitry inside the DerrEsser to process
their audio. With the LISTEN button IN, and the HP/LP switch OUT, the user will be hearing the high
frequencies that are being controlled with the dynamic/compression circuits. The corner frequency is
adjustable by the Frequency knob. Once the LISTEN switch is engaged, all bargraph LED’s should
light as indication.

LOWPASS – (Bypass Button IN, Listen IN, HP/LP IN, HF LIM doesn’t matter). With the LISTEN

button IN, and the HP/LP button IN, the user is now listening to the low frequencies, those not
affected by the VCA and dynamic/compression circuits. This is a 12 dB per octave filter whose
corner frequency can again, be adjusted by the Frequency knob.

USING FOR THE FIRST TIME

The DerrEsser is not only a high frequency problem solver, but can be used as a super-quality HP or
LP filter, AND as a coloring device to give a more analog sound to digital sources. Use the
DerrEsser when you have a vocalist with prominent unnatural “S’s. The standard DS Mode is
usually used, with the Frequency set to 2 – 6K. Adjust the threshold till the S’es are tamed and not
much else is affected. The HF Limit will more generally smooth the high frequencies, gently
subduing high frequencies that exceed the user adjusted threshold. Great on so many sources.

The DS Mode can also help difficult problems like high hat bleed in the snare mike, or occasional
SQUEEKS on an acoustic guitar or other instrument. See example settings.
The HF Limit Mode is a general high frequency smoothing setting. Use it to soften the high end on
zillions of sources, not just vocals. If you have a track that has high frequency spikes, or plucks, or
edges, this can let you keep the air of the high end except when it really piles up.

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Example Settings

Vocals - One of the worlds favorite vocalists, Frank Sinatra, became so good at ” working the

mic”, moving in when he was singing soft and wanted intimate body, moving back when he belted
and needed to get the higher notes out… he became so proficient that I have heard the engineers
used very little or no EQ his voice. He got the sound at the source. As he sang soft, he would
move in a little closer to the mic, giving his voice an intimacy. He would even turn his head quickly
to the side so certain breaths wouldn’t be heard. Modern singers of every style could learn from
what Frank was doing 40 yrs ago. He pronounced his S’s very soft and short. Here are some tips
that may help prevent needing the De-Esser or any radical EQ.

Pick the right mic, the right distance and the right angle for the singer. The most expensive
mic isn’t always the best mic for a person’s voice. U2’s Bono uses a cheap ol Shure SM58, but…
who could complain about his vocal sound? Moving a person a couple inches in and out from the
mic can make all the difference in the world. Putting the mic up above the person’s mouth around
their nose level can warm things up, avoid pops, and make a singer sound less nasal. A distance of
6 – 10 inches from mouth to mike is common. When a mic is aimed down a little towards the
singer’s mouth, you will be aiming it at their body also, where lots of low frequency resonance
occurs. Conversely aiming it up can work, having the singer sing over the top of the mic.
Remember that a leading cause of “nasality” is the lack of sound and air coming from a persons
nose, so by aiming up or being level with the nose, an engineer can often improve the basic quality
of a voice. Remember to remind the singer they can move slightly in on soft intimate parts, working
the microphone ala “The Frank”.
There are some other dynamic equalizers out there that work pretty well, but… hoping to get a
great vocal sound using one “holy grail” setting on a wildly dynamic vocal is dubious in our minds.
On an occasional overly sibilant vocal, use the standard De-ess mode which is level insensitive.
Adjust the frequency for around 2.5 - 6Khz and adjust the threshold till the sibilants start sounding
natural. If lisping starts occurring, raise the frequency or lower the threshold to lower the De-essing.
The De-esser should only be working on the offending fricatives and sibilants.
Often the sibilants only become a problem after eqing. However, one very useful technique is
to add the high frequencies AFTER the DerrEsser to add overall sheen back into the vocals, where
the De-Essing can’t undo the Eqing. Of course, many aggressive engineers EQ before and after the
De-Essing.
If a vocal is kind of “generally harsh” and “ESS-y”, the high frequency limiter can provide a
smoother sound. This limiter is extremely smooth and will sound pretty natural working on just about
every line of an overly bright vocal. Just make sure that a gentle EQing wouldn’t be a better solution.
The HF Limiter can sometimes give an analog tape-like effect; warming the vocal the harder you hit
the DerrEsser with level.

Various Instruments
Elec. guitar

notes, taking the harsh freqs out surgically. Analog tape was always a big help with vocals and
electric guitars because it clipped all the pointy peaks and saturated when the high frequencies piled
up. Using the DS dynamic HF limiter can get a verrry tape like affect if used judiciously. We have
found it to be verry useful on overly crunchy plucky guitars, and “spitty” vocals alike.
Bandlimiting the top end can tighten up and quiet the hiss of electric guitars, especially “heavy”
ones. Put the DerrEsser in LP Mode and close down the top end to 8 – 10KHz. You will usually find
you don’t miss these frequencies on heavy distorted guitars at all. It lets the cymbals and vocals etc
have more clarity up there.

- If there’s just an occasional peaky note, the normal DS mode can tame specific

Plucked Instruments & Acoustic Guitar – Sometimes you may want to keep the

dynamic range of a plucked instrument but need to smooth out just the hard front edge of the attack.
The DerrEsser’s HF Limiting is perfect here. Adjust the threshold until you have a smoother, more
natural sound - usually 3 - 10 dB of HF attenuation is enough. In addition to your normal monitoring
levels, listen very softly, and very loudly to the adjusted track to make sure it isn't too dull, or still in
need of "softening". Squeaks from hands sliding on strings can often be “fixed” using the De-Ess
mode judiciously. Problems such as these often become more pronounced after compression, but
the DerrEsser can be effective placed before or after the compressor.

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