Empirical Labs EL-DS - Manual (Page 5)

Installing & Wiring the DerrEsser
Installing the card: Simple! Unplug powered rack, remove two screws on top and bottom of
designated slot on powered rack, line up the card in the connector, and gently press into place.
Check module is right side up and properly mated, and then re-install the two screws.
Most API 500 series racks offer XLR inputs and outputs. The DerrEsser module is almost
completely insensitive to wiring as long as Pin 2 is hot on the XLR.
It is best to attach both input signals to something, with an unused pin (pin 3 usually), tied to ground.
At least Pin 1 (ground) and pin 2 (main signal) should be connected on the output. Pin 3’s
impedance is balanced to Pin 2 on the output XLR connector. Pin 3 can be connected or not.
Differential Output – There is a jumper in the middle rear of the board that can be moved to make
the output Differential. The downside is that the gain will increase 6dB, making the output drop in
level when bypassed. To change to differential, pull the jumper up and off, and move it to the rear
position.
Now start fixing those high frequency problems!
Troubleshooting
‰ Bad! light comes on – You are coming into the DerrEsser with too hot (loud) of a signal.
Turn down the stage or device before it.
‰ Unit is on but not doing anything - The unit may be bypassed or operating subtly. If bypassed,
you need to press the "BY-PASS" button IN.
‰ Distorted output - If there is any un-musical distortion, chances are you're hard clipping. If the
Bad! light isn’t coming on, check that the output cable is properly wired (see Wiring the DerrEsser).
Shorting an active output pin will not harm the unit but can show up as distortion in the output
driver.
‰ Bargraph on DS shows gain reduction but very little or no limiting is actually occurring -
The section is bypassed, or the unit is possibly severely out of adjustment. We use very stable
trim pots and high quality components, and it’s rare that long term component aging or failure will
cause failure, but… things do happen. At present you will have to return the DerrEsser to factory
for re-calibration. In the future there will be local dealers and/or service centers to help.
‰ Unit seems noisy - The dynamic range of the DerrEsser is much greater than CD (16 bit)
quality. However, if you are working with a really low level signal such as a microphone, you need
to preamp it. Microphones almost always need 20 –50dB of gain to be at “Line Level”.
‰ No sign of life - Check power cord for firm connection. Press LISTEN button in and see if
bargraph lights up. If still no life unplug unit and open fuse holder to see if it is blown. If it is
blown, pull it out and replace it with new fuse. If fuse is OK, ensure Voltage select switch is set to
current wall outlet voltage (115, 230 VAC). If other modules are in the rack with the DerrEsser,
perhaps you could pull the modules out one at a time and see if one of them is affecting operation
of the others. If one module seems to cause problems, it should be removed till it is repaired.
‰ Unit seems too aggressive or causes lisping. Raise the frequency, or lower the threshold. A
little can go a long way. Also, perhaps the HF Limit mode is what you need to smooth out the
highs instead of the more brickwall type of curve the DS mode offers.
‰ All GR LEDs are on and won’t go off – The LISTEN Mode is engaged. Press the Listen Button
so it is OUT and the LEDs should go off.
‰ There’s a level drop when using quarter inch input (compared to bypass). You may be
using a stereo input cable (1/4”) that doesn’t have the ring connected to ground or something. Try
an unbalanced input cable.
‰ There is a 6dB increase in gain thru the unit when not in Bypass. The gain jumper in the
middle rear of the board is in differential mode. Moving the jumper to the forward to pins will set
the unit back to unity gain. The output is still balanced impedance wise, but not differential.
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Example Settings (Cont’d)
Percussion
Snare/Toms – Hi-hat bleed. Snares often need some top sizzle, but adding hi frequencies can often
cause problematic hi-hat bleed. The DerrEsser can easily tame the hi hat bleed in standard DS
Mode. Set the frequency between 2KHz and 8KHz and adjust threshold to catch the problem areas.
Putting the DerrEsser before the EQ boost can help keep the snare sizzle from getting clamped on
every hit. Cymbal and hi-hat bleed on tom mics can also be treated the same way.
Again, analog tape was always a big help in getting a fat, punchy, natural snare. If the snare
has a plastic edge to the front end (especially after EQing), the HF limiter can be engaged to fatten it
up, allowing the “snares” to stay present after the initial offending attack… like analog tape. The HF
Limit Mode can be useful in evening out the overall top end of the snare.
Overhead cymbals – It is a common practice for some engineers to roll off much of the low end on
the overheads, but it is prudent to leave this for mixdown, after tracking. Overly bright or percussive
cymbals are irritating. Here in the digital recorder age the front edge of cymbals can be harsh and
too “pingy” once the engineer gets to mixdown. Analog tape used to soft clip and self erase these
sometimes annoying transient pings. The DerrEsser’s HF Limiter can be a wonderful tool to soften
these edges. Enable the limiter (the orange LED will be on, as well as the DS Blue LED) and dial in
1 – 6 dB with the threshold in the DS section. Adjust the frequency for 4 – 10Khz depending on the
severity of the cymbals edge. The limiter should only work on the very front edge of the cymbals.
Make sure you aren’t squashing the clarity and overall air of the cymbals.
Room Mics – You can use the DerrEsser to tame splashy cymbals which are usually a problem
after compression. Set frequency to 2 – 5KHz. The DS mode or HF Limit mode may be helpful. The
DS will mainly remove cymbals when no other drums are played. Alternately you can also use the
LOWPASS mode to more or less get rid of the cymbals. This can be dangerous!
Keyboards
– Obviously in this sampled age, this covers a lot of sounds. Acoustic Pianos are a
whole subject unto themselves, so lets start there.
Acoustic Pianos – Often in digital recordings, excessive hammer attack can cause “plucky”
sounding acoustic pianos that pop out in a mix. Using the HF LIM mode in the DerrEsser can gently
soften excessive transients and bright notes. It can often be most effective after compression, which
lets the “sharp” first 10-100mS through. Try adjusting the frequency lower around 2KHz and
adjusting threshold till the piano “edges” start to sound more natural.
Synthesizers – You can probably plug a synth straight into the DerrEsser. Synths often have plucky
top ends. One can band limit the top end with the LISTEN LP mode, or try the HF Lim to control the
high frequency peaks. Compression can help get rid of the pointy peaks also, but often more other
treatment is necessary. Sometimes theres simply too many highs and the LP Mode can warm the
synth up by rolling off unneeded highs. Cutting freqs on one track, gives room for them elsewhere.
Bass
– Bass is a critical element in all mixes. The DerrEsser offers some solutions to several
common Bass instrument problems.
If a bass is very clacky and has excessive pick noise etc, engage the DS mode (Only the
BYPASS button pushed IN). Adjust the frequency to 1 – 6Khz and adjust the threshold till the clacks
and clicky notes are attenuated and fit better into the mix.
You can also add harmonics by using the fast attack/release times, to modulate and saturate
low frequencies. Set Freq to Min (about 830Hz) and raise threshold to activate gain reduction.
Engage the HF LIM and the DS circuitry will be working on faster rising edges of low frequencies,
adding low order harmonics.
Band limiting the bass by rolling off the high frequencies is a verrrry useful technique. Engage
the LP Mode by pressing LISTEN In on the DerrEsser, ensure the HP/LP switch is IN, and adjust
FREQUENCY to taste. Start gentle since one doesn’t want to lose the definition on the bass,
especially in small speakers. I have seen engineers “band limit” the top and bottom end of the bass
to approximately 70Hz through 4 KHz, letting the rest of the tracks fill in above (and below) this band.
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