Empirical Labs EL-9 - Manual (Page 5)

Block Diagram
Section Details
The Input The “Input” section is a transformer balanced low impedance circuit. It is relatively
insensitive to all kinds of wiring, be it balanced or unbalanced. The Input phone jack on the back is
also balanced but will terminate (“short out” in a GOOD way) one leg of the balanced input when a
non-stereo guitar type cable is inserted. The input impedance of the main inputs is quite low at 600
ohms. Do not let this input section clip, causing the BAD! LED to light.
The Instrument Input on the front panel is an unbalanced, high impedance input (340Kohms),
designed for lower level, and higher impedance signal such as electric guitar, electric bass, and
other sources that may be sensitive to input loading. It will sense when something is plugged in and
automatically switch off the rear inputs. It uses circuitry that was designed for a DI box, and goes to
the input transformer for some “iron” in the sound, and gain adjustment. If your instrument is low
impedance and has a good output level, plug into the rear phone jack.
The Output – The basic Mike-E has an active output section going to two jacks in parallel, with the
¼” phone jack output being unbalanced. The output driver has 14dB of clean gain available. All of
the output jacks can be used the same time. Pin 2 of the active output XLR is directly connected to
the tip of the phone jack output. See Wiring on page 10 for more details.
The output driver has tremendous headroom, so don’t be afraid to run the output knob between
8 – 10 (all the way up) if necessary. As long as the BAD! doesn’t light, there is no degradation.
Mic Preamp Section
– This is a super low noise transformer input amplifier section, with the
gain digitally controlled. This section comes standard with a shielded Lundahl transformer, but
provides for a Jenson transformer also. The signal to noise far exceeds any microphone in
existence, typically over 130 dB with the input shorted and 40dB of gain. Having used many mic
preamps over the years, we have implemented a unique stepped gain control that should be
impervious to the normal flakiness that age causes to pots and detented switches. Counting the
output gain of 14 dB, a total of 74 dB of gain is available to the user, with the CompSat section
bypassed. A 48 Volt Phantom power is provided for condensor mikes. The Phantom power will reset
to OFF whenever unit is turned on to protect a different mic, such as a ribbon microphone.
Highpass Section
This is a specially shaped, digitally controlled 3rd order high pass filter. The shape has been
selected to prevent thinning out frequencies just above the corner frequency. The slope of the roll
off is 18dB per octave, and because of this steepness, the HP must be used with caution, especially
during tracking. No compromise was used in this filter, with a single active stage design, 5% caps,
1% resistors used throughout. This filter is capable of .0005% THD and over 124dB dynamic range.
11
EXAMPLE SETTINGS PT 2
With a soft instrument like an acoustic guitar, start with Mic Gain set at 50dB, and do the CLIP
TEST by having the player hit a really hard chord. If the mic doesn’t have a nice HP filter, you can
engage the 80Hz HP on the Mike-E to cut sub-frequencies.
Smoothing out the dynamic range of plucked instruments with a fast compressor is extremely
common., using a LN1176 or our own Distressor is sometimes all you will need when tracking or
mixing. BUT… The Mike-E has an amazing compressor, as good as any, in our highly respected
opinions… so lets use it!
Start setting up the compressor by turning the mix to 10 (full CW or 100%). If you want a
smooth glassy sound, we should keep the attack really fast (LN1176 speed) and set it to .9mS. The
release too can be fast which smoothes out the pumping. Lets start with Release on .1, and ratio
4:1. This can keep the compressor working most of the time with peak Gain Reduction around 10
dB. This should sound natural even while tracking. If the instrument or part is overly dynamic, even
more compression can be applied by turning up the DRIVE control. If the instrument starts to sound
squashed, you can back off the compression or use the MIX control to add back in some
uncompressed signal. This will bring up the low level stuff while keeping the loud emotional
passages more intact. If there are shrill or brittle parts, engaging the Emphasis can saturate the
higher frequencies sooner and soften them.
Saturation Only - If you are recording a solo instrument and wish to keep all the dynamic range,
but fatten up and soften the brittle edges ala analog tape, you can put the CompSat on 1:1 and
simply round out the pointy peaks and make them easier on the ear, and with the Emphasis
engaged, get a very warm tape like sound. Again, turn the Mix to 100%, and adjust Drive so the
WARM LED is on most of the time the musician is playing, letting the Toasty light come on frequently
on peaks. The unique dual clip Germanium circuits will softly and subtly clip the peaks of the
waveforms, rounding them out. If desired, the MIX control can be used to mitigate over -saturation in
a wonderfully musical way. This saturation with emphasis may be worth the price of the Mike-E
alone, bringing back a familiar smooth sound to those familiar with analog tape.
Elec. guitar
– Digital recorders do not enhance Electric guitar sounds in any way. Mike-E’s
CompSat is a wonderful tool to bring back some smoother, monstrous electric guitar sounds, while
tracking, or while mixing. The CompSat section is incredibly deep, and offers many options to color
the sound. Don’t forget the high quality HP filter, which will not affect any useful guitar frequencies.
Using Saturation - After adjusting the Mic Gain using the CLIP TEST, engage the CompSat and
start with 1:1, simply soft clipping the grittiness, and subs. The Emphasis will again further soften
the high frequencies by clipping them earlier. Very analog tape-like.
Using the Compression – If compression is to be used, one should be careful on heavy,
distorted guitars, since they are already “compressed” from the Distortion, and the main outcome will
be just bringing up hiss and noise, especially during pauses. A low ratio would probably be a first
choice on heavy guitars, using only 1 – 4 dB of compression. On clean electrics, one can use liberal
amounts of compression usually. 6 – 20dB or more may not be unusual, but unless you’re a master,
prudence is called for when tracking since it cannot be undone. Use the fastest attack to get sustain
and smooth attacks, probably with a very fast release also. Try 8:1 attack .9, release .1S. Usually
you would keep the mix 100% (10). On the other hand, if you want to get a nice “Poppy” attack and
front edge to each note, but still have lots of “hang time” sustain, try 20 or 100mS attack, release
.1S. OR, try over compressing and then blending in the DRY Signal with the Mix Control.
Also, for clean guitar, you must try “INSTRUMENT IN” DI input. Great with CompSat.
Keyboards
– In this sampled age, this covers a lot of sounds. Acoustic Pianos are a whole
subject unto themselves, so let’s start there. Their sound begins with a great, well tuned piano and
good mics. Treatment also depends on the final setting, I.E. Solo piano, or as part of a larger
ensemble. Getting a big full sound is usually the goal of solo pianos pieces, whereas with a piano
that is part of an ensemble or rock mix is often brightened and compressed somewhat, and high
passed, especially if there are potential conflicts in the low end between the piano and bass parts.
So one can use the CompSat with just subtle Saturation, or for pop recordings, lots of compression.
Engineers use all kinds of approaches, fast attacks or slow, fast to medium release. Often however,
when a piano is part of an ensemble, you may want to use a fast attack to keep the attacks low in
relation to the main decay of the piano. One can also employ the MIX control to keep the attack and
dynamics, while bringing up the sustain as the compressed signal appears under the fading dry
unprocessed signal, eventually dominating the blend.
4
1
3
2
2
3
1
Balanced In
Digitally
Controlled
Preamp
10dB
Atten
Comp/Sat
Gain
HP
Filter
Main Output
Unit shown with all processing "Out"
Unbal
Dig Ctrls
HP Relay
Dig Control
Pre-Emphasis Atten
Relay
Circuit
Dig Ctrls
Saturation Mix
Output
Gain
Inst
Preamp
Balanced Out
Mike-E
De-Emphasis
Inst Sense
Phase Invert
Input
XFRM
Comp/Sat
Comp
Bypass
(Tip)
Dig Ctrls
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