Empirical Labs EL-500 User Manual

INST.

IN

(Hi-Z)

(Auto Sense)

API 500 Series Rack

(-16V)

(+16V)

Horizontal Rack for API500 Modules

Features:

o Unique Flush Mount system for durability & looks.
o Super Quiet ± 16Volt Supplies. Perhaps quietest available.
o More than 280mA available on both supplies.
o 48 volt Phantom supply. 35 mA of current.
o Link Switch to Stereo Link two Compressors.
o Built in “Inst In” (Instrument In) for high impedance inputs built

into front panel. Direct box built right in!

o “Inst In” THD is less than .0006%.
o A performing musician can use the INST IN combined with his

favorite modules, using the super quality preamp on this front
panel jack.

o Auto-Sense on “Inst In” jack
o XLR & Phone Plug Inputs and Outputs. A total of 9 input and

output connectors.

o Front panel Link Switch for Stereo linking dynamic devices such

as compressors/limiters/gates.

o Power Consumption – 14 Watts max. 9 Watts Typical with

modules installed.

Empirical

Labs

Empirical Labs - Technology for the Artist

Installing the Modules

Cards can be tricky to install in any rack with a concealed mating connector. If the technique
below doesn’t go easily, one can always unplug the unit, unscrew the top cover and do it more
directly. The mating electrical connector is called a 15 pin EDAC connector.
Slide the new module in and tilt the rear of the card up so the rear of the card is resting on the
hidden connector. Slowly and with a firm square grip on the card, pull the card forward till you feel
the card “fall” off the internal connector. With both hands on two points on the modules front (knobs,
switches), try to slightly lower the rear of the card till it “feels” the entrance to the EDAC connector
inside. The card should now be aimed at the entrance to the connector and with a little pressure
slide into the “funnel” of the connector. The front panel should be sticking out of the EL500 Front
Panel by about .2” as it starts to enter the card connector. Firmly press on the module and you
should feel it slowly seat into the slot.
Some modules are two high to tilt the rear up far enough to rest on the EDAC connector inside.
These you can often let rest on the bottom and then slightly tilt up into the ’Funnel” of the EDAC
connector.
Removing cards generally requires one to grab a knob or switch, and gently pull while wiggling
from side to side and up and down to slowly unseat the card from the connector.

Wiring

Most studios will probably use the XLR inputs and outputs, which should operate
problem free. However, high quality, hand-wired ¼” phone jacks are included on the
EL500. With cable runs under 20 feet or so, there will be no degradation using the Phone
jacks. The phone jack tips are in phase with pin 2 of the XLR connectors, so generally
the device would be said to be wired with Pin 2 Hot.
The output ¼” phone plugs need special consideration. As shipped from the
factory, the ring, tip, and sleeve are all connected, with the tip connected to pin 2 on the
XLR output, and the ring connected to Pin 3. The sleeve is always ground (pin 1 on the
XLR). The possible problem is if the module associated with a ¼” output has an active
driver pushing on the ring (XLR pin 3) and the user shorts it to ground. This would
happen with a normal guitar cable (a mono cable without the ring). If the associated
module has a transformer, a regular guitar type cable will work fine and terminate the
output transformer properly. Empirical Labs has included an internal jumper however to
“lift” (disconnect) the ring of the output phone plug and prevent shorting an active amp
output driver going to the ring, and pin 3 of the output XLR. If you use the output ¼”
phone jack, try to determine if it has a transformer OR an active output driving that ring,
and move the jumper to lift the ring if the output is active and shouldn’t be

ground.

shorted to

Instrument Input on Front Panel

This built in Direct Box has a 330K input impedance (minimum), and is excellent for
plugging in a guitar, bass or synthesizer directly to the first (left) 500 module. As soon as
a standard guitar cable is plugged in, the EL500 senses it and switches the input to the
left module to the Direct Box amplifier. A musician can have a great live performance
preamp, with modules tailored to his needs just by plugging in.
As it comes from the factory, the “Inst In” operates at unity gain. However, there is
a jumper inside that can change the gain to +10dB for lower level instruments. Most
single coil guitars and basses could benefit from this gain, and provide a hotter level to
the left module. This will usually improve the signal to noise of the instrument. But listen
carefully for clipping by having the musician play his loudest notes. It is a hassle to have
to open and shift the jumper to switch the gain if clipping occurs.