OVERVIEW

FEATURES

Microphone Pre-Amplifier

Your EUREKA contains a Class A discrete input buffer followed by a dual servo gain stage. This arrangement results in ultra low noise and wide gain control allowing the EUREKA user to boost desirable signal without increasing unwanted background noise.

48 Volt Phantom Power

The EUREKA has 48V Phantom power available. This assures optimum performance of your condenser microphones that require Phantom power and that the power supplied will be free of noise or distortion. * Pad. A 20dB pad is available for reducing the in-coming signal level. This pad provides a more manageable signal from high output devices giving greater control over the in-coming signal and a much reduced chance of over-driving the input and avoiding distortion.

+22dBu Headroom

The EUREKA mic-pre has +22 dBu of headroom. This feature gives you wide dynamic range and excellent transient response characteristics.

Saturation Control

The EUREKA offers a very high quality transformer and features an SATURATION control (this control adjusts the drain current on the input FET amplifier altering the even harmonic levels of the signal being passed) with an adjustment range of 0% to 100%. The 0% position passes a pure signal. As the control is rotated to the 100% position, the signals even harmonic series is boosted giving the signal warmth very much like a vacuum tube or similar to the sound of analog tape saturation. This remarkable effect gives you the sound of a tube without the headache of uneven performance often encountered with vacuum tube devices (no tube to pick-up RF or to age and become microphonic).

Variable Microphone Input Impedance

This feature enables you to tune your microphone by matching the output impedance of your microphone with your microphone preamplifier. This works especially well for ribbon microphones. Changing the input impedance is also effective for dynamic and condenser microphones and can be the perfect solution for a given recording application.

Phase Reverse

Use the phase reverse switch to combat phase cancellation with other open microphones.

Full Featured Compressor with High Pass Filter

The EUREKA is equipped with a Compressor with a high pass side chain filter designed especially for frequency specific processing.

Soft Knee Compression

Soft Knee Compression causes the compression to set in gradually producing a more musical response

Bypass

The Bypass switch lets you compare the compressed sound quickly to the uncompressed sound.

3-Band Parametric Equalizer

Total tonal control is what the Equalizer section provides. The EQ will let you fine tune the sound to suit your taste with exacting precision.

Bypass Switch

A bypass switch is provided to audition the signal in an equalized version as compared to a direct unaffected signal.

Variable Q

Adjusts the width of the frequency band between wide and narrow during equalization.

EQ COMP

Switches the order of the signal chain putting EQ before the Compressor.

Master Section

Gain Reduction to Meter

Shows gain reduction on the meter implemented by the compressor.

Level

The output of the EUREKA is adjusted by the Level control and is useful for compensating for gain loss due to compression or to decrease output signal that boosting frequencies with the Equalizer section may have caused. The output is variable from 80 dB to +10 dB.

VU Meter

The VU meter provides an accurate reading of the output level and a reference of signal presence. It can also be switched to monitor gain reduction when using the compressor.

CONTROLS & CONNECTIONS

FRONT PANEL BASIC LAYOUT

The front panel of the EUREKA is divided into four sections Preamplifier, Compressor, Equalizer and Master.

PREAMPLIFIER

GAIN

Provides +52dB of gain for the microphone input and +44dB of gain for the instrument input.

IMPEDANCE SELECTOR

Selects the amount of resistance that is applied to the microphone input. This selector allows you to match (or intentionally mismatch) the input impedance of the Eureka with the impedance of your microphone. As the Eurekas impedance is lowered, different filtering effects can result delivering a tailored sound for a particular application.

SATURATION CONTROL

Selects the amount of increase (0% to 100%) applied to the even harmonic series of the signal being amplified by the EUREKA. The effect of manipulating the harmonic distortion is of increasing or decreasing the apparent warmth of the signal. This feature is derived from manipulating the drain current of the FET input buffer of the Mic Preamp. Experiment with the SATURATION control and see what type of sounds you can get from your present microphone selection.

LINE

Selects the line input on the back as the input in use. When using the Line input, the microphone preamplifier stage is bypassed and thus the GAIN, IMPEDANCE and SATURATE controls are inactive.

+48V

The 48 volts supplied by way of the XLR connector, provides power for condenser mics and any other devices requiring continuous phantom power through the XLR input. This power is supplied at a constant level to prevent any degradation of audio quality.

PAD

Engaging the Pad switch provides -20dB of attenuation with the push of a button. This is a very useful feature for rapidly reducing the level coming into the EUREKA and thus preventing the input signal from over-driving (distorting) the input. This may occur due to high output level from a microphone or other device. Padding the input serves to provide increased headroom for the operator while lessening the likelihood of input signal overload.

80Hz

The 80Hz button is a low-end roll-off filter. When pushed in, the 80Hz button causes all frequencies below 80Hz to be attenuated (dropped) by 12dB. This filter can be handy in live and studio applications. For example, the 80Hz filter can help to reduce the boominess or muddiness of a vocal and improve the overall clarity.

Phase Reverse

Reverses the polarity of the signal. Use the phase reverse when recording with more than one open microphone to combat phase cancellation between microphones.

INSTRUMENT

TS connector. When an instrument is plugged into the instrument input, the microphone preamplifier is bypassed and the Eureka becomes an active instrument preamplifier.

COMPRESSOR

THRESHOLD

Sets the level at which compression begins. The below and above LEDs over the Threshold knob indicate whether the input signal is below or above the Threshold setting. When the signal is above the Threshold setting, it becomes eligible for compression. Basically, as you turn the Threshold knob counter-clockwise, the input signal is compressed. (If you have a ratio setting of greater than 1:1.)

RATIO

Sets the compression slope. This is defined as the output level versus the input level. For example, if you have the Ratio set to 2:1, any signal level above the Threshold setting will be compressed at a compression ratio of 2:1. This simple means that that for every 1dB of level increase into the compressor, the output will only increase dB, thus producing a compression Gain reduction of 0.5 db. As you increase the Ratio, the compressor gradually becomes a limiter. A limiter is defined as a processor that limits the level of signal to the setting of the Threshold. For example, if you have the Threshold knob set at 0 dB, and the Ratio turned fully clockwise, the Compressor acts as a Limiter at 0 dB. This means the signal will be limited to an output of 0 dB regardless of the input signal.

ATTACK

Sets the speed at which the compressor acts on the input signal. A slow attack time (fully clockwise) allows the beginning envelope of a signal (commonly referred to as the initial transient) to pass through the compressor uncompressed, whereas a fast attack time (fully counterclockwise) immediately subjects the signal to the Ratio and Threshold settings of the compressor.

RELEASE

Sets the length of time the compressor takes to return the Gain reduction back to zero (no gain reduction). Very short Release times can produce a very choppy or jittery sound, especially in low frequency instruments such as bass guitar. Very long Release times can result in an overly compressed signal, sometimes referred to as squashing the sound. All ranges of Release can be useful at different times however and you should experiment to become familiar with the different sound possibilities. (Refer to the applications section of this manual for some ideas.)

SOFT

selects Soft Knee and Hard Knee compression curves. When this button is pushed in, Soft knee compression curves are used, otherwise hard knee compression curves are used. With Hard knee compression, the gain reduction applied to the signal occurs as soon as the signal exceeds the level set by the threshold. With Soft knee compression, the onset of gain reduction occurs gradually after the signal has exceeded the Threshold, producing a more musical response (to some folks).

EQUALIZER

The EQ is divided into three sections or bands (Low, Mid and High) Each band has the following controls:

GAIN

Controls the amount of cut or boost of the corresponding frequency. Each gain control offers +/-10dB of attenuation.

FREQUENCY

Selects the center frequency of equalization. If the gain is set to 0, this control will have no effect.

Q (Bandwidth)

Controls the width of the frequency being adjusted. Q is defined as the ratio of the center frequency divided by bandwidth. If the gain is set to 0, this control will have no effect. The Q on the Eureka ranges from 0.4 (wide) to 2.0 (narrow). In octaves the Q on the Eureka ranges from 3 octaves to 2/3 octaves.

BYPASS

When pushed in, the EQ is no longer equalizing the signal.

MASTER

MASTER (LEVEL)

This control adjusts the output level of the EUREKA. It functions as a master fader for the entire processing strip. It is useful for adjusting the overall output level up or down to match the optimum input level of a recorder, mixer, etc.

GR TO METER

When pushed the VU meter reads Gain Reduction of the Compressor. When not pushed, the VU meter reads output level.

BACK PANEL BASIC LAYOUT

Connectors

All Input and Output connectors are servo balanced. XLR or TRS.

INSERT: Return and Send connectors are provided for use in conjunction with audio process devices such as reverbs, delays, de-essers, etc.

NOTE: The LINE IN jack does not work unless the LINE button on the front of the unit is pushed in.

POWER SUPPLY

The Power Jack on your EUREKA accepts a standard IEC cord like those found on most computers and professional recorders.

The Power button on the Eureka is located next to the Power Jack.

Note: The input power voltage is set at the factory to correspond with the country in which it was shipped..

OPERATION

MICROPHONES

The Eureka works great with all types of microphones including dynamic, ribbon and condenser microphones. Dynamic microphones and ribbon microphones are generally lower output devices and require no external power source. Condenser microphones are generally more sensitive than dynamic and ribbon microphones and typically require external 48V phantom power.

Microphone Input Impedance

You can adjust the input impedance on the Eureka to match or tune a particular microphone to achieve a desired sound. Most microphone preamplifiers have a fixed microphone input impedance of 1000 to 2000 ohms. The Eureka has five different impedance values to select from: 50, 150, 600, 1500 and 2500.

Refer to your microphone specifications to find the microphone output impedance and experiment with matching the Eurekas input impedance with the microphones output impedance. As the impedance on the Eureka is lowered, a resistive load is put on the microphone. This will not damage a microphone. However lowering or raising the impedance can create subtle coloring and filtering effects and can be a perfect solution for a particular application.

SEND AND RETURN

The EUREKA features TRS balanced Send and Return jacks. These connectors allow the use of external processors such as reverbs, de-essers, limiters, EQs, etc. Simply connect the send jack, balanced or unbalanced to the input of the external processor. Then connect the EUREKAs return jack to the output of the external processor. The signal is now routed out of the EUREKA, into the external processor, then back into the EUREKA. The final, processed signal will be available at the EUREKA output connector. The Send and Return signal will be inserted after the microphone preamplifier, before the compressor.

192K/24-BIT DIGITAL OUTPUT CARD (OPTIONAL)

A 192K/24-BIT Digital Output Card is available as an option for the PreSonus EUREKA. It has AES/EBU and SPDIF output connectors, as well as, an auxiliary TRS analog Line input connector. The card has a selectable sample rate of 192kHz, 96kHz, 48kHz and 44.1kHz. The A/D converters provide psycho-acoustic dithering for improved BIT resolution when conversion from 24-BIT to 16-BIT sampling is necessary. The TRS Line input will provide the benefit of allowing two EUREKAs to share one Digital Output Card and in so doing, share both sides of the A/D converter.

APPLICATION SETTINGS

The following are application settings to get you started in using your Eureka. Feel free to experiment by pushing any and all buttons and turning knobs to their extreme values - remember there are no rules when creating music. Let your imagination and ear guide and direct the way you set your Eureka.

Note that the application settings do not include the main preamplifier controls: GAIN, IMPEDANCE and SATURATE. Set these preamplifier controls with the compressor and EQ in bypass for initial levels and tonal quality. Use the 80Hz hi- pass filter to roll off low frequency rumble and muddiness.

Once you get a sound that you like, go back to the IMPEDANCE and SATURATE controls to further tailor your sound.

Vocal Compressor Settings

Acoustic Guitar Compressor settings

Nar = Narrow Q

Electric Guitar Compressor settings

Bass Compressor Settings

MN = Medium Narrow, MW = Medium Wide

Keyboards Compressor settings

Kick Drum Compressor Settings

Compressor Settings

Snare Compressor settings

Drum Overheads Compressor settings

Categories: Manuals | PreSonus Manuals