CONTROLS & CONNECTIONS

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 simply means that that for every 1dB of level increase into the compressor, the output will only increase ½ dB, thus producing an attenuation of 0.5 dB.

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).

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Eureka Microphone Preamplifier user manual Controls & Connections
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Microphone Preamplifier specifications

The Eureka Microphone Preamplifier is a versatile and high-performance tool designed for audio professionals seeking clarity and detail in their recordings. Known for its exceptional sound quality and innovative features, the Eureka has become a popular choice for both studio and live sound applications.

One of the standout features of the Eureka is its Class A vacuum tube circuitry, which provides a warm and rich tonal character to the audio signal. This analog warmth is complemented by the preamp's exceptional bandwidth, allowing for a natural representation of the sound source. The use of high-quality components contributes to its low noise floor, ensuring that even the most delicate sounds are captured with precision.

The Eureka preamp is equipped with an impressive gain range, enabling users to amplify their microphones effectively without compromising sound quality. Its gain is adjustable up to 64 dB, which makes it suitable for a wide variety of microphones, including low-output dynamic mics and high-sensitivity condenser mics. This flexibility ensures that it can adapt to any recording scenario, whether it's capturing vocals, instruments, or ambient sounds.

Another noteworthy characteristic of the Eureka is its built-in high-pass filter, which eliminates unwanted low-frequency rumble and wind noise. This feature is particularly advantageous for field recording and live situations, allowing users to achieve a cleaner and more focused sound. Additionally, the preamp features a phase reverse switch, which is essential for combating phase issues when using multiple microphones.

The Eureka's user-friendly design includes LED metering for input level monitoring, providing real-time feedback on the signal's strength. This visual aid helps engineers make informed decisions about gain settings, ensuring optimal headroom and preventing clipping.

For connectivity, the Eureka offers both XLR and 1/4-inch outputs, making it compatible with a wide range of audio interfaces and mixing consoles. The robust build quality ensures that it withstands the rigors of both studio and live environments, making it a reliable choice for audio professionals.

In summary, the Eureka Microphone Preamplifier combines advanced technology with practical features, delivering outstanding sound quality and versatility. Its Class A vacuum tube circuitry, adjustable gain, high-pass filter, and solid build make it an essential tool for anyone serious about their audio recordings.
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