Spectra 1964 STX100 Mk2 500 Series Microphone Preamp

Spectra 1964 STX100 Mk2 500 Series Preamp

The Spectra 1964 STX100 Mk2 500 Series Preamp is a 500-series version of the classic Spectra 101 amplifier circuit. The STX 100 is a high-bandwidth microphone preamp with 64 dB of gain and a 10 Hz to 50 kHz frequency response. A 10 dB input pad and a dual potentiometer offers continuously variable input pad and output level controls allow the STX 100 to be used with both microphone and line level sources.

The STX 100 represents an affordable alternative for employing the same Spectra technology of our famous recording desks made over 40 years ago. The unique circuit topology of the STX 100 utilizes a 100 series discrete preamplifier design that was at the heart of every console built by the company. The result is unequaled performance in terms of expanded dynamic range, (headroom), low noise and distortion, as well as extended harmonic content of the amplified signal.

Most, if not all, conventional analog audio amplifiers live in a world whereby dynamic range limitations are dictated by audio program peaks. Audio program peaks, which can average 6 dB to over 20 dB, effectively reduce the undistorted output of a given amplifier by that peak to average ratio. The reduction in output limits headroom, (dynamic range), increases numerous forms of distortion, and limits the harmonic content of the amplified audio signal.

The STX series lives in the VU world, irrespective of peak to average transient audio program signal material. When a percussion instrument is the source, it is not uncommon to measure transient peaks that are 12 dB - 24 dB above the program material average. Again, the STX series products are not affected by the high transient peak excursions. The first and second stages of the STX 100 utilize independent LED overload indicators to monitor program overload conditions. The result is faster set-up time with consistent and definable results. Drums sound like you are positioned next to them. Guitars have full harmonic content. The dynamic range of vocals is preserved.

To complete the classic Spectra console channel configuration, the STX 100 has integrated connections for inserting the STX 500 2-Band Passive Equalizer module.

Specifications

• Gain: 64 dB
• THD: Less than .01% @ 20 Hz - 20 kHz
• Signal/Noise: Better than 120 dB, (unweighted)
• Maximum Output: +18 dBm, 20 Hz – 20 kHz
• Power Requirement: Less than 50 mA, +18 dBm
• Input/Output Control: Continuously Variable/10 dB Pad
• Input Impedance: 5K Ohms, nominal
• Output Impedance: Less than 50 Ohms
• Frequency Response: 10 Hz - 50 kHz
• Phantom: 48 Volts
• Polarity: 180 Degrees/Reverse/Mic or Line Input