Description
The STM-1 is a compact microphone preamplifier designed to raise mic-level signals into standard line-level ranges. It provides a fixed 50 dB nominal gain to ensure consistent level matching across inputs. The unit is suitable for commercial sound and broadcast environments where a small footprint and reliable gain are required.
Key features include selectable high or low impedance inputs and balanced or unbalanced outputs. The STM-1 accepts 24 Vdc supply and can provide phantom power where required – the input circuitry is RF filtered to minimize interference. The preamplifier maintains low distortion and low residual noise for clean signal amplification.
Technical performance includes a frequency response of 50 Hz to 30 kHz within ±1.5 dB and THD+N under 0.05%. Common-mode rejection is better than 50 dB across the audio band and residual noise is below -70 dB relative to +4 dBu with a 150 ohm source at 50 dB gain. Headroom exceeds 20 dB on a 24 Vdc supply and remains greater than 14 dB when powered at 12 Vdc.
Connectivity covers a 500 ohm balanced input or 5 kohm unbalanced input plus two outputs available as +4 dBu 150 ohm balanced or -10 dBV unbalanced. Phantom power is provided at 24 Vdc filtered to IEC 61938 guidance and the phantom input draws up to 10 mA. Outputs and inputs are RF-filtered to help prevent interference in broadcast and live environments.
Typical applications include broadcast talent microphones, intercom interface where speaker input operation is needed, and compact stage or field rigs requiring a small preamp. The fixed 50 dB gain simplifies system setup and provides predictable level control for downstream processors and mixers. The STM-1 is engineered to operate in ambient temperatures from 0 C to 55 C for reliable field performance.
Installation is straightforward using the STICK-ON convenience package or standard mounting in confined spaces – the cardboard package is compact at 2 x 2 x 4 in. The STM-1 is ground-referenced and draws 24 Vdc at 25 mA, keeping power needs minimal. Its build and RF-filtered I/O deliver a dependable, easy-to-integrate mic preamplifier for professional audio systems.