RDL
STM-1,
STM-2 and
STM-3 Microphone Preamplifiers all seem to look alike and indeed they do have some
similarities: GENERAL- Identical noise, distortion, frequency response, headroom and common mode rejection specifications.
- Identical power requirements. 24 vdc @ 25 mA or 12 vdc with a 6 dB reduction in headroom.
INPUT- Balanced or unbalanced
- Balanced input accepts dynamic or condenser microphones with impedances from 150 to 600 ohms.
- Unbalanced input impedance of 5 k Ohms or dynamic HI-Z mics.
- Allows the use of 4 or 8 ohm loudspeakers to be used as a microphone in monitoring and intercom applications.
- Selectable 24 volt phantom power for condenser microphones.
Outputs- Balanced +4 dBu, unbalanced -10 dBv
So here are the Differences:
STM-1- Fixed gain of 50 dB
- 1 unbalanced output
- 1 balanced output which can be configured unbalanced
- Used in applications where the mixer or amplifier being fed has plenty of gain adjustment
STM-2- Adjustable gain of 35 – 65 dB
- 2 balanced outputs either or both of which can be configured unbalanced
- Used in applications where the microphone has normal to high output sensitivity
STM-3- Adjustable gain of 45 – 75 dB
- 2 balanced outputs either or both of which can be configured unbalanced
- Used in applications where the microphone has low to normal output sensitivity or where higher levels are required
