RDL STM-1 Stick-On Microphone Preamplifier - Compact 50 dB Gain

In this review of the RDL STM-1 Stick-On Series microphone preamplifier, the bottom line is clear: this is a compact, no-frills preamp built for installers and broadcasters who need reliable gain in spacerestricted environments. The reviewer found the STM-1 delivers a fixed 50 dB gain that consistently raises mic-level signals into line-level range, and its tiny footprint makes it useful where larger preamps are impractical. Power is supplied externally and the unit is optimized for 24 Vdc operation, so buyers should plan their power solution before installation.

Key Features

• Compact form factor: Small, stick-on housing fits into tight spaces and mounts where larger preamps cannot be used.
• Fixed high gain: A built-in 50 dB gain reliably converts mic-level outputs to line-level for nearly any line input without extra adjustments.
• Broadcast and commercial focus: Designed with sound and broadcast installations in mind, it performs consistently in professional routing and mixing chains.
• Single-ended supply input: Accepts a simple single-ended DC feed, simplifying wiring in many installation scenarios.
• 12 Vdc compatibility: Can operate from 12 Vdc with about 6 dB less headroom for battery or low-voltage setups when needed.
• Intercom input flexibility: The input will operate directly from a speaker for certain intercom applications, adding installation versatility.

Who It's For

The STM-1 is aimed at audio installers, broadcast engineers, and AV technicians who need a reliable, unobtrusive preamplifier to boost microphone signals in racks, behind panels, or in tight enclosures. Its fixed gain and compact size make it especially handy for permanent installs where adjustment and space are limited.

It is less well suited to users who need variable gain control, phantom power, or integrated power supplies; those who require adjustable thresholds or multi-channel preamps should look to larger modular units. Also, purchasers must provide an appropriate DC power source, ideally 24 Vdc, to achieve full headroom.

Pros & Cons

Pros

• Reliable fixed 50 dB gain brings a wide range of mics up to line level without extra gear.
• Very compact and lightweight design simplifies installation in cramped spaces.
• Flexible power options let it run from 24 Vdc or 12 Vdc when necessary.
• Works for intercom setups by accepting speaker-level inputs in some uses.

Cons

• Power supply is not included, so buyers must source a compatible 24 Vdc (or 12 Vdc) supply separately.
• Fixed gain means no onboard trim or phantom power for condenser microphones.

Specifications

Product	STM-1 Stick-On Series Microphone Preamplifier
Gain	Fixed 50 dB
Power input	Single-ended DC, nominal 24 Vdc
Alternate power	Operable from 12 Vdc with 6 dB reduced headroom
Application	Commercial sound, broadcast, intercom
Input capability	Mic-level; will operate directly from a speaker in intercom use

Our Verdict

The RDL STM-1 is a practical, budget-friendly preamp for installations that require dependable gain in a tiny package. Installers and broadcast setups that need a simple way to boost mic signals will appreciate its compact size and consistent 50 dB gain, though buyers should budget for an external 24 Vdc power supply and consider alternatives if they need adjustable gain or phantom power.

Frequently Asked Questions

Does the STM-1 include a power supply?
It does not include a power supply; plan to provide a compatible single-ended DC source, preferably 24 Vdc for full headroom.

Can it run on 12 Vdc?
Yes, it can operate from 12 Vdc but with about a 6 dB reduction in headroom compared with 24 Vdc operation.

Is this suitable for condenser microphones?
The STM-1 provides fixed gain but does not supply phantom power, so condenser mics requiring phantom will need an external phantom power solution.