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Whirlwind

Whirlwind LM2B 2-Channel Unbalanced to Balanced Converter

★★★★★5.0 (1 reviews)
20Hz-20kHz

Bring consumer gear onto a professional console without audible compromise — the Whirlwind LM2B converts unbalanced -10dBV to balanced +4dBm with active circuitry across the full audio band.

$219.00*
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*Price sourced from Amazon.com. Last updated:Jul 14, 2026.Price and availability are subject to change.

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Overview

The Whirlwind LM2B addresses one of the most common signal chain problems in professional audio: interfacing consumer or prosumer gear — running unbalanced at -10dBV — with professional mixing consoles and interfaces that expect balanced +4dBm. Left unconverted, that mismatch means your laptop playback, DJ controller, or media server feed arrives at the console 14dB quiet and riding an unbalanced line susceptible to hum and RFI over any meaningful cable run. The LM2B's active circuitry performs both the level conversion and the unbalanced-to-balanced transformation in a single pass, and delivers the result through gold-plated XLR outputs at 100 Ohm impedance — a driven, stable signal that travels clean from a broadcast studio rack to an FOH console 100 feet away.

The practical design choices here are worth noting for working professionals. RCA and 3.5mm stereo mini inputs cover the overwhelming majority of consumer source formats without adapters. Per-channel gain controls mean two sources at different levels — a laptop and a CD transport, for example — can be individually trimmed to match before hitting the desk, keeping your gain staging clean without eating console faders. The external 24VDC power supply keeps the active circuitry stable and thermally unstressed in continuous-run installs. At 1.25 lbs and roughly half-rack width, it's not a compact utility box, but it's engineered to Whirlwind's tour-grade standard — the kind of device that lives in a broadcast rack or venue equipment closet and is simply expected to work every time.

Key Features

2-channel line level converter

20Hz-20kHz frequency response

100 Ohms balanced output impedance

Specifications

Type
2-Channel Unbalanced to Balanced Line Level Converter
Frequency Response
20Hz – 20kHz
Output Impedance
100 Ohms (Balanced)
Input Level
-10dBV Unbalanced
Output Level
+4dBm Balanced
Unbalanced Inputs
Gold-Plated RCA, 3.5mm Stereo Mini
Balanced Outputs
Gold-Plated XLR
Gain Control
Individual per channel
Circuitry
Active
Power Supply
External 24VDC (included)
Dimensions
8.7 x 3.7 x 2.8 inches
Weight
1.25 lbs

Pros & Cons

👍 Pros

  • Active conversion circuitry drives a low-impedance 100 Ohm balanced XLR output that resists noise pickup over long console runs — you hear the source, not the cable.
  • Per-channel gain controls on both channels let you trim level disparities between two unbalanced sources before they reach the console, giving you precise gain staging without touching the desk.
  • Accepts both RCA and 3.5mm stereo mini inputs, covering virtually every consumer device output format from DJ gear to laptops and media servers.
  • Gold-plated connectors on both input and output contacts resist corrosion and maintain reliable electrical connection in live event environments.
  • Frequency response flat across 20Hz–20kHz means no audible band-limiting or rolloff — the full audio spectrum passes through without coloration.

👎 Cons

  • Requires an external 24VDC power supply — one more power connection to manage in a rack or on a cart, and a potential failure point if the supply is lost on the road.
  • Active circuitry introduces a conversion noise floor that passive transformer-based alternatives avoid — in extremely quiet studio settings, this may be audible on sensitive monitoring chains.
  • Physical size (8.7 x 3.7 x 2.8 inches, 1.25 lbs) is relatively large for a two-channel utility device — it occupies bench or shelf space rather than fitting neatly in a standard rack unit without additional hardware.
  • No switchable input padding means very hot consumer sources may require attenuation upstream before reaching the LM2B.
  • Only two channels — multi-source installations requiring four or more channels need multiple units.

Frequently Asked Questions

Active conversion from unbalanced -10dBV to balanced +4dBm. Consumer and prosumer gear — DJ controllers, laptops, synths, media players — operates at -10dBV unbalanced. Professional consoles and studio interfaces expect +4dBm balanced on XLR. Without conversion, you get a level mismatch and an unbalanced signal prone to noise pickup over cable runs. The LM2B bridges both gaps: it actively lifts the level and converts to balanced differential output simultaneously.
The active design uses a 24VDC external power supply and is specified across the full 20Hz–20kHz band with 100 Ohm balanced output impedance. Active designs can introduce some noise floor contribution from the conversion circuitry, but the tradeoff is a driven, low-impedance balanced output that rejects common-mode noise over long cable runs — which in most real-world setups is a net gain in signal cleanliness compared to running unbalanced.
Inputs accept unbalanced signals via gold-plated RCA connectors and a 3.5mm stereo mini connector, covering the most common consumer device outputs. Outputs are gold-plated XLRs carrying the balanced +4dBm signal. Per-channel gain controls allow individual level trim, so you can match disparate sources before they hit the console.
No. The LM2B uses an included external 24VDC power supply — it is not phantom-powered and should not have phantom power applied. This is an active line-level converter, not a DI box or microphone device. It must be powered by its dedicated supply to operate.
Yes. Whirlwind builds gear for touring and installed applications, and the LM2B is designed for continuous duty. Its external power supply means it runs stably without thermal stress from internal components, and the gold-plated connectors hold up to permanent installation or frequent venue changes.

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