RDL ST-MX3 3 Channel Line Level Audio Mixer

MSRP: $221.75
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The ST-MX3 is a line-level mixer module in the STICK-ON Series of products. It provides audio mixing of three line-level inputs with individual input gain adjustments. The line-level output is capable of driving either high or low impedance, balanced or unbalanced loads.

The ST-MX3 operates from ground-referenced floating or bipolar dc power.

For installations with microphone level inputs, use the ST-UMX3 Universal Audio Mixer.


  • Mix Line-Level Signals
  • Three Individually Adjustable Inputs
  • Add Additional Line Level Inputs to an Existing Mixer
  • Combine Signals of Different Level, Impedance or Balanced /Unbalanced Configuration
  • Isolation Between Input Signals
  • Low-Noise and Low-Distortion Performance
  • RDL® SupplyFlex™ Power Input Configuration


Inputs (3):
30 kΩ balanced or unbalanced bridging

Input Level:
-20 dBu to +18 dBu (for +4 dBu output)
-24 dBu to +14 dBu (for 0 dBu output)

400 Ω to drive low or high impedance balanced or unbalanced lines

Output Level:
+4 dBu nominal, (adjustable; unbalanced output 6 dB below balanced line level)

< 0.03% (10 Hz to 20 kHz)

Frequency Response:
10 Hz to 20 kHz (± 0.5 dB)

Noise :
< -80 dB (all inputs @ 10 dB gain, referenced to +4 dBu)

18 dB

Gain (each input):
-14 dB to +24 dB (adjustable)

> 50 dB (50 to 120 Hz)

Ambient Operating Environment:
0° C to 55° C

Power Requirement:

Package Type:
Cardboard Box

Package Dimensions:
2 x 2 x 4 in.

Shipping Weight:
0.17 lbs.

WEEE weight:
0.12 lbs.

Tariff code:


RDL Three-Year Limited Warranty Installation of these products by the Purchaser shall constitute Purchaser’s acknowledgement and acceptance of the terms and conditions for sale and of this warranty, and shall constitute the Purchaser’s determination of the suitability of this product for the Purchaser’s intended application. Radio Design Labs, Inc., also referred to as RDL®, warrants to the Purchaser that products manufactured by RDL are free from defects in material and workmanship. This warranty applies to the period of three years from the date of shipment, except for component parts or products purchased from other sources and supplied by RDL. Such component parts or products bear only the warranty of the manufacturer thereof in effect at the time of shipment to the Purchaser. RDL will, without charge, and after written notice has been received and acknowledged by RDL, repair an RDL product if proved to be defective according to the usage of the trade, when such equipment is received by RDL at the location it designates with shipment costs prepaid by the Purchaser. RDL shall not be liable for any expense whether for repairs, replacements, material, service, or otherwise, incurred by the Purchaser or modifications made by the Purchaser to the product. No equipment shall be deemed defective if it shall fail to operate in a normal or proper manner due to exposure to excessive moisture in the atmosphere, excessive temperature extremes, improper environmental cleanliness, or any other environment not consistent with the principles of good engineering practice. In no event shall RDL have any liability for consequential damage or expense directly or indirectly arising from the use of the products, or any inability to use it either separately or in combination with other equipment or materials, or from any other cause, whether used in accordance with instructions or not. This warranty is void if equipment is altered in any way by other than RDL. RDL products are NOT intended for use in life support appliances, devices, or systems. Use of RDL products in such applications is done solely at the liability of the reseller/installer and/or end user. RDL reserves the right to change design parameters and specifications at any time without notice. The performance measurements reflect the products at the time of printing. This warranty is in lieu of all others, either expressed or implied. No representative is authorized to assume for RDL any other liability in connection with RDL products.