Lecture Notes on dbx 234XL Crossover

Overview

• The dbx 234XL is a versatile and robust crossover unit, designed for both professional and portable audio systems.
• This product is now discontinued but remains notable for its construction quality and professional features.

Construction Features

• Design:
  • The 234XL crossover is aesthetically pleasing with precision controls that provide a solid click feel.
  • Includes an internal power supply, avoiding the complications of external power supplies.
• Connections:
  • All inputs and outputs feature XLR balanced jacks, securely bolted to the chassis to prevent damage to the circuit board.

Operational Modes

• Stereo vs Mono Modes:
  • Operates in stereo 2-way, stereo 3-way, or mono 4-way configurations.
  • Back panel switches allow for mode selection and mono summing of LF (subwoofer) outputs.
• Crossover Frequency Selection:
  • Back panel switches adjust crossover frequencies individually for each channel.
  • Includes a green LED indicator for the x10 switch activation.

Front Panel Features

• Indicators and Controls:
  • LEDs show whether the unit is in mono or stereo mode.
  • Gain control for input levels and individual band outputs.
  • 40 Hz low cut (high-pass filter) to eliminate unwanted low frequencies.
• Output Controls:
  • Gain controls allow for output level matching and muting.
  • Phase reverse switches that can also be configured as mute switches.

Performance and Reliability

• dbx has over 20 years of experience producing high-quality audio processors.
• The 234XL meets professional standards with Linkwitz-Riley 24 dB per octave filters.
• Recommended for portable use, offering reliability and advanced features at a competitive price.

Key Features

• Balanced XLR inputs and outputs.
• Mono 4-way or stereo 2-way/3-way mode switches.
• Summed low-frequency output for subwoofers.
• High-pass filter and phase reverse switches.
• Individual level controls for each output band.
• LED indicators for status monitoring.

Specifications

• Inputs/Outputs:
  • XLR connectors, electronically balanced/unbalanced.
  • Input impedance: >50k ohm balanced, >25k ohm unbalanced.
  • Output impedance: 200 ohm balanced, 100 ohm unbalanced.
• Performance:
  • Bandwidth: 20Hz to 20kHz.
  • Frequency Response: <3 Hz to >90 kHz.
  • Signal-to-noise ratio: >94dB (Low Output)
  • Dynamic Range: >114 dB unweighted.
  • THD+Noise: <0.004% at +4 dBu.
• Crossover Frequencies:
  • Stereo Mode: 45 to 960 Hz or 450 Hz to 9.6 kHz.
  • Mono Mode: 45 to 960 Hz (Low/Mid).
• Physical Specs:
  • Dimensions: 1.75" H x 19" W x 6.9" D.
  • Unit weight: 4.0 lbs.
  • Shipping weight: 5.8 lbs.

Downloads

• Various technical documents and manuals are available for download.
• Check the dbx website for CAD drawings and owner’s manuals.

Conclusion

• The dbx 234XL offers robust performance, unique construction features, and reliable operation suitable for professional audio setups.
• Despite being discontinued, it remains a respected product in the audio processing industry.