dbx 120 Subharmonic Synthesizer

dbx 120
The dbx 120 is a compact, two-channel bass enhancer that analyses 55–110 Hz and adds a coherent octave-lower band at 27.5–55 Hz, restoring weight and punch with low noise, low distortion, and easy hi-fi integration.

dbx 120 Subharmonic Synthesizer Details

The dbx 120 Subharmonic Synthesizer was designed to restore the visceral low end often reduced during recording and difficult to reproduce on typical stereo systems. Positioned as a “feel it rather than hear it” processor, the dbx 120 analyses programme material between 55 Hz and 110 Hz, then generates new content exactly one octave below, between 27.5 Hz and 55 Hz, and mixes it back into the signal.

By reconstructing these natural subharmonics, the dbx 120 gives music the weight and drive associated with disco-era playback systems, delivering a renewed sense of power without masking mid and high frequencies. Its signal path and metering are optimised for home and studio hi-fi integration, with stereo inputs and outputs on phono connectors, ample headroom, and low noise performance.

Frequency response extends from 25 Hz to 20 kHz within ±1 dB, with total harmonic distortion kept to 0.05 percent and intermodulation distortion to 0.1 percent. Nominal input sensitivity is 300 mV with a generous 7 V RMS maximum input and 6 V RMS maximum output, ensuring compatibility with receivers, preamps, and tape loops of the period.

The dbx 120’s synthesis is entirely programme-dependent, tracking bass content in real time so that added sub-octave energy follows the groove rather than appearing as static boost. Housed in a compact 1U-tall chassis, it is straightforward to integrate into existing systems and modest in power draw, making it a practical route to deeper, more physical bass response that can be felt through the room.

Features

  • Restores low-frequency power by generating an octave-lower band from existing bass
  • Operates on programme material between 55 Hz and 110 Hz, creating 27.5–55 Hz content
  • Stereo operation for seamless insertion in tape loops or processor paths
  • Low noise design suited to home and studio hi-fi systems
  • Compact rack unit with modest power consumption

Specifications

Released in: 1982
Made in: Japan
  • Channels: 2
  • Operating principle: Samples 55–110 Hz and synthesizes 27.5–55 Hz one octave lower
  • Frequency response: 25 Hz to 20 kHz ±1 dB
  • Input impedance: 47 kΩ
  • Nominal input level: 300 mV
  • Maximum input level: 7 V RMS
  • Output impedance: 470 Ω
  • Maximum output level: 6 V RMS
  • Equivalent input noise: −88 dBV unweighted
  • Total harmonic distortion: 0.05%
  • Intermodulation distortion: 0.1%
  • Connectors: RCA phono
  • Power requirements: 117 or 220 VAC, 50/60 Hz
  • Power consumption: 10 W
  • Dimensions: 440 mm x 44 mm x 190 mm
  • Weight: 2.15 kg
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User Reviews

dbx 120 Subharmonic Synthesizer User Reviews

Still adding back thump over 40 years later

By Jim Wilson

Sound Quality 90%
Build Quality 100%
Usefullness 70%
Mojo/Funk 90%
Reliability 100%

I was just getting into high school when the dbx 120x released so I had no concept it existed or really what a rabbit hole old hi-fi would eventually become for me. Of course the music of that era has a special place in my heart, but it always seemed to be lacking the decent bass found in recordings from later decades. Someone tipped me off to these dbx units and I found one well used but in some disrepair on ebay, so I took a chance. A few replacement caps and some contact cleaner on a few sketchy buttons and it was miraculously operating again like new. Now any time I play something of my preferred vintage it’s a genuine delight to be able to augment these old over compressed recordings with a generationally appropriate analog subharmonic augmentation. All the low end bump and resonance I wished was there as a kid now rolls out and I know that young would have been just as delighted to hear these songs “restored” to how we just knew they could have sounded. If you have ever felt the same about older music and you see one of these up for grabs, definitely do yourself a favor and give it a try. You won’t be disappointed.

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The details provided above are drawn from historical documents like advertising brochures or user manuals. They’re shared without bias or review. This info is given solely for your consideration, helping you gauge its usefulness to you.

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