SUB-2XX Two channel sub-woofer isolator

The Iso-Max SUB-2XX is a two channel low-frequency isolator created specifically for sub-woofers to eliminate hum and buzz caused by ground loops in balanced audio systems.

  • Eliminates hum and buzz caused by ground loops
  • Extended low frequency response down to 0.1 Hz
  • Less than 0.01% distortion at 20 Hz
  • Plug and play easy to use, no power required

The design begins with a rugged flanged enclosure that comes standard with gold plated XLRs and a removable screw-down barrier strip for easy installation in a NEMA enclosure. Plug and play easy to use, this passive interface does not require any power to work. Inside are two specially designed Jensen audio transformers with extended subsonic response to deliver powerful and articulated bass for maximum impact. Even when being subjected to extremes, the SUB-2XX is able to gracefully handle low frequencies down to 20 Hz with less than 0.01% distortion and less than 1 dB of phase shift. To further optimize the performance, a bottom mounted 8 position ‘set & forget’ dip switch enables the user to configure the SUB-2XX grounding scheme as needed. And with better than 100 dB of common mode noise rejection, you can enjoy the full performance of your audio system without noise.

Simply connect the SUB-2XX between the source and the input destination to eliminate ground loops, electromagnetic interference (EMI) and RFI problems. The SUB-2XX will quietly go to work without introducing distortion, phase shift or artifact of any kind. These combined features make the Iso-Max SUB-2XX ideal for balanced home theater systems, professional studios, PA systems and the most demanding post production facilities.


Isolating a sub woofer in the studio

Many sub woofers have stereo inputs with an internal mono summing mixer. Send the balanced output from your playback system to the SUB-2XX and the output to your sub. The Iso-Max SUB-2XX will faithfully deliver the signal without smearing or choking.

Isolating a sub woofer in a PA system

The use of sub woofers in a PA system has become common in most touring setups. Use the SUB-2XX to isolate the sub-woofer amplifier racks to eliminate ground loops without affecting the audio signal path. The SUB-2XX is able to withstand tremendous signal levels without distortion.


All levels are input unless noted, +4 dBu = 1.23 V RMS

Input impedance, Zi 100 Hz, -10 dBV, test circuit 1 39.0 kΩ 39.4 kΩ 39.8 kΩ
Insertion loss 100 Hz, -10 dBV, test circuit 1 -0.30 dB 0.00 dB .30 dB
Magnitude response, ref 100 Hz 2 Hz, -10 dBV, test circuit 1 -0.25 dB -0.11 dB -0.00 dB
Magnitude response, ref 100 Hz 2 kHz, -10 dBV, test circuit 1 -0.8 dB -0.65 dB -0.50 dB
Deviation from linear phase (DLP) 10 Hz to 2 kHz, -10 dBV, test circuit 1   +0.7/-0° ±2.0°
Distortion (THD) 100 Hz, -10 dBV, test circuit 1   <0.001%  
Distortion (THD) 20 Hz, -10 dBV, test circuit 1   0.01% 0.05%
Maximum 20 Hz input level 1% THD, test circuit 1 +16 dBV +18 dBV  
Common – mode rejection ratio (CMRR) 60 Hz, test circuit 2   105 dB  
Common – mode rejection ratio (CMRR) 3 kHz, test circuit 2 50dB 65 dB  
Output impedance, Zo 100 Hz, test circuit 1   5.00 kΩ  
Allowable source impedance (output impedance of device driving the ISO-MAX input) 0 600 Ω 2 kΩ
Allowable load impedance (input impedance of device loading the ISO-MAX output) 20 kΩ 47 kΩ ∞ 
Allowable load capacitance (cable & input capacitance loading the ISO-MAX output) 0 50 pF 1000 pF
Optimal cable length input   30 m (100’) 200 m (650’)
Optimal cable length output   1 m (3’) 3 m (10’)
Temperature range operation or storage 0°C   70°C
Input to Output Voltage Difference* input to output shield or either shield to chassis, 60 Hz     24 V RMS 34 V peak


Phase Distortion
Frequency Response
THD vs Level at Low Frequencies
THD vs Frequency at Various Levels

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