Sensor controlled subwoofer

  • 2 x Coda Audio 18” extreme high output subwoofer
  • Velocity sensors for feedback loop control
  • Extended frequency range down to 20 Hz (-6 dB), 25 Hz (-3 dB)
  • Ultra low distortion
  • Fast transient response, the upper and the ultra low frequency are time aligned
  • Compact size for reduced labor and transport costs
  • Optional rigging hardware


The advanced design aligns several new technologies for outstanding performance.

  • Feedback loop control – ultra low distortion, very extended and controlled response
  • Long excursion drivers with integrated velocity sensor

The Feedback loop controlled subwoofer has clear advantages over conventional amplifier / subwoofer solutions when it comes to sonic performance, output and size.

The SC4 subwoofer
Description: Sensor controlled subwoofer incorporating double 18” long excursion woofers.   
The SC4 subwoofer provides perfectly flat response down to 20 Hz (-6 dB) and very high output and low distortion.

What is Velocity Feedback Loop Comparator?
The new designed 18” driver includes a built in “velocity sensor” that measure precisely the movement of the voice coil.
The “velocity sensor” sends information to the Comparator about velocity, excursion and speed of the voice coil (using XLR cable).    
The comparator compares the original input signal to the movement measurement from the “velocity sensor” and adjusts the amplifier driving voltage and/or current so that the diaphragm moves the way it should move. This compensates in real time for the non linearity of the speaker/cabinet.

Main advantages of the Active Feedback Loop Comparator:

Total Harmonic Distortion is reduced significantly
THD drops 80 - 90% at low frequency (about 20dB less distortion at 20Hz compared to the same driver without velocity sensor).

Extended Frequency response
Using this technology the frequency response of the speaker can be modified without equalization. The comparator is adjusted to compensate not only the loudspeaker nonlinearities, but its frequency response as well. The flat frequency response goes down to 25 Hz (-3 dB). No high pass filters or equalizers are required.
Reduced group delay
This is a big issue that is most often overlooked in conventional designs. The feedback comparator technology offer great advantages in the time domain. In fact the upper bass and the very low frequency are time aligned which means they are reproduced at the same time resulting in extremely accurate and musical bass reproduction.

Reduced truck space
The sealed enclosure ensures best output to size ratio reducing up to 50% the cabinet volume.
Therefore the SC4 - 2 x 18” cabinet has similar size as a conventional 18” subwoofer. (For example the 18” drivers in the SC4 are working in 93 liter each while a port loaded cabinet needs 150 to 180 liter net volume and the port adds additional around 30 liter more for each driver).


The SC4 is equipped with double extremely long excursion 18” neodymium ultra low distortion woofers with integrated velocity sensor that measure, compare and control cone movements. The neodymium motor delivers extreme high magnetic flux for increased efficiency. The 4” voice coil is 50 mm high, ensuring ultra linear excursion of 40 mm / pp at consistent magnetic force. State of the art carbon-fiber cone ensure maximum stiffness and low moving mass. Three aluminum shorting rings reduce inter-modulation distortion; minimize induction variation while reducing thermal compression. This design reduces dramatically the distortion of a typical subwoofer at longer excursion levels, and improves the overall sound quality and performance characteristics of the cabinet. The sensor is in fact an additional voice coil connected to the loudspeakers voice coil in a high precision, magnetically shielded system.


Using the Comparator
The Coda Audio LINUS10 DSP amplifier provides integrated power and feedback loop control solution for the SC4 subwoofer. The unit has two amplifier channels as well as two comparators connected to a 5-pol Neutrik XLR input. The Comparator’s electronic circuit loop measures the voice coil excursion of the driver and corrects the signal, significantly decreasing distortion. The unit is set for flat frequency response down to 25 Hz (-6 dB).

Rigging Hardware
The SC4 can be ordered with or without flying hardware.

The SC4 is also suited for a variety of applications in touring and installations where high precision, deep bass is needed.
The SC4 subwoofer is perfect suited as a sub-extension for G700-Series and CUE-Series and an addition to LA4 ultra compact line array systems in:
Houses of Worship

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