d&b DSP and amplifier plan

To wrap up this mini-series on the new d&b rig (if you missed any posts, be sure to go back through the past three for more info on what is going on), today’s post will focus on DSP & amplifiers.

On our old KF650 rig, DSP was extremely important.  We used a BSS London BLU-80 to provide an insane amount of processing to the entire rig, essentially trying to polish it to a point of usability.

When we decided on going with d&b, a significant bonus to the system is the awesome amplifiers with built-in DSP for system processing.  While some manufacturers lock down almost all system settings making it too difficult to customize the rig to the room, d&b has done a great job of creating a system with what I believe to be just the right amount of control to tune the room.  Because of this, my goal was to have as little DSP as necessary to make the rig sound good.

Our signal chain now is a left/right feed from the console that hits the first system amplifier, then simply loops through to each of the other amps.  The system is run full range from the console rather than aux fed subs so that the phase and spectral response of the PA as a whole will remain consistent from service to service and engineer to engineer.

Each amplifier channel has a 4 band fully parametric EQ & signal delay.  The coolest part of the DSP, though, is a few other settings available that provide subtle ways to sculpt the rig artistically for different responses depending on what’s desired.

• The CPL (Coupling) circuit compensates for coupling effects between the cabinets. These effects increase as the length of the line array is extended. CPL begins gradually at 1 kHz, with the maximum attenuation below 400 Hz, providing a balanced frequency response when T10 cabinets are used in arrays of four or more.  The function of the CPL circuit in these amplifiers can be set in dB attenuation values between –9 and 0, or a positive CPL value which creates an adjustable low frequency boost around 65 Hz (0 to +5 dB).
• The HFC (High Frequency Compensation) circuit compensates for loss of high frequency energy due to absorption in air when loudspeakers are used to cover far field listening positions. It’s almost like an “air” control that gives a few options for how open the high end responds.

The D6 and D12 amplifiers have three configurations for T10 cabinets, Line, Arc and PS (point source). The Line or Arc configurations are selected when the T10 loudspeaker is used as a line array. The chosen configuration will depend on the curvature of the array. The Line configuration is selected when groups of four or more T10 cabinets are coupled in a straight long throw array section, where the splay angles to adjacent cabinets are 0° to 2°.  The Arc configuration is selected when T10 cabinets are used in curved array sections, where the splay angles to adjacent cabinets are 3° or more. Within a typical array both amplifier configurations are used. The PS configuration is selected when the T10 is used as a single spherical loudspeaker.

Wrapping up this section on DSP and amplifier control, I’m very impressed by the R1 software included with the amplifiers to provide remote control from FOH of the entire rig.  Tuning functions such as EQ, delay, HFC, and CPL are all included, but the coolest function to me is a page we set up that shows the input level into the amps, the output level the amps are actually sending so you can visually see your system headroom, actual ohm loads on the amps, actual RMS output wattage, power supply voltage, gain reduction, and temperature warnings.  The software is completely customizable so you can set up pages to show exactly what you want, how you would best like the information.  Great stuff!