Frequently answered questions
How does the C3 work?
The C3 is the long throw extension for the d&b C4 system. It comprises two 10" hornloaded mid-range devices accompanied by a vertical array of three 1.3" HF drivers loaded on a cylindrical wave transformer to give a 35 x 5° dispersion (5° wave segment). It is driven by a d&b D12 in 2-way active mode with the C3 configuration selected. Two C3s can be flown vertically with 0° - 5° vertical splay giving a maximum total vertical coverage of 10°, and a cylindrical wave segment in the HF band above approximately 2 kHz. This is the exact frequency region that larger C4 arrays with close-coupled C4-TOPs cannot project coherently.
How many C3s can substitute the close-coupled C4-TOPs?
Two C3s exceed the performance of three close-coupled C4-TOPs.
Is C3 a line array?
Yes, indeed it is. But unlike the standard line array technology, it provides a properly defined horizontal dispersion of 35° and therefore, takes advantage of C4s total scalability in the horizontal plane (multiline array). In the HF section of the C3, line array technology is used by a vertical array of three HF drivers working on a wave transformer which provides a cylindrical wave down to a certain wave length depending on the number of vertically arrayed C3 cabinets. The combination of that HF wave transformer and the controlled behaviour of the mid-range horns (powered by two 10" drivers) keeps the flexibility of horizontal scalability and compensates the loss of HF power in long throw applications.
Does the weight of a C3 affect the maximum number of cabinets a Transformer/Installer can support?
Yes, because the C3 weighs 71 kg (156.5 lb), given the maximum WLL of the flying hardware this reduces the maximum number of cabinets that can be flown. Please refer to the TransCalc and InstallCalc array calculation tools,which are available in the Support/Download/Array calculators section of this website.
What optimum rigging angles do you recommend for the C3?
The best compromise horizontally between sound pressure level and interference between adjacent columns is to keep exactly to 30°. The vertical dispersion (cylindrical wave segment) is designed for +/- 2.5°. This means that vertically we suggest using two C3s with the standard 23 link load chains in order to obtain a vertical coverage of 10°. Angles > 5° do not make sense, as they will result in gaps in the vertical coverage. The E6524 Vari-chain enables vertical splay angles of 0° - 5° and has calibrated detented settings.
Does d&b supply a calculation tool for C4/C3 set ups?
Yes, calculation spreadsheets including the C3 are available in the Support/Downloads/Array calculators section of this website.
The HF section in the C3 is mounted to one side - how does this affect the performance?
It is not possible to design the C3 as a coaxial device without compromising the mid-range performance. However the active crossover is designed so the -6 dB isobar is as horizontally symmetrical as possible, as you can see from the isobar plot. Keep in mind that the C3 only covers +/- 15° (!) horizontally, this means interference does not occur within the nominal horizontal dispersion.
How is acoustic transition and behaviour between C4 and C3 cabinets in the vertical obtained?
The combined set up C4 and C3 requires a delay for the C4-TOPs and SUBs of 0.3 msec behind the C3. This provides a coherent phase response of C4-TOP and C3 up to approximately 5 kHz. This can easily be achieved using the delay function in the D12 amplifier.
Can I drive one or two C3 cabinets per D12?
A D12 can drive two C3s. Each C3 has to be wired individually from the amplifier to avoid inductance losses through the cabling which will cause severe HF roll off. The low HF impedance coupled with long cable runs causes this HF roll off.
Can we use the C3s as a stand alone system?
No. Subwoofers are required for full range mode as the C3 frequency response is 120 Hz - 16 kHz. The LFC function switched on the C3 controller module runs C3 down to 90 Hz for program material such as speech.
How many C4 stacks can be substituted by a single C3?
The C3 does not substitute a complete C4 stack. It substitutes the C4-TOPs addressing audience areas with distances of approximately > 30 metres (98.4 ft).
What is the cut away for in the C3 HF section?
The cut out ensures smooth coherent transition vertically between cabinets up to high frequencies.
What is the C3 to C4-SUB ratio? Is it the same as the C4-TOP?
This will depend on the total C4-TOP/C3 ratio. The C3 provides a 5 dB higher SPLmax to the C4-TOP, therefore the ratio will change proportionally to the total number of cabinets starting from 3 x C4-SUB / 2 x C3. Please refer to TI-323, which is in the Documentation/White papers/Technical information section of this website.
Can I modify my C-Series loudspeakers and B2 subwoofers for use with EP5 / MC5 cables?
Yes, it is possible to replace the connector panels, however the C4-TOP and SUB is complicated because you cannot access the panels from the outside, therefore we propose that this is only done at a d&b Service Partner.
Is it possible to use the Q1 with the C3?
It is not an option to use the Q1 as a downfill in a C4/C3 system. It may be possible to use Q-Series loudspeakers as side and rear fills with C4/C3 systems, but this is not a recommended use.
