Accordo is a proprietary algorithm developed by Audison R&D to tune a car- audio system. Its goals are to reach the target frequency response, with good phase performance.

To achieve this, first the system is measured. Accordo can use a USB measurement microphone, or it can use the bit Tune measurement system. In either case, a spectral weighting analysis is applied to the measurement which delivers almost identical performance as spatial averaging (but in a much shorter period of time). Accordo performs very brief measurement sessions.

Accordo then uses both delay and an innovative approach to DSP filter design to reach the objectives (target frequency response and good phase performance). Accordo repurposes a number of DSP “biquads” for use in creating IIR filters which address both magnitude and phase of the signal. (Accordo always reserves several biquads for use in further equalizing each output channel, if desired).

The results are very good! In repeated testing, Accordo delivers a tuned system with bass up front, a centered stereo image, and great sound! Of course, Accordo delivers the best results with the highest-performance systems.

You need a measurement microphone. This could be a USB microphone, an XLR microphone with a USB audio interface, or a bit Tune measurement system.

You will want a microphone stand for best results. Select a stand which does not damage automobile upholstery.

You may need some USB active extension cables to make sure the PC can be connected to both the microphone and the PC at the same time.

No test tones are needed for Accordo – it generates its own test tones.

The most common issues when using Accordo come from installation error:

• Incorrect input channel assignment
• Improper OEM input correction
• Output connection errors in polarity or driver assignment

Therefore the most important preparation for using Accordo is proper QC testing of the installation.

With OEM integration projects, ensure a flat frequency response with time and phase alignment before performing the Accordo process.

While this is very unlikely due to the short duration of the Accordo measurement process, it can happen – especially in a production environment. Click “Back” and repeat the measurement once the loud sound is over. It only takes a few seconds.

Depending on the situation, there are basically three paths that you can follow. Which path you choose is generally a function of the performance the client is expecting, and the time available in the project.
First, perform proper QC as mentioned above. Then perform the Accordo process. Afterwards, follow one of the three paths below:

Accordo Level One – listen to the system, make any Final Tuning EQ adjustments by ear, and finalize the file to the device.
Accordo Level Two – measure the overall system response using the bit Drive’s acoustic RTA and mono pink noise. Make any Final Tuning EQ adjustments based on this measurement. Then listen and make any additional adjustments to the Final Tuning EQ. Finalize the file to the device.
Accordo Level Three – measure the left front, right front, and sub responses individually using the Acoustic RTA and mono pink noise. Use the Channel Tuning EQ adjustments to make sure that left front and right front match – if there is a deviation on one side, better imaging can be achieved by adding the same deviation to the other side. After left and right fronts match the target response, listen to the system and make any tonality adjustments using the Final Tuning EQ. The time this path adds to the process averages around 10 minutes.

NOTE:
Due to the wavelengths and frequencies involved, Accordo does not EQ the subwoofer. For the most advanced systems, you may choose to EQ the subwoofer manually.

Frankly, because in listening test after listening test, delay adjustments were not needed.

Mostly because Accordo does not attempt to measure distance, but to optimize the phase interactions (in conjunction with adjustments made using Accordo’s IIR filters). Accordo does not attempt to approximate distances, but it does find delay settings which help us meet the objectives.

This is very straightforward. Before the Accordo process is started, select the Memory Preset you want Accordo to write to.

Accordo is currently focused on the main listening position. However, if you would like a 2-seat presentation, you can use Accordo to adjust for only Level and EQ (deselect Delay). Then raise the near-side levels to match the levels of the far side. This process works well in conjunction with the internal Upmixer (you may also want to adjust the center level for best results).

NOTE:
The Listening Position marker in bit Drive is only for your use to differentiate the microphone position used in a given tune. The selected Listening Position does not affect the results Accordo provides. Every Memory Preset has the Listening Position defaulted to the center location in the vehicle.