Auto-EQ tuning with REW

Welcome to the world of system tuning and DSP!

There isn't much to argue on the fact that speaker building is an art requiring time and understanding of acoustic theories. While some simulation software may help for the design of your enclosure, audio measurements are the basis for any evaluation of your system. No matter how pretty your box is or the choice of high specs drivers, your "system" (i.e. enclosure + speakers + crossover) may very well have poor specifications if it isn't properly tuned (equalization/time alignment).

Thanks to the partnership between the miniDSP platforms and the well known freeware Room Eq Wizard (REW), miniDSP is much more than a digital audio processor. By providing a complete measurement + system tuning solution fitting in the palm of your hand, the miniDSP product line innovates once again, yet keeping our price very competitive.

How does it work?

Integration between REW and minDSP consists of 5 steps:

1) Setup your miniDSP system with some basic settings
2) Measure your audio system using impulse response or FFT measurements to optimize your system
3) Export the Auto/Manual EQ settings to the biquad section of miniDSP Advanced
4) Finally, enjoy your processed system without the need of any PC

Tools

What you will need to make this project happen:

• PC/Mac running the latest version of Room EQ Wizard (REW) V5 available for download here.
• At least one miniDSP board (kit/2x4/balanced)
• The latest version of the advanced plug-ins 
• 1 x measurement microphone to perform your audio test
• Basic understanding of the biquad filter programming as already highlighted in this application note.
• Finally, this application will not cover the wealth of features provided by REW since the REW Help file already did a great job at it! Careful reading of the user manual is therefore recommended.

Step by Step tuning

Step 1: With your miniDSP already pre-configured to operate a basic configuration, start REW V5.
REW V5 provides a comprehensive interface for RTA measurement to Impulse response. More details about how to run these measurements with your microphone can be found in the home page of REW.

Step 2: The miniDSP/REW linking happens from the EQ interface. Click on the EQ button in the top right to access the following dialog box.
REW provides multiple equalizer formats so please select miniDSP as a default device.

Step 3: The next step consist in configuring the "EQ filters" by clicking on the button above the graph. With the choice of either Automatic or manual mode, REW provides an easy interface to configure 1 of the 6 filters. These filters correspond to either the input or output filters of a typical Advanced plug-in configuration. REW will basically automatically calculate the optimum biquad filter coefficients for your system.

Step4: Once the system optimized, it is time to export the filters to the miniDSP. Click on the "Filter Tasks" banner on the right hand side and select "Send filter Settings to Equaliser"

This step will bring up a dialog box to choose the file name and location for the coefficients file. The default is minidsp.txt.

Step5: Finally, you can copy and paste the pre-formated biquad coefficients in the text file to your Advanced plug-in PEQ section. Note that pasting EQ filters on the input section will affect the whole system while the output filters will only affect one of the outputs. Choose whichever methods applies to your measurement.(single driver measurement or whole system)

Hoping this information helps to get you started, we look forward to seeing REW + miniDSP installs on the miniDSP showcase section!

Credits

The whole miniDSP team would like to thank John Mulcahy, Author of REW, for working along us in providing this neat feature. John is doing an amazing work by providing REW free of charge and we seriously recommend that you take the time to evaluate the potential of this powerful software!

Support REW! 

Enjoying REW? Complex software like REW means a lots of behind the scene hours with a very generous philosophy to offer it free of charge. So make sure to remember to support REW with a donation at the following link. Donations entitle you to extra benefits in the discussion forums at Home Theater Shack.