Multiple Subwoofers: Optimize Them With Multi-Sub Optimizer Software

What is Multi-Sub Optimizer?

Multi-Sub Optimizer (MSO) is a free Windows-based software program for optimizing the bass performance of audio and AV systems having multiple subwoofers.

This document contains the Getting Started Guide, the User Guide and technical information about MSO in particular and multiple subwoofers in general.

The Problems That It Solves

MSO is designed to be used in the modal frequency region of typical home listening rooms. In this frequency region, it can:

The modal frequency range usually extends from the lowest frequencies that can be reproduced up to around 200 Hz for typical listening rooms.

Multi-Sub Optimizer Main Window

The MSO main window is shown below.

Multi-Sub Optimizer Main Window
Multi-Sub Optimizer Main Window

What You Need In Order To Use It

MSO places some requirements on your DSP hardware, the hardware and software you use for measurements, and your computer operating system. These are described below.

DSP Hardware Requirements

A multi-channel DSP device or equivalent software using IIR filters, such as a miniDSP device or Behringer DCX2496 or similar is assumed to be present in your system. All the subs must be driven by a single mono signal originating at a single AVR sub output. This single mono signal must be split internally to the DSP device, as is done with the miniDSP 2x4 and Behringer DCX2496 devices. The DSP device must provide separate EQ and delay adjustments for each sub individually. If there are no input channel filters available in the mono signal path of the DSP device before the signal's internal split into multiple channels, the potential of MSO can't be fully realized.

Some AVRs and preamp-processors have more than one subwoofer output, with independently-controlled gains, delays, and sometimes more. MSO must only be used with the AVR configured for a single sub output. It does not support connecting two independent AVR sub outputs to both inputs of, say, a miniDSP 2x4 HD device. Such a DSP device must be used with only one input enabled via its input routing matrix. This also means that if you use two miniDSP 2x4 HD devices for driving more than 4 subs, each one must be configured to use only a single input, and a y-cable must be used to combine the two inputs to a single one to be connected to the AVR's single sub output.

Some devices (such as the miniDSP SHD and Flex 8) contain their own bass management, with some of the equalization being upstream of the bass management. Such hardware configurations are not supported by MSO, unless they are set up to be used with subwoofers only and are configurable for use with a single analog input.

Some two-channel and even multi-channel systems operate the subs in stereo mode. In the case of multi-channel systems, the stereo bass option is sometimes called "directional bass". Two-channel systems must be configured to have a single mono subwoofer output. Multi-channel systems that have a "directional bass" option must have this feature disabled to be used with MSO. If the hardware does not support traditional bass management with a mono subwoofer output, MSO must not be used with it, as such usage will cause unpredictable results.

Measurement System Requirements

Your measurement system must be capable of using either an acoustic timing reference or a hardware loopback timing reference to achieve time-synchronized measurements. For the most common case of a USB microphone, you must use an acoustic timing reference. If you try to use a hardware loopback with a USB microphone, the measurements may not look suspicious in any way, but the timing data will be wrong, causing MSO's predictions to not match the final measured results. A loopback timing reference must only be used with a microphone having an analog output.

Room EQ Wizard (REW) is the recommended measurement software, as its acoustic timing reference has been thoroughly tested over time with USB microphones. For more information, see the measurements section.

System Software Requirements

MSO runs only on Windows. MSO requires Windows 7 or a later version of Windows.

Click the Download button at the top or bottom of this page, or just use this link. That will download the mso.zip file. Unzipping this file gives you install_mso.exe, which you run to install the program. See the revision history page of the MSO web site for the latest information on the most recent MSO update.

How to Get Help

This document takes you to MSO's Getting Started Guide, User Guide and other technical resources. You may be reading it either on the web or via MSO's offline help. The offline help is installed on your computer when you install MSO. It uses the Windows .CHM format (compiled HTML help). You can get help within the program itself, by using the offline help as a standalone document, or by reading the MSO website.

Within the program itself, you can perform the following actions to get help:

Within the offline CHM help file, you can use its search capability.

You can download standalone versions of MSO's CHM help file, as well as a plain HTML version. The help file is sometimes updated without an update to the MSO program or its installer if an error or unclear explanation is found in the help.

Suggested Ways of Reading the MSO Help

The MSO documentation contains both instructional material that can be read sequentially, and reference material with topics that are somewhat independent of one another. The following methods are suggested for navigating the help.

Tutorials and Online Discussion

License

Acknowledgments

Getting Started

To get started with MSO, click the Getting Started button below or at the top of this page.