Multi-Sub Optimizer (MSO) Reference Manual

About the MSO Reference Manual

The MSO reference manual contains information of a detailed technical nature to help users get the most out of MSO. It's undergone a major revision from the previous version, which was originally written before the introduction of the Measurement Import Wizard and the Configuration Wizard in version 1.1.0. These features changed the usage model to the extent that the original reference manual contained a lot of out-of-date information and assumptions and had to be overhauled.

The vast majority of projects can now make use of the Configuration Wizard to make the creation of MSO configurations easier and eliminate the need to create them manually. However, there are some unusual situations that might still require creating configurations manually. These are described below. Because most setups can use these wizards to simplify the usage of MSO, this reference manual is now primarily oriented toward wizard usage. Manual creation of configurations has been moved to a separate section. The order of discussion of MSO features has been changed to roughly match the order in which you'll encounter them in the process of using the wizards, making this document more task-oriented than its previous version.

To get up to speed quickly, users are encouraged to read and work through the examples found in the tutorial. Even experienced users of versions prior to 1.1.0 will benefit from at least browsing the tutorial, as it introduces several features that are either brand new starting with 1.1.0, or enhanced from previous versions, including the Measurement Import Wizard and the Configuration Wizard.

Users wishing to find detailed information regarding subjects that are either glossed over or omitted entirely in the tutorial should be able to find the information they need in this reference manual. Although there is necessarily some overlap, this manual will provide the details when needed.

The Different Usage Models of MSO: Configurations

At its core, the usage of MSO invloves creating and optimizing Configurations. A configuration is a collection of information that includes such things as the number of DSP channels you have for subs (and optionally main speakers), which subwoofer or main speaker is connected to which DSP channel, which measurements are associated with which DSP channel, what filters are used in each channel, the number of listening positions measured, which measurements correspond to which listening position and so on.

The Easy Way and the Hard Way to Create Configurations

In MSO, there are two ways of creating configurations: the easy way using the Configuration Wizard and the hard way using manual creation. Fortunately, the vast majority of MSO projects can use the Configuration Wizard, but not all can. We'll discuss the reasons for this next.

The Role of Measurement Groups in Configurations

One important component of a configuration is a Measurement Group. You can think of a measurement group as a generalization of the REW A + B feature for adding two measurements together (taking phase into account). This kind of addition is called a complex summation because it is implemented using complex numbers. An MSO Measurement Group can implement a complex summation of as many measurements as you choose to add to that group, and multiple measurement groups can be defined.

Let's look at how measurement groups might work in practice. Assume you have data of four subs measured at three listening positions. At each of the listening positions, the four sub responses, each one modified by the response of the filters in the channel with which the sub is associated, add up to give the total response at that listening position. Since each measurement group represents a collection of measurements to be added up, this means that for this specific use case, each measurement group corresponds to a listening position. Each measurement group would contain the four sub measurements taken at that listening position, and MSO performs a summation of the sub responses at each listening positioncan, plots each one as a trace on a graph, and optimizes them when the optimizer is run.

Standard and Non-Standard Configurations

In order to describe when the Configuration Wizard can be used, we'll group potential MSO usage models into standard configurations and non-standard configurations.

Properties of Standard Configurations

The setup described above with the four subs measured at three listening positions is an example of a standard configuration. Standard configurations have the following set of properties.

Properties of Non-Standard Configurations

Non-standard configurations have the following properties.

All known non-standard configurations involve subs+mains configurations, so if you're planning on using a sub-only configuration, that's a standard configuration for which the Configuration Wizard can be used.

An Example of a Non-Standard Configuration

The simplest example of a non-standard configuration is a 2.1 configuration with a single sub, measured at a single measurement position. Such a system might have three meaasurements: the Left channel, the Right channel and the sub, all taken at the main listening position (MLP). Suppose this system had independent PEQs for each of the Left, Right and sub channels, as well as sub distance and sub trim. This non-standard configuration might have three measurement groups as follows.

Here, each measurement group does not correspond to a listening position. Rather, all measurement groups are composed of measurements taken at the same listening position. Also, the measurement for the sub at the MLP appears not just once, but in all three measurement groups.

Such a system might be optimized by MSO to get the Left plus subs, Right plus subs, and Left plus Right plus subs as flat as possible simultaneously. In this case, you'd want the response of each individual main speaker plus the sub to be flat, but also to force a flat response when both the Left and Right speakers are energized at the same time. The purpose of this latter goal is to minimize phase-related interference between the left and right speakers when they are energized simultaneously in the bass frequency region.

When the Configuration Wizard Can be Used

You can save a lot of time and effort by using the Configuration Wizard whenever you can. The Configuration Wizard can be used for standard configurations but not non-standard configurations. Fortunately, the vast majority of configurations are standard configurations according to the above properties.

When you use the Configuration Wizard to create configurations, you don't even need to worry about what measurement groups are, as the wizard creates them for you. It is only when you use non-standard configurations that you need to understand measurement groups and their role in the optimization process.

Overview of the Wizard-Based Process of Using MSO

To use Multi-Sub Optimizer with the Measurement Import Wizard and the Configuration Wizard, you perform the following steps:

  1. Decide whether you want to optimize the subs and their integration with the main speakers, or just the subs by themselves.
  2. Determine how you will configure your AVR and DSP devices before making measurements. [Details]
  3. Measure the frequency response of your subs, and optionally your main speakers, at multiple listening positions using separate measurement software. [Details]
  4. Export measurement text files from your measurement software for import into MSO. [Details]
  5. Import the measurement text files using the Measurement Import Wizard [Details]
  6. Create a configuration and a graph of the responses at each listening positon using the Configuration Wizard. [Details]
  7. Set optimization options. [Details]
  8. Run automatic optimization. [Details]
  9. List all filter parameters in a filter report. [Details]
  10. Enter the calculated filter parameters into your DSP device. If you're using a miniDSP device, manual parameter entry of each filter individually is not necessary. Instead, export data a channel at a time as biquad text files from MSO and import them into the appropriate channels of the miniDSP device. [Details: reference manual], [Details, tutorial]
  11. Measure your system with the filter parameters set up as calculated by MSO and loaded into your DSP device. Do these measurements with all subs energized at once.
  12. Export the final measurements as text files from your measurement software.
  13. Import these measurements into MSO as plot-only measurements. [Details]
  14. Plot these imported measurements on the same graph as the one that contains MSO's predicted responses.
  15. If there's a significant mismatch between predicted and actual measurements, you'll need to track down the discrepancy and correct it.