Multi-Sub Optimizer Reference (page 16)

Special Topics: Understanding Configurations

MSO works by evaluating many different combinations of filter parameter values and finding combinations that satisfy the optimization criteria. However, it cannot determine automatically what types of filters are necessary or how many of them are needed. Parametric EQ (PEQ) is the primary tool for manipulating each sub's response. To determine how many PEQs are needed per subwoofer channel, some experimentation is necessary. For each experiment, you'll probably want to keep the results to compare with other experiments. This is one problem that configurations were designed to solve. Instead of having a separate project for each experiment, you create multiple configurations within a given project. This allows for comparing the results of multiple configurations either on a graph in the project, or by comparing different graphs in the project with one another.

For detailed instructions about configurations, see the configurations section of the tutorial.

The Initial Configuration

When starting from scratch with an empty project, MSO creates a single, empty configuration called "Config 1". You can rename this configuration by clicking on its node in the Config View and pressing F2. After importing your measurements, you flesh out the configuration by performing the following steps.

Configuration Types

Depending on your application goals, two types of configurations are supported.

Ordinary Configurations

Ordinary configurations require that you have measurement data and filter channels for both subs and main speakers. When you create measurement groups, these groups must contain measurements that are associated with both main and sub speaker channels. The integration of mains and subs will then be a part of the optimization.

Sub-only Configurations

Sub-only configurations do not require that main speaker measurements be imported, associated with main speaker channels or included in measurement groups to be optimized. The optimization therefore does no integration of the subs with the main speakers, but only optimizes the subs as a group. This can be useful when you want to use another tool such as Dirac to EQ the low-frequency response of the system. In this way, MSO can minimize the seat-to-seat variation of the sub responses, while another program, possibly used with dedicated hardware, can apply more powerful filter resources than the simpler DSP hardware ordinarily used with MSO.

Cloning a Configuration

To evaluate an alternative set of filters and compare the results with the initial or subsequent configuration, you can clone a configuration. This means you'll only have to perform the steps mentioned above in The Initial Configuration once for a given project. These filter alternatives might include different numbers of PEQ filers per subwoofer channel or different crossover frequencies. For each discrete alternative you want to evaluate, you'll need to create a new configuration. To save the effort of creating a new configuration from scratch, clone an existing configuration instead. This can be done in two different ways.

If you choose Config, Clone from the main menu, a dialog box will pop up, asking which configuration you wish to clone. Make sure that the Clone associated graphs option is checked. Choose the desired configuration to clone, and a name for the new configuration and click OK. The cloned configuration initially takes on all the elements of the original, but it is completely independent of the original in all other respects. To rename the newly-cloned configuration after cloning it, click its name in the Config View and press F2.

If you clone a sub-only configuration, you have the option of making the new configuration an ordinary configuration. By adding main speaker measurements and filter channels, you can then have MSO optimize the integration of main speakers and subs in the new configuration. Ordinary configurations cannot be converted to sub-only configurations by cloning.

Cloning Associated Graphs

When you choose the Clone associated graphs option in the Clone Configuration dialog, MSO will search the project for graphs that contain traces referring to the configuration to be cloned. If it finds any such graphs, it copies each graph, giving it a new name. The traces of the newly-created graph that used to refer to the original configuration are then set to refer to the newly-created configuration. In this way, if you had set up all the graphs you needed for the old configuration, you'll have all the graphs you need for the new one too. You may want to change the name of the newly-created graph to your liking.

Evaluating Different Crossover Frequencies

If you are using MSO to find the optimum crossover frequency, the configuration feature should be used. To get more detailed information about this process, see the section on optimization strategies. MSO treats each filter as a completely independent entity. This has an unfortunate side effect when working with crossovers. If you were to set the Optimization allowed property to True for the cutoff frequency parameter of each of the low-pass and high-pass filters filters that make up the crossover, MSO would adjust each one independently to optimize the system. But this would generally result in different cutoff frequencies for the high-pass and low-pass filters. AVRs and pre-pros force the cutoff frequencies of the high-pass and low-pass sections of the crossover to identical values. In this case, MSO's optimized result would be incompatible with your hardware. The solution is to set the Optimization allowed property to False for these cutoff frequency parameters, then set the cutoff frequencies to the same value manually. To try out different crossover frequencies, use a separate configuration for each one.

Once you have cloned a configuration, you can change the cutoff frequency parameter of the crossover low-pass and high-pass filters of the clone to the desired value. Always make the cutoff frequencies of the low-pass and high-pass halves of the crossover equal to one another, and always ensure that the "Optimization allowed" property of each low-pass and high-pass cutoff frequency parameter is set to False. See the manual of your AVR or pre-pro for allowable crossover frequencies.

Evaluating Different Parametric EQ Combinations

The configuration feature is also a good way to explore the effects of having different numbers of PEQ filters per subwoofer. It's a good idea to start simple with the initial configuration, possibly using only gains and delays to flatten the overall response. Then clone the configuration to add more PEQ filters.