Originally Posted by Geronimo.USMC
Following the miniDSP tutorial, "Under Sub Channel 1, right-click on "Filters" and select "Add Gain Block". Do the same for "Add Delay Block," then three times for "Add Parametric EQ"."
Why did the author add 3 PEQ to each Sub Channel? Was it 1 for each sub in the project? If I only have 2 subs, 3 positions, do I only add 2 PEQ to each Sub Channel?
There's no hard and fast answer to this, but there are some general guidelines. You can consider each per-sub PEQ to be a tool
to fight a problematic room mode. So within reason, the more PEQs per sub, the more problematic room modes you can fight. A good rule of thumb is to start with 4 PEQs per sub, run an optimization, and if you don't think the results are good enough, add one PEQ per sub channel and try again. Each sub channel should have the same number of PEQs.
Some people have used as many as 10 PEQs per sub, but the results I've seen from this can sometimes show weird time domain behavior in the waterfall plot of all subs combined. Also, the more PEQs per sub that you use, the longer the optimization will take for best results.
By comparison, the Harman SFM (Sound Field Management) system only uses one PEQ per sub. Their optimization in effect tries to find the one "killer room mode" and attacks that.
In your case, with that curve if you started out with 75 dB SPL at 100 Hz, you'd end up ideally with 75 + 6 dB = 81 dB at 30 Hz. Your curve says that the SPL at 30.0 Hz should be 6 dB higher than it is at 100 Hz. If you import the target curve, you can see what it looks like by plotting it on a graph. This is kind of clumsy, as you can't see the curve while you're creating it. That's why I created the target curve example, referenced in this section of the help
. To use it, do the following:
- Download the linked target curve example and unzip it.
- Open up the .msop file in MSO. It will show the response of an LF shelf filter.
- Using the tuning feature described in the tutorial, adjust the center frequency, Q, and LF boost of the LF shelf filter to taste. See attached image.
- When done, save the filter's response as a target curve per the documentation linked above.
- Close this project and open up your original project
- Import this target curve into your project.
- In your project, in the Config View, select the "Shared Filters" folder under "Subwoofer Channels"
- Right-click and choose "Add LF Shelf Filter->LF Shelf Variable Q Second Order (Alt)
That last step will give you a filter that will be optimized to force the response to the target curve
. So PEQs in individual sub channels are used for fighting modes, and LF shelf filters in the shared sub channel are used to boost the low end and make the response match the target curve. You don't want to use PEQs for setting target curves, only for fighting modes.
Can I keep my UMIK the same height for all measurements?