MSO Case Study: Optimizing Mismatched Subs
imgur.com/a/uPZ9ms5
imgur.comPosted May 13, 2023, 5:26 PM UTC
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imgur.comNice! Rare to see such thorough documentation. It's a really nice feeling when you remeasure at MLP to see that it matches perfectly with the prediction from MSO :)
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You absolutely need subs in the front and back walls if you plan on sitting near the middle of the room
You can get away with 2 that way (opposite corners)
If you just have one row near the back then you can get away with them being in the front
Check out REW Room Simulator to get a pretty good idea of how bass will interact in your room
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+1 to this. My front row is in the middle of the room where you'd get bass nulls. Two subs, one in front and one in back, with miniDSP+MSO gets me good bass for both my rows. My subs are at wall midpoints, which gives better uniformity, although a little less output than corners.
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That's gonna be a tight fit for 2 rows! I feel like i barely fit with a depth of 17.4'. Will you do in-wall speakers?
I assume you have seen the Todd Welti White Paper since you planned on 4 subs in the corners? He also found that 2 subs at wall midpoints works well, but that's not very practical in a small room. This method works well in a sealed rectangular room and even works with simple global EQ.
MSO is more flexible for oddly shaped spaces and mismatched subs. Three subs is usually enough to get the job done, but you could start out with two and see if you get lucky. My personal decision wasn't all that complicated: I have 3 corners available so I'm using 3 subs! If my door wasn't in the 4th corner I likely would have gone with 4 even though it's clearly not all that necessary in my room.
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Oh yeah you can definitely fit a normal couch as a back row. I can highly recommend the Arendal 1961 series as a compact speaker with excellent dynamic capability. I didn't go in-wall since two of my walls are finished exterior walls filled with insulation, but I still needed something compact to fit. The 1961 monitors are only ~6in deep, but don't compress at high volume.
https://www.erinsaudiocorner.com/loudspeakers/arendal_1961_bookshelf/
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I didn’t catch any discussion of adjusting the phase of each subwoofer, unless you did that here “I was able to fix the crossover dip by adding 8ms to each miniDSP output channel.”
All the manuals basically say “tinker with your phase knob until the sub blends in.” I have a Monitor Audio FB210 and a Yamaha YST-SW315 that I’m trying to match using a Denon X-3300w (2 sub outs). Thanks for such an informative post!
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MSO accounts for the phase relationship among the subwoofers when running the optimization. The all-pass filters have no effect on gain, but can change the phase relationship at certain frequencies to improve summing.
My manual 8ms delay increase was to improve the phase relationship between the subwoofer array and the LCR at the crossover. This ensured proper summing rather than a phase cancelation that led to that dip at the crossover frequency. All I did was increment my subwoofer delay and run sweeps until the crossover dip filled in.
If you are trying to optimize phase between your subs manually with the knobs, you probably want to use the RTA feature in REW. You can watch the summation improve or get worse in real time as you play with one of the phase controls. Make sure the placement of the subs complement each other. You don't want them to have the same nulls or no amount of phase tinkering will fill in the dips.
Your AVR has Sub EQ HT, so it will set individual delays and thus affect the phase relationship between your subs. I would check behind it to see if you can improve the response. I haven't actually tried this yet, but plan on it for my living room setup: you could load measurements into MSO and run the optimization with only delay blocks on each output to see if it finds better settings than Audyssey.
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Would mind sharing pics of the room and Esp MLP?
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Here is a view from behind the MLP before ceiling panels went up. I need to get better images to share the finished product.
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Oh nice.. You have the one row near the back wall? Sadly I cannot get MSO predictions to match actual.. I'm assuming it's becuz my MLP is near the middle of the room and I have 2 rows to optimize for so it's difficult to get MLP without messing up the back row in my room
How many peqs are you using?
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Correct, the back row is only ~6in off the back wall. I only optimized for the front row and the back row gets what it gets. It's going to be difficult to get a consistent result so close to a boundary. FYI, you can include the back row measurements to see what happens but exclude them from the optimization.
My final optimization was 6PEQ on the input limited to 20-200Hz, 0 to -16dB (no boost), and Q<8.651 (1/6 octave). Each output has 2 All pass filters (10-200Hz) and 4 PEQs limited to 50-200Hz, 0 to -16dB (no boost), and Q<8.651 (1/6 octave).
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You're using filters on the input? Would this mean you're unable to use BEQ since it applies its boosts on the input side?
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Yeah I don't use BEQ currently. I do have 4 unused filters on the input which seems to be enough for the majority of BEQ titles. I imagine it might introduce some complications on the automation of applying BEQ filters, but I haven't looked into it.
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Should you mix subs with different output capabilities? How well can you optimize ported and sealed subs together? These are common questions for folks looking to add onto their existing system with a second or third subwoofer. In this case study, I go through my methodology for optimizing 2 Hsu VTF-15H Mk2's with a Rythmik E15 in Multi-Sub Optimizer (MSO). Of course, I have REW measurements to validate the results as well!
Nice, very informative! Few questions:
What benefit is the Rythmik providing? The HSUs alone seem to be plenty capable down to 10 Hz. Is it mostly for better seat to seat consistency?
Are you using BassEQ? Wondering how that would get applied. Usually I've seen it done on the minidsp input but looks like this method has MSO using the input.
How is group delay in your system after EQ, is it managed well?
Check out the 3rd to last pic showing each sub from the MLP and the optimized response. The E15 is adding output below 15Hz and fills in from 40-50Hz and 80-120Hz. I didn't do an MSO run with just the Hsu subs to do a clear comparison.
I don't use BEQ, but a lot of people do reserve input filters for that purpose.
I'll have to add that later when I can get back into REW.