It appears that this user's approach is as follows:
1. Calculate your room size (say 5000 ft^3)
2. Understand your listening level, relative to reference, say -20db (you can see this information from your receiver, if you already have one)(if you don't have a receiver, most people listen to -10 to -20db from the reference level, so pick a representative value that you think you'll listen to, say -20db).
3. Look at this user's chart (mind you, it's only showing 57 CEA-2010-A rated subwoofers, whereas I have 400+ CEA-2010-A rated subwoofers in my spreadsheet) for you room size of 5000ft^3, then look down the table until you see the -20db value (which I've shown as the arrow below)
4. This shows you that you need
at least a SVS SB-2000 (NA GBP/ea) for your listening level and room size.
Of course, this also means that if you increase the volume to be louder than -20db from reference, the SVS SB-2000 won't be capable of hitting this output for you room size.
Say, if you want to listen at -10db, then you need
at least a SVS PB-1000 (450GBP/ea)(cheapest of the 4 options at -10db listening level).
But hold on, if you spend 500GBP/ea for a
Monoprice 10" THX, you get -8db from reference level. This is better than SVS PB-1000 by 2db for an extra 50 GBP. I picked a sub that wasn't the minimum recommended, but at a higher price point. So the user has to hunt this information down in this table.
5. This shows you how much $$ you need to spend for your room size and listening level. This approach ignores the user's budget at first, which is often the primary factor when purchasing, not last.
Can you not get the same information from my spreadsheet, with a few filters? Yes, since you can filter by any frequency that's important to you (say 15hz)(not just 20hz, as this user has ranked subs for). In other words, I like my spreadsheet's capabilities a lot more.
The limitation of this user's approach is he's ranking for a single frequency, 20hz. What if you only care about 10hz? Then this table is obsolete. Whereas my spreadsheet has your answer.
A simple and intuitive approach is to just use my spreadsheet, calculate the room size, pick a budget, see if your budget is too low compared to the subwoofer's output for that budget, save up until you have $ for that room size, then choose a subwoofer based on the frequency that's important to you (say 10hz to 20hz, if you're into watching movies) or (higher than 25hz if you're listening to music only).
My calculations for the Audioholic's room rank are as follows:
Small:
=IF(AND(25hz<103,31.5hz<109), "Small", "")
Small/Medium:
=IF(OR(AND(25hz<103,31.5hz>=109), AND(25hz>=103,31.5hz<109)), "Small/Medium", "")
Medium:
=IF((AND(25hz>=103,31.5hz>=109,40hz>=109,50hz>=109,63hz>=109)), "Medium", "")
Large:
=IF((AND(25hz>=109,31.5hz>=115,40hz>=115,50hz>=115,63hz>=115)), "Large", "")
Extreme:
=IF((AND(25hz>=117,31.5hz>=123,40hz>=123,50hz>=123,63hz>=123)), "Extreme", "")
Which shows you that Audioholic's rating is primarily based on the 31.5hz and above frequencies.
Audioholic's room ranking system, is based on this principle:
"The standard calibration "Reference Level" (RL) is 75dB at the listening position. The goal is to ensure the system calibrated at 75dB can hit clean 105 dB peaks for each of the speaker channels and 115 dB peaks for the LFE channel. Note that the LFE channel is boosted 10 dB over the speaker channels. Technically speaking, most people redirect the bass from other channels to the subwoofer, which in conjunction with LFE could in theory ask the sub for a 123dB peak signal. However this is NOT a common scenario and most people don't listen at reference levels (especially if they value their long term hearing). It is much more common for A/V enthusiasts to listen between -15 to -10db from reference. Thus a 115 dB peak at the listening seats in-room is a more realistic benchmark goal for large rooms. To really stand out, a sub must hit the 123dB mark to earn our "Extreme Bassaholic" rating."
So as you can see, if the subwoofer is capable of hitting "Large", this means it's capable of playing at -10db from the reference level. Which is already the loudest playback to what most people should be listening to.
If you buy a subwoofer that isn't rated for a "Large room" but you have a "Large room", then the subwoofer won't have enough output for your maximum level of playback (in other words -10db from reference on your receiver).
Here's a problem I see with this user's table.
Let's say a consumer finds this user's table, and decides to purchase a subwoofer for a -20db reference level of playback, thinking that's all he's ever going to need. Then, when his friends come over, and he's blasting content, his subwoofer will run out of power trying to hit -10db reference level. Guess what? The user bought the wrong sub. He should have bought a subwoofer capable of -10db playback in the first place. Now what? The consumer was fooled into thinking that's all he needed simply because this information wasn't understood by this table. How many people could get fooled like this? Audioholic's room rank (and by extension my spreadsheet) doesn't have this problem.
