How Audioholics Determines Bass Output Ratings in Subwoofers

[Jor4President]

They're certainly a useful starting point. I owned a PB10-NSD for several years that I thought gave a good accounting of itself in a fairly open floor plan room in an apartment and in my current room which is ~2500 cubic feet; I'd expect the new PB1000 to carry on that tradition reasonably well.

That's good to hear. The pb10 is slightly more powerful than the new pb1000 I heard but WAF dictates that black ash will be tolerated better. If I end up needing something bigger svs will need to release a pb12 in black ash. (or whatever will match the furniture in the future)

 

[StoopidMonkey]

@shadyJ One thing I'm having trouble understanding is the relationship between room size and the Bassaholic rating. For example, near the end there is a statement that says "If the 4 meter 1/8th freespace SPL data equals/exceeds 109dB then sub is suited for "Medium" room", but why? I don't think the suggestion is "If you have a medium room your LFE peaks @ MLP should be 109dB, but if you have a large room you'll want to listen louder at 115dB." If that's not it, what's implied here? Does the max "RL SPL Output @ 4 meters 31.5-63Hz" change in different sized rooms, and if so how is that calculated?

 

[shadyJ]

@shadyJ One thing I'm having trouble understanding is the relationship between room size and the Bassaholic rating. For example, near the end there is a statement that says "If the 4 meter 1/8th freespace SPL data equals/exceeds 109dB then sub is suited for "Medium" room", but why? I don't think the suggestion is "If you have a medium room your LFE peaks @ MLP should be 109dB, but if you have a large room you'll want to listen louder at 115dB." If that's not it, what's implied here? Does the max "RL SPL Output @ 4 meters 31.5-63Hz" change in different sized rooms, and if so how is that calculated?

The sub has to get louder to maintain the same SPL at the listening position in a larger room. Larger rooms have less gain and usually have a longer distance from sub to listening position, so the sub has to work harder for the same effect. I think that is what you are asking about?

 

[StoopidMonkey]

The sub has to get louder to maintain the same SPL at the listening position in a larger room. Larger rooms have less gain and usually have a longer distance from sub to listening position, so the sub has to work harder for the same effect. I think that is what you are asking about?

Yes that's what was tripping me up. The original article didn't delve into this too much. More on this: I've read elsewhere that the amount of room gain one gets and what frequencies get this boost depends on the length of the longest wall. If true did this get used in the size calculations, where a 3,000 cubic foot room with 8ft ceilings would be presumed to have 19ft walls? Anything you can share about how room volume or wall dimensions translate into room gain on top of the measured groundplane output would be very helpful.

Also I'm curious about this criteria: "The sub must not exceed the following deviation limitation criteria to earn a room size recommendation: Reference Level (dB) from 31.5Hz to 63 Hz with no greater than -6 dB @ 25 Hz." What happens if the 25Hz measurement IS more than 6dB off than the average of the 31.5, 40, 50, and 63Hz measurements? Looking at the recent review of the Arendal 1723 1S, it looks like this does indeed happen. The 31.5-63Hz average is 111.3dB and the 25Hz output is 10.2dB lower @ 101.1dB. Does a 4.2dB "penalty" get applied to the +6dB "CEA to 4m 1/8 Freespace" conversion? It says the 1S missed the Large room rating (115dB) by 1dB, and applying that penalty gets me to 113.025dB for the 31.5-63Hz average. This stuff interests me!

Finally, on a previous forum post in 2021 you hinted at an article in the works about subwoofer room pressurization, or rather how you think the term should be "put to bed". Did that article ever get finished?

 

[shadyJ]

Yes that's what was tripping me up. The original article didn't delve into this too much. More on this: I've read elsewhere that the amount of room gain one gets and what frequencies get this boost depends on the length of the longest wall. If true did this get used in the size calculations, where a 3,000 cubic foot room with 8ft ceilings would be presumed to have 19ft walls? Anything you can share about how room volume or wall dimensions translate into room gain on top of the measured groundplane output would be very helpful.

Also I'm curious about this criteria: "The sub must not exceed the following deviation limitation criteria to earn a room size recommendation: Reference Level (dB) from 31.5Hz to 63 Hz with no greater than -6 dB @ 25 Hz." What happens if the 25Hz measurement IS more than 6dB off than the average of the 31.5, 40, 50, and 63Hz measurements? Looking at the recent review of the Arendal 1723 1S, it looks like this does indeed happen. The 31.5-63Hz average is 111.3dB and the 25Hz output is 10.2dB lower @ 101.1dB. Does a 4.2dB "penalty" get applied to the +6dB "CEA to 4m 1/8 Freespace" conversion? It says the 1S missed the Large room rating (115dB) by 1dB, and applying that penalty gets me to 113.025dB for the 31.5-63Hz average. This stuff interests me!

Finally, on a previous forum post in 2021 you hinted at an article in the works about subwoofer room pressurization, or rather how you think the term should be "put to bed". Did that article ever get finished?

Low-frequency room gain is a combination of two things: pressure vessel gain and boundary gain. I think the closer proximity of the sub to listener can also be a factor. Also, the smaller the room, the less affected that very deep frequencies are by cancellation modes, although what modes there are tend to be more severe.

As for the calculations for the bassaholics room rating, while I have gone over them awhile ago, I didn't create them, and I am too sick to reacquaint myself at the moment, lol.

Yes, if the 25Hz criteria is not met, but the 31.5Hz to 63hz criteria is, the assigned room rating is what the 25Hz measurement can support. Sometimes we give the sub a pass to the higher room rating if it only misses its target criteria by a small margin, if we think that it will be able to handle the higher use levels over the long term without beating itself to death.

As for the article that you referenced, it's not a full article but rather a point in a listicle, namely point 4 in this article about audio myths.