Seaton Sound SubMersive1 - Page 259

Originally Posted by Mark Seaton 

...which is complicated further in being a 4D problem most often visualized in 2D or 3D.

Originally Posted by BeeMan458 


How well can we hear a dip that's 5Hz wide and 3dB deep?.

How well can we hear a dip that's 8Hz wide and 7dB deep?

Based on your above, the reason I ask is to find out how sensitive our hearing is to these types of expected fluctuations one might find in a standard REW frequency graph.

Originally Posted by craig john 

Oh no.. don't let audioguy see this! He'll want to go out and get a 4D display so he can better visualize his frequency response. Chuck, just don't say it was *me* that made you spend more money this time!

Craig

Originally Posted by BeeMan458 


Based on Bill and your response, I'll try to articulate my question better. My question concerns LFE or subwoofer content limited to <120Hz. Using today's captured graph, no smoothing applied, as an example:



The 3Hz wide dip at 43Hz that's 3.4dB deep; highest shoulder to trough.

And a dip that's roughly twice the above dip in size.

The 7.4Hz wide dip at 72Hz that's 7.3dB deep; highest shoulder to trough.

I don't know the best way to express the above in octaves. Is 43Hz considered the middle of an octave, the beginning of an octave or the end of an octave? In each of the above examples, with a fast paced action scene flashing before a viewer's eyes, will a listener notice the exampled anomalies?

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Originally Posted by BeeMan458 

I understand what an octave is. That's why I specify in my above, the range of frequency (<120Hz) and two specific graphed examples (43Hz and 72Hz) as I ask; when a specific frequency is referenced, is that considered the beginning, middle or end of an octave?

Originally Posted by BeeMan458 

When one learns how to think three dimensionally or spatially, they can see what's going on in a room as plain as one's hand in front of their face. Example, as long as one knows the rules and what the variables are, complex math equations are easy. That sort of thing.

The first trick is to know it can be done. Until then it seems impossible.

I have few talents but one of my talents is the ability to see and think three dimensionally and it gets old people telling me I can't do what I can do, all day long.-

Originally Posted by BeeMan458 

How well can we hear a dip that's 5Hz wide and 3dB deep?.

How well can we hear a dip that's 8Hz wide and 7dB deep?

Based on your above, the reason I ask is to find out how sensitive our hearing is to these types of expected fluctuations one might find in a standard REW frequency graph.

Originally Posted by BeeMan458 

Thanks.

I did some quick math and the first example is 10% the width of the centered 43Hz octave and the second example is 15% of the width of the centered 73Hz octave. Is either sufficient to degrade the overall sound quality or are they so small that they don't degrade the sound quality; much in the same fashion that in the <120Hz range, THD distortion can hit 10% before it becomes noticeable? That sort of thing?

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Originally Posted by JHAz 

Whether a particular frequency deviation is audible depends on a lot of factors, including what it is you're listening to. IIRC, it's easier to hear narrower, shallower deviations with broadband noise than with real program material. Both dips are quite narrow (2 semitones is the widest) and both are pretty shallow. I frankly would not expect to be bothered by it. I wouldn't necessarily expect to achieve superior performance in home-sized rooms. Once you get all your room dimensions over 40 or 50 feet, then you stop being controlled by the room and you have an easier time of getting flat deep into the bass.

Originally Posted by craig john 
 

<Snip>
To get back "on-topic, I will agree with crazy4daisy and say that I too LOVE my Submersives.

Craig

Originally Posted by craig john 

I think it's important to differentiate between peaks and dips. Peaks are fairly easy to hear and identify. Dips are far harder. Peaks are excessive energy at a specific frequency range. This peak would be very easy to hear as a boomy, one-note sound:



The fact that it hangs around in the room for a very long time would make it even easier to notice and identify:



OTOH, dips are diminished energy at a specific frequency range. It's much easier to notice and identify something that is too much than to notice and identify something that is *missing*. Still, if the missing energy spans a broad enough frequency range, it is clearly noticeable.

Here is a graph that shows an easily noticeable deficit of the frequency response, as well as a correction of that response:



The difference in the sound between these two graphs was night and day. The graph with the huge, 20 dB dip from 63 to 125 Hz sounded lifeless, weak and thin. The trace where the dip is corrected sounded full, and solid and powerful. (The only adjustment made between these two graphs was an adjustment of the subwoofer Distance setting in the pre/pro.)

Here is another graph that shows the results of the same type of adjustment in another system:



Again, the only change made between the two graphs was a change to the subwoofer Distance setting in the receiver. In this case the difference in sound between the two graphs was more subtle, but still easily noticeable. The corrected graph sounded more powerful.

What would be much harder to discern is a steep, deep null over a very narrow frequency band width. Something like this:



That narrow, steep null at about 260 Hz would only be seen on a high resolution, unsmoothed measurement. It would only be heard, (technically, the better definition is that it would "not be heard") on content at exactly that frequency range. It would be impossible to identify such a null with your ears only. High resolution, unsmoothed measurements would be required to identify this null. In fact, in measurements at other locations in the room, it would show up as a peak in the response.

Correcting such an acoustic problem would best be accomplished with bass traps. EQ would be tough at a 260 Hz frequency. More importantly, it is impossible to EQ out a null. Adding energy, (boost) to a true null just increases the energy cancellation at the null location. Adding boost to try to eliminate the null will also add energy at room locations were the null is a peak, making those locations WORSE. The only effective treatment for this problem is to absorb the offending waves, so you have no reflections, and no corresponding peaks and nulls.

To get back "on-topic, I will agree with crazy4daisy and say that I too LOVE my Submersives.

Craig

Originally Posted by MIkeDuke 

I like my HP too .

Originally Posted by MIkeDuke 

I like my HP too .

Originally Posted by hydrotex 


I like all you guys' Submersives, too! (I don't have one yet, so i live vicariously though ya'll)

Originally Posted by hydrotex 


I like all you guys' Submersives, too! (I don't have one yet, so i live vicariously though ya'll)

Originally Posted by calentz 

 Mike, you were the 4th poster in this thread in 2006.

Originally Posted by hydrotex 

I like all you guys' Submersives, too! (I don't have one yet, so i live vicariously though ya'll)

Originally Posted by SOWK 

Buying two SubMersive HP's tomorrow.

Looking for advice...

For optimal setup in this room...









I was thinking of placing the SubMersives in the spots my other subs are located (black boxes at 45 degrees in each corner)

*Leaving the SubMersive amp gain at default on both... Use Program 2 designed for larger rooms and lower htz +/-3db... And just run Audyssey MultEQ XT32...*

Anything else I'm missing or should do first?


I know to check Audyssey after and make sure it's not -15db on the sub, I will play with the volume controls on the HP after temp calibration and try to get the receiver to 0db after calibration..