Localizing Bass

[Pano]

MOVED FROM GEDDES ON WAVEGUIDES
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Originally Posted by whgeiger

3b) Below 100 Hz it is also know that signal direction cannot be detected by human ears.

This is very wrong, I'm afraid. I've said it before and I just tested it again. While it may be true for pure tones, it is NOT true for complex signals.
I just tested this on my system with sharply low passed white noise - about 60dB/octave low pass. Going down by third octaves I could pick direction down to 32Hz.

Below ~160Hz it does get more ambiguous, but location ability does not go away.
There were some spots, like 120Hz, that gave me trouble in my room (nodes), but noise filtered below that was still fairly easy to locate. I did not test below 32Hz as that's the bottom limit for my system.

I can supply the test files if anyone cares to try the same test.

[RockLeeEV]

Originally Posted by Pano

This is very wrong, I'm afraid. I've said it before and I just tested it again. While it may be true for pure tones, it is NOT true for complex signals.
I just tested this on my system with sharply low passed white noise - about 60dB/octave low pass. Going down by third octaves I could pick direction down to 32Hz.

Below ~160Hz it does get more ambiguous, but location ability does not go away.
There were some spots, like 120Hz, that gave me trouble in my room (nodes), but noise filtered below that was still fairly easy to locate. I did not test below 32Hz as that's the bottom limit for my system.

I can supply the test files if anyone cares to try the same test.

I think it depends on (Dr. Geddes is gunna eyeroll me on this one ) the harmonic distortion signature of your bass driver. If its distortion is low enough, bass sounds extremely dry. With the typical hi fi drivers what you're localizing is the harmonic. To me the "rules" for subwoofers are a bit different. Obviously multiple subs is the #1 solution. But I run sealed 18" subs and they to me are virtually inaudible below 100hz when EQ'd flat in room until the SPL is very high as it is. Low bass with low distortion is so subtle that if you take it away and aren't paying attention you won't notice anything's missing. One of my subs is actually to the right of me which on paper would be an awful idea. Even when if it's the only sub running I can't localize it crossed at 100hz.

The only time i've ever localized bass, is when there's wierd phasing issues. That's because my ears get an uneven balance.

I don't think distortion in subwoofers is offensive mind you, but I definitely think it's audible as a sonic signature. Others will disagree and that's fine by me.

[Pano]

Good point, but not with mine. I don't hear the harmonics. Altec 416-8A 15" drivers. I consider it a valid test.

[Sheldon]

Originally Posted by Pano

Good point, but not with mine. I don't hear the harmonics. Altec 416-8A 15" drivers. I consider it a valid test.

Are they there when you measure - that is content significantly above 100Hz? Doesn't take much to localize.

Sheldon

[Pano]

I'll only know by measuring. Will try to tomorrow. It's possible there are more harmonics than I notice. But from a practical standpoint who uses a 60dB/octave crossover for their subs? The old "subs can't be localized below 100Hz" thing is not true at all in my experience.

[RockLeeEV]

I'll only know by measuring. Will try to tomorrow. It's possible there are more harmonics than I notice. But from a practical standpoint who uses a 60dB/octave crossover for their subs? The old "subs can't be localized below 100Hz" thing is not true at all in my experience.

IME, I can't localize a sub on any material when it's low passed 24db/oct at 100hz. At 120hz I start to get a sense of "sound is coming from this side of the room. A much bigger issue is that male vocals start to get "aggressive". I think it's a panel resonance on my (tall and pretty well braced but not extremely since it's just a sub) sub.

[Pano]

I don't think I know the difference!
All I hear is a low rumble. 32Hz is barely there. But I'll have to measure to be sure.

[rob g]

Hi Pano,
Is the sub vented? Port distortion possibly?
What about bass doubling harmonics.

[Pano]

It is vented, but it's not really a sub. Low pass for the 15s is about 700Hz, acoustic. I won't rule out that I'm locating the harmonics and will measure to see just how much there is above the cut off frequencies where I low passed.

But also read what I said about the practical side of it. That's important. Probably need to move this to its own thread, as it has little to do with waveguides.

[rob g]

I have had two tiny modest size closed box sub's in my little room crossed at 80hz, I cannot locate them. I could locate them more easily individually.