Locating bass <80Hz?

[kemmler3D]

Finally, on to the discussion of the frequency range of the human voice.
Plosives have content down to the single-digits of Hz.

Yes, this, and technically any sharp transient is broadband - an infinitely sharp impulse has infinite bandwidth. This is not just a theoretical math thing, but true in practice. Often the lowest frequencies of transients are filtered out, but if you look at the spectrum of even a cymbal, you'll sometimes see content at 20hz or even below, for stick strikes.

You often hear people citing the lowest fundamental frequency of piano, bass guitar, or organ as reasoning for why you do or don't need subs. This is ignoring the fact that all sharp transients theoretically need the bottom octave (or two) to be properly reproduced, not just bass drums.

 

[Mnyb]

fwiw , i think its's harmonics , if ported air sounds from BR tubes or not steep enough filter ( with loud enough volume you have audible 200hz or something ).

Dual subs close to the speakers myself , but they are pplaying in mono.

 

[Torin Krell]

When I only used one off center sub for my pair of symmetrically placed Genelecs I found that the distance disparity from my left speaker to the sub and right speaker to the sub, made blending the sub seamlessly significantly more challenging than my later (and current) setup with two subs (in stereo configuration) placed symmetrically in my music room, each one at the same distance from its nearer speaker.

 

[OldHvyMec]

The core of the issue is the breakdown of the harmonic relationship, and the root cause lies in the inherent physical differences between the speakers.

A subwoofer is designed to move a lot of air for a very narrow bandwidth—often just two octaves. This demanding task, combined with the steep low-pass filter required to confine it, results in a significant inherent processing delay (group delay). In contrast, a satellite speaker, handling a much wider bandwidth of over seven octaves, is a far more agile system with much lower latency.

This timing discrepancy is critical. The higher harmonics (2nd, 3rd, 4th) from the fast satellites arrive at our ears first. Our brain initially attributes the entire sound to them. The fundamental frequency from the delayed subwoofer then arrives later, disconnected from its harmonics.

Because this low-frequency fundamental arrives as a separate, late event without its harmonic context, our ears can localise it to the subwoofer's position. The brain fails to fuse it with the sound from the satellites.

Therefore, the delay from the subwoofer isn't just a minor offset; it's a fundamental timing error that breaks the perceptual link between a note's foundation and its character, allowing the subwoofer to be localised. Time-alignment is essential to compensate for this and re-unite the fundamental with its harmonics.

If you read this response very closely, it explains how and why you can locate any speaker. It also explains how to blend the complement of speakers with the following tools.

1. Time alignment
2. The place where you cross subs with mains
3. The steepness of the slope from both mains/satellites vs subs

4. The number of subs addressing room modes and distortion at a given spot in a room. (the seated position preferably)

# 4 is not addressed, but by following the above and measuring at the seated position. ROOM modes may not affect what you hear at the seated position, but it will account for ADDED distortions you could eliminate and clear the muddiness (distortion) that you likely don't even notice until it's gone.

It doesn't actually say that the fewer subs you have, the lower the crossover should be (NOT HIGHER.)
nor does it address decay time because of room treatment. You cannot substitute any electronic device in place of room treatment, it just won't work.

OP, you can locate your sub because of the arrival time and the fact that it looks to be a first-order 6db XO. (via your graph) It's a very gradual slope (and 10 to 1) a very long decay rate because of NO room treatment.

The more subs you add with the lower XO, along with lower sub gain, will lower the decay times and remove distortion (for one) but synchronize arrival times in the room and to your ears (the seated position)

Note: Sorry for the way this is written, but it hits on what actually happens if you study sub/bass and the breaking point between the two.
60Hz and below (<) and 60-250Hz, (which is very easy to place and use) if you want to produce a center phantom bass channel (again, at the seated position).

Steep XOs become your very best friend, and the difference is clarity in the lower octaves.

Delays and placement become very apparent if you use bass columns (60-250Hz).

Now, if you address decoupling, it becomes even sharper, clearer, and the word muddy doesn't apply to your system at all. LOL

If it's all done correctly, you won't be able to place any of your speaker cabinets, only where the instruments are coming from, or how it was mixed.

Regards

 

[Curvature]

OP, you can locate your sub because of the arrival time

Look, this is not how the ear works at low frequencies. There are reams of texts on the precedence effect that explain this.

At high frequencies above 1.5kHz, when a wavefront strikes one ear before the other, what is the auditory cortex using for localization cues based on the physical qualities of the stimulus at each ear? Level difference. The SPL in one ear will higher than the other and the firing of left/right neurons will reflect this. At low frequencies below 1kHz, the cortex uses phase locking. Measured neuron firing rates that show them synchronizing to the minima/maxima of the soundwave. This synchronization takes time, and as the frequency decreases the amount of time required increases and becomes less precise. Below 15Hz the tonal sensation collapses and phase locking stops working. Most psychoacoustic testing doesn't use signals below 250Hz, so unfortunately we don't have a lot of good data to tell us definitively what's happening.

Griesinger has shown that once you get to the subwoofer range, bass decorrelation is the most relevant measured quality, primarily phase difference over time between ears. Exactly what kind of decorrelation is not clear and is an open question.

There is a lot which detracts from our ability to sense bass localization cues: music (because of monoed bass), soundsystems (because of monoed subs), and sitting in pressure maxima of room modes (because of long decays).

The primary localization sensation at VLF is not direction, but inside vs. outside (also called externalization). Mono bass sounds like it is centered in your head, while decorrelated bass sounds external. That is what Griesinger's contrived signals try to demonstrate. The generalized term that he and Lund use here is "envelopment". Lund has claimed that we can localize bass down to 0Hz. There is clear experimental data which shows we can hear bass that low at very high SPLs, but none as far as I am aware that shows our ability to localize that low.

One of the main ambiguities of this topic is localization of subs vs. localization of bass. Bass localization is covered in what I wrote above, in the way our hearing system processes sound.

Sub localization is about what kinds of problems give away sub locations, since subs are not always in the same place as mains and may not even carry the same signals with bass management in multichannel setups. What you and others have mentioned regarding about localizing subs makes sense: most importantly anything causing the production of higher frequencies, most importantly shallow crossovers or resonances in the cabinet or drivers, less importantly nonlinear distortion and timing differences.

Optimizing for even FR across a wide area, impulse response correction and bass decorrelation are contradictory goals at the moment. Should subs be placed in the same location as mains? Should multiple subs be used? Monoed or not? How does Dirac ART change all of this given that it assumes no crossover? What about bass arrays (source-sink)? Treatment?

 

[DanielT]

From page 52, #1027 in the thread linked below regarding a bass horn speaker:

You should of course optimize all the properties of the system, but often in practice it is a matter of choosing the highest possible crossover frequency because the bass modules have significantly higher sound pressure capacity.

The upper limit frequency for non-detection of direction with bass modules varies with the characteristics of the room and the setup (equivalent absorption area and distance between listening position and bass modules), but typically you can reach up to about 125 Hz without problems here. With bass modules placed near the front speakers you can choose a significantly higher crossover frequency.

All reasoning of this type is based on the front speakers being activated (masking), that the low-pass filtering is steep (at least 24 dB/octave) and that the distortion is low (because otherwise you can perceive the direction of the harmonics).

Horn Speakers - Is it me or.......

Also, the L-pad significantly reduces hiss and noise. For the lowest noise amps (Benchmark, Hypex, PuriFi, to name a few), this isn't an issue. I compared some low-noise amps to some higher noise models, since noise is an audible, and passive components like L-pads and capacitors can make a...

www.audiosciencereview.com

 

[Curvature]

From page 52, #1027 in the thread linked below regarding a bass horn speaker:

You should of course optimize all the properties of the system, but often in practice it is a matter of choosing the highest possible crossover frequency because the bass modules have significantly higher sound pressure capacity.

The upper limit frequency for non-detection of direction with bass modules varies with the characteristics of the room and the setup (equivalent absorption area and distance between listening position and bass modules), but typically you can reach up to about 125 Hz without problems here. With bass modules placed near the front speakers you can choose a significantly higher crossover frequency.

All reasoning of this type is based on the front speakers being activated (masking), that the low-pass filtering is steep (at least 24 dB/octave) and that the distortion is low (because otherwise you can perceive the direction of the harmonics).


View attachment 482695View attachment 482696

Horn Speakers - Is it me or.......

Also, the L-pad significantly reduces hiss and noise. For the lowest noise amps (Benchmark, Hypex, PuriFi, to name a few), this isn't an issue. I compared some low-noise amps to some higher noise models, since noise is an audible, and passive components like L-pads and capacitors can make a...

www.audiosciencereview.com

Yes, bass SPL capability is an important factor too for many people.

 

[DanielT]

Yes, bass SPL capability is an important factor too for many people.

That's exactly what I thought when I set up a desktop setup with small audio pro satellite speakers, two-way with 3.5 inch bass, and a Yamaha subwoofer. The speakers near the subwoofer to mask the sub bass sound. Crossover, 24 dB HP -LP, set at 200 Hz. I don't know if that's stretching it too far, but I don't think I can detect where the subwoofer sound is coming from.
In addition, the small satellites can't operate further down than 200 Hz, approximately. To begin with, I missed connecting an HP filter to the satellites, so that they operated full range. Damn, I thought I had burned one of them when it started to sound bad (it wouldn't have been a financial disaster, they are a flea market find) but it recovered after a while.

That setup, even though desktop setups aren't really my thing, together with Wiim's RoomFit I think sounds pretty good. Really good if you consider that it's a budget solution.:




Edit:
The subwoofer operates up to 200 Hz. I have measured and checked it. The subwoofer rolls off nicely at 200 Hz together with the satellite speakers where they take over.

 

[Kyle_PL]

When I only used one off center sub for my pair of symmetrically placed Genelecs I found that the distance disparity from my left speaker to the sub and right speaker to the sub, made blending the sub seamlessly significantly more challenging than my later (and current) setup with two subs (in stereo configuration) placed symmetrically in my music room, each one at the same distance from its nearer speaker.

What speakers You have? Are they calibrated by GLM?

 

[Hayabusa]

Lots of words, not any measurements. Is anyone going to post any measurements?

just did the test on my two subs L/R 3 meters apart.
Tested 60,70,80,90,100 Hz , toggled L/R
could hear direction for 90 and 100Hz.. so the 80Hz limit was confirmed for my ears...

 

[DanielT]

just did the test on my two subs L/R 3 meters apart.
Tested 60,70,80,90,100 Hz , toggled L/R
could hear direction for 90 and 100Hz.. so the 80Hz limit was confirmed for my ears...

What kind of subwoofers do you have? How steep is your LP filter on your subwoofers?

Did you test with only the subwoofers plugged in or with the speakers at the same time?

With music or test tones?

 

[Hayabusa]

What kind of subwoofers do you have? How steep is your LP filter on your subwoofers?

Did you test with only the subwoofers plugged in or with the speakers at the same time?

With music or test tones?

two SVS PB16 ultras, xover 250Hz 12db/oct.
Played full range, test tones REW sine wave...

 

[levimax]

two SVS PB16 ultras, xover 250Hz 12db/oct.
Played full range, test tones REW sine wave...

How did you determine when you could not localize the subs anymore?
The OP did his "spin in the chair" test, which I don't know if it is valid or not, but when I tried it I found that the frequency I could localize the subs at went way lower. There was a clear difference in what I heard when facing different directions as I spun around.

 

[ChrisG]

FWIW, I'd still recommend using tone bursts for locatability testing. Pure tones mean the room is in a steady-state condition, and this does not apply for most program material.
IIRC, the CEA burst is a good signal to use because it has a narrow bandwidth. Bursts with rectangular windows will have wider bandwidth due to the abrupt start/stop, although the subwoofer crossover should alleviate that somewhat.

OP, you can locate your sub because of the arrival time and the fact that it looks to be a first-order 6db XO.

Please note that the graph you're referring to isn't mine. As previously explained, I have a 24dB/oct lowpass at 60Hz from the RME audio interface, and an additional (I think) 24dB/oct slope at 85Hz, built into the subwoofer.

The resulting slope is 48dB/oct above 85Hz.


Some testing will be done this evening, and I'll post the results.

 

[Oddball]

How did you determine when you could not localize the subs anymore?
The OP did his "spin in the chair" test, which I don't know if it is valid or not, but when I tried it I found that the frequency I could localize the subs at went way lower. There was a clear difference in what I heard when facing different directions as I spun around.

Why again are we doing the spin the chair thingy? Probably nothing better to do?

Or some really algorithmic high-match answer that few will understand and non will use as I would hope that most of us obviously don't spin while listening to our favorite content. Or do you like to spin?

 

[ChrisG]

Why again are we doing the spin the chair thingy? Probably nothing better to do?

Or some really algorithmic high-match answer that few will understand and non will use as I would hope that most of us obviously don't spin while listening to our favorite content. Or do you like to spin?

It was an easy way to test if I can tell where the subwoofer is. As I moved, the subwoofer's location seemed to be fixed in the room: I found I could point straight to the subwoofer reliably, regardless of my listening angle.

Do you have a better way of achieving the same test?

 

[Hayabusa]

How did you determine when you could not localize the subs anymore?
The OP did his "spin in the chair" test, which I don't know if it is valid or not, but when I tried it I found that the frequency I could localize the subs at went way lower. There was a clear difference in what I heard when facing different directions as I spun around.

just stationary on the listening position (4m), purely subjective: If I could think I heard it so double sighted

 

[Oddball]

It was an easy way to test if I can tell where the subwoofer is. As I moved, the subwoofer's location seemed to be fixed in the room: I found I could point straight to the subwoofer reliably, regardless of my listening angle.

Do you have a better way of achieving the same test?

You are sitting at MLP. The effort to optimize bass response is limited to MLP. Not aware of any solutions that would work for the entire room. This is with ART, included.

Proving that after optimizing your MLP the bass is bumpy in the rest of the room as you move along is kind of what is known. We also don't perceive sound like omni-directional mic, so spinning around might capture how different the perception is.

 

[levimax]

It was an easy way to test if I can tell where the subwoofer is. As I moved, the subwoofer's location seemed to be fixed in the room: I found I could point straight to the subwoofer reliably, regardless of my listening angle.

Do you have a better way of achieving the same test?

I had a similar experience but I would describe it differently. As I rotated I could hear differences depending which way I was facing so it was easy enough to tell when I was facing the speaker. This effect disappear at 45 Hz and as I rotated everything sounded the same no matter which way I was facing.

 

[levimax]

FWIW, I'd still recommend using tone bursts for locatability testing. Pure tones mean the room is in a steady-state condition, and this does not apply for most program material.
IIRC, the CEA burst is a good signal to use because it has a narrow bandwidth. Bursts with rectangular windows will have wider bandwidth due to the abrupt start/stop, although the subwoofer crossover should alleviate that somewhat.

Hopefully I will get a chance to try tone bursts soon.