Jump to content

Gestating large sensitive passive 15" augmenting subs


BioBrian

Recommended Posts

8 minutes ago, BioBrian said:

 

What sort of track did you play?

 

I've been wondering how to find a track with only less than say 60 Hz, but your technology has apparently made that redundant. I'd like to know if it contains sudden impulses, as I presume it isn't just a sine wave.

It was just some Radiohead I had on. I set the filter and listened. I tried another track just in case it was something weird about that track but same again. I can generate a track with nothing above 60hz and send to you if you like.

TBH I wasnt expecting it to be so easy to discern. 

Link to comment
Share on other sites



5 minutes ago, BioBrian said:

Of course there can be sudden impulses of low frequency. One now, one 30 seconds later. Another one 19 seconds later. I've been talking about the first hit, the first wave, which is not frequency dependent.

 

There is still the "first hit"

 

1 minute ago, frednork said:

It was just some Radiohead I had on

 

One of my all time favourites.  🥰 

Edited by davewantsmoore
  • Like 1
Link to comment
Share on other sites

We are talking about an impulse spike without ringing or reverberation, correct?

If so, does that put this debate in a different frame of reference?

 

ie,  does the speed of attack (akin to slew rate) sit in the pass band of VLF, LF, MF, or HF??

Link to comment
Share on other sites



1 minute ago, Auracle said:

We are talking about an impulse spike without ringing or reverberation, correct?

If so, does that put this debate in a different frame of reference?

 

ie,  does the speed of attack (akin to slew rate) sit in the pass band of VLF, LF, MF, or HF??

 

If we are limited to "subwoofer frequencies" (< 100Hz) ... which is what everything I've been saying is strictly limited to.

 

.... then this is hardly an "impulse spike" per se.   The waveform has no steeper features than 100Hz.

  • Like 1
Link to comment
Share on other sites

8 minutes ago, BioBrian said:

Of course there can be sudden impulses of low frequency

not without higher frequencies, otherwise they wouldn't be "sudden"

15 minutes ago, BioBrian said:

I've been talking about the first hit, the first wave, which is not frequency dependent.

It is frequency dependant - take a pistol shot - close to a pure impulse - every frequency is included

Link to comment
Share on other sites

Just now, almikel said:

take a pistol shot - close to a pure impulse - every frequency is included

@frednork has specifically isolated the low frequency component of a track, so we can get ahead in this conversation here.

  • Like 1
Link to comment
Share on other sites

3 minutes ago, almikel said:

not without higher frequencies, otherwise they wouldn't be "sudden"

It is frequency dependant - take a pistol shot - close to a pure impulse - every frequency is included

 

Yes... (that's right, but)  I don't think Brian mean it like that.

 

He just means the example where ..... you have no sound .... and then "suddenly" you have a LF sound.  (eg. where he says "the first hit"   

Link to comment
Share on other sites



2 minutes ago, davewantsmoore said:

 

Yes... (that's right, but)  I don't think Brian mean it like that.

 

He just means the example where ..... you have no sound .... and then "suddenly" you have a LF sound.  (eg. where he says "the first hit"   

OK - good luck to @BioBrian, @frednork localising that in a room...below the transition (modal) region of a room down into the pressure region of  a room.

 

Mike

Link to comment
Share on other sites

10 minutes ago, davewantsmoore said:

If it contains only low frequencies, then it has (practically) identical level and phase in both ears.    Even if the source was directly to his left (for example).

Level is not important, as long as it's audible. It will be in the same phase, yes. But my personal interest is in time of arrival, and our sensory perception of that.

 

Whether a single, or randomly executed, low frequency pulse (OK, not a common occurrence) is heard first by one ear (or other relevant body part) is the question. I don't know the research that is being referred to, and suspect it's not entirely relevant to this exact question. I would prefer to have us discuss actual experience of the directionality of LF impulses, as @frednork has offered us.

Link to comment
Share on other sites

24 minutes ago, almikel said:

OK - good luck to @BioBrian, @frednork localising that in a room...below the transition (modal) region of a room down into the pressure region of  a room.

I'm hoping we can get somewhere without luck. The implications are potentially significant.

 

Any chance of doing a single 24 Hz pulse into 1 of your TD 18s?

Link to comment
Share on other sites

1 minute ago, BioBrian said:

Any chance of doing a single 24 Hz pulse into 1 of your TD 18s?

I don't run my TD18s down to 24Hz (I high pass them at 60Hz) - and the concept of a "pulse" implies higher frequencies.

 

Good idea though - they're setup as stereo...but 24Hz is a big stretch...major EQ would be required to get that low in their small boxes (natural roll-off is around 100Hz)...

...that's why I added a sub...EQ can only get you so far...

 

Happy to run some experiments on my TD18s at 70Hz or so...ie within their passband...what do you propose?

 

Mike

Link to comment
Share on other sites



10 hours ago, BioBrian said:

Level is not important, as long as it's audible. It will be in the same phase, yes. But my personal interest is in time of arrival, and our sensory perception of that.

 

Level would be important..... but the level in your left ear vs the right ear is always equal at these frequencies .... no matter anything to do with where/how the sound originated from.   It is the same for phase.... there is no phase difference between your ears.

 

I understand what you are saying.....   ie. If you have one bass sound arriving (from the left speaker) ... and then a delay... and then another bass sound (from the right speaker) ..... what happens?

 

Neither are perceived as coming from a location.... because (as above) each wave is perceived in both ears with equal phase and level.

 

If the delay between each sound (from the L and from the R speaker) is small enough (which is still large) .... and the frequency is equal ..... then it's all just sums together.

 

If the time delay, and/or frequency difference is large enough ...... then this creates intermodulation effects.... which you can perceive.

 

This can translate into spatial perception (as in audio with and without such effects can be though to move, or swim, or sound with a certain 3d-ness to it) ..... but before you say "ah ha!" ..... this isn't "locating the subwoofer".    It' a virtual effect.... and isn't a case of "I can hear the subwoofer is over there"   (the identical effect could be recreated with the subwoofer in a completely different location).

 

 

10 hours ago, BioBrian said:

Whether a single, or randomly executed, low frequency pulse (OK, not a common occurrence)

 

It depends what you mean by "pulse".   There is essentiall no such thing.

 

Let;s take a 40hz "pulse" ..... we have no sound.... and then suddently we have sound.   The "first hit" so to speak.

 

We have nothing.... and then the pressure begins to rise.   It continues to rise for a half a wavelength... ie. 12.5 milliseconds.

This is slow.   There is no "wavefront which hits you".

 

 

If you are thinking of a sound which does "pulse".... ie. "hit" you.     This sound contrain high frequencies.   You can hear the direction of these.

 

These are common.... much more common than you might imagine.    That is because the shorter the sound, the more frequencies it contains from the entire spectrum.

 

The shortest possible pulse contains every single frequency.    1hz, 2hz, 3hz, 3000hz, 300khz.... etc.

 

The longest possible pulse (eg. an "infinitely" long sound) ... contains one single frequency only.

 

A short ish sound has lots of frequencies .... and lots of high frequencies (these are what makes it "stop", by interfering with the longer bits thay would otherwise continue onwards).

 

10 hours ago, BioBrian said:

is heard first by one ear (or other relevant body part) is the question.

 

It arrives at one ear first (of course this is always true) .... but the distance to the second ear is small.    As a fraction of the wavelength in question it is (super) small.

 

So.... No.    It isn't "heard" in one ear first.    Because while the time delay between the ears (the speed of sound and your head size) is there..... the phase of the time delayed sound reaching the other ear is not changed enough to be perceived.

 

10 hours ago, BioBrian said:

I don't know the research that is being referred to, and suspect it's not entirely relevant to this exact question.

I understand your question.... it is relevant.

 

10 hours ago, BioBrian said:

I would prefer to have us discuss actual experience of the directionality of LF impulses, as @frednork has offered us.

I don't doubt his or your experience was exactly what you say it was.

 

... and I'm discussing it.   There is another reason for what you experienced than what you think caused it.

Link to comment
Share on other sites

10 hours ago, BioBrian said:

Any chance of doing a single 24 Hz pulse into 1 of your TD 18s?

 

It's very important to clarify what you mean by this.

 

If you want the tone to stop or start more abruptly than the "gentle" way a 24hz tone must start an stop ...... then this implies the precense of high frequencies.

 

If you want a short "sharp" crack/bang/pulse .... then this implies LOTS of high frequencies.   This might or might not be filtered out adequately by the low pass filter of the subwoofer.

 

... but to the degree that they are not..... in a regular system (where main speakers are also playing) .... the main speakers are significantly louder, which mean they completely dominate the location cues.

 

 

I hope I'm not making you sick.... I honestly wouldn't bother writting all this if I wasn't trying to help.

  • Like 2
Link to comment
Share on other sites

9 hours ago, almikel said:

Happy to run some experiments on my TD18s at 70Hz or so...ie within their passband...what do you propose?

 

You will need a very steep filter.    Small amount of low frequencies could cause the subwoofer to be localised when it is playing on it's own.     As in the previous comment.... if you add main speakers into that mix (which are significantly louder) they dominate.... so it's not relevant generally.

 

... but the sort of filter that Fred used should be fine.... but you would also want to check the output to be sure.

 

 

As I've said a few times.... at the risk of being blunt (ore than usual, lol) ..... if we get these results where it's audible ..... then there is an explanation that isn't "bass is directional"....  Or said another way, if we want to conclude that every text book on physics and hearing are fundamentally wrong.... and that all the well controlled experiments that have shown it to be true over the past century missed demonstrating it ....  then you will have to demonstrate it wasn't something else first before you collect your nobel prize.... and there's lots of things it could be.

 

Especially when we get results like Brian did where a LFE sub crossed over, got a very very different sound "missing bass" etc.   It's obviously not setup right.   We've all seen the measurements of the gesties and the main speakers ..... they weren't flat (so will be different to what the oppo targeted) .... and they are more sources in the room, so there's going to be a different modal distribution of sound.   Of course it gave a really different result... but you can fix that   (and it isn't becuase stereo bass, or timing bass, or anything like that).

 

For me, I can locate my subwoofers with the right test...... it is things in the room rattling differently.  Hard to tell as the rattles are a lot shorter (normally, lol) than the woofer response.    Outside, no.

 

I could locate my mini (6") tapped horn outside... but that turned out to be narrow bands of distortion.

 

FWIW... If we are perceiving direction bass.... then if it were me, I'd be interested to figure out why (and how I could "fix" anything which was wrong) ..... not "we've made a new discovery" (LOL).   Like when Brian, your Oppo "didn't work" (missing bass, etc.) ..... not draw a conclusion as to "why".... but figure out what the real difference was (and find the real, actual cause) .... and hopefully resolve it.   <shrug>

As I said, I wouldn't bother with any/much of this, if I wasn't really trying to help someone.

Link to comment
Share on other sites



On 05/05/2021 at 11:06 AM, davewantsmoore said:

This doesn't exist until someone demonstrates that it does.

 

The wind blows on my face and I know the direction from which it comes.  Perhaps localisation of bass frequencies is a similar thing.  When I am in the chair and listening I can feel my shirt and chair and sometimes the floor vibrating (needs to be really loud and really low for that last one).  That is what I meant by tactile.

 

Anyway, I'm not arguing and have not had time to read through the rest of the thread up to this point so may have missed some other discussion on the point.

Edited by acg
Link to comment
Share on other sites

33 minutes ago, davewantsmoore said:

As I said, I wouldn't bother with any/much of this, if I wasn't really trying to help someone.

 

If it is a bother to you, stop trying to "help".

 

Don't worry, the world still turns without you.

Link to comment
Share on other sites

2 hours ago, davewantsmoore said:

I hope I'm not making you sick.... I honestly wouldn't bother writting all this if I wasn't trying to help.

 

I appreciate your patience again, and obvious care taken to understand the workings of my system. Some snippets appear, every so often, that help complete the picture for me but I confess to having low tolerance to undue repetition, especially when I think it's wrong 🙂.

 

TBH I did feel brutalized by your post the other day, just as I thought the thread had wound itself up neatly. I guess you couldn't leave it, as that might be seen as complicity, so I wasn't surprised it came. Sometimes I'm just too delicate to be playing this internet thing, and for some reason you pushed some really ugly buttons for me, which I wasn't prepared for, and it's been hard to pull back onto the road.

 

Just before, I was trying to find any clues from the way whales use LF sonar as navigation. Didn't get anywhere - they apparently use between 30 and 8000 Hz (I had thought it included lower than 20 Hz) - but this noise they make is pretty close to what my brain's been sounding like:

 

https://journeynorth.org/sounds/humpback4_omi.wav

 

I do hope we can make some good progress on the directionality of bass; it's obvious to me that there's more to it than e = mc2, etc.

 

 

Link to comment
Share on other sites

9 minutes ago, BioBrian said:

I confess to having low tolerance to undue repetition, especially when I think it's wrong 🙂.

🤣 I've been told I have a high tolerance (to most things) ..... but I don't like it either  🤣

 

9 minutes ago, BioBrian said:

TBH I did feel brutalized by your post the other day

This wasn' t the intention.....  sometimes I'm a bit to "objective"... but I'm only honestly trying to help.

 

9 minutes ago, BioBrian said:

just as I thought the thread had wound itself up neatly. I guess you couldn't leave it

Dunno... I just a it in the new posts box and replied.

 

9 minutes ago, BioBrian said:

Just before, I was trying to find any clues from the way whales use LF sonar as navigation. Didn't get anywhere - they apparently use between 30 and 8000 Hz (I had thought it included lower than 20 Hz) - but this noise they make is pretty close to what my brain's been sounding like:

 

A whale has a head much larger than a human.... which would give it the ability to hear lower (the distance is larger) .... but sound travels faster in water, so that would undo some of it.

 

In thoery (I'm not 100% sure how wales hear) ... but that's how the waves and distances work.

 

On 01/05/2021 at 12:19 PM, BioBrian said:

The best recordings I've found are recorded in "5.0".

 

I did think about this..... and realised that given that "non-movie" sound standards don;t use a dedicated LF channel of content (ie. in the mix/recording) .......  that you might assume, that is because it's important to send the full range audio (ie. the bass) to each individual speaker.

 

ie.    Something like..... "They tell you to use 5 (or whatever) full range channels, and they have bass in all channels ..... so of source, "bass is directional".... why would they do it otherwise?! 

 

But no.   This is not the reason.

 

If you're interested, I can explain why music is recorded in 5.0 (and other standards have 5.1).    It's not because it's important to send back-left bass to the back-left speaker (for example).

 

... but I won't, if not interested.

 

21 minutes ago, BioBrian said:

it's obvious to me that there's more to it

 

I still don't really understand why you think so.....  aside from you heard it in your system.... but without accounting for any number of things which could have caused it  (the way you describe the result is an immediate tell something is "wrong").

 

Anyways.... I think you know by now not to take that as an "attack".  I'm just suggesting you should focus on it, if you're interested in the things you say you are  :)

Link to comment
Share on other sites



  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...
To Top