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10 hours ago, BioBrian said:

One thing that keeps being reinforced in various ways for me, is the benefit of keeping the subs stereo. I know you and thousands of decent people might disagree, but my experiences keep confirming this.

 

Anyway, the point of my post was that I've found some music which does demo the subs well, and it's high-def enough to also be a great showpiece for the 4-ways, and their integration. Poulenc's Organ Concerto might not be everybody's favourite organ stimulation, but I have a quaint personal history from performing it in the past - another story. I think it's an awesome piece.

 

Edit: Actually I have quite a strong personal history with the Rachmaninov Paganini Variations too (on the same download). If anyone knows the original piano and orchestra version, what this guy does using his organ instead, is an absolute riot! Two hands (5 manuals/keyboards, and about 150 stops/switches), both feet (full keyboard, and at least 5 other pedals).

If physically plausible, installation of stereo subs will yield more realistic results.  Primal sensing let us detect direction of approaching thunderstorm, whilst in modern applications, quality recordings should replicate sub-harmonics setup by venue dimensions, giving that subtle extra depth.

 

Nothing like the sound of a live organ. Doesn't always transfer well to recordings though.

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Just a quick announcement that twins were painlessly born today, to a badly-presented but relieved BioBrian and his wonderful StereoNetter cohorts. I'd really like to gratuitously thank all staff, but

It's an odd experience when I find someone referring to something I wrote that I can't remember.   When you compare different kinds of subs, there are two experiences. The first is the easy

Both boxes now all trimmed, ready for final sand and varnish. Don't think I'll need DuraTex after all...   Worst problem has been lack of handles to move them.   110 kg each, so wi

On 14/09/2020 at 10:08 AM, Auracle said:

Nothing like the sound of a live organ. Doesn't always transfer well to recordings though.

Too true. I've been swotting up on organs and came across this 43 second demo of Sydney Town Hall's Contra Trombone stop. They are equal longest pipes in the world, apparently. Sounds like something recorded in 1890, too! And consigned to mp3...

 

https://www.sydneyorgan.com/STH64.mp3

 

Edited by BioBrian
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  • 2 months later...

  • 4 months later...

No changes. Still learning what they do, and appreciating their subtle completion of room frequency response.

 

Currently upgrading multi-channel system, including thinking of LFE sub(s) for the .1 channel...

 

It could be argued that I can use these for the LFE channel. Now they just double the woofers in the main 4-ways, but I probably wouldn't need them to do this in a full 7.1 setup. Bass would be enough in the room, and if LFE bass comes from these up on the wall in a null, then that could well be enough. It'd be just the flick of a switch on the back of the power amp, to change from balanced (as at present) to single-ended (LFE). Cool if it works - 2 input choices from a power amp.

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Just tried it (again). LFE to Gesties. Nah, nuh. Dead bass. Bass missing from front L & R, even with Oppo XO set to 40 Hz.

 

So much better, telling Oppo there's no sub, and getting the full stereo, in the full-range 4-ways and supplementary subs. Even with 5.1 material.

 

But I'll have to test whether the Oppo does what it's told - might check with another amp/speaker, as it (or the Oppo 83-SE, can't remember) has tried to pull a swifty before.

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1 hour ago, BioBrian said:

Just tried it (again). LFE to Gesties. Nah, nuh. Dead bass. Bass missing from front L & R, even with Oppo XO set to 40 Hz.

 

So much better, telling Oppo there's no sub, and getting the full stereo, in the full-range 4-ways and supplementary subs. Even with 5.1 material.

 

But I'll have to test whether the Oppo does what it's told - might check with another amp/speaker, as it (or the Oppo 83-SE, can't remember) has tried to pull a swifty before.

 

Maybe that's a problem with 'LFE' and a 5.1 system?

 

In my, purely music, 2.2 system (with a miniDSP providing 4-way XOs) ... there is no bass missing!  (Mains' bass panels are rolled off to match the subs' roll on.)

 

Andy

 

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Posted (edited)
On 24/04/2021 at 7:22 PM, andyr said:

Maybe that's a problem with 'LFE' and a 5.1 system?

 

I think that's the case, for sure. I would think the vast majority of systems would be 'sub-sat', where the LFE channel does all the subbing and the 5 or 7 others ('satellites') do the mid and high ranges. That's a sure recipe for destruction of acoustic music recordings.

 

And a more general rave from my perspective:

 

In my case, the front L&R 4-ways are truly full-range, so sending their low bass to the LFE channel removed a lot of their character and just bass into the room. Utilizing the LFE also removed bass from all the other speakers, limiting bass in the room to just the mono sub(s). One result of this is the removal of 5 other sources of low bass, hence an increase in modal problems, which mean less bass, but also dodgy bass.

 

The main point here for me here (can't be bothered arguing it in the other threads) is that keeping bass stereo gives a live, open sound, and mono bass kills that.

My little 5.1 experiment the other day put all above 40 Hz to the 5 "sats", and LFE to the twin (not stereo) subs up on the walls. The sound was thin generally; the bass sounded localized to the middle of the room behind me, and I just felt like leaving the room - it was horrible.

 

So to anyone sweating over the theoretical arguments out there - just try stereo bass, and see for yourself. Make sure the subs are a similar distance from you as your front L & R speakers (or adjust timing with DSP if you are of that persuasion), and no closer together than the mains, or you will just get "acoustic summing" of the bass, same as joining them electrically. There are lots of choices with rotations, inversions, and different heights to play with, if you want to improve modal room behaviour at the listening position. (Ask your spouse's opinion after you've nailed it, and make sure they're doubly blinded).

 

I've had a re-read of what Jim Smith says in "Get Better Sound", and it makes perfect sense to me. P 35 in the book, if you have it, under: "Don't believe the "experts" when they tell you that you only need one subwoofer". Spatial cues, soundstage collapse. Cancellation of bass timing differences, when joining, resulting in weaker bass. Etc.

 

As for the directionality of bass, I don't believe it's omni at all. You can tell where thunder comes from (it's the lightning, LOL), and it's not just the high frequencies. All frequencies travel at the same speed, so the initial impulse hits you from the direction of its epicentre. What happens later (echoing around them-thar hills, or like a sine-wave signal in a room) is more omni, as it bounces around and changes character. Live acoustic music (and good recordings do convey this) presents impulses from the instruments that produce them, and these are directional. Nothing to do with frequency - it's timing. Joining the bass signals L & R kills that. The music is dead.

 

The best recordings I've found are recorded in "5.0". If you want a serious blast of excellent multi-channel acoustic music, I can heartily recommend John Wilson's SACDs. The YouTube version may give a tame impression, but if you're passing by in Southern Tasmania...

 

 

Edited by BioBrian
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:thumb:  :thumb:  :thumb:, @BioBrian!

 

But I find it extraordinary how some people just don't "get" it.  :(

 

Andy

 

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Posted (edited)

This may have already been mentioned or carried out Brian. If so, please ignore.

Low frequency phase/reflection interaction is a more difficult thing to comprehend just because its effects can be so noticable, IMO.

 

Sometimes all the math at your disposal cannot beat a manual test procedure.

 

If I was going through this exercise, in order to minimise part of the unknowns causing the acoustic nulls, I would employ LFE electronics with the ability to vary the phase from 0 to 180 degrees. An acceptable balance may be achieved. You may also find that, say, the left channel is set at 20 deg's, and the right channel at 110 deg's. Symmetrically unbalanced one might say, but works great!

 

Of course, once the results are in, the interpretation and implementation of same is then up for debate.  -Ask "why" at your own risk.

Edited by Auracle
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Intriguing, Sam!

 

I see the alteration of phase as the same as alteration of distance from the LP. So if you change the distance of the subs from identical with the distance from the mains, you need to correct phase (as I think you are suggesting) too. But to what? 'Correcting' distance or phase can only target one frequency, and all the others will be wrong? As I still see it, the only way to retain the "spatial cues", or timing distances, is to place the doubling subs at the same distance, with no electronic mucking around, as in all though this Gestie thread.

 

The LFE thing is being pursued, but really is OT here. As indicated in my ePizzle above, I've decided LFE's a no-no for music reproduction, so (if at all) I'll only use it for movies: what it does best and was intended for. I think any subtle phase issues (to a point - it really is bottom octave stuff) are going to be lost on explosions and dinosaurs crashing through 'between the notes'. As long as it shakes the room and challenges the state of one's viscera, the job's done. Placement will be done; it's a mono signal, but my plans include 2 separate boxes.

 

Some entertainment could be had from a couple of active subs with phase adjustment, but I won't be financing it. DSP? Happy to stand back and watch, but placement and setting the timing (distance) in the Oppo 205 player is my expectation.

 

Even in movies, I am expecting that results will be better if I tell the player there's no sub, and the lows will be re-directed to the 7 other (full-range) speakers, giving a much better balanced bass. But I have a suspicion that the Oppo might just back off on the really aggressive stuff, in the expectation of non-subs not being able to handle the amplitudes/excursions. Whatever, I'll have 2 amp channels available for testing this, when the 7-channel Elektra arrives.

 

I'm doing more multichannel upgrades as we speak; I can either try for SNA hibernation, or start a new bits-n-pieces thread on a combination system.

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I began typing the previous post with regards to long wavelengths causing havoc that can sometimes be unsolvable unless you have a stopwatch, but ended up with some generic text. You got the gist anyway.

 

Sounds like you've gone as far as you can on this gestation.

You've confirmed one of my arguments that LFE speakers should not be used for properly recorded music programs, but for material containing synthetic bass only.

 

Whatever you decide, know that the work you have undertaken here is vast and done to a high professional standard.  For your contributions alone you are greatly respected. I hope other SNA members have taken something positive from this thread and add the information into their builds.

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

The main point here for me here (can't be bothered arguing it in the other threads) is that keeping bass stereo gives a live, open sound, and mono bass kills that.

 

There is a reason for this that is something specific to your system.

 

There's nothing wrong with you leaving them stereo, or whatever you want to do, of course ..... but the general conclusion you seem to be drawing about this, are incorrect.

 

.... even the conclusion that "in my system, stereo sounds better" ... is "flawed", as you have not conducted an "apples to apples" comparison... so of course it sounds different (likely very).

 

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

So to anyone sweating over the theoretical arguments out there - just try stereo bass, and see for yourself.

 

They will get very different result.... as in, when the do the change, it would sound different (just like you have noticed).

 

This isn't because one is better than the other...... but because without both being calibrated correctly, the results will be different (potentially very).

 

If you had to take a roll of the dice (without any sort of calibration) ..... you would always expect to get better result if you allowed VLF to come from more sources.

 

 

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

Make sure the subs are a similar distance from you as your front L & R speakers (or adjust timing with DSP if you are of that persuasion)

 

Pretty much irrelevant at LF.... aside from its impact on levels, which is taken into any rudimentary calibration.

 

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

As for the directionality of bass, I don't believe it's omni at all. You can tell where thunder comes from

 

Because it contains high frequencies.

 

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

and it's not just the high frequencies

 

It's definitely not the low frequencies.   What you are saying simply contradicts the laws of physics and all known experimental evidence.

 

Quote

As the frequency drops below 80 Hz it becomes difficult or impossible to use either time difference or level difference to determine a sound's lateral source, because the phase difference between the ears becomes too small for a directional evaluation

 

 

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Posted (edited)
16 hours ago, davewantsmoore said:

It's definitely not the low frequencies.   What you are saying simply contradicts the laws of physics and all known experimental evidence.

 

Quote

As the frequency drops below 80 Hz it becomes difficult or impossible to use either time difference or level difference to determine a sound's lateral source, because the phase difference between the ears becomes too small for a directional evaluation

 

 

Dave,  I'm not saying the the laws of physics are wrong,  or that the ear/ wavelength ratio is irrelevant (I have a massive noggin by the way) but perhaps there is more to this LF directionality than just what the ears hear.   There is so much energy in those bottom few octaves that they are felt as well as heard,  and maybe it is a tactile thing people like Brian and myself are processing which augments a poorly triangulated sound source due to limited ear to ear separation. 

 

Something to consider,  a supplementary method of sound location...

Edited by acg
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5 hours ago, acg said:

but perhaps there is more to this LF directionality than just what the ears hear

 

I'm not really sure what to say to you.

 

Our understanding of how perception of sound works.... tells us that we should not be able to perceive low frequency directionality.

 

Experiments show we cannot perceive low frequency directionality.... all of them.   I'd be very excited to see any which shows otherwise, at it would say that our whole understanding of hearing and sound is incorrect.   (I'll wait)  ;) 

 

There are somethings we should not confuse.....

 

We can make recordings of bass (typically it has to be "artificially constructed" due to the atypical phases involved, ie. it could never be recorded with any normal 'multi mike recording technique') .... which sound like they "move"... phase around your head or whatever.....   but this effect is not you hearing the source (speaker) direction....  it's a tonal type effect... and the effect can be created with the subwoofers in any position  (as their location is largely irrelevent, because you don't hear where the sound originates from).

 

Different frequency response between testing single vs multiple, "stereo" vs "mono" bass sources.    The difference is usually substantial  (even just a dB or two is a very signaificant difference in energy... and 3 is double) .... when we measure the differences, we see often 5, 10 or many 10s of difference.

 

Subwoofers which play substantially up into the hunreds of Hz.... all bets are off (we're no longer talking about "subwoofers" or "bass") ...... often overlooked here is distortion products or rattles, etc.   You may have a low pass filter at 50Hz, but you might be putting out tones at 100hz+ which are just as loud as 50hz.

 

 

5 hours ago, acg said:

Something to consider,  a supplementary method of sound location...

 

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

 

 

I don't doubt for a monent that BBs experience is exactly how he describes..... he's not imaginging anything.    There is just a different explanation for what he's experienced than what he says it is.

 

The most obvious tell is the description of "big changes" and "missing bass" etc. etc...... completely obvioust that it's not setup right.    Leaping to "bass must be directional" is nonsense.

 

FWIW, I would be surprised if there is even any signficant stereo bass content on the recording that he used to hear these effects.  ;)

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On 02/05/2021 at 12:44 PM, Auracle said:

Sounds like you've gone as far as you can on this gestation.

You've confirmed one of my arguments that LFE speakers should not be used for properly recorded music programs, but for material containing synthetic bass only.

 

Whatever you decide, know that the work you have undertaken here is vast and done to a high professional standard.  For your contributions alone you are greatly respected. I hope other SNA members have taken something positive from this thread and add the information into their builds.

 

Much appreciated, Sam.

 

You're right - I did feel the thread had come to a close, after setting up the experiment, doing the hard yards, and trying to understand and express why it was successful.

 

Maybe it's time to sit back and watch again, as the "shoulds" express their need to dominate and discredit the whole phenomenon with the "same old", but that just makes me ill.

 

The "Gestation" days are well gone; I'm really over it, and keen to get on with life.

 

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1 hour ago, BioBrian said:

dominate and discredit

That isn't the intention.   I'm sorry you feel that way.

 

Quote

On 02/05/2021 at 10:24 AM, BioBrian said:
So if you change the distance of the subs from identical with the distance from the mains, you need to correct phase (as I think you are suggesting) too. But to what?

He's suggesting that if you had "acoustic nulls" (or some other level problems) when using subwoofers for the LFE....  then a way to combat that is by adjusting the phase of each source so that they are uneven.

 

Tho... This doesn't just apply to LFE... it applies to any source of bass.

 

He's spot on when he says "all the math won't beat a test procedure".   ie. without measuring 

 

Quote

On 02/05/2021 at 10:24 AM, BioBrian said:
'Correcting' distance or phase can only target one frequency, and all the others will be wrong?

No.

 

 

In your specific example ...... you have a subwoofer..... then you move the subwoofer... and how to do make the phase after the move the same as the phase as it was before it was moved.

 

You adjust the phase by the same amount at every frequency.   ie. delay.    By doing this the phase before the move with be the same as the phase after the move (at all frequencies).

 

If OTOH.... you are trying to align two sources which have phase vs frequency that have different slopes..... then yes, you can only match them at one (or a small range of) frequency.

 

On 02/05/2021 at 12:44 PM, Auracle said:

You've confirmed one of my arguments that LFE speakers should not be used for properly recorded music programs, but for material containing synthetic bass only.

 

Hmmmm..... so the "shoulds" ??!?   ;) 😅

 

What IS an "LFE speaker(s)" .... really? .... All it is just bass being crossed over to a subwoofer.   That's it.    It doesn't care whether the content is music, or dinosaurs, or both, or whatever.

 

The simple fact is that if the crossover is setup "properly" ..... that it will have the same result as some other bass setup/crossover.... if everything else is equal.

 

If you have two scenarios configured (as Brian did) .... and you get a big difference in sound between the two (as described) .... one is setup differently to the other.   It's that simple.

 

If anyone doesn't believe me?..... Just measure it and you will see  (or ask for help) ;) 

 

BB has his bass sources overlapped substantially in his "stereo setup" ..... by asking the oppo to cross them over .... the bass output will be lower.... for a start.

 

 

Quote

On 02/05/2021 at 10:24 AM, BioBrian said:
I think any subtle phase issues (to a point - it really is bottom octave stuff) are going to be lost on explosions and dinosaurs crashing through 'between the notes'.

 

 

"subtle phase issues" have no effect on any content.

 

.... but any actual significant phase issues (in so far as they relate to substantial differences in level) are relevant to all types of content.

 

You noticed this in your experiment.   The bass went "missing" ..... this is caused by a substantial difference in level.

 

We don't know what caused that .... it may have been a phase issue causing the level to be different ... or as mentioned, it might have been simply the lower overall level caused by the lack of "overlap" compared to your stereo setup.

 

Quote

 

On 02/05/2021 at 10:24 AM, BioBrian said:

As long as it shakes the room and challenges the state of one's viscera, the job's done. Placement will be done; it's a mono signal, but my plans include 2 separate boxes.

 

 

I'm unsure if your processor supports it...... but a suggestion, if I may.

 

You have stereo speakers which have both substantial bass capability, and bass that you are happy with.

 

You "should" (sorry), configure your system so that all bass is redirected to your Left and Right speaker.... ie. all LFE bass, and all bass from any other channel, is played through the stereo speakers.

 

 

Quote

 

Even in movies, I am expecting that results will be better if I tell the player there's no sub, and the lows will be re-directed to the 7 other (full-range) speakers

 

 

Exactly.   You already have a "LFE capable" channel.   It's your LR channel.     If you processor supports it, redirect all bass there....   don't bother making your surround channels "full range".....  unless you actually have the capability to correctly integrate those bass sources.     If you don't, then just adding more incorrectly integrated bass sources in the room, is going to be a "bad" result.

 

What I mean by this is that the LF phase of the surround channels will need to match that of the LR... (and of the LFE woofer if present)
 

Quote

 

But I have a suspicion that the Oppo might just back off on the really aggressive stuff, in the expectation of non-subs not being able to handle the amplitudes/excursions.

 

 

This isn't what a processor typically does.....  but it will depends on specifics.

 

Typically... You can declare your LR as your subwoofer.... and have all bass (ie. LFE, and bass from surround channels) mixed there.

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I read the above with interest.

I did this

 

1620215442726.thumb.jpg.c7353ac46d110b44f2ed0fd5595b12dd.jpg

 

Its 2x36db filters set at 47hz as shown. 

I then played a track and compared signal sent to left right or both. They were all very easy to discern where the sound was coming from.  What am I missing? 

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8 minutes ago, frednork said:

I did this

 

Love it! Thank you!

 

Should 

 

I'll duck now and get back to my therapy.

 

 

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19 minutes ago, frednork said:

 What am I missing? 

I don't know.

Could it be distortion?


My subwoofers don't do that.... nor would one expect them to.    (There's a reason why all the books say you cannot perceive the source of such low frequencies).

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2 minutes ago, davewantsmoore said:

I don't know.

Could it be distortion?


My subwoofers don't do that.... nor would one expect them to.    (There's a reason why all the books say you cannot perceive the source of such low frequencies).

Dont think so, not because my system is so amazing that there is no distortion, but because the reason it is easily identifiable is there is a noticeable pressure in the same ear the on the side the sound is coming from.  I can try and lower the  low pass if you think its too high?

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Posted (edited)
59 minutes ago, frednork said:

I then played a track and compared signal sent to left right or both. They were all very easy to discern where the sound was coming from.

 

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.

Edited by BioBrian
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34 minutes ago, frednork said:

I can try and lower the  low pass if you think its too high?

No, it's plenty low enough.

 

Something is causing it..... but it isn't low frequency localisation, as there's not enough phase difference between each ear to make this possible.  It's been very extensively researched.....  If there isn't something explainable going on (then you guys will be proper famous ;) )

 

You have a measurement microphone?  Yes?

 

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1 minute ago, davewantsmoore said:

No, it's plenty low enough.

 

Something is causing it..... but it isn't low frequency localisation, as there's not enough phase difference between each ear to make this possible.  It's been very extensively researched.....  If there isn't something explainable going on (then you guys will be proper famous ;) )

 

You have a measurement microphone?  Yes?

 

 

Yes

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11 minutes ago, BioBrian said:

I'd like to know if it contains sudden impulses

 

After the low pass filter is applied .... then there's no "sudden impulses" remaining, as all the high frequencies are gone.

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

 

 

 

The best recordings I've found are recorded in "5.0". If you want a serious blast of excellent multi-channel acoustic music, I can heartily recommend John Wilson's SACDs. The YouTube version may give a tame impression, but if you're passing by in Southern Tasmania...

 

 

It was a recording of the Boston Philharmonic Orchestra's version of "Fanfare for the Common Man" that convinced me to build a sub....

 

23 minutes ago, frednork said:

but because the reason it is easily identifiable is there is a noticeable pressure in the same ear the on the side the sound is coming from. 

In a room? below the transition zone of the room where modal behaviour dominates? and below that in the pressure zone where modes won't propagate?

 

The laws of physics always applies.

 

Mike

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2 minutes ago, frednork said:

Yes

I would initially look at things like THD, and ETC, for anything that stuck out.

 

... but at the end of the day, consulting the textbooks is really the best bet if you want to know what is what (don't listen to me). 

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6 minutes ago, davewantsmoore said:

After the low pass filter is applied .... then there's no "sudden impulses" remaining, as all the high frequencies are gone.

 

Therein lies the problem?

 

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.

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1 minute ago, davewantsmoore said:

  

I would initially look at things like THD, and ETC, for anything that stuck out.

 

... but at the end of the day, consulting the textbooks is really the best bet if you want to know what is what (don't listen to me). 

Will do some recordings , hopefully tomorrow 

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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. 

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2 minutes ago, almikel said:

The laws of physics always applies.

There will be something going on which explains what he is noticing.

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Posted (edited)
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
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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??

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10 minutes ago, davewantsmoore said:

There is still the "first hit"

Yes. I believe that's what @frednork is hearing.

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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.

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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

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1 minute ago, BioBrian said:

Yes. I believe that's what @frednork is hearing.

 

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).

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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.

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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"   

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