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What measurement is used for Subwoofer "SPEED"? - Page 2

post #31 of 76
Quote:
Originally Posted by BeeMan458 View Post

But the LFE channel is basically, 0Hz to 80Hz content as anything >80Hz is locatable.

What am I missing as I'm stuck on subwoofers and managed bass with LPF's set to <80Hz and bass content of the LFE channel being reproduced by our subwoofers...................
The LFE channel can contain info as high as 120Hz. You can crossover your individual speaker channels at whatever frequency is appropriate or that you deem preferable. The speaker channels' bass is low-passed completely independently from the LFE channel bass.

But unless you can justify setting it lower for a particular reason, there is really no reason to low-pass the LFE channel, itself, any lower than 120Hz. So, if you have your LPF of LFE set to 80Hz, you are missing the LFE channel info that MIGHT be encoded between 80Hz and 120Hz.

Otherwise, you are not really missing anything in this thread.
post #32 of 76
Quote:
Originally Posted by sivadselim View Post

The LFE channel can contain info as high as 120Hz. You can crossover your individual speaker channels at whatever frequency is appropriate or that you deem preferable. The speaker channels' bass is low-passed completely independently from the LFE channel bass.

But unless you can justify setting it lower for a particular reason, there is really no reason to low-pass the LFE channel, itself, any lower than 120Hz. So, if you have your LPF of LFE set to 80Hz, you are missing the LFE channel info that MIGHT be encoded between 80Hz and 120Hz.

Otherwise, you are not really missing anything in this thread.

Cool.

FWIW, I'm aware of the range of the LFE being greater than 80Hz but due to issues which surround locatability, measurements of LFE mixes show content to be mostly in the <80Hz range, hence why I posted, "... basically, 0Hz to 80Hz content..."

I'm also aware that speaker channel content is separate from LFE or subwoofer channel content, hence why I posted the comment regarding "managed bass" and the LPF for the other channels being set at <80Hz.

Sorry for any confusion these comments cause anybody as in my comments, I do try to do my best to accurately flesh out my thoughts and remain pithy in the process.

What I seem to be missing, is not understanding why anybody's subwoofers care about anything above 80Hz to 120Hz. After that, the other speaker channels have taken over and in my opinion, conversation about subwoofers and the sub's response to higher frequencies, becomes moot.

...confused.gif

In my opinion, bass management and ID subwoofer manufactures has totally changed the face of Home Theater sound, based on what it was just ten or fifteen years ago. Now, one no longer needs big expensive towers like the Klipsch, RF-7 II's. Today, something much smaller will do as long as it's an efficient design to 40Hz with an equally capable center channel.

Today, when speakers are coupled with three subs for smoothness of sound distribution, capable bass management and using DSP's to integrate and EQ a room's acoustics, pretty much, for Home Theater purposes, all decent speakers become capable of quality Home Theater sound reproduction.

The point of the above, I still don't get why folks are worrying about subwoofer's response above 80Hz as today, in the $300.00 and above, all subwoofers are very capable and response is not a worry.

-
Edited by BeeMan458 - 5/4/13 at 1:25pm
post #33 of 76
Quote:
Originally Posted by sivadselim View Post




Again, the speed (or even the way) that a sub-woofer's driver moves has no real relevance to the characteristics that people often describe as "fast", "slow", "loose", or "tight" bass. The same exact sub-woofer could sound "slow" or "loose" to you in one room, yet sound "fast" or "tight" to you in another room. Or in another location in the room. Or with the addition of room treatments. Or by simply moving to another seat to listen to it. So, how does it have anything to do with the way the driver is moving?

I again disagree with your first sentence but again i believe we are describing two different things. example a 40hz signal is the same speed no matter the driver/ system/ room/ or anything else related to the 40hz signal. However the ability of a driver/ system/ etc to change from that 40hz signal to a 15hz signal to a 80hz signal and back to the 40hz signal can vary greatly between driver/ system.

I do agree that the room has a large effect on what we hear and sometimes perceive as a faster or slower response. But the room means little when two different (or more) drivers/ systems sound completely different in their ability to seem fast or slow in the exact same room and location. That goes back to the individual driver/ system characteristics.
post #34 of 76
Quote:
Originally Posted by Mr. Bubbles View Post

.................i believe we are describing two different things.

I'm describing the characteristic(s) of a subwoofer's sound that people often describe as "fast", "slow", "tight", or "loose". We can add "muddy" and "clean", too. And there are others. How articulate the sub is MIGHT be the best way to sum them all up. At least that is my interpretation of what miost people are describing when they use those terms. They are all very subjective, of course, and may even mean different things to each of us.

And I am saying that the driver's movement - be that its actual speed or how it moves - is not what dictates the perception of those subjective characteristics, as was posited. So, for example, if you're talking about a subwoofer's transient response, the driver's movement is not what is PRIMARILY responsible for the differences in transient response between subwoofers. There are other characterstics besides transient response which contribute to the perception of articulation, too, and none of those are really DIRECTLY related, simply, to the movement of the driver.

Did you read any of the links that were posted in the thread. Several of the links to threads here and in other forums contain some good discussions. But you have to read through the whole thread to get the gist; not just the initial post or a cursory scan of the thread. Here is another, btw:
http://www.avsforum.com/t/868241/subwoofer-speed-in-reference-to-size
Edited by sivadselim - 5/4/13 at 6:29pm
post #35 of 76
Quote:
Originally Posted by Mr. Bubbles View Post

However the ability of a driver/ system/ etc to change from that 40hz signal to a 15hz signal to a 80hz signal and back to the 40hz signal can vary greatly between driver/ system.
The fly in that ointment is that we never listen to 40Hz or 15Hz or 80Hz signals. We listen to complex waveforms that consist of literally hundreds to thousands of frequencies produced simultaneously.
It's true that different systems sound different, but not because of anything that has to do with 'speed' or the ability for a driver/system to track changes in frequency content.
You're making one of the classic errors of one untrained in acoustical engineering, which I already touched on. For the reaction speed of drivers to be audible variations in said speed would have to occur as measurable percentages of the speed of sound, 1130 feet per second. Drivers don't react to impulses at the speed of sound. They react to impulses caused by electron waves flowing through voice coils at roughly 130,000 miles per second. Even if two drivers varied in reaction speed by 50% 65,000 miles per second as a percentage of 1130 feet per second is so small that my nine place calculator can't put a number on it. Neither can your ears.
post #36 of 76
Quote:
What measurement is used for subwoofer speed

A consistent group delay plot? (no big spike at the port tuning frequency)
Sealed subs have better group delay
post #37 of 76
Quote:
Originally Posted by Joe0Bloggs View Post

A consistent group delay plot? (no big spike at the port tuning frequency)
Sealed subs have better group delay
You can't hear group delay below 80Hz unless it's so severe as to render the speaker unusable. It's one of those things that keeps oddiophools awake at night fretting over it because they can see it on a chart. We professional speaker designers hardly pay attention to it at all.
post #38 of 76
Slow and fast are descriptions of "speed." Speed is calculated as distance traveled over time. With cars, we talk about "miles per hour." "Light-speed" is a measure of the distance light travels in a year. The speed of sound is described in feet per second.

A subwoofer driver's "speed" is described in oscillations per minute, (oscillations being distance traveled "back and forth" over time.) This is measured in "cycles per second" or, "Hertz", (as named after the physicist who first described them, Heinrich Hertz), or abbreviated as "Hz." Each Hz is a specific number of cycles per second, and each Hz is a "note." A 40 Hz note is 40 cycles per second. An 80 Hz note is twice as many cycles per second as a 40 Hz note. A 20 Hz note is half as many cycles per second as a 40 Hz note.

I say all of the above to make the following point: If a subwoofer can reproduce a note, it is BY DEFINITION "fast enough" to reproduce that note If it were playing "slower", (or "faster"), it would be playing a different note. eek.gif

Bottom line, there is no such thing as "slow bass" or "fast bass." These are meaningless descriptions that don't describe anything about the physical properties of a subwoofer. People should stop using "slow" and "fast" to qualify or quantify the characteristic of a subwoofer. If one wants to take about the time domain response of a sub, then discuss the transient response, or the dampening characteristics, or the room interactions of the sub. Let's be more precise with our terminology.

Craig
post #39 of 76
Quote:
Originally Posted by craig john View Post

People should stop using "slow" and "fast" to qualify or quantify the characteristic of a subwoofer.

Why? tongue.gif

How about "juicy"? Can I say that? Or "lean and mean"?

wink.gif
post #40 of 76
Quote:
Originally Posted by sivadselim View Post

The LFE channel can contain info as high as 120Hz. You can crossover your individual speaker channels at whatever frequency is appropriate or that you deem preferable. The speaker channels' bass is low-passed completely independently from the LFE channel bass.
But unless you can justify setting it lower for a particular reason, there is really no reason to low-pass the LFE channel, itself, any lower than 120Hz. So, if you have your LPF of LFE set to 80Hz, you are missing the LFE channel info that MIGHT be encoded between 80Hz and 120Hz.Hz.
Otherwise, you are not really missing anything in this thread.

I set my to 80Hz as it does blend and sound sound much better, as for missing some info above 80hz, not so, it just rolls off afew db. I like the trade-off, it just sounds much better to me. I found dialogue to be much clearer and cleaner with all my speakers and sub set @80Hz. The 80 to 120hz seems just to add a hollow boom, my sub sounds soild and tight below 80hz. 80hz to 120hz doesn't seem add to the HT experience, but lessens it.
post #41 of 76
Not to mention the conflicts created in a room between 80Hz and 120Hz.

There's many reasons to LPF >80Hz as nulls and locatability are two very good reasons. Personally, based on REW measurements, we use asymmetrical LPF settings. Each subwoofer set to offer their best in integration efforts with a room's acoustics.
post #42 of 76
Quote:
Originally Posted by craig john View Post

A subwoofer driver's "speed" is described in oscillations per minute, (oscillations being distance traveled "back and forth" over time.) This is measured in "cycles per second" or, "Hertz", (as named after the physicist who first described them, Heinrich Hertz), or abbreviated as "Hz." Each Hz is a specific number of cycles per second, and each Hz is a "note." A 40 Hz note is 40 cycles per second. An 80 Hz note is twice as many cycles per second as a 40 Hz note. A 20 Hz note is half as many cycles per second as a 40 Hz note.
There are actually two speed factors. One is that described above, which is related to time. The other is the velocity of the cone, which is related to distance. As excursion increases in proportion to voltage applied the velocity of the cone also proportionally increases. For instance, if voltage swing, and therefore excursion, is doubled, the velocity of the cone is also doubled, so that it may cover twice as much distance within the same time period.
post #43 of 76
Many years ago during a study that included measurements and listening we found what people called "speed" was most closely correlated with a sub that did not ring after a pulse. That is, subs that were poorly damped/controlled and exhibited several (or many, in some cases) cycles of damped ringing/decay after the signal stopped were almost universally deemed "slower" by listeners. Interestingly, subs with higher bandwidth (100 - 200 Hz vs. <100 Hz) were not deemed "faster" by listeners. A lot of listeners were also surprised at what 60 Hz "sounded" like; they were treating the 100+ Hz info as "sub" when it was really the higher harmonics/overtones they thought was "deep" bass.
post #44 of 76
Quote:
Originally Posted by DonH50 View Post

A lot of listeners were also surprised at what 60 Hz "sounded" like; they were treating the 100+ Hz info as "sub" when it was really the higher harmonics/overtones they thought was "deep" bass.
+1. On average listeners will be off by a full octave in their estimates of what they're actually hearing. That includes one class of listener that you'd think would know better: Electric bass players. On electric bass forums you see them asking about what speakers will go flat to 40Hz, 32Hz, or even lower, based on the fundamental of the lowest note that their instrument will play. But the acknowledged king of electric bass cabs since 1969, the Ampeg SVT, has an f3 of 58Hz, and few complain of its low frequency capabilities. That's because the main component of electric bass tone isn't the fundamentals, it's the harmonics that start an octave above the fundamentals.
post #45 of 76
Regarding, DonH50's above comment, that's what happens when folks try to base perception on emotion rather then taking the time to use room measurements in which to integrate their subwoofer system into their room's acoustics.

And FWIW, four string bass is limited to ~41Hz and five string bass is limited to ~31Hz. Being an ignorant, all I know is what I read and what I measure.
post #46 of 76
Quote:
Originally Posted by BeeMan458 View Post

And if we wanted the room to be "boomy," one need only to turn up one of the subwoofer's gain a smidge and voila, instant boomy.

Which is definitely the problem with the OPs experience. So many reasons why the setup could have favored the JL Audio Sub. As the OP admitted, he wasn't certain if the gain on either sub had been calibrated. Moreover, Audyssey had been calibrated with a completely different sub, and who knows if that was left engaged. Finally, the Fathom has built in room optimization. Could be it was already calibrated for that placement (with no Audyssey engaged), whereas the SVS could have responded equally well with some room correction.
post #47 of 76
Quote:
Originally Posted by joehonest View Post

.................as for missing some info above 80hz, not so, it just rolls off afew db.

Yes, so. But suit yourself. True, you aren't missing much. Honestly, I do not know how steep the 'LPF of LFE' is on most AVRs. What is your AVR?

Quote:
Originally Posted by joehonest View Post

I found dialogue to be much clearer and cleaner with all my speakers and sub set @80Hz.

The 'LPF of LFE' setting will not affect the dialog at all as there is no dialog supportive material encoded in the LFE channel.

Quote:
Originally Posted by joehonest View Post

The 80 to 120hz seems just to add a hollow boom, my sub sounds soild and tight below 80hz. 80hz to 120hz doesn't seem add to the HT experience, but lessens it.

That little bit of LFE info between 80Hz to 120 Hz makes that big a difference, huh? Yeah, sure it does.


Quote:
Originally Posted by BeeMan458 View Post

Not to mention the conflicts created in a room between 80Hz and 120Hz.

There's many reasons to LPF >80Hz as nulls and locatability are two very good reasons. Personally, based on REW measurements, we use asymmetrical LPF settings. Each subwoofer set to offer their best in integration efforts with a room's acoustics.

Maybe you have some REW measurements you can show us to support these assertions.



Seems to me some folks STILL do not understand the LFE channel or bass management. What the LFE channels is, how the LFE channel is encoded at production, how an AVR decodes it, and how the other speaker channels' bass is bass managed completely independently from it.
post #48 of 76
Quote:
Originally Posted by sivadselim View Post

Maybe you have some REW measurements you can show us to support these assertions.

There's no assertions being made. You know I don't save anything. I make many, many measurements, confirm what the measurements show me and fa-git-about it. If you don't want to work with what I share, then don't. I'm passed worrying what you or others think about what my personal measuring experiences are.

What I did was make a boatload of measurements, seeing how minor changes affected graphed REW measurements. And when REW showed me what was what with what, I believed what REW was showing me.

We all know about nulls and locatability, so there's no argument on that point. I've found each driver set adds it's own signature to a room's acoustic measurements. I collect a measurement, make "parametric" setting changes accordingly, collect and graph more data and adjust according to what each progressive data collection set shows me. After five or six measurements, I start erasing captured data as there's no purpose to saving it. There is no argument as this is something anybody with room measuring capability is easily able to confirm for their room's acoustics.

If your bolded comment is intended for my benefit, I'll stop communicating with you as personally, I'm well aware of bass management and what the LFE channel's purpose is and I'm quite comfortable with my measurements and what is being graphed.
post #49 of 76
Quote:
Originally Posted by BeeMan458 View Post

We all know about nulls and locatability, so there's no argument on that point. I've found each driver set adds it's own signature to a room's acoustic measurements. I collect a measurement, make "parametric" setting changes accordingly, collect and graph more data and adjust according to what each progressive data collection set shows me. After five or six measurements, I start erasing captured data as there's no purpose to saving it. There is no argument as this is something anybody with room measuring capability is easily able to confirm for their room's acoustics.

Right. So why would someone who goes to a a lot of trouble to measure, EQ and calibrate their setup then feel that there is a need to unnecessarily truncate the LFE channel? It makes no sense at all. The engineer who mixed the soundtrack put exactly what he intended into the LFE channel and speaker channels in the 80Hz to 120Hz range. Why would you not want to reproduce the soundtrack exactly as intended, especially after going to a lot of effort to measure, EQ, and calibrate your setup? That is the whole point.

(I can't remember whether your measurements are particular peaky in that region or not. IIRC, though, you had a trough there.)

Chris is pretty emphatic about the 'LPF of LFE' setting, here, don't you think?
https://audyssey.zendesk.com/entries/321931-LPF-on-LFE

Quote:
Originally Posted by BeeMan458 View Post

If your bolded comment is intended for my benefit..................

It is interesting that you would use the word "benefit" because I do not think you are willing to listen. wink.gif
post #50 of 76
Quote:
Originally Posted by sivadselim View Post

Right. So why would someone who goes to a a lot of trouble to measure, EQ and calibrate their setup then feel that there is a need to unnecessarily truncate the LFE channel? It makes no sense at all.

Looking at the results of the measurements, it makes all the sense in the world as two of the sub's LPF are set to 120Hz and one of the subs is set to 70Hz. I go by what the measurements tell me, not what an expert tells me how things should be. Experts will get me in trouble and then with a straight face say it's my fault for listening to what they have to offer.

Quote:
It is interesting that you would use the word "benefit" because I do not think you are willing to listen. wink.gif

And you'd be wrong. I encourage everybody to acquire room measuring capability and measure the results of settings and note how minor changes will influence measured results as opposed to trying to use the cookie cutter approach recommended by experts, not measure the room and for their lack of effort, most assuredly not understand why they're failing to get the results they're wanting......and they did everything exactly like the experts told them to.

-
Edited by BeeMan458 - 5/5/13 at 1:49pm
post #51 of 76
Quote:
Originally Posted by BeeMan458 View Post

Looking at the results of the measurements, it makes all the sense in the world as two of the sub's LPF are set to 120Hz and one of the subs is set to 70Hz.

Now you are truly affirming that you don't know what we're talking about, here.


Quote:
Originally Posted by BeeMan458 View Post

And you'd be wrong.

Apparently I'm spot-on.
post #52 of 76
Quote:
Originally Posted by sivadselim View Post

Now you are truly affirming that you don't know what we're talking about, here.

And well it shouldn't as my comment was to something you commented about when you posted:

Quote:
Right. So why would someone who goes to a a lot of trouble to measure, EQ and calibrate their setup then feel that there is a need to unnecessarily truncate the LFE channel? It makes no sense at all.

Your comment had nothing to do with the thread so it would rationally be expected for the reply to not reflect the content of the thread.

I'm going stop replying to your comments in regard to this matter.
post #53 of 76
Quote:
Originally Posted by BeeMan458 View Post

I'm going stop replying to your comments in regard to this matter.

Yes, you would be much better off not posting at all. smile.gif
post #54 of 76
Quote:
Originally Posted by Bill Fitzmaurice View Post

The fly in that ointment is that we never listen to 40Hz or 15Hz or 80Hz signals. We listen to complex waveforms that consist of literally hundreds to thousands of frequencies produced simultaneously.
.

Exactly!!!! That is what I have been saying. Speed of the driver (As I perceive it and believe many others do) is not relative to a certain frequency and therefore its relative oscillations per minute but the drivers ability to reproduce the complex waveforms without muddying them as compared to the original input signal.
post #55 of 76
Quote:
Originally Posted by craig john View Post

Slow and fast are descriptions of "speed." Speed is calculated as distance traveled over time. With cars, we talk about "miles per hour." "Light-speed" is a measure of the distance light travels in a year. The speed of sound is described in feet per second.

A subwoofer driver's "speed" is described in oscillations per minute, (oscillations being distance traveled "back and forth" over time.) This is measured in "cycles per second" or, "Hertz", (as named after the physicist who first described them, Heinrich Hertz), or abbreviated as "Hz." Each Hz is a specific number of cycles per second, and each Hz is a "note." A 40 Hz note is 40 cycles per second. An 80 Hz note is twice as many cycles per second as a 40 Hz note. A 20 Hz note is half as many cycles per second as a 40 Hz note.

I say all of the above to make the following point: If a subwoofer can reproduce a note, it is BY DEFINITION "fast enough" to reproduce that note If it were playing "slower", (or "faster"), it would be playing a different note. eek.gif

Bottom line, there is no such thing as "slow bass" or "fast bass." These are meaningless descriptions that don't describe anything about the physical properties of a subwoofer. People should stop using "slow" and "fast" to qualify or quantify the characteristic of a subwoofer. If one wants to take about the time domain response of a sub, then discuss the transient response, or the dampening characteristics, or the room interactions of the sub. Let's be more precise with our terminology.

Craig

Though technically correct on the definitions this is not correct in this context. oscillations per minute do not describe any amount of distance traveled over time, only the amount of times the object moves back and forth in a given amount of time, not the distance it traveled in those back and forth movements. Your definition only describes frequency. Just to be more precise.
Edited by Mr. Bubbles - 5/5/13 at 5:55pm
post #56 of 76
Quote:
Originally Posted by Bill Fitzmaurice View Post

There are actually two speed factors. One is that described above, which is related to time. The other is the velocity of the cone, which is related to distance. As excursion increases in proportion to voltage applied the velocity of the cone also proportionally increases. For instance, if voltage swing, and therefore excursion, is doubled, the velocity of the cone is also doubled, so that it may cover twice as much distance within the same time period.

Exactly again! This is what I have been arguing. I would like to add to the car analogy though in an effort to describe my explaining why Mms is a factor in this while describes as being unimportant in the previous related article. You may compare many different types of cars like a Kia to a Bugatti or VW to a Ferrari, etc. But for this case lets assume to almost Identical cars (top fuel dragsters for example). They have the exact same everything except weight. This may or may alter the ultimate top speed but within a given distance of travel (drag-strip (or Xmax for speakers)) it can very easily determine ho quickly the car gets there. In other words the acceleration and deceleration are greatly effected by the weight. As we also say in racing weight = horsepower.
post #57 of 76
Quote:
Originally Posted by DonH50 View Post

Many years ago during a study that included measurements and listening we found what people called "speed" was most closely correlated with a sub that did not ring after a pulse. That is, subs that were poorly damped/controlled and exhibited several (or many, in some cases) cycles of damped ringing/decay after the signal stopped were almost universally deemed "slower" by listeners.

Again this is what I have been saying I believe most people describe as speed in a speaker, but also extending it to not just the ability of the speaker to stop after a signal is removed, but the speakers ability to change and control itself during playback of the information.
post #58 of 76
Quote:
Originally Posted by Mr. Bubbles View Post

Speed of the driver (As I perceive it and believe many others do) .................

But the original poster was not describing the "speed" of the driver. Nor is that what most in this thread were discussing, We were discussing the errant use of the terms "fast" and "slow" as used to describe the sound of a subwoofer's bass. Which really has nothing to do with the "speed" of the driver's movement,
post #59 of 76
Quote:
Originally Posted by Mr. Bubbles View Post

Exactly again! This is what I have been arguing. I would like to add to the car analogy though in an effort to describe my explaining why Mms is a factor in this while describes as being unimportant in the previous related article. You may compare many different types of cars like a Kia to a Bugatti or VW to a Ferrari, etc. But for this case lets assume to almost Identical cars (top fuel dragsters for example). They have the exact same everything except weight. This may or may alter the ultimate top speed but within a given distance of travel (drag-strip (or Xmax for speakers)) it can very easily determine ho quickly the car gets there. In other words the acceleration and deceleration are greatly effected by the weight. As we also say in racing weight = horsepower.
The problem with your analogy is that it would only be accurate if it was comparing a 2000 pound and a 4000 pound car, both driven by 10,000 HP turbofan jet engines. That would be a fair comparison, as the Mms relative to the force provided by the driver motor is miniscule.
post #60 of 76
Quote:
Originally Posted by sivadselim View Post

But the original poster was not describing the "speed" of the driver. Nor is that what most in this thread were discussing, We were discussing the errant use of the terms "fast" and "slow" as used to describe the sound of a subwoofer's bass. Which really has nothing to do with the "speed" of the driver's movement,

Ok now I know where we are discussing different things. i was discussing driver/system characteristics while you were not.
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