Speaker dynamics - what enables it?

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snock

Speaker dynamics - what enables it?
« on: 24 Feb 2010, 05:54 pm »
Hi,

This is probably asking for a text book sized answer but what makes a speaker have great dynamics?  For example if I compared a line source (or efficient pro speaker or whatever) and a N2X.  I have both level matched (at 1khz (?)) and N2X are within their safe limits - the LS will be more dynamic, yes?  But what enables this?  Efficient LS interaction with air?  And is the difference in dynamics identifiable on any typical spec or graph?

I have been in the hobby for quite a while and was a physics guy in college.   I feel like I should have all the pieces to work this out but its stumping me.  Thanks

PS- Point me toward books/articles etc. if that is easiest.

nickd

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Re: Speaker dynamics - what enables it?
« Reply #1 on: 25 Feb 2010, 04:43 pm »
Danny is the expert here,
That said, in my expierence, a combo of an efficent driver set (+90db), simple (but correct) crossover and enough driver surface area to excite serious air seem to make the difference. Line source designs have an advantage because sound pressure loss as you back away from the speaker is 1/2 that of a point source.

Check out Dannys "Super V" design. 3 ea 12" drivers and a 4" mid/tweeter at 97db 1 watt, 1 meter (the 2ea 12" subs are powered). That will give you the goosebumps your looking for :eyebrows: 

Hank

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Re: Speaker dynamics - what enables it?
« Reply #2 on: 25 Feb 2010, 06:40 pm »
What nicd said about the line source spl fall-off being less than point source regular speakers at the same distance.  Line source sound radiates as a half column forward as opposed to the spherical radiation of point source speakers.  Also, line sources, with their multiple drivers do move some "serious air".  Another benefit is that multiple drivers in a line source each have to move their cones a lot less than the typical 2 or 3 drivers in a regular speaker to get the same spl, thus are all operating in their lowest distortion pistonic area, with voice coils staying well within their magnet gaps.  There's probably a clearer way to say that :scratch:

m-fine

Re: Speaker dynamics - what enables it?
« Reply #3 on: 26 Feb 2010, 01:19 am »

Here's my take:  Dynamics are created by several factors which are relatively simple, although not always simple or cheap to achieve.

First, you simply have to be able to move a lot of air relative to your space and distances.  Technically that means displacement, but as Hank alluded to, there are advantages to having a lot of driver area rather than long strokes.  If you do not have the displacement capability, you can only move so much air and achieve clean peaks at certain SPL limits and therefore your dynamics are limited no matter how much power you have.

Next is the ratio of power and sensitivity.  Speakers with a high sensitivity (or a lower roll off with distance like the line source) require less power to hit the same SPL.  If you have 200 watts of clean power, hooking it up to a 97db 1w speaker will give you the same SPL as a 87 db 1w speaker and a 2000 watt amp.  Most of us are severely limited in the amount of clean power we can deliver to the speakers so higher sensitivity speakers like the LS-9's or the V1's allow you to get more dynamics out of the power available.

To a lesser degree you need a low sound floor or high dynamic range.  There needs to be a spread between the quieter sounds and the louder sounds to give you the full perception of dynamics.  These days this is not really hard to get, but I mention it anyway.  You also need to hit a certain SPL level which I think may be related to the dynamic range of our hearing.  Kind of like how sitting real close to a 10" screen does not give the same effect as watching a movie on a 10 foot screen even if the screen width to eye distance ratio is the same.  Going big (loud) has an effect on perception that can not be achieved with the MV dialed back.

Finally, you need decent source material.  It seems obvious, but your speakers can only play the signal you feed them, so if you want to be wowed, you need to give them some decent material to work with.

snock

Re: Speaker dynamics - what enables it?
« Reply #4 on: 26 Feb 2010, 04:43 am »
Thanks for talking this out, guys.   :thumb:

So the big parts of the puzzle I am hearing so far are

Efficiency - contributes to low distortion through lesser amp stress.  Is line source radiation pattern factoring in under efficiency?
More drivers - lower distortion through shared load
Power handling - creates the peaks.  I get this one.  More power in means more out.   But see my example below.


So in an example of a bookshelf , say an n2x, playing with 2watts (something easy for amp and speaker) with and a level matched pair of super V at same SPL level playing the same tracks will the super V be more dynamic?  If they are level matched how can that be?  Are dynamics all about 'going to eleven'?  I think the answer is no but.... :duh:

I must be missing something easy or assuming something I should not.   Could it all be a distortion game?  Even at such low levels?  uggh  :?

Danny Richie

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Re: Speaker dynamics - what enables it?
« Reply #5 on: 26 Feb 2010, 05:00 am »
I held off on answering this one until I had a little bit of time. The problem is that I never have any time. Even now, it is really late at night.

Most think of dynamics like the range to go from soft to loud. And it is true that this is dynamic range in a true sense. It is more than that though. More than just playing loud. And m-fine really hit on it.

A speaker can show great dynamics even when not played really loud if it can separate the differences between the soft or dead quiet notes and the peaks. It is the space between the notes, the quiet parts that most speakers loose it.

A single woofer can hit high SPL's with a lot of power and a lot of X-Max. The real problem is that the high moving mass and tons of stored energy that causes the driver to keep on keeping on long after the signal stops.

This is why line sources can be so dynamic. Sure they can hit the SPL, but it is doing so then returning to rest so quickly that sets them apart.

Some of these high sensitivity speakers like the V-1 and Super-V do it really well too, but in a different way. Hitting the high SPL's above 200Hz is not that hard. Having a tight suspension 12" woofer allows it to hit pretty good levels without having to move so far and the suspension brings it back to rest very quickly.

Low frequency ranges are another thing. To hit high SPL's you have to move some air and create some pressure. The way the V-1's and Super-V do it is with light weight 12" woofers being servo controlled. And with 4 total in a pair of speakers it will hit good SPL levels. The cool part, and the thing that really makes them stand out as being super dynamic, is that they so quickly return to rest.

It's the space between the notes that makes all the difference.   

Danny Richie

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Re: Speaker dynamics - what enables it?
« Reply #6 on: 26 Feb 2010, 05:09 am »
Another factor that is an issue in the upper ranges are capacitors. Capacitors are an energy storage device. They store and release energy, and there are big differences to how different types of caps handle this. The slower discharging caps tend to smear the signal and cloud that dead space between the notes and makes the music sound less dynamic.

Another issue is just the noise floor level alone. This can be as associated with the electronics as anything. Having gone to a system now with an extremely low noise floor by being almost totally off the grid really makes a big difference. Dropping the noise floor of everything down to next to nothing REALLY makes a difference. Now everything is a little more dynamic.

stevenkelby

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Re: Speaker dynamics - what enables it?
« Reply #7 on: 26 Feb 2010, 11:40 am »
Agree with everything above by m-fine and I was going to post the same things as Danny about the low SPL instants in between high SPL instants.

Here's my understanding of that bit, correct me if (where) I'm wrong!

Snock, to answer your thought experiment (without having heard any GR speaker yet), imagine a speaker with good dynamic range and one with poor dynamic range, both set to the same SPL level, both comfortably within their limits, both happy, at medium volume.

Now imagine a Double Bass or Cello note, one string is vibrating, centered at say 100Hz. The sound on the source material is theoretically going from quiet to loud, 100 times per second. The speaker with bad dynamics isn't actually going very quiet though, it's staying louder during the quiet bits, adding it's own sounds that shouldn't be there.

Both speakers will hit the same peak SPL, but the one with great dynamics willl hit a lower minimum SPL during that note, if it were possible to measure that (you would need a pretty fast DB meter! :) )

Great dynamic range sounds like silence between the individual vibrations of the string. It sounds like better resolution, more detail etc, etc, but really, it's just better dynamic range.

Capacitors have the same effect as Danny said. It's about starting and stopping the music quickly, and only reproducing what is in the recording, not all the other sounds that all systems introduce on their own.

Does that make sense?

Out of curiousity, is it possible to measure the SPL range of a note at say 100HZ (or 10'000HZ) and see in a graph what the SPL level does 100 times (or ten thousand times) a second? Does equipment to do that exist?

Could that be the area of sound that we can hear but not measure? I'm thinking of cable debates and things here.
 

snock

Re: Speaker dynamics - what enables it?
« Reply #8 on: 26 Feb 2010, 12:32 pm »
Ok. Thank you.  Thank you.  Thank you, Everyone for posting!   This makes sense now.  You guys rock. :D

And so my last question from above is

"Is there a typical mesurement that would be an indicator of a speakers with good dynamics?"   

Would it be transient response?  Or is there no real way to know without doing transient resposnse at several frequncies like stevenkelby suggests?  Anyway, thanks again.

m-fine

Re: Speaker dynamics - what enables it?
« Reply #9 on: 26 Feb 2010, 02:16 pm »
I think you need to look at a number of factors. Driver area and sensitivity would be good clues but not the entire story. Quality of components ( drivers and crossover caps  etc. ) will give you further evidence.  I think based on those factors most of us could make a darn good "guess" before listening tests or looking at any graphs.  Your ears will also tell you quicker than interpreting graphs.

I also dissagree with Danny a bit on the loudness factor. I think you need to play fairly loud to get full effect. The reason I think is because we have a fairly fixed noise floor. Even if your system is 100% silent, your room and your hearing will set a floor. If for example, the floor is 20 db and you are playing at a level with max peaks at 80 db, you will only have a range of 60 db no matter how good the speakers are.  Crank up the volume to allow 115db  peaks in the same room and your range is now 95 db. You also have to account for our non-linear  hearing response in the bass region as well as the physical perception of louder sounds, in particular the lower frequencies. In my experience, the perception of dynamics definitely changes as the volume level goes up ( to a point).   

jdbrian

Re: Speaker dynamics - what enables it?
« Reply #10 on: 26 Feb 2010, 04:15 pm »

Now imagine a Double Bass or Cello note, one string is vibrating, centered at say 100Hz. The sound on the source material is theoretically going from quiet to loud, 100 times per second.

  Hi Folks

  Just thought I'd put in my 2 cents. In the above example the sound is not going from quiet to loud at 100hz. The string vibrates at it's resonant frequency of 100hz and the amplitude of that 100hz tone varies with the decay and attack times of the instrument and how it is played. A stringed instrument like a bass has a long natural decay time so it would take a really really slow driver to not be able to keep up. Percussion is a different matter.
  Compression from heat buildup in the driver Voice coil and port compression in vented systems are also responsible for poor dynamics in many speakers. There are also mechanical limits that come into play at quite low levels with small drivers trying to reproduce low bass notes. When xmax and /or suspension linear travel is exceeded the effect is like a soft limiter(unless it is extreme) . All of these things have the effect IME of causing a sense of strain and lack of realism when you turn up the volume.
   Amps can be clipping as well without any gross distortion evident, which further leads to unnatural sound. The combination of a 85db efficient speaker and a 50w amp is bound to end up restricting dynamics. I have experimented with active low level crossovers and bi/tri amping and dynamics can be improved significantly with this approach.
  This is a good discussion! Lets hear from more people on this. How we percieve dynamics also changes depending on how you are feeling. If you have been exposed to a lot of noise during the day then sit down to listen, your system may not seem that loud compared to if you have been doing something quiet for a while then listen. The percieved dynamic range is expanded on the bottom end as well as the loud bits which makes it all the more important to have good low level linearity in your system.


Cheers
Brian

konut

Re: Speaker dynamics - what enables it?
« Reply #11 on: 26 Feb 2010, 04:50 pm »
"Is there a typical mesurement that would be an indicator of a speakers with good dynamics?"   

Would it be transient response?  Or is there no real way to know without doing transient response at several frequencies like stevenkelby suggests?  Anyway, thanks again.

Transient response is part of it, and yes, at different frequencies. The other part is how long does the cabinet hold on to the energy produced by the drivers. This measurement is presented in a cumulative spectral-decay plot. Check out fig. 9 in this review of the Harbeth HL-P3.
 http://www.stereophile.com/standloudspeakers/1293harbeth/index3.html
Better speakers are made with a triple constrained layer box to dampen unwanted resonance. Open baffle construction is another way to address this problem.

roscoeiii

Re: Speaker dynamics - what enables it?
« Reply #12 on: 26 Feb 2010, 05:13 pm »
And to see if I am understanding it correctly, does the below logic hold up?:

One would get better dynamics with dual subs since they each have to move less air and can thus more quickly and easily return to rest??

I remember "Get Better Sound" recommending dual subs for a number of reasons but don't recall if this was one of them.

cujobob

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Re: Speaker dynamics - what enables it?
« Reply #13 on: 26 Feb 2010, 05:30 pm »
Using more than a single sub has a lot of advantages...better, more even, in-room response (if set up properly), increased headroom, and it would lessen the work of each sub.

When looking for dynamics...design and drivers make the biggest difference.  Caps have an effect, from my experience, but won't tell you much about how dynamic a design is.  Horns/waveguides, line sources, efficient large woofers...those types of things can indicate great dynamics.

Danny Richie

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Re: Speaker dynamics - what enables it?
« Reply #14 on: 26 Feb 2010, 05:47 pm »
Quote
I also dissagree with Danny a bit on the loudness factor. I think you need to play fairly loud to get full effect. The reason I think is because we have a fairly fixed noise floor. Even if your system is 100% silent, your room and your hearing will set a floor. If for example, the floor is 20 db and you are playing at a level with max peaks at 80 db, you will only have a range of 60 db no matter how good the speakers are.  Crank up the volume to allow 115db  peaks in the same room and your range is now 95 db. You also have to account for our non-linear  hearing response in the bass region as well as the physical perception of louder sounds, in particular the lower frequencies. In my experience, the perception of dynamics definitely changes as the volume level goes up ( to a point).   


I don't think we disagree at all. I completely agree with all of that. I was just pointing out the importance of a low noise floor. Two systems playing hard both hitting peaks of 100db may not both sound the same in regards to dynamics. The one with the most dead space between notes will stand out as more dynamic. And most listening rooms will have a noise floor between 40db (really quiet) and 50db. And if you can drop it from 50 to 40 that is 10db more dynamic range.

Quote
The other part is how long does the cabinet hold on to the energy produced by the drivers. This measurement is presented in a cumulative spectral-decay plot. Check out fig. 9 in this review of the Harbeth HL-P3.  http://www.stereophile.com/standloudspeakers/1293harbeth/index3.html

Oh yeah, good point. Cabinet resonances can also smear the output and cloud over the dynamic range of the speaker.

But if you look at figure 9 in that review you will see the spectral decay of the drivers and it is not bad at all.

In figure 10 you will see the spectral decay of the cabinet wall and there are two bad resonances there in that one.

poseidonsvoice

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Re: Speaker dynamics - what enables it?
« Reply #15 on: 26 Feb 2010, 06:42 pm »


I don't think we disagree at all. I completely agree with all of that. I was just pointing out the importance of a low noise floor. Two systems playing hard both hitting peaks of 100db may not both sound the same in regards to dynamics. The one with the most dead space between notes will stand out as more dynamic. And most listening rooms will have a noise floor between 40db (really quiet) and 50db. And if you can drop it from 50 to 40 that is 10db more dynamic range.

Oh yeah, good point. Cabinet resonances can also smear the output and cloud over the dynamic range of the speaker.

But if you look at figure 9 in that review you will see the spectral decay of the drivers and it is not bad at all.

In figure 10 you will see the spectral decay of the cabinet wall and there are two bad resonances there in that one.

I strongly agree with Danny w/regards to minimizing noise and maximizing signal (i.e. signal to noise ratio). This is where an excellent room makes all the difference. And limiting vibrations from HVAC, using flexible ductwork, etc...the quieter the room, the more easily dynamic range be heard and appreciated. Floyd Toole goes into this in some detail in his latest book. For those with extra $$$, a dedicated room built from the ground up is a very worthwhile investment and MUCH cheaper than uber expensive amps, etc...the room will always be the elephant holding things down.

Anand.

tasar

Re: Speaker dynamics - what enables it?
« Reply #16 on: 26 Feb 2010, 08:22 pm »
Dynamics is really best described as the presence or absence of distortion. All unwanted resonance, whether by box, baffle, electronics, or environment, steal the note's enunciation. It is the way the speaker "speaks" that determines it's dynamic quality. If your speaker's design suffers with a "Boston accent", nothing completely solves it's native "tongue", up front attempts to do so only changes but never eliminates inherent distortion. If you want to hear "vowels and consonants" you need clear articulation, the more distinct, the more dynamic. When listening I want the music equally articulate, soft and loud. Many may think what they hear at higher volume is "dynamic", but much could be simply distortion. 

Speaker design is the "whipping boy" of distortion. As with Danny's Super V, the "waveguide" attributes of the coax driver, baffle design, and servo-mechanical woofer control have all to do with dynamics, the result of removing as much distortion as possible. Grid or off the grid feeds not withstanding, when the speaker is "dynamic", everything sounds good !

m-fine

Re: Speaker dynamics - what enables it?
« Reply #17 on: 26 Feb 2010, 09:42 pm »

A speaker can show great dynamics even when not played really loud if it can separate the differences between the soft or dead quiet notes and the peaks.   

this is the statement I said I dissagreed with "a bit"
but I probably was reading too much in to not "really loud".   

I should try to get a noisefloor reading in my room this weekend. I think it is quite low because there is no forced air, and cinderblock walls between the room and the rest of the basement, and another 2 foot rock wall to get to the mechanical room. The thick blanket of snow also helps. If the wind is not blowing, it can get real quiet on a winter night.  I am going to guess below 40 db but the meter could prove me wrong.

My electronics are certainly not quiet enough, but we all need to have some areas to upgrade.

drphoto

Re: Speaker dynamics - what enables it?
« Reply #18 on: 12 Mar 2010, 02:30 pm »
Isn't one issue limiting speaker dynamics the compression effect that sets in as volume goes up? From what I understand, when a conventional speaker is driven hard the VC heats up and becomes less efficient. Plus during a loud transient even at moderate volumes the drivers will distort, prompting any sane listener to turn down the overall volume.

Isn't one of the big advantages to pro audio based drivers (in theory) is they can remain much more linear under the conditions of home audio playback?

jdbrian

Re: Speaker dynamics - what enables it?
« Reply #19 on: 12 Mar 2010, 03:47 pm »
Hi

  Pro drivers are usually much more efficient than HI Fi. I think that is because they are generally larger drivers and have higher Fr. Compression due to VC heating will not occur until a much higher level on a 98 db 15" pro woofer than on an 87db 7" hi fi driver.
  I think it is very important to have a low noise floor in your room and also speakers that can resolve small sounds. I live far from any road or city noises and my listening room is in the basement and insulated to stop sound getting in and out.
   Although I sometimes like to crank it up for a bit I find the most enjoyable listening is at a moderate level when the room is very quiet and when I can relax. I can't take really loud levels for long.


Cheers
Brian