Yes I saw their curves. That's the first thing that made me look again... It's just not physically possible for a driver with the same BL, Re and similar Cms to all the other drivers, to have 20db better sensitivity.
That's why I doubt the Dayton measurement.
Here's the formula to find efficiency (in %) given BL, Re and Cms for any magnet/voice-coil motor:
Plugging in the values from the Dayton datasheet, one gets an efficiency of over 8,500%. I think this is inaccurate.
The Cms figure on the datasheet is 0.0001mm/N. And I think this is why the above is inaccurate.
However, the Billionsound factory data figure for Cms for the same driver is 133.6mm/N.
This results in an efficiency of 0.64%. And THAT sounds accurate!
I suspect Dayton Audio needs an audio engineer on their staff. 🙄🤣
Never found much value in listening to phone recordings to evaluate speakers, so I haven't listened to them.
But I noticed right away on my first panel that it needed damping, and been tweaking and adjusting damping to get best possible sound from my plates since then.
Perhaps if I had your genius design, suddenly ringing would not be an issue like on the all the different PC, wood, thermoplastic and styrofoam plates of different sizes with different exciter configurations I tried. But for simpletons like myself I end up in the same situation as for example Tectonic, and need to dampen my plates.
But I noticed right away on my first panel that it needed damping, and been tweaking and adjusting damping to get best possible sound from my plates since then.
Perhaps if I had your genius design, suddenly ringing would not be an issue like on the all the different PC, wood, thermoplastic and styrofoam plates of different sizes with different exciter configurations I tried. But for simpletons like myself I end up in the same situation as for example Tectonic, and need to dampen my plates.
I have to say that I think REW is absolutely amazing, and is absolutely free. There is a bit of a learning curve, but it's worth the effort.
So, just to be clear, we are talking about an adaptation for using the impulse technique to measure the elastic modulus, E, right? You are right that there are indeed lots of ways you could support and excite the beam for this test, and then calculate E, as long as you have the equation relating fundamental frequency and modulus for that configuration. And indeed you could drive the sample with an exciter. But the way that seems to work best, is as shown in this video for the "Resonalyser" instrument:
If you don't want to watch the whole thing, just watch from about 1 minute to 2:45. Rather than supporting the beam on rods or the like, they actually hang it from strings. They don't mention it in the video, but the support points are ideally 0.22 times the beam length from either end. The reason for this is that those points are nodes (points that don't move), for the fundamental bending mode, and hence, supporting the beam there has virtually no influence on its frequency of vibration. So you can then use the equation for a so called "free-free" beam, which is well known (below).
You could use an exciter to drive the beam, but adding the exciter changes the natural frequency, so you'd have to be able to account for that somehow. It can be done, but the easier way is simply to tap the beam without an exciter, and not have to worry about the effect of the exciter itself.
In the video, they show how they use an accelerometer to measure the beam vibration. But with REW and a mic, you don't need an accelerometer at all. With REW in RTA mode, place the mic very close to the center of the beam, tap the beam, and watch the signal on REW. There will be peaks in the mic response corresponding to the beam natural frequencies. Find the frequency of the lowest peak, and use it in the appropriate equation (see below). In the video, they mention how the software corrects for the effect of the accelerometer mass, but if you use the mic signal instead, there's no need for any mass correction!
The equation for modulus is here. It's actually a bit simpler than it may appear, as the correction factor (T) is negligible as long as the beam is more than 20 times longer than its thickness. There's no need here for the Resonalyser computer, as this can be easily set up and calculated in Excel.
Eric
I can't argue with that. But as Andre said, the point of the damping is to affect the sound.
As far as damping of cones is concerned, I think Andre correctly points out the a surround provides some damping. That said, I think that a DML is a bit like a transmission line cone speaker. A transmission line (TL) layout has some advantages over others, but introduces lots of resonances. In a good TL, these are mitigated by heavily damping the line with Acousti-Stuf or similar.
Eric
Cone speakers haver rubber roll surrounds, really!
And what is that for, can you explain more Clearly why .
The answer may give a clue why they are flawed.
Steve.
Eric, leob.
I think we are getting damping mixed up with tuning, instruments are tuned for a certain sound to the instrument in question.
A hi fidelity speaker should have as little sound of its own, only natural sounds.
Once damping is added, you cannot get away from this smooth softness , lacking in life and sparkle.
Steve.
I think we are getting damping mixed up with tuning, instruments are tuned for a certain sound to the instrument in question.
A hi fidelity speaker should have as little sound of its own, only natural sounds.
Once damping is added, you cannot get away from this smooth softness , lacking in life and sparkle.
Steve.
Without damping of the cone, the cone can vibrate freely, which means it will take time to settle from an impulse. That causes cone movement that is not part of the signal and that causes interference.
There are really two similar but separate issues with a free plate.
First of all the impulse does not only create a wave in the structure of the plate, but causes the whole plate to swing.
Adding just a little damping stops the plate from swinging freely, and instead the only motion generating sound is the motion exciters induce directly to the plate. An undampened plate will have worse LF reproduction compared to a very carefully dampened plate because of the cancellations this results in. Strict damping on the other hand will reduce the LF reproduction by resisting the motion of the plate that are actual waves in the material from the exciter.
The second issue is that the waves in the material will bounce back and forth for a longer time if plate is not dampened. This is the ringing chorus like effect in mids and treble of a undampened plate. Like I said it can sound good on some material as an effect, so it is like having high THD. It can sound good sometimes, and if you want it is a matter of taste. But it is degrading the fidelity, and IMO makes a lot of music sound worse.
Just a little extra info. regarding driver suspension >
I actually owned an 8" pair built as 2way speakers that I foolishly left with someone who disappeared > GONE!
They do use 2x spiders, hence, the reality of damping.
https://www.google.com/search?q=fos...YCsICBhAhGAoYCsICCBAAGIAEGKIE&sclient=gws-wiz
More info on damping:
There are generally TWO locations for support on a basket piston cone, one is the surround, and the other is the spider. The spider sits around the voice coil, just above the pole gap, and ensures that the voice coil is centred in the pole gap. The other support is the surround that connects the edge of the cone to the basket and which also keeps the coil vertical.
If all of the idiots who have been designing loudspeakers since the 1920's wanted to have completely undamped, free-moving cones and spiders, then they would have needed only six (three for the spider, and three for the surround) spring steel or carbon fibre leaves to do the job of keeping the coil centred and vertical. This would be completely sufficient to ensure that there's zero damping on the coil and cone (besides the unavoidable damping caused by the reverse EMF of the coil in the magnetic field.)
A patent does exist for "edgeless" speakers which is an attempt to describe reduction of "resonance caused by elastic edges" in speaker surrounds, 🤦♂️ but it seems that the inventor has only a vague grasp of the relationship between resonance and damping in speakers. He's not a speaker designer.
There are generally TWO locations for support on a basket piston cone, one is the surround, and the other is the spider. The spider sits around the voice coil, just above the pole gap, and ensures that the voice coil is centred in the pole gap. The other support is the surround that connects the edge of the cone to the basket and which also keeps the coil vertical.
If all of the idiots who have been designing loudspeakers since the 1920's wanted to have completely undamped, free-moving cones and spiders, then they would have needed only six (three for the spider, and three for the surround) spring steel or carbon fibre leaves to do the job of keeping the coil centred and vertical. This would be completely sufficient to ensure that there's zero damping on the coil and cone (besides the unavoidable damping caused by the reverse EMF of the coil in the magnetic field.)
A patent does exist for "edgeless" speakers which is an attempt to describe reduction of "resonance caused by elastic edges" in speaker surrounds, 🤦♂️ but it seems that the inventor has only a vague grasp of the relationship between resonance and damping in speakers. He's not a speaker designer.
If some one is interested in mounting a panel cone style why not get on with it. The requirements aren't as extreme as a cone speaker so simple suitable wide strips of some thin substance would do the job.
A cone speaker needs the arrangement it uses to support the cone which can have varying degrees of pistonic action. Variations in that, Xmax, limit the obtainable spl as the drive frequency is reduced.
A cone speaker needs the arrangement it uses to support the cone which can have varying degrees of pistonic action. Variations in that, Xmax, limit the obtainable spl as the drive frequency is reduced.
@Veleric, you seem to prefer Revolution (5 ply) plywood. Wish we could source that here. Or Beech plywood.
Do you have a gut feel for what the smallest panel size in 5 ply would be to still give satisfactory results if we cut off the LF at say around 100 Hz? I know it is bit of an unfair question. Just trying to establish a practical size for my next planned build. And I want to try and keep the panels on the smaller size for a smallish lounge and WAF.
I made Tall Blondes (300 mm x 1200 mm) before, but they were a bit oversized for my room. The plan is to also mount the panels in frames which will add to the overall size.
Eric, leob.
I'm glad you mentioned free edge cones.
Further back on this forum, I mentioned G A Briggs book loudspeakers.
In it he describes, with a picture, of the free edge cone they used to make.
They had to stop production, not because it was bad performing, but because it was too expensive and difficult to produce, there was also maintenance problems.
So they had to use full surrounds with all the problems that that imposed.
He was very sad as the unit was very good sounding.
This guy trusted his ears, but he had no choice but to move to roll surrounds because it was easier to manufacture and they would get fewer returns to rejig.
As far damping the cone with the roll surrounds, this is also to prevent reflections from the edge of the cone, to try to keep the cone in pistonic mode only or should I say bending wave?
Basically to try and kill any dml action, the last thing I wish to do is prevent dml action.
Willy-nilly Damping the edge of the panel (Depending on panel material ) will alter the frequencies on the panel that you desperately want.
It restricts the vibrations of all the frequencies on the panel, not just the odd ones you wish to remove.
It is very easy to hear the differences this makes.
You are basically using a hammer to crack an eggshell.
Leob.
When I talk about panels, I am talking about home audio for sound precision.
I am not talking about PA speakers that take hundreds of Watts and dBs.
I have not built this type of PA speaker , but I would think it very necessary to use damping of some sort, to prevent some of the bad problems you will , have encountered .
It is a shame that you have not even bothered to listen to my recordings.
I had the decency to listened to your recordings and thought they were pretty good.
But if your shell like ears are too offended by such lowly recordings and you wish to remain ignorant of the sound they can produce, so be it.
Steve.
I'm glad you mentioned free edge cones.
Further back on this forum, I mentioned G A Briggs book loudspeakers.
In it he describes, with a picture, of the free edge cone they used to make.
They had to stop production, not because it was bad performing, but because it was too expensive and difficult to produce, there was also maintenance problems.
So they had to use full surrounds with all the problems that that imposed.
He was very sad as the unit was very good sounding.
This guy trusted his ears, but he had no choice but to move to roll surrounds because it was easier to manufacture and they would get fewer returns to rejig.
As far damping the cone with the roll surrounds, this is also to prevent reflections from the edge of the cone, to try to keep the cone in pistonic mode only or should I say bending wave?
Basically to try and kill any dml action, the last thing I wish to do is prevent dml action.
Willy-nilly Damping the edge of the panel (Depending on panel material ) will alter the frequencies on the panel that you desperately want.
It restricts the vibrations of all the frequencies on the panel, not just the odd ones you wish to remove.
It is very easy to hear the differences this makes.
You are basically using a hammer to crack an eggshell.
Leob.
When I talk about panels, I am talking about home audio for sound precision.
I am not talking about PA speakers that take hundreds of Watts and dBs.
I have not built this type of PA speaker , but I would think it very necessary to use damping of some sort, to prevent some of the bad problems you will , have encountered .
It is a shame that you have not even bothered to listen to my recordings.
I had the decency to listened to your recordings and thought they were pretty good.
But if your shell like ears are too offended by such lowly recordings and you wish to remain ignorant of the sound they can produce, so be it.
Steve.
Eric.
If you could post the patent of the edgeless cone speaker, that would be interesting.
Just to see if his idea is good or bad.
Steve.
If you could post the patent of the edgeless cone speaker, that would be interesting.
Just to see if his idea is good or bad.
Steve.
Steve, we are not talking about "Willy-nilly Damping" but using damping to control the plate to get a tight sound and good FR.
Like I said, for me the need to dampen was immediately obvious on the first plate I did, even at reasonable sound levels. Getting someone to just hold an edge of the plate cleared up the sound and made it more defined. Admittedly that was a polycarbonate plate extra susceptible to ringing, but I found the same issue with EPS, although a bit less pronounced.
I don't think it is about "decency" to listen to phone recordings. If you feel they give you valuable information that is great, but I have to be frank and say that I personally think it is a waste of time. No disrespect to you or your recordings, it is just not my thing.
I can understand your preference for undampened plates, perhaps they suit the kind of music you play and your preference on how a speaker should sound. But I am a bit surprised that you consider damping as wrong or clearly detrimental. It is a bit like someone having an amp with lots of THD telling everyone with clean amplifiers that they have bad amplifiers. Higher fidelity is not bad, even if it might not be what you personally is looking for.
Like I said, for me the need to dampen was immediately obvious on the first plate I did, even at reasonable sound levels. Getting someone to just hold an edge of the plate cleared up the sound and made it more defined. Admittedly that was a polycarbonate plate extra susceptible to ringing, but I found the same issue with EPS, although a bit less pronounced.
I don't think it is about "decency" to listen to phone recordings. If you feel they give you valuable information that is great, but I have to be frank and say that I personally think it is a waste of time. No disrespect to you or your recordings, it is just not my thing.
I can understand your preference for undampened plates, perhaps they suit the kind of music you play and your preference on how a speaker should sound. But I am a bit surprised that you consider damping as wrong or clearly detrimental. It is a bit like someone having an amp with lots of THD telling everyone with clean amplifiers that they have bad amplifiers. Higher fidelity is not bad, even if it might not be what you personally is looking for.
Leob.
If it is not your thing and is a waste of time , why did you post recordings of your speakers ?
Also my panels ,play every type of music going.
Oh , of course you wouldn't know as you have not listened to any of my recordings.
I too have held the panel edges and changed the spread of frequencies, I too thought it sounded promising, but after careful listening, I found it had lost more than I had gained.
As I said in my previous post , I am not interested in building a PA speaker.
Steve.
If it is not your thing and is a waste of time , why did you post recordings of your speakers ?
Also my panels ,play every type of music going.
Oh , of course you wouldn't know as you have not listened to any of my recordings.
I too have held the panel edges and changed the spread of frequencies, I too thought it sounded promising, but after careful listening, I found it had lost more than I had gained.
As I said in my previous post , I am not interested in building a PA speaker.
Steve.
I never post recordings other than to show how the setup looks at events, and certainly never to get feedback about the sound quality of the panel.
Something must be very different since you have come to such a to such a different conclusion. I listen to my panels with all kinds of music at all levels, and have many decades of experience with music production and mastering, so think I have at least a decent ear for what is good reproduction. And to my ears there is no doubt that a free hanging plate gives less fidelity.
Yes you loose more by clamping, specifically ringing and interference. Many people think that can sound good though, and hence many producers use effects like phaser, flanger and chorus, that also adds ringing and interference, to make things sound fatter. On all tracks all the time it is a bit much for my taste though.
Something must be very different since you have come to such a to such a different conclusion. I listen to my panels with all kinds of music at all levels, and have many decades of experience with music production and mastering, so think I have at least a decent ear for what is good reproduction. And to my ears there is no doubt that a free hanging plate gives less fidelity.
Yes you loose more by clamping, specifically ringing and interference. Many people think that can sound good though, and hence many producers use effects like phaser, flanger and chorus, that also adds ringing and interference, to make things sound fatter. On all tracks all the time it is a bit much for my taste though.
Leob.
how many decades have you been designing and building DML panels?
I myself have only been building them for one and a half decades.
The fact that I have been a very keen audio enthusiast for 5 decades has nothing to do with DML knowledge.
The fact you setup PA equipment does not impress me, especially when it comes to DML PANELS.
Steve.
how many decades have you been designing and building DML panels?
I myself have only been building them for one and a half decades.
The fact that I have been a very keen audio enthusiast for 5 decades has nothing to do with DML knowledge.
The fact you setup PA equipment does not impress me, especially when it comes to DML PANELS.
Steve.
Eric.
https://www.diyaudio.com/community/threads/surround-less-spider-less-mid-bass-driver.258526/page-3
I did not realise there was so much information about free edge cone units on this site , this is one .
Is this the guy who made the patent you were talking about.
Steve.
https://www.diyaudio.com/community/threads/surround-less-spider-less-mid-bass-driver.258526/page-3
I did not realise there was so much information about free edge cone units on this site , this is one .
Is this the guy who made the patent you were talking about.
Steve.
I trained my ears to understand audio signals since early 80s. So I can confidently identify issues like ringing and interference since I spent countless hours making mixes, mastering releases using different processes and techniques to analyse and manipulate audio.
So when someone tells my that what I hear is wrong and they know better I will question their credentials.
With 15 years of building panels you must have some really good panels and measurements by now? Care to share graphs with FR, RT60 and distortion for your best panel?
Or you spent 15 years putting together panels nilly-willy without even bothering to take any proper measurements to help refine your designs?
Or are you one of those people who think that hearing is totally objective and measurements are useless? In that case I'm not surprised if you being working with flawed assumptions for such a long time.