Christian,
But does damping really hurt the highs? It's one of those things that seems intuitively obvious, but is it so? Pettals doesn't seem to think so. The sims below (on axis SPL) compare Q's ranging from 1000 (blue) to 3 (yellow) for an otherwise identical free (FFFF) panel. Above about 500 Hz, the only effect of lower Q (higher damping) seems to be smoother response.
Eric
By this way, this assumes that the plate is made of something like acrylic where the properties don't change much over the audio frequency range. Gatorboard, by contrast, will show very high-Q modes at low frequencies but "damp" high frequencies very effectively (meaning effectively low-pass filter them out of existence), and it's for a completely different reason related to the sandwich board structure (as discussed previously in this thread).
Steve, you are the Burt Munro of DML's! (The World's Fastest Indian) I mean that as a well deserved complement! A great story and film.
Hello Eric,
It is also what my engineer's brain tells me.
In an other hand, I also know Steve (@spedge ) has a much better hear than mine, hours of experiments and training over all the panels he tested and other audio activities, that I think it is an element of the DML jigzaw to take into account and to try to place in the overall picture.
Dave just before reminded how complex the damping over the frequency can be.
An other possibility, because nothing says it is in the physics of the panel, was proposed by Rui (@RMAM ) that DML could have an effect of reverberation. So it would be then psychoacoutics.
Just to list what comes to my mind just now.
Christian
That`s my listening impression also, and that`s why i use PMMA.
Nowadays active for convenience (i use a stack of alpine pdx 4.150 and 1.100 (sub only) with internal crossovers).
In the serious system is hibrid, passive for panels/conventional speakers and active for the rest.
Good auditions.
Hello Eric.
This is one of my drawings I sent to Christian in February and my comments on WhatsApp.
What are your thoughts.
Steve.
Hello Christian.
Sorry for the delay.
I have been doing too much lately.
I even forgot about the Bristol audio show last week 😭
This is the (not very good) drawing of the coil foot of an audio exciter .
I am imagining the frequency to be above 8k to 20k not 2hz as usually depicted in tin can mode.
The two black dots at opposite sides of the foot ring are just single points of vibrations that send out waves into the central area of the coil.
You can see how choppy it gets towards the centre.
For clarity, I have not shown the waves reaching the other side, or the other clear dotted areas that will also be radiating waves into this area.
As you can imagine, the whole central area will get far messier.
Producing large variations in the response in this ring area.
Cancellations and peaks.
This is comb filtering taken to another level.
This produces a very harsh sound to my ears and removes clarity and depth of imaging .
Obviously these are my imaginations, it would be interesting to see a program that could show what really happens in this area in the 8k to 20k or even above and below this.
I am sick and tired of seeing the central area always depicted as just bobbing up and down in slow motion, and calling it the oil can resonance.
I look forward to your opinion on this theory in my head.🤯
This is how I see the problem.
What will the computers make of it ?
Steve.
This is one of my drawings I sent to Christian in February and my comments on WhatsApp.
What are your thoughts.
Steve.
Hello Christian.
Sorry for the delay.
I have been doing too much lately.
I even forgot about the Bristol audio show last week 😭
This is the (not very good) drawing of the coil foot of an audio exciter .
I am imagining the frequency to be above 8k to 20k not 2hz as usually depicted in tin can mode.
The two black dots at opposite sides of the foot ring are just single points of vibrations that send out waves into the central area of the coil.
You can see how choppy it gets towards the centre.
For clarity, I have not shown the waves reaching the other side, or the other clear dotted areas that will also be radiating waves into this area.
As you can imagine, the whole central area will get far messier.
Producing large variations in the response in this ring area.
Cancellations and peaks.
This is comb filtering taken to another level.
This produces a very harsh sound to my ears and removes clarity and depth of imaging .
Obviously these are my imaginations, it would be interesting to see a program that could show what really happens in this area in the 8k to 20k or even above and below this.
I am sick and tired of seeing the central area always depicted as just bobbing up and down in slow motion, and calling it the oil can resonance.
I look forward to your opinion on this theory in my head.🤯
This is how I see the problem.
What will the computers make of it ?
Steve.
Attachments
The damping properties of using different materials and the roll surrounds on cone speakers, and tweeter domes, has been well documented over the years.
DML panels are no exception.
They will react the same, with different damping methods and materials.
Dome tweeters are a prime example, soft Dome tweeters are renowned to have a soft smooth sound but different hard dome materials tend to sound harsh and bright.
Eric says that his response plot shows a smoother response above 500hz, this causes a smoother soft sound which is not natural and tends the make music sound boring and lacking in life.
Many UK speakers in the 1970s souned like this, usually for classical and smooth jazz 😎.
Prog rock was OK ish, but heavy rock, ........forget it !
Steve.
DML panels are no exception.
They will react the same, with different damping methods and materials.
Dome tweeters are a prime example, soft Dome tweeters are renowned to have a soft smooth sound but different hard dome materials tend to sound harsh and bright.
Eric says that his response plot shows a smoother response above 500hz, this causes a smoother soft sound which is not natural and tends the make music sound boring and lacking in life.
Many UK speakers in the 1970s souned like this, usually for classical and smooth jazz 😎.
Prog rock was OK ish, but heavy rock, ........forget it !
Steve.
spedge said: "Eric says that his response plot shows a smoother response above 500hz, this causes a smoother soft sound which is not natural and tends the make music sound boring and lacking in life."
Steve, that`s a complex thought, let`s see:
- a smoother response is not necessarily correlated with a "smoother soft sound", it`s just a trasduction property which tends to a lesser or null audio processing;
- so "smoother response" is to be considered as "neutral", and, at a glance, it seems to be what most is aiming for,
- "which is not natural", well what is not natural will be the sound signature of materials added to the recording, so a smoother response, i.e, less peaks and dips, is the way to go;
- "and tends the make music sound boring and lacking in life": well the psychoacoustic is overwhelming. How many systems change their sonic character by increasing soun pressure? The Fletcher-Munson curves are a way to explain those changes.
On other hand, hear the presence zone of spectrum (the life of music) in almost all studio monitors, voicing, or better, go to a studio and hear a mixing engineer working, and compare to hifi reproduction. Maybe some of us will consider that studio sound is realistic but tiring for continuous listening experience (i,e, excess of liveliness that reduce life musical enjoyment to few minutes).
Nevertheless, the reason why i enjoy DML is precisely because they are not neutral, by acoustic measurements, but they easily convey a psychoacoustical context which many studio engineers are struggling to have in their recordings with a plethora of processing gear.
Steve, that`s a complex thought, let`s see:
- a smoother response is not necessarily correlated with a "smoother soft sound", it`s just a trasduction property which tends to a lesser or null audio processing;
- so "smoother response" is to be considered as "neutral", and, at a glance, it seems to be what most is aiming for,
- "which is not natural", well what is not natural will be the sound signature of materials added to the recording, so a smoother response, i.e, less peaks and dips, is the way to go;
- "and tends the make music sound boring and lacking in life": well the psychoacoustic is overwhelming. How many systems change their sonic character by increasing soun pressure? The Fletcher-Munson curves are a way to explain those changes.
On other hand, hear the presence zone of spectrum (the life of music) in almost all studio monitors, voicing, or better, go to a studio and hear a mixing engineer working, and compare to hifi reproduction. Maybe some of us will consider that studio sound is realistic but tiring for continuous listening experience (i,e, excess of liveliness that reduce life musical enjoyment to few minutes).
Nevertheless, the reason why i enjoy DML is precisely because they are not neutral, by acoustic measurements, but they easily convey a psychoacoustical context which many studio engineers are struggling to have in their recordings with a plethora of processing gear.
Hello Rui,
This is an interesting new way to think about DML in this trhead.
In one of your previous post: #13620
(Thank you for the links in this post about reverb)
Do you have more now on that?
I would be interested by some IR (at their final level) of some "pleasant" reverbs, ie for vocals to see how it looks like from a spectrogram view. Do you have that?
Christian
It is not the smooth response that is the problem, it is the method used to attain it.
A flat frequency response is not the same as a smooth sound.
I have made panels that have very flat frequency response curves, but sound excellent.
I have also made panels that also have flat frequency responses, but they sound boring.
It is to do with the materials used and the methods used to try and make them sound or measure better.
You have to understand what makes a good panel and what makes a bad panel.
I like my panels to sound clean clear and uncoloured full of detail.
I am not keen on adding reverberation to enhance the sound, panels that do add reverberation would end up in the bin pretty quickly.
As for Recording studios ???
Steve,
I'm inclined to think the simulations that show the central area bobbing up and down are pretty much correct, as boring as that may be. I have no reason to doubt them. Also, I did my own model using my finite element program (sadly I could model only a beam and not a plate) and it showed pretty much the same thing. Before doing the model I kind of expected the exciter area to look more like it was "riding the waves" that reflected back and forth across the panel. It did, but only at low frequency. Once the frequency starting getting pretty high the bobbing motion appeared.
Eric
And just to be clear, I never said a smoother freq. response was better (or worse) than less smooth. I only shared evidence from Pettals that suggests that even quite high damping levels "don't hurt the highs". By which I meant do not reduce the high frequency SPL. Is there level of damping at which the SPL is reduced, sure, but it's a pretty high level it seems. Now if you want to debate other aspect of the high frequency sound beyond just the SPL, be my guest, but don't bring me into that. When people start talking about sound that is "neutral, or "smoother", or "boring", or it's "psychoacoustical content, I don't want any part of that.
Eric
Eric.
Do you believe that the centre of a 25mm is bobbing up and down just like the slow motion bubble animation at 20k.
I did not bring up any psychoacoustical conten.
The difference in sound and measurement between a light paper cone and a heavily damped paper cone using mastic for instance has been well known for many years.
Some materials like XPS will sound soft and dull, while glass will sound hard and bright.
This is not psychoacoustics.
Steve.
Do you believe that the centre of a 25mm is bobbing up and down just like the slow motion bubble animation at 20k.
I did not bring up any psychoacoustical conten.
The difference in sound and measurement between a light paper cone and a heavily damped paper cone using mastic for instance has been well known for many years.
Some materials like XPS will sound soft and dull, while glass will sound hard and bright.
This is not psychoacoustics.
Steve.
Hello Eric
Don't be afraid ;-)
There are some well established facts in psychoacoustics like loudness contours, the cochlea filter bank (close to spectrograms), the frequency and time masking (used in the compressed file formats), the precedence effect (note fully clear for me this one!), the time horizon of echo, the role of the early reflections depending of their delay and level... for what I have in mind quickly right now.
I agree there is a risk to put behind it unverified things.
Christian
But if you take away that "there's something special about the sound", what are the big benefits of a dml panel as opposed to a conventional speaker?
I'm intrigued by the "special"sound, but also interested in the broad spread and dipole pattern of this panel. But I think most people don't care for these aspects.
In practice using these panels in larger spaces is not as easy as I had hoped, thought, and been told.
Hans
HvdZ.
What are these larger spaces that you are trying to use the panels in ?
I have only tried once to take my rigid ply panel outside.
It seemed to work quite well, but I did not want to upset the neighbours to much, so it was a very short experiment.
Steve.
What are these larger spaces that you are trying to use the panels in ?
I have only tried once to take my rigid ply panel outside.
It seemed to work quite well, but I did not want to upset the neighbours to much, so it was a very short experiment.
Steve.
Hello Hans,
I am intrigued too. For pure technical point of view, I agree. The main characteristics of a DML are the wide radiation pattern, the dipole with sources being frequency dependant, its wide bandwidth. Even if we have sometimes difficulties, it is remarkable to cover roughly 300Hz to 10kHz with such a large membrane.
Christian
Christian.
Even my 6x9inch panels have a response from around 160hz to 20k with a little help from a few weights.
This is my in room response.
The video I sent you of my card panel had a remarkable full sound for its size, which I commented on.
It played the music and microphone sounds surprisingly well for such a small panel.
Even if I did get a little bit carried away 🤣
Steve.
Even my 6x9inch panels have a response from around 160hz to 20k with a little help from a few weights.
This is my in room response.
The video I sent you of my card panel had a remarkable full sound for its size, which I commented on.
It played the music and microphone sounds surprisingly well for such a small panel.
Even if I did get a little bit carried away 🤣
Steve.