Oh, I forgot to say that Joppe inspires me too. I gave a link to Joppe's video before. The image of the back is here.
By the way, Lee De Forest was also using an 'exciter' and Paddock was using a piezoelectric one, only don't know if he had ever made that loudspeaker. I have only those exciters, haven't got any flat magnets yet.
In some way, the convex curve gives more clear and fuller sound somehow than a flat or concave panel. Still pondering on that.
Last edited:
Just compare Lee De Forest's 1925 patent with Paddock's 2001 patent. The drawings are in the pdf file. It's all about edge transfer of sound, or
Here's another strange (?) patent of 1926, granted in 1933. As the present assignee is AT&T Corp, most probably the ideas are/were used somewhere. Convex appears to be the idea, then and now.
Hello
I would like to share (already done?) a reading : the first chapter "How Sound Propagates" of the book Why You Hear What You Hear: An Experiential Approach to Sound, Music, and Psychoacoustics, Eric J. Heller . The access to it is free. The approach is interesting without difficult equations of math. In this chapter :
Christian
I would like to share (already done?) a reading : the first chapter "How Sound Propagates" of the book Why You Hear What You Hear: An Experiential Approach to Sound, Music, and Psychoacoustics, Eric J. Heller . The access to it is free. The approach is interesting without difficult equations of math. In this chapter :
- the introduction of small cells (of air) to study the propagation which is a direct introduction to computing method like finite differences
- the description of the behavior of those cells : as a cube, when one face is pushed, the 5 others expand, pushing their neighbors.
- the concept of impedance with the consequence in the energy transfer.
- we can read the impedance adaptation (criteria to maximize the energy transfer) is not always desired like in the horn of a trumpet to create modes (remind some previous posts?).
Christian
Does that book explain how the sound moves up and down, left and right on it's plane, when the voice coil only moves to and fro? If you take the speaker outside, put it on height of your ears (on a pole or something) facing upwards to the unlimited space, and you stand few meters away, you still hear the sound coming from the speaker. How does it come to your ears, when the voice coil movement is to the sky and back?
My take: sound balloons out into a full sphere, once it is released into the medium, in this case air. Every sound starts always from a point source.
Last edited:
chdsl,
You should think about near field and far field effects here is a good short video on the subject https://duckduckgo.com/?q=near+fiel...i=https://www.youtube.com/watch?v=PcwFjB6z17A
You should think about near field and far field effects here is a good short video on the subject https://duckduckgo.com/?q=near+fiel...i=https://www.youtube.com/watch?v=PcwFjB6z17A
That doesn't answer the question, how does the to and fro motion of the VC sends up and down, right and left sound, does it?
But this is not a genuine question though, is it? Your question does have an answer, but people respond to you and you ignore what they say, go off on another different tangent, only to return the next day asking the same 'question' from your soap box.
Great find! I only a few paras in and it corrects a recent misunderstanding of mine.
Energy Vampire, but in text. If you watch the comedy What We Do In The Shadows (the series) you'll understand. These posts reminded me of that from the beginning.
Here is a lecture on psychoacoustics by Prof Heller.
I think there are some hints here as to the 'unreasonable' effectiveness of DML speakers, given their less than perfect measured response.
Interestingly, he mentions in his intro a later book he has written that covers the Semiclassical approach, and that it is relevant to acoustics. This is the same topic I mentioned a few weeks ago under the heading 'quantum chaos'.
There is also a website: whywehearwhatwehear.com
Last edited:
Christian
You will be happy to know that the first biographical inset of the book you alerted us to, is of a countryman:
"Father Marin Mersenne (figure 2.4) is sometimes called the father of modern acoustics. His experimental methods were remarkable for their day, as documented in his 1636 treatise, Harmonic Universelle. In this work, he spelled out the Mersenne laws (see chapter 8), the connections between length, tension, diameter, and frequency of a string. Mersenne established that an octave was an exact 2:1 ratio of vibrations per second. Starting from oscillations so slow he could count them accurately, Mersenne ascended by exact octaves, and in this way was the first to associate a specific number of oscillations per second (84 exactly) of a string with a given audible pitch. Galileo (1564-1642) may have actually beaten Mersenne to many of his discoveries, but Mersenne was first in print. Mersenne possessed a remarkable gift for networking with other scientists (and their work) from far-flung places. He became a kind of one-man clearinghouse for scientific information. Many of the most famous scientists of the time corresponded and visited with Mersenne. French philosopher Rene Descartes (1596-1650) Minim Friar Marin Mersenne (1588- 1648). and mathematician Blaise Pascal (1623-1662) met each other for the first time in Mersenne's cell at the monastery. Upon Mersenne's death in 1648 from a lung abscess, letters from 78 correspondents, including Per mat, Huygens, Pell, Galileo, and Torricelli, were found in his cell, along with various scientific instruments and unfinished manuscripts. Mersenne was the founder of the French Academy of Sciences, which began with his prodigious correspondence and frequent meetings at his Paris cell. He was also a staunch defender of Galileo in the latter's travails with the Catholic Church, even though Galileo was his strongest scientific competitor. The list of Mersenne's talents continues: he was a fine musician and a world-class mathematician. The Mersenne prime numbers, as they are called, are a lasting reminder of his mathematical discoveries and talents."
It's amazing how many french mathematicians appear in the foundations of applied math from the 18th and 19th centuries. While I know of Newton and Hamilton in Britain, and Gauss, Riemann in Germany, I can name (even after a couple of drinks!) Laplace, Fourier, Galois, Poisson, Fermat, D'Alembert, Cauchy, L'Hospital, Lagrange and more. I've been told it's because of the success of the schools of that period.
You will be happy to know that the first biographical inset of the book you alerted us to, is of a countryman:
"Father Marin Mersenne (figure 2.4) is sometimes called the father of modern acoustics. His experimental methods were remarkable for their day, as documented in his 1636 treatise, Harmonic Universelle. In this work, he spelled out the Mersenne laws (see chapter 8), the connections between length, tension, diameter, and frequency of a string. Mersenne established that an octave was an exact 2:1 ratio of vibrations per second. Starting from oscillations so slow he could count them accurately, Mersenne ascended by exact octaves, and in this way was the first to associate a specific number of oscillations per second (84 exactly) of a string with a given audible pitch. Galileo (1564-1642) may have actually beaten Mersenne to many of his discoveries, but Mersenne was first in print. Mersenne possessed a remarkable gift for networking with other scientists (and their work) from far-flung places. He became a kind of one-man clearinghouse for scientific information. Many of the most famous scientists of the time corresponded and visited with Mersenne. French philosopher Rene Descartes (1596-1650) Minim Friar Marin Mersenne (1588- 1648). and mathematician Blaise Pascal (1623-1662) met each other for the first time in Mersenne's cell at the monastery. Upon Mersenne's death in 1648 from a lung abscess, letters from 78 correspondents, including Per mat, Huygens, Pell, Galileo, and Torricelli, were found in his cell, along with various scientific instruments and unfinished manuscripts. Mersenne was the founder of the French Academy of Sciences, which began with his prodigious correspondence and frequent meetings at his Paris cell. He was also a staunch defender of Galileo in the latter's travails with the Catholic Church, even though Galileo was his strongest scientific competitor. The list of Mersenne's talents continues: he was a fine musician and a world-class mathematician. The Mersenne prime numbers, as they are called, are a lasting reminder of his mathematical discoveries and talents."
It's amazing how many french mathematicians appear in the foundations of applied math from the 18th and 19th centuries. While I know of Newton and Hamilton in Britain, and Gauss, Riemann in Germany, I can name (even after a couple of drinks!) Laplace, Fourier, Galois, Poisson, Fermat, D'Alembert, Cauchy, L'Hospital, Lagrange and more. I've been told it's because of the success of the schools of that period.
Hi everyone
Long time lurker, first time poster
Just wanted to share my attempt trying to build a pair of DML's:
Few details:
So, how they sound?
The vocals and mid range in general is good and precise. Treble response feels a bit piercing and sharp arround 8-10k. Above 10k the panel is lacking.
Bass is a problem - although the response goes down to 50-60Hz, I'm hearing quite strong humming and echo at the low end, which tends to ''color'' the sound. This could be resolved by increasing clamping area but I suspect, at the cost of losing the bass.
Panel is loud but not sensitive - have to turn the volume up quite a bit.
I'm now hunting some poplar plywood for further tests. Also looking into EPS panels - have bought some 20mm thick ones, but have not experimented with them yet. And maybe I might return to Dayton audio exciters
Long time lurker, first time poster
Just wanted to share my attempt trying to build a pair of DML's:
Few details:
- I'm using AIYIMA 25W exciters. The price was good and I like the mounting solution, which allows me to try out different panel materials quickly and with good clamping
- Used Birch plywood, had nothing thinner than 6.5mm at the shop, so to save time and as I had a CNC laying arround, just machined it to 3mm thickness. First I tried 1200x600mm but to make it more practical, decided to make it half the size. There was no major difference when listening by ear.
- The proportion to width and length was chosen to be golden ratio. This might not be the best ratio, some have suggested to make it 4:3. Also I am now tempted to try long panels, similar to BurtnCoil's Tall Blondes.
- Exciter placement was chosen by ear - just moved the driver around the panel, where I felt like it sounded best.
- Rounding corners did not make any significant change in sound quality
- Decided to clamp on two sides - kept the contact area short, so I would keep some low range output.
So, how they sound?
The vocals and mid range in general is good and precise. Treble response feels a bit piercing and sharp arround 8-10k. Above 10k the panel is lacking.
Bass is a problem - although the response goes down to 50-60Hz, I'm hearing quite strong humming and echo at the low end, which tends to ''color'' the sound. This could be resolved by increasing clamping area but I suspect, at the cost of losing the bass.
Panel is loud but not sensitive - have to turn the volume up quite a bit.
I'm now hunting some poplar plywood for further tests. Also looking into EPS panels - have bought some 20mm thick ones, but have not experimented with them yet. And maybe I might return to Dayton audio exciters
It is not a question, but an answer. Pushing air doesn't make sound. Sound moves in air, in all directions, starting from a point. That's one of the reasons why the edge transfer of sound energy brings out clearer, fuller sound, which many people in the past had fathomed (Telefunken, Siemens, Lee de Forest, etc), lately by Paddock, Deminier, Sony. Only, its cheaper to make cone speakers.
Last edited:
The humming is coming from the aluminium plate of those Aiyimas. You might get rid of that by changing it to something else, like a head cut off screw or something that fits. Also, the 4 small screws on the 'spider' are sometimes not that well screwed in. Or, make a hole to the width of the aluminium plate in the panel and fix it with glue on and around the plate, so that it won't bump. Or, make the hole deep up to the last ply and paste the aluminium plate to it.
Last edited:
Why did you choose your panels to stand horizontally instead of vertically?
Hey chdsl! Thank you for your feedback
The humm is almost gone, if I hold the corners of the panel with my fingers - I have some doubt that the mounting plate is to blame. It's more like a hollow sound, rather distortion. But I will check if the bolts are tight anyway.
For now, as I am still playing around with different panel materials, I would prefer mechanical mounting rather than gluing.
Some years ago, when I first started to look into DML's I remember what a pain in the butt it was to mount and detach Dayton audio exciters. I feel like the ease and quality of exciter mounting could be greatly improved in general
Audiofrenzy,
It was purely aesthetic decision, did not notice any audible difference between horizontal or vertical mounting. I suspect there might be a difference if the width-to-height ratio would be greater, but maybe someone else can comment on that