picowallspeaker,
Horn theory is going to include much more information than would seem necessary. A simple study of Helmholtz resonators should cover the subject and a basic knowledge of transmission line theory will give him what he needs.
As to testing the device I would assume that a simple online tone generator or a test tone CD could be used for much of the test signal if he has no tone generator. The microphone that he has should be sufficient for crude testing and the oscilloscope can be used. Keep this simple, we are not designing a high end audio system here. If he has access to a computer with a sound card that may come in handy for the testing with some simple free software.
Horn theory is going to include much more information than would seem necessary. A simple study of Helmholtz resonators should cover the subject and a basic knowledge of transmission line theory will give him what he needs.
As to testing the device I would assume that a simple online tone generator or a test tone CD could be used for much of the test signal if he has no tone generator. The microphone that he has should be sufficient for crude testing and the oscilloscope can be used. Keep this simple, we are not designing a high end audio system here. If he has access to a computer with a sound card that may come in handy for the testing with some simple free software.
Aye, the idea is not to learn about horns, TL and all that. The main reason is to teach the students to work project-based. Just to quote mondogenerator: "The 'write-up' of the project, design selection, costing, implementation, testing and conclusions are indeed the most important."
It's just that I'm allowed to chose my project, so therefore I picked an interesting topic instead of doing something boring in chemstry or biology. It doesn't have to be that very in-depth at all.
It's just that I'm allowed to chose my project, so therefore I picked an interesting topic instead of doing something boring in chemstry or biology. It doesn't have to be that very in-depth at all.
Ok . It is not High End . Tests and conclusions would finally bring to evidence that
the object examined had not fulfilled completely the purposes for which it has been built .
I'm asking : so what's the reason ? To measure sound decay after 1 meter ?
I thought it was for music reproduction .
the object examined had not fulfilled completely the purposes for which it has been built .
I'm asking : so what's the reason ? To measure sound decay after 1 meter ?
I thought it was for music reproduction .
The reason for building a set of speakers is to have something to actually see, instead of just a bunch of papers where I have written the exact same things that are in my books. And since I then have built a pair of speakers I will show them at the exhibition so other people can see what I've done and easily understand it.
I sure could produce just a thick bunch of papers but that would be boring for both me and everybody else and I doubt I'd be able to do it good enough with only papers.
I sure could produce just a thick bunch of papers but that would be boring for both me and everybody else and I doubt I'd be able to do it good enough with only papers.
I find the argument very amusing , and if the text or speech has solid arguments , it
would not be boring .
But you have forgotten that the speaker is the stop-end of a bigger system ; you can start with the very beginnings , like Edison end the wax cylinders , and so on .
How sound is captioned , how it is stored ; how it is processed .
The speaker is only the last part of the whole process : it 'transduces' , it converts
current into air motion .
It is a product of mechanics , but also includes many fields , that are all measurable .
Fluid dynamics , thermical excursion , vibration , rigidity and compliance of the materials . What you get is a certain Q with a BW and an amplitude .
would not be boring .
But you have forgotten that the speaker is the stop-end of a bigger system ; you can start with the very beginnings , like Edison end the wax cylinders , and so on .
How sound is captioned , how it is stored ; how it is processed .
The speaker is only the last part of the whole process : it 'transduces' , it converts
current into air motion .
It is a product of mechanics , but also includes many fields , that are all measurable .
Fluid dynamics , thermical excursion , vibration , rigidity and compliance of the materials . What you get is a certain Q with a BW and an amplitude .
Something VERY historical
the first records where obtained only mechanically , and the reproduced only mechanically.
The diaphgram placed attached to the stylus was then amplified by the horn .
No great power at all !
So , in 2012 , more than 100 years after the discovery of the thing ,
you are still proposing a single speaker in a wooden box , as the terminus of a long research ?
the first records where obtained only mechanically , and the reproduced only mechanically.
The diaphgram placed attached to the stylus was then amplified by the horn .
No great power at all !
So , in 2012 , more than 100 years after the discovery of the thing ,
you are still proposing a single speaker in a wooden box , as the terminus of a long research ?
lol give the guy a break Pico, its a college level project not a walk thru audio history and its many permutations!
Correct
Uh uh Dawn of audio
I remember about a year ago that an indian member was
interested in OB speakers and he produced a photo of an
old Whaferdale speaker system ; then I directed him to the more
modern work of MJK .
Not sure he's now REALLY appreciating them as long ...
And that project with the Eminence+ Fostex seemed to cost about 500$
Which is not a bad budget to build something durable .
So the best advice would be to build and study all together .
Or making a step ahead and consider 'loudspeaker and a room as a system' and
also a step beyond and bring to attention the behavior of Qts when the speaker is driven by an amplifier having a damping factor above unity , or
changes from voltage amplifier to current amplifier in freq. response .
Those may seem doable experiments .
Otherwise the usual goal would be to project a loudspeaker system -so no fullrange allowed- that can play a record at normal levels in a normal room ,
allowing to have 100% more dynamic to reproduce the peaks
Yes , my first thought in the FR Forum
is from the speaker side
How can it produce so many frequencies all together , varying in amplitude
I remember about a year ago that an indian member was
interested in OB speakers and he produced a photo of an
old Whaferdale speaker system ; then I directed him to the more
modern work of MJK .
Not sure he's now REALLY appreciating them as long ...
And that project with the Eminence+ Fostex seemed to cost about 500$
Which is not a bad budget to build something durable .
So the best advice would be to build and study all together .
Or making a step ahead and consider 'loudspeaker and a room as a system' and
also a step beyond and bring to attention the behavior of Qts when the speaker is driven by an amplifier having a damping factor above unity , or
changes from voltage amplifier to current amplifier in freq. response .
Those may seem doable experiments .
Otherwise the usual goal would be to project a loudspeaker system -so no fullrange allowed- that can play a record at normal levels in a normal room ,
allowing to have 100% more dynamic to reproduce the peaks
Yes , my first thought in the FR Forum
is from the speaker side
How can it produce so many frequencies all together , varying in amplitude
no Dummies here
Didn’t say or imply there was.
OK, but I was responding to Rullknuf's post in a totally appropriate way considering the limited scope of his assignment. After all, there’s already a plethora of published ‘dummies’ tutorials, so don’t see why anyone would take issue with the suggestion, lighthearted or not.
GM
Didn’t say or imply there was.
OK, but I was responding to Rullknuf's post in a totally appropriate way considering the limited scope of his assignment. After all, there’s already a plethora of published ‘dummies’ tutorials, so don’t see why anyone would take issue with the suggestion, lighthearted or not.
GM
You're still missing the point.
Regardless, everything he needs technology wise for his project is all right here and its related links: Resonances of open air columns
GM
GM,
That is a great resource page you just gave our young student there. He just has to remember to reference it on his reference page of his report. Very nice simple explanations. Gets a little more complicated if it is a twin tube design with the driver offset from the middle though. Still a great start to his project.
Steven
That is a great resource page you just gave our young student there. He just has to remember to reference it on his reference page of his report. Very nice simple explanations. Gets a little more complicated if it is a twin tube design with the driver offset from the middle though. Still a great start to his project.
Steven
Hi,
I get the distinct feeling you think building speakers is a trivial exercise,
that you want to stick a small speaker in a big cabinet, wow everybody
with how "great" the result is, and waffle a bit about pipe resonances
and the like without describing any fundamentals of proper design.
One thing for sure is likely the assessor will have no real idea about
speaker design, but should be good at working out neither do you.
Another thing for sure is anything done properly is not easy to understand,
unless you logically layout and explain the important factors that lead you
to your design choice, there is no sign of that happening here.
Its easy to understand the thinking process of someone putting a small
driver in a big cabinet because "bigger is always better", but also easy
to understand you have no real idea of what is going on, or whether
your assumption and your implementation is anywhere near optimum.
Having said that I'll repeat you can keep it fairly simple for a small driver
in a big / impressive box. Start off with something small clearly designed
for AV satellite usage, i.e. for use down to 80Hz, e.g. :
Speaker kit 4: Compact AV Monitor | eBay
Realise any bigger cabinet your going to put it in shouldn't be more than
2 to 3 times the recommended vented volume, (for the above that's 8L),
and should be tuned to to about 40Hz. It can be a BIB -an expanding 1/4
wave (see Voigt), or a mass loaded expanding 1/4 wave (see MJK).
A "Metronome" is an interesting quadratic example of the latter.
Essentially the low tuning means you aren't going to go horribly wrong,
and the MLEQW has the advantage of being able to tune the port, that
a simple TL / QW doesn't.
rgds, sreten.
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No dummies here, con't...
...GM, I thought I'd clarify the point that I was trying (apparently unsuccessfully) to make: there are some good people here, who in my eastimation are not dummies, although I was a little "tongue in cheek" in my comments.
picowallspeaker and others: I am not trying to trivialize loudspeaker design, I am just suggesting that trying to compare expected results with reality. This does not address subjective performance, but was suggested so that objective expectations could be compared to the outcome. Ruffknulls, being in high school, will be expected to relate he outcome to some expectation if discussing anything science based. That is the reality of a score based education system.The measureable results will allow him to compare (in a scientific manner) his success or lack of quantitatively, not qualitatively. As this is a school project, qualitative comments can be included in a summary as part of his opinion (which strictly speaking is not present in a scientific project or paper).
Ruffknulls' project may not result in a successful loudspeaker build, but yet result in a very successful project. And that is the goal.
GM, great reference sites for basic concepts in physics, although perhaps too advanced in some aspects for high school.
...GM, I thought I'd clarify the point that I was trying (apparently unsuccessfully) to make: there are some good people here, who in my eastimation are not dummies, although I was a little "tongue in cheek" in my comments.
picowallspeaker and others: I am not trying to trivialize loudspeaker design, I am just suggesting that trying to compare expected results with reality. This does not address subjective performance, but was suggested so that objective expectations could be compared to the outcome. Ruffknulls, being in high school, will be expected to relate he outcome to some expectation if discussing anything science based. That is the reality of a score based education system.The measureable results will allow him to compare (in a scientific manner) his success or lack of quantitatively, not qualitatively. As this is a school project, qualitative comments can be included in a summary as part of his opinion (which strictly speaking is not present in a scientific project or paper).
Ruffknulls' project may not result in a successful loudspeaker build, but yet result in a very successful project. And that is the goal.
GM, great reference sites for basic concepts in physics, although perhaps too advanced in some aspects for high school.
Nanook,
I think again that you have succinctly stated what this school assignment truly is supposed to be. A demonstration of physics and mathematics with both a physical apparatus and the written information to confirm the results and state the hypothesis. This was never a project to build a loudspeaker per say. Though we are in an audio forum this is not the point of this exercise, though it would be nice if Rullknuffs, came out with a useable pair of transmission line speakers in the end. I think that if Rullknuffs is half as intelligent as I am assuming here by his responses that the reference given by GM will give him most of what he needs to proceed. He will obviously need more than one reference in his paper and finding that information perhaps should be up to him as he should also learn from this assignment what a research paper entails. We can advise and perhaps even question his assumptions to help him on his way, but the work should be his. Perhaps he will become the next Webster or Olsen and teach us all something new about about audio in the future.
I think again that you have succinctly stated what this school assignment truly is supposed to be. A demonstration of physics and mathematics with both a physical apparatus and the written information to confirm the results and state the hypothesis. This was never a project to build a loudspeaker per say. Though we are in an audio forum this is not the point of this exercise, though it would be nice if Rullknuffs, came out with a useable pair of transmission line speakers in the end. I think that if Rullknuffs is half as intelligent as I am assuming here by his responses that the reference given by GM will give him most of what he needs to proceed. He will obviously need more than one reference in his paper and finding that information perhaps should be up to him as he should also learn from this assignment what a research paper entails. We can advise and perhaps even question his assumptions to help him on his way, but the work should be his. Perhaps he will become the next Webster or Olsen and teach us all something new about about audio in the future.
Ending up with a good usable speaker pair...
...is a bonus. As long as Rullknufs picks respectable drivers that are suitable for the enclosure envelope, at worst he will end up with everything less the enclosures for a set of good speakers. If the enclosure design is less than what might be considered successful, after submitting the project, he can always design and build a pair of new optimized enclosures, so nothing lost.
As this discussion is becoming a little convoluted, I should bow out so as not to find myself repeating myself.
Ruffknulls: feel free to PM me anytime.
...is a bonus. As long as Rullknufs picks respectable drivers that are suitable for the enclosure envelope, at worst he will end up with everything less the enclosures for a set of good speakers. If the enclosure design is less than what might be considered successful, after submitting the project, he can always design and build a pair of new optimized enclosures, so nothing lost.
As this discussion is becoming a little convoluted, I should bow out so as not to find myself repeating myself.
Ruffknulls: feel free to PM me anytime.
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