My action would be to ask you to keep the CMP conversation in your CMP thread and to not insist on constantly inserting it here. There are those of us who follow this for it's original intent, not for your personal interpretations.
Dave
I agree.
From diyaudio rules:
"If a project gets close to commercial availability, the topic must be continued in a Commercial Sector thread."
There is only one conclusion to be drawn from this:
By letting the this thread to remain in a regular forum, it is an implication that no commercially available HOM free waveguide exist in this world !
But wait, this thread was started by diyAudio Editor
It appears that diyaudio forum rules do not apply for diyAudio Sponsors diyAudio - Sponsors Money talks also here.
- Elias
Waveguides are used in other speakers besides Geddes. This isn't the "Geddes' Waveguides" thread, it is "Geddes on Waveguides", so where is the commercial focus? Just that he also happens to manufacture speakers using waveguides (and so his views naturally tend to focus on how he designs with them). Earl's input is valued by designers and people interested in waveguides in general. Should other theory discussions exclude an expert if he happens to also have products or books based on his research? If so, better also exclude LeCleach, Curl, Cordell...
Best option - if you don't like the thread, don't read it.
Best option - if you don't like the thread, don't read it.
I would also prefer this thread to stay "Geddes on Waveguides", and not "Michael on Geddes". Michael, you are not doing anyone any favour by so actively trying to discredit Geddes in this thread. Please do it in another thread.
Personally, I don't care where the thread ends up, as long as it will still be here somewhere, and the title still fits.
Bjørn
I personally have learned very much from discussions going on in this thread. It it not and easy task to build a wave guide or horn device that will perform perfectly. I think as long as people present new data and measurements, continued discussion is worthwhile. Earl certainly has become more accepting in different views throughout the years. I wish I had new results to present on the subject, but the fact is I have not yet made any improvements to my satisfaction. Although I do have some concepts in mind, I still need to figure out the math, which is the weakest link in my brain.
Michael has been involved in this discussion for a long time as well, however, continuously bringing old arguments back to the table without new applied technology really does not prove anything. Certainly we all have better things to do than just sit around and argue.
My recommendation would be that, if anyone want's to prove something is better, just do it.
Michael has been involved in this discussion for a long time as well, however, continuously bringing old arguments back to the table without new applied technology really does not prove anything. Certainly we all have better things to do than just sit around and argue.
My recommendation would be that, if anyone want's to prove something is better, just do it.
I was going to ask a question but I feel as if I should wait 'till we've all had a group hug
If HOMs are produced due to a discontinuity, for example a concentric ridge on a waveguide wall, what dimensions, if any would the HOMs be related to? i.e would you get frequency products related to a wavelength at the circumference at the discontinuity?
If HOMs are produced due to a discontinuity, for example a concentric ridge on a waveguide wall, what dimensions, if any would the HOMs be related to? i.e would you get frequency products related to a wavelength at the circumference at the discontinuity?
Diffraction in any situation is produced directly proportional to the rate of change of the walls slope. The proportionality has to do with the wavelength. Short wavelengths "see" small changes, large ones don't. This diffraction gives rise to HOMs under certain conditions. HOMs are "modes" which means that they have "characteristic frequencies" and "characteristic shapes". So when a wave hits a discontinuity that is comparable to its wavelength and this wavelength corresponds to a mode, then that mode will be created and propagate down the device - following behind the main wave, lagging more and more as it propagates. The sharper the discontinuity, in terms of rate of change of slope, the more energy there will be in this HOM. The circumference only eneters the problem as it influenes the "modes" - the larger the circumference the lower the modes will be in frequency.
Think of an impulse traveling down a waveguide and impinging on a discontinuity. Since an impulse contains all frequencies, those frequencies that correspond to the HOM frequencies will continue to propagate as HOMs down the device, its kind of like a filter - basically a HP filter. The larger the device the lower and more plentiful these HOMs will be (like modes in a room). The energy in these modes will only depend on the rate of change of the slope (or rate of change of the rate of change, i.e. the 2nd derivative). Thus it is easy to see that minimizing the 2nd derivative will minimize the energy in the HOMs. It can be show that the OS is such a curve, it is a catenoid that minimizes the 2nd derivative of a curve with a fixed starting and ending slope.
Therefor, the least HOMs possible (well practical at least) would be a 1" OS waveguide. What a surprise! But also note that even in this case, they are not zero! I think that it would be posiible to design a zero HOM device if one could redsign the compression driver, but from my perspective these are fixed.
Think of an impulse traveling down a waveguide and impinging on a discontinuity. Since an impulse contains all frequencies, those frequencies that correspond to the HOM frequencies will continue to propagate as HOMs down the device, its kind of like a filter - basically a HP filter. The larger the device the lower and more plentiful these HOMs will be (like modes in a room). The energy in these modes will only depend on the rate of change of the slope (or rate of change of the rate of change, i.e. the 2nd derivative). Thus it is easy to see that minimizing the 2nd derivative will minimize the energy in the HOMs. It can be show that the OS is such a curve, it is a catenoid that minimizes the 2nd derivative of a curve with a fixed starting and ending slope.
Therefor, the least HOMs possible (well practical at least) would be a 1" OS waveguide. What a surprise! But also note that even in this case, they are not zero! I think that it would be posiible to design a zero HOM device if one could redsign the compression driver, but from my perspective these are fixed.
I knew you'd show up like that.
I don't want people to think that my not objecting or responding directly to some comments means that I agree or am admitting to being wrong as some here have taken my silence to mean. I'm simply not going to continue to discuss ridiculous points with people who get insulting when you don't agree with them. I have a 12 year old at home and I get plenty of this from him.
Anyone who does, I would put into the same category as a 12 year old. You have my sympathy
Hi Earl
Hope things are well with you and yours. I have meant to post a couple times but have been so busy.
I saw something the other day that made me think of you.
I was at the demonstration below when the TV snooze guys came and we had to stop, (near the end they panned where Doug and I were standing near a pillar).
Anyway, in post processing one can zoom in on anything in the picture and hear or measure the content coming from that location. In the case of a noise transmission test room inside, after capture, one could clearly see and “hear” (through the computer speaker) the leakage coming from under the door etc.
In other words after the capture, the 255 microphones signals can be processed into a very direction mic where you wish to interrogate.
For example, after capture, one could highlight a person walking across a parking lot and follow him, listening to him talk.
My thought was that if one viewed a horn from the front side, the diffraction and non-simple behavior may be “visible”.
I am not sure when yet but I am going to get a chance to spend some time with one of these, if/when that happens, if this sounds interesting, I will let you know.
Best,
Tom Danley
Danley Sound Labs
Just how noisy is Chicago? -- WGN
Hope things are well with you and yours. I have meant to post a couple times but have been so busy.
I saw something the other day that made me think of you.
I was at the demonstration below when the TV snooze guys came and we had to stop, (near the end they panned where Doug and I were standing near a pillar).
Anyway, in post processing one can zoom in on anything in the picture and hear or measure the content coming from that location. In the case of a noise transmission test room inside, after capture, one could clearly see and “hear” (through the computer speaker) the leakage coming from under the door etc.
In other words after the capture, the 255 microphones signals can be processed into a very direction mic where you wish to interrogate.
For example, after capture, one could highlight a person walking across a parking lot and follow him, listening to him talk.
My thought was that if one viewed a horn from the front side, the diffraction and non-simple behavior may be “visible”.
I am not sure when yet but I am going to get a chance to spend some time with one of these, if/when that happens, if this sounds interesting, I will let you know.
Best,
Tom Danley
Danley Sound Labs
Just how noisy is Chicago? -- WGN