In researching the Austin, I came across a comment by RonC concerning rounded corners in a folded horn. After much discussion of epoxy and bondo, Ron said he just used a piece of floor tile. Actually, free samples of floor tiles. I'm assuming he's talking about synthetic floor tile that is flexible and has an adhesive back.
If rounding corners is that easy, shouldn't this be incorporated in most designs?
A question: We know long wavelength sound reflects less than high frequency. Why do some long waves follow the horn and others undoubtedly pass through the cabinet material.? It seems that when low frequencies encounter a material it is absorbed, reflected and/or passed through. What do we know about possible building materials when it comes to these properties?
Don
If rounding corners is that easy, shouldn't this be incorporated in most designs?
A question: We know long wavelength sound reflects less than high frequency. Why do some long waves follow the horn and others undoubtedly pass through the cabinet material.? It seems that when low frequencies encounter a material it is absorbed, reflected and/or passed through. What do we know about possible building materials when it comes to these properties?
Don
Hi Don
You'll get lots more knowledgeable answers from others on this forum (Ron and Scottmoose for a start, I'd expect), but here's I'll stick this in here to bump the thread and hope it gets noticed by the ones who do know.
My understanding is that in BLHs and BVRs there is some advantage in sharp corners, in that they tend to be more or less invisible to low-frequencies, but help to suppress the higher-frequecies. And since it's the lows that we're trying to reinforce, this is desirable.
Your other question - about long waves following the horn - interests me as well. I think it may be an error to say that long waves are "passed through" - as I envisage it, the only way this can happen is for the long wave to vibrate the material and start a new wave front on the other side. If the wall was completely rigid, no waves would pass through. (Note that I'm using "horn" loosely here, just to mean an expanding path of some sort)
As to how they follow, I imagine an expanding bubble of pressure (the wavefront); as long as it is longer than the width of the horn at a given point, it will tend to expand along the centre-line of the horn even if there are curves or folds. Think of an air bubble in a vertical underwater tube, and then the tube curves - the bubble should still follow.
Whether any of this is at all accurate, I have no idea - I'm pulling on my flameproof suit as I speak, to prepare for gentle correction at the hands of fellow forum-members.
Regards.
Aengus
...ergo, you want to ensure that the natural resonance frequency of a panel is well outside (above or below) the operating BW of the cabinet in question.
The bubble analogy is actually pretty good. Not far off from Voigt's take on things really. A line that expands toward the terminus sufficiently to cause a transition toward 1/2 wavelength behaviour is a horn BTW; no looseness apologies needed.
Smooth / constant expansion provides maximum efficiency for a given horn profile -of course, whether you actually want maximum efficiency is another matter. The comments about bends / edges are quite correct.
The bubble analogy is actually pretty good. Not far off from Voigt's take on things really. A line that expands toward the terminus sufficiently to cause a transition toward 1/2 wavelength behaviour is a horn BTW; no looseness apologies needed.
Smooth / constant expansion provides maximum efficiency for a given horn profile -of course, whether you actually want maximum efficiency is another matter. The comments about bends / edges are quite correct.
There natural resonance frequency and damping , right. So we want a very stiff box, that perhaps has a resonance above 20khz, and is highly dampened?
The curve in folded horns. In an old post RonC stated that curves when changing angles sound better. We know in fluids that a square bend causes turbulence and decreases flow.
Since my first post I've found that many of the Austin builders added circular turns. So back to my original question, is it meaningful to do if it's easy to do? I could make a curve faster than cutting all the pieces for the step turns in the Changs.
Also, what about the CC? Is there an optimal shape?
The curve in folded horns. In an old post RonC stated that curves when changing angles sound better. We know in fluids that a square bend causes turbulence and decreases flow.
Since my first post I've found that many of the Austin builders added circular turns. So back to my original question, is it meaningful to do if it's easy to do? I could make a curve faster than cutting all the pieces for the step turns in the Changs.
Also, what about the CC? Is there an optimal shape?
So to understand this, do you want a smooth horn path? Lately it seems that guys that have access to CNC machines are going for the layered look. So is it worth doing a smooth horn path or is the standard horn path out of straight panels just as good. The reason I ask is I am wanting to build the Dallas II speakers. I have had some 206e drivers sitting hear for a while. I modeled the speaker from the plans on Dave's site and there was only one dimension I was missing to have everything match the dimensions from the plans. I guessed on it and I think I have come close but anyway I also created a curve in the model to show a smooth horn path. I was going to build it using this smooth path. So I guess I am asking if its worth it to do the smooth path or if the path using straight edges is as good.
John
John
kazoo said:
John, if you look at the Dallas II photos, the kerfboard implementation would not be hard to build. But if you don't want some curved exterior features, the square build only requires adding three curves. This shouldn't change dimensions.
I'm a bit confused by Ron's water analogy. The analogy to water is air, not sound. Is it safe to assume sound waves behave the same as flowing fiuids and gases?
Also, I did read a comment from RonC that the Dallas II does does not incorporate his latest design thinking. Sorry, I didn't think to save the link.
There are a lot of designs of back-loaded horns like the Dallas. It might be worth looking at the most developed. Or use the available tools to rerun the numbers on the Dallas.
There are a lot of designs of back-loaded horns like the Dallas. It might be worth looking at the most developed. Or use the available tools to rerun the numbers on the Dallas.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.