moray,
I don't think there is. People like to surmise that non-parallel sides will reduce standing waves, but they really don't.
It's possible that there could be some other benefit to non-parallel sides in terms of the distribution of natural frequencies or influencing the radiation efficiency of modes, but if there is I am not aware of it.
Eric
I'm not certain that epoxy resin has similar characteristics to UV resin. I've never chanced comparing them.
What is the (Skin) made of that comes from the factory and why does everyone stand it off?
What are the sonic benefits of sanding the surface then applying a mixture of PVA and water?
XPS seems to have an inherent tendency to ring on it's own when pulsed clicks are sourced through an amplifier.
Can PVA and water actually calm the ringing?
Jack
Steve CD's are made from optical grade Poly-carbonate (on the read side probably a lesser grade on the top side). Carry on.
I have no experience with UV resin, but think that most resins have quite similar characteristics and the main difference is how they are hardened, and the quick hardening is touted as the main advantage of UV resin, not different material properties.
Not sure if there is only one type of skin on styrofoam blocks. You get different surfaces when you cut with hot-wire or press in a mold, and perhaps some brands have some extra chemical layer for fire protection.
The plates I use is pressed in mold, but are not for use as building material and not surface treated afaik, so did not seem to be any need to sand.
The sonic benefits are a tighter more controlled sound, and if done carefully, without loosing efficiency. When analysing I would expect to see a little shorter RT60. Other forms of damping such as clamping the edges tend to also reduce sensitivity apart from bass region where it can help control the plate to avoid self-cancelling. But by forming a tight skin on the styrofoam it seems to make it a bit more sensitive overall instead, I guess in a way similar to how a drumskin that is tight will generate more sound from a small excitation than a loose one. For that to work you want the skin to be tight but not too stiff. A thin sheet of acrylic or epoxy would be a poor replacement for a goat skin. While that is a different kind of excitation, it goes to show how much the material properties matter when it comes to acoustics.
Epoxy can certainly be used as part of a composite like the case with the Tectonic carbon/nomex plates, but IMO high grade EPS is quite good as it is, and covering it epoxy seems like it would change to properties too much. You probably want a different core if going with epoxy skin. At least on EPS it seems easier to get a really thin skin that tightens up the plate without overdamping using hide glue, shellac or PVA, .
Steve that is the patent for the Highwood Audio loudspeaker marketed as the Sumo Aria in 1988. I co-developed this design along with paul my partner at the time we started Highwood Audio in Calgary.
aagas if you nest the woofers as opposed to having them face to face then you can cancel the difference in the compliance of the woofer suspension. not a huge deal but one more thing cleaned up. very nice looking system and room. thanks for the peek at home.
you could fit this into an H-Frame cabinet. cheap bass seems very attractive.
Ok ... Should have been obvious, mils are often used as shorthand for mm in Aus. Your mils are often called thous here.
Oh for worldwide consistent units!!
Tagis would you please post the address for your omni loudspeaker blog? I have listened to a number of omni designs such as the balloon/globe types and find them very interesting and I would like to follow along. Thank you.
you have a myriad of options for diaphragms using polyester silk screen material available is a wide range of weights and weave sizes. This as lots of internal loss built in and makes a good sounding diaphragm. Hope this is of interest.
the Quad 63 does not generate a travelling wave, it simulates an expanding wave using delayed lines to drive the panel sections which are driven as pistons. Panel sections decrease in area from the largest area for the bass to end with a small area piston to provide high frequency dispersion.
The Highwood Audio panel did do a pretty good job of recreating a travelling wave panel speaker. We could place a 1/8 inch B&K condenser microphone at a right angle at the outer edge of the panel and measure out to10 KHz. Dispersion was uniform generating a reasonably even hemispherical wavefront. This sort of radiation pattern does however light up the room with both floor and ceiling bounce which has to be considered, you can have too much of a good thing.
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you would get come extra floor bounce to add to the overall output of the system same as the difference between a woofer up off the floor in a cabinet and being close to the floor in the same cabinet. a panel on its side will present a larger surface are which the floor will reflex.
Museatex of Montreal was the name of Ed Meitners company which merged with Highwood Audio in Calgary after Highwood had to part ways with Sumo Audio. So the Highwood Audio speakers were sold under the Museatex Melior banner.
Moray's dip into the past has me re-reading the old posts 😵💫
Made me idly wonder what the results would be if a ply panel was tissue/paper et al stiffened on the rear face more than the front so the rear waves were dampened more than the front.. It'd be like shifting the neutral axis rearwards....
Thoughts...???
Eucy
Made me idly wonder what the results would be if a ply panel was tissue/paper et al stiffened on the rear face more than the front so the rear waves were dampened more than the front.. It'd be like shifting the neutral axis rearwards....
Thoughts...???
Eucy
I would assume that the parchment sounds this way is due to a combination of the cotton fiber and wood pulp in its structure. There are so many materials to try and combine. Consider Fostex in Japan who make full range drives. Over the decades hey have produced so many different types of papers for cone material it is amazing. Interesting to read your comments on modern parchment. Have you tried parchment on any lo grade low density expanded polystyrene which is on the warm side and rolled off sounding?The reason you dont see much NXT products is because they catered mostly to "Pro/live audio" instead of Audiophiles/DIYers. They are two completely different marketing catagories. Most of NXT products werent sold in the common hi fi audio stores but rather Music/Instrument stores hence the lack of popularity in the audio enthusiast community. Occasionally NXT would license there product to other companies like Teac but failed to build anything note worthy.
If my memory serves me correctly I warned yawl about Tech Ingredients. Its not my problem if you dont want to listen to my advice.
You never read NXT patents before? I find that odd, since you are the patent king?
Hmmm I just recently mentioned skins in my previous post. Anything touching the surface of said panel material becomes the skin and will take on some of the skins sound signature depending on the skin used. For example paper has a warmer/duller sound but it will sound more accurate. While Aluminum will have a brighter more lively sound. Many factors involved its not as simple as one might think. If your core material is already warm sounding to begin with then you wouldnt want to use paper unless you want it to sound really warm, you have to find the RIGHT combination which again boils down to personal preference. Like Goldie locks and the three bears you dont want it too hot or to cold but "JUST RIGHT".
Anyone ever hear a "CERAMIC", type of tweeter or woofer? Ceramic is very clean and articulate sounding but also can sound very dry. The SKIN material that sounds like a ceramic driver is one of my many preffered skins is "PARCHMENT" paper. Here is another tip> One side of the parchment paper does not sound the same as the other side. You have to listen for yourself which side you prefer. Ahhh man giving away to much secrets.
so forgive me for not knowing, please which panels are these?these panels need a tweeter as much as i need another hole in my head
this is another bright sounding cd.
these panels can handle anything.
still having fun
steve.
if I had to choose I would pick the ply as the proplex has a somewhat subdued character though the spectral balance is indeed close.
I would think that DE used as an admixture to PVA would help to extend the high frequency transmission of a coated panel surface especially around the exciter mount. Well worth experimenting with.The point is its not soil or rock in there natural form. Shellac and wood grain fiber filler are not in there natural form. Its used to harden the panel at the same time damping the panel like a layer of skin.
Diatomaceous Earth is not in its natural form nor is Chitosan.
Its like trying to adhere an exciter to D.E.
Hi moray.
You keep bringing up old interesting ideas ,which I had forgotten about.
Some are even mine 😃
I do have a lot of DE , which we use for our chickens.
I might splash some on an eps chill box panel I am testing at the moment.
Not sure about the colour though 🤔
I will use the 50x50 mix to keep the weight down ,and see how it goes.
Steve.
You keep bringing up old interesting ideas ,which I had forgotten about.
Some are even mine 😃
I do have a lot of DE , which we use for our chickens.
I might splash some on an eps chill box panel I am testing at the moment.
Not sure about the colour though 🤔
I will use the 50x50 mix to keep the weight down ,and see how it goes.
Steve.