|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
72.130.96.11
In Reply to: RE: eigenmodes posted by hawkmoon on June 13, 2014 at 05:21:13
I've written this before: by the laws of thermodynamics, energy can not be created or destroyed. All we can do is to alter its amplitude or frequency, but the energy still remains.Thus the issue is how break up the nodal patterns into something more amorphous and random instead of being one set pattern.
One thing to note is that the darker areas represent the area where the plate is vibrating more, hence the salt is moving to an area where there is relatively little vibration. One thing I notice is that the area between corners seem to have the most dark spots and hence must be vibrating more ( at least in many of the patterns)
When using cones under components I find that placing them under the roughly midway points from the corners seem to generate the best overall sound: more even and dynamic and certainly more extended over the frequency response. I certainly do not place it perfectly centered however, and my guess is that it breaks up the patterens even more so.
YMMV and FWIW
Edits: 06/14/14Follow Ups:
Would it therefore follow that we should not locate our speakers symmetrically in the room?
Regards,
Andy
IIRC Cardas recommends it
"I've written this before: by the laws of thermodynamics, energy can not be created or destroyed. All we can do is to alter its amplitude or frequency, but the energy still remains."
Energy can also be converted. I would think a little extra heat in a normally ventilated listening room might be less annoying than repurposed unwanted mechanical energy.
"repurposed unwanted mechanical energy."
Or, as they say in the profession: R.U.M.E. Colloquially 'rummy'. I'm not too sure just which profession that would be but I've worked on lots of rummy stuff in my time...
Your point is an excellent one, heat's the final repose for energy so we all need to do our bit to increase entropy!
Breaking up resonances seems like a good thing as it broadens the energy and reduces the radiation efficiency of the source. But does it also reduce the "impact" of the music? I don't know, audio systems are tricky...
Rick
Lol. Not bad as acronyms go.The trick is always protecting that stupid cat. Dead or alive though it's all a just another path on a downward spiral to heat death.
I think the best bet is ensuring there isn't a possibility of standing waves from forming in the enclosures in the first place and any enclosure resonance causes distortion since it's energy robbed from the acoustic signal. How can one possibly re-use this energy constructively once it has been converted from it's acoustic energy source?
Since no one can design perfect enclosures we will always have unwanted resonance.
Who knows? Maybe breaking up nodes and damping work well together. I'm no ME.
Edits: 06/18/14
"I think the best bet is ensuring there isn't a possibility of standing waves from forming in the enclosures in the first place"
Right! And that means improving the impedance match to the air or increasing the loss of the radiator. Or both. Ya' gotta keep the effective Q down...
I think Quad has or had some scheme using a delay line that mapped the size of the driven surface to the frequency components. That makes sense to me as it should make the radiation resistance more real and consistent. I wonder if you couldn't do the same sort of thing with dynamic drivers in an array on a panel. Sort of a sweet 128... We can make low power amplifiers really small and cheap and if the array was circular each Amp. could run several drivers at a given circumference.
And then, of course, we totally damp the back wave or put the whole Mary-ann in a wall so it feeds two rooms. Or use horns...
Meanwhile, I've found that the only speaker topology I really like long-term is sealed "acoustic-suspension" styles. They just sound truer to me in an actual room than other styles. I think that well implemented horns (Geddes?) might also work but I've not heard them.
And "in the room" is a huge factor. At one time I has big ESS speakers with a Heill (sp?) tweeter and TL woofers. We were moving around a bit then so I had them in three houses and they almost worked in all three, but not quite. I replaced them with Infinity quantum 3's and was very happy. BUT the interesting thing was that if I opened the sliding door and sat out on the patio the ESS's really sounded like there were live instruments playing in the house. The Infinity's sounded like a good stereo was playing on the house under the same condition. But sitting inside they flipped and sounded like you were more at the original venue and were far more enjoyable and less irritating.
Which is a long-winded way to say that you have to match your tastes AND environment. I suppose it's obvious but some of us are slow... By the way I happened to go to a show at the Griffith Observatory during all this and they were using small banks of ESS home speakers, the one's with a port, at each corner for sound. It sounded wonderful!
Rick
It would be almost impossible to make a 100% conversion to heat. Nodes would thus still exist.
That makes a lot of sense. I currently am listening to a preamp that is very sensitive to cone placement. I'm using the mapleshade big brass ones and have been moving things around quite a bit. I'll give your idea a whirl.
Thanks
Which model Mapleshade brass cone are you using?
See link:
I'm using the original heavy feet brass footers. I like them more than the next generation feet with the micro point. I have both so I have compared. Of course I have the Boston Audio tone blocks, isoblocks, golden sound Jumbo cones, etc. They all sit on 4 inch thick Maple blocks.
Thanks
What footers or pads (if any) are placed between the bottom of the maple blocks and the surface (such as a rack shelf) they are placed upon?
Under the four inch thick maple platform I have a set of mapleshade isoblocks which than sit on top of another four inch thick block of maple which is supported by another set of isoblocks. These sit on the floor. I use this arrangement under my CD player, amp, preamp, and each part of my external crossover for my speakers. I have a lot of maple blocks in my listening room. The isolation is very good such that any changes in the brass footer under each component is quite audible. It keeps me out of trouble playing around with different isolation/coupling techniques. Ps thanks for all of your advice!
I can understand why you like to keep out of trouble playing around with different isolation/coupling techniques. It can be a difficult progression.
That said, I have suggestions that might be worthy to try in order to modify the stock configuration.
Cool!
Images: Carbon fiber composite discs (30mm W x 10mm H), Herbie's Audio Lab Thin grungebuster Dots, Herbie's Audio Lab Big Fat Dots (dBNeutralizer pads).
I happen to use a somewhat similar DIY amplifier stand configuration positioned directly on the floor, that I use for a stereo power amplifier, that feeds a pair of passive subwoofers with an outboard active crossover unit. However, the configuration of the amplifier stand features two kinds of wooden boards, each of a different thickness, and different footers than yours are implemented to support and decouple the stacked boards, and with different cones than yours for the component that is positioned on top of them:
The bottom board is 2-1/4 inch thick Maple, coupled to the floor with a tripod set of carpet-piercing brass tiptoes. The top board is 1-3/4 inch thick Lyptus (hybrid eucalyptus) placed on top of the Maple board, decoupled by a set of four Herbie's Audio Lab Big Fat Dots (dBNeutralizer pads). The power amplifier is supported by a tripod set of Black Diamond Racing Pyramid Cones MK4 positioned point-side-up, with a Herbie's Audio Lab "Thin" Fat Dot (1-5/16" W x 1/8" H dBNeutralizer pad) adhered to the base of the cone for use as a decoupling interface with the surface of the platform.
Here's a configuration that I think may improve performance vs. your current configuration:
1. Place a Herbie's Audio Lab Thin grungebuster Dot (the Thin grungebuster Dot, not the regular grungebuster Dot), black color, with adhesive backing at the base of each brass cone (the opposite end of the point) to help the cones work more efficiently and mitigate microphonics. Measure the flat surface area of the brass cone base. See link:
http://herbiesaudiolab.net/gb.htm
2. Instead of placing the point of the cone directly on top of the Maple platform, use a set of carbon fiber composite coupling discs (30mm W x 10mm H), with a 1-1/8 inch diameter Herbie's Audio Lab Thin grungebuster Dot (the Thin grungebuster Dot, not the regular grungebuster Dot), black color, with adhesive backing on the base of each coupling disc to help the cones work more efficiently while dissipating vibration/mitigate microphonics. See links:
http://www.ebay.com/itm/3pcs-30mm-Carbon-Fiber-Spike-Isolator-/181439345497
http://herbiesaudiolab.net/gb.htm
3. Instead of Isoblocks, use a set of four Herbie's Audio Lab Big Fat Dots (dBNeutralizer pads) to decouple and efficiently block sound pressure waves from entering the system via the floor, as well as decouple and provide a low-compliance vibration blocking interface between the two boards. See link:
http://herbiesaudiolab.net/spkrfeet.htm
YMMV, so you might at first consider trying a complete configuration for just one platform system, then if you like what you hear, you can order more for the other platforms.
A cool idea-I will try it in stages and report back. Again, my thanks to you! This is the sort of conversation that makes the asylum a great place to hang out. I'll try the Herbies on the tops of the brass first and go from there using my CD player as the test bed. I have used the Boston Audio Tuneblocks as well, but found the sound a little thinner in the mid bass. I guess I won't be going out for awhile now.
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: