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In Reply to: RE: Piezoelectric crystals posted by geoffkait on July 17, 2010 at 04:34:25
Interesting post Geoff. I know you've mentioned this before but I appreciate the details. Maybe those jars of agates are doing more than I would have thought. They sit on a half-wall just behind my chair and above my head. I've always thought I should try a diffuser on the wall but it's never seemed cause problems as have other walls in the past. I'm sure being short helps but maybe it's also the rocks...
Is being in a lattice important? I think this would be good excuse for an experiment, I could go collect a bunch of basalt rocks from the beach which are far more common than agates. In fact I've always joked that if the beach were mostly agates that we would collect the black rocks.
Have you measured these effects? I've got an accelerometer around somewhere but I need to build a preamp for it. I could glue it to various rocks and, er, see if they Rock? I know they roll, even a casual observer can see that at the coast.
Rick
Follow Ups:
The basalt rocks don't have the well organized symmetrical crystal lattice that one finds in clear quariz, smokey quartz, aquamarine, topaz rumbled stones. When I refer to *crystals* I refer to quartz, agate, aquamarine, ruby, topaz, jade, tourmaline, etc. Of course, the purer the crystal the more uniform and symmetrial the lattice structure. This is not to say basalt will do nothing, there could be mass loading going on...who knows?The lattice is important because the atoms in the material are allowed to move back and forth with ease. If the structure were not symmetrical the atoms could not move freely.
Big doesn't necessarily mean better. My Mikro size BP comprise crystals of various types that are only 2-3 mm each. A Mikro packet comprises only 25-30 of these minuscule crystals.
Measurement is best done with SPL meter and test tone. This method allows determination of locations in the room where improvements to the sound will be experienced. Such as in or near room corners. Or on the wall at first reflection points, for example. Of course, anyone is free to measure these things any way they wish.
Edits: 07/17/10
A couple of questions...
1. Doesn't the container, i.e. Jar or Bag make a large difference in how rocks rock?
2. So if one were to set up his SPL meter on it's cute little tripod in the corner, note the SPL vs Frequency of a swept tone and THEN add the jar of pebbles and repeat... what sort of deltas would one expect?
I've come to believe that the details of acoustical specular reflections and general absorption have an outsized impact on our perceptions but I don't how to optimize it except raw trial and error.
On another note, you offer small packages of pebbles intended to be stuffed or propped where wires enter gear. Is that mechanical also?
Rick
I use the spl meter/test tone strictly to determine the points in the room where there are peaks more than 6-8 dB above the average level. These pressure peaks can be anywhere in the room, in the ceiling, on a wall, or anywhere in the 3-D space.The ziplock bags of crystals dissipate energy where the peaks are located. There are a great many peaks in the room, so the question will arise as to which ones should be treated first. :-)
The Mikro is smallest BP (about 1 oz) and can be placed on top of the RCA jacks, and yes, am pretty sure they act mechanically. They can also be placed next to small vacuum tubes, on top of CD player, on power cord plugs, taped to glass windows, sliding glass doors, taped to the wall in stategic locations, etc.
I should also add that my BP undergoes special treatments, even the assembly and choice of crystals is proprietary. All of this, including all of various applications for the different sizes, took a little bit of time to work out, as you can appreciate.
Edits: 07/17/10
"All of this, including all of various applications for the different sizes, took a little bit of time to work out, as you can appreciate."
I do appreciate that, way too many variables in audio. It almost is the very definition of audiophilism.
A few years ago I stuck a piece of RG-58 in my ear (NO, don't go there! It had a BNC connector on it and didn't go all the way through) and tapped on the other end (it was maybe three meters long). Twas right up there with Big Ben albeit monotonic. Rang for seconds. So I hooked it up to a scope and did the same thing and it looked just like it sounded. There's dielectric helping things out. Maybe I should try again with a crystalized version...
By the way it was regular ol' solid dielectric, I suspect foam would be better.
Rick
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