GRANITE STAND UPDATE
Posted by: Rich Jerskey on 06 December 2003
I've made an advance in the acoustic functionality of my granite stand. Simple but very effective and somewhat labor intensive at least for 6 hours or so.
The upgrade for the granite stand is as follows.
At present the granite shelves are supported by stainless steel threaded rods. If you detect any high frequency non-transparency or non-optimal resolution at these frequencies then this can be somewhat explained if you put your head between shelves (as best as possible) and talk in normal tones without any other noise/sound in the room. What do you hear? Well, I hear kind of a "bell-like" response and that tells me that any vibrations transmitting up and down the stand are being colored negatively by the acoustic properties of the dense granite coupled to the steel rods (3/4 inch). As soon as I discovered this effect I realized I was shortchanging myself but I still had the potential of a very decent stand acoustically.
The solution:
There is the main problem that sound vibrations readily move up and down the stand because of the denseness and rigidity of the rack. Is there a way to maintain the strength and relative rigidity of the stand but have a different coupling from shelf to shelf and thus diminish the negative bell-like effects? The idea is to get PVC pipeing that will effectively contain the length of rod and associated washer/nut between each shelf. This of course means taking the whole damn thing apart except for the very bottom shelf. I ended up with cutting 7 inch lengths, spray painting them black (with a spray that would adhere nicely to PVC - it helps to sand lightly first). I then slid them over the rods to rest on the bottom shelf. (I taped the rods first leaving enough space so that a bolt and nut would fit slightly less than flush at the top of the PVC.) After taping, I poured sand into the PVC, tamped it a little and screwed down the bolt followed by a washer so that they was just a 64th or so of an inch below the top of the PVC. I did this for the three rods at each level and rested the next granite shelf on the PVC filled with sand and nut/washer in place. It's now mainly the PVC cylinder filled with sand that supports the shelves with the overlaying shelf bolted down gently but firmly from above. The procedure is repeated for each of the shelves. We now have cylindrical supports filled with a semi-dense material (sand) instead of just the rods themselves. The difference in sound is apparent right away and makes good sense when you think about it. Also, a big bonus: the magnetic factor that no doubt was detrimental to some extent here has been insulated to a large degree by the sand and PVC support/housing.
I'd be interested to hear (if you go through this weekend hassle) if you don't also notice a very pleasant but marked improvement.
Rich
p.s. the stand now looks 100% better as well, very nice touch having black cylindrical supports matching black granite and black components.
The upgrade for the granite stand is as follows.
At present the granite shelves are supported by stainless steel threaded rods. If you detect any high frequency non-transparency or non-optimal resolution at these frequencies then this can be somewhat explained if you put your head between shelves (as best as possible) and talk in normal tones without any other noise/sound in the room. What do you hear? Well, I hear kind of a "bell-like" response and that tells me that any vibrations transmitting up and down the stand are being colored negatively by the acoustic properties of the dense granite coupled to the steel rods (3/4 inch). As soon as I discovered this effect I realized I was shortchanging myself but I still had the potential of a very decent stand acoustically.
The solution:
There is the main problem that sound vibrations readily move up and down the stand because of the denseness and rigidity of the rack. Is there a way to maintain the strength and relative rigidity of the stand but have a different coupling from shelf to shelf and thus diminish the negative bell-like effects? The idea is to get PVC pipeing that will effectively contain the length of rod and associated washer/nut between each shelf. This of course means taking the whole damn thing apart except for the very bottom shelf. I ended up with cutting 7 inch lengths, spray painting them black (with a spray that would adhere nicely to PVC - it helps to sand lightly first). I then slid them over the rods to rest on the bottom shelf. (I taped the rods first leaving enough space so that a bolt and nut would fit slightly less than flush at the top of the PVC.) After taping, I poured sand into the PVC, tamped it a little and screwed down the bolt followed by a washer so that they was just a 64th or so of an inch below the top of the PVC. I did this for the three rods at each level and rested the next granite shelf on the PVC filled with sand and nut/washer in place. It's now mainly the PVC cylinder filled with sand that supports the shelves with the overlaying shelf bolted down gently but firmly from above. The procedure is repeated for each of the shelves. We now have cylindrical supports filled with a semi-dense material (sand) instead of just the rods themselves. The difference in sound is apparent right away and makes good sense when you think about it. Also, a big bonus: the magnetic factor that no doubt was detrimental to some extent here has been insulated to a large degree by the sand and PVC support/housing.
I'd be interested to hear (if you go through this weekend hassle) if you don't also notice a very pleasant but marked improvement.
Rich
p.s. the stand now looks 100% better as well, very nice touch having black cylindrical supports matching black granite and black components.