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AV Racks. What difference does it make?

Im not sure i understand what difference your rack could possibly have.

I understand everybody here seems to feel that reducing all sorts of vibrations is important as well.

How is that? its not like 1's and 0's get rattled off the circuit board by vibrations

Whats the point in a better rack? What is a better rack? And how does a $1,500.00 rack make anything sound better? I mean, technically, in depth, can anybody explain this phenominon?

Sounds like a buncha horse pucky to me. Kinda like the kinds new clothing.

Does anybody have a theory of how one AV rack can sound different than another? And dont give me any of that room accoustics stuff, i dont see people talking about which sitting chair is best for sound!!!! :)

"I found that wearing wingtips and khaki shorts really opened the soundstage compared to my nikes and TH bluejeans."

I have a good understanding of electronics and accoustics, but i cannot imagine any way a rack could make a difference.
What is the theory of how a Maplewood rack might sound better than an oak for example?

Do you all use racks and isolation pods at the same time?
slappy
gunbei
2,327 posts
 
Sean, I'll have to show you those darling baby pictures some time over a nice cup of warm milk. When Viggen was a little tyke he loved to mash his hands in his own poop. Needless to say he wasn't allowed near a remote control or allowed to adjust the volume knob when his mitts were in that state. Hahhhh!!

How does an accelerometer represent the measured vibration? Is it a graphic display like a sine wave? Would the device be placed directly on the platform or rack being tested? Would it be able to show both the amount and frequency of the measured vibrations? Is there a way to correlate the measurements with the possible effects on the audio system, such as if a noted bunching of measurements around a certain frequency possibly causing a tonal change in that area during playback? Yeah, that would be an interesting test.
slappy OP
903 posts
 
I think im going to try making an AV rack using Maple and seismic Bolts. A nice 200LB job.

I dunno if anyone has used sseismic bolts, but they can be bought at any telco harware store like Greybar. they are supposed to supress vibrations against earthquakes, im curious how much they do to prevent vibrations from the floor.

Has anybody ever messed around with various types of suspension to see if they can eliminate vibrations? I dont mean little rubber feet and stuff, but used car shocks, or tension springs, or maybe even some type of neumatical or gell based suspension system?

What about Dynamat? they used that to eliminate vibrations in cars. Ill bet that stuff would make a pretty wicked isolation pad.
sean
6,231 posts
 
Slappy: I think that you'll find that there are MANY schools of thought as to what makes for a "great rack" ( oooh boy.... ), but there is no single ideology that covers every aspect perfectly. That is why there is such a vast market of products available in terms of racks, isolation, damping, absorption, coupling, etc... I think that this is something that people have to learn / experiment with on their own and learn from that i.e. the hard way. It seems to be about the only way that people "open their minds" when dealing with controversial subjects like this.

Unfortunately, this can be both expensive and time consuming, so try and learn as much as you can from others and be selective about what you spend your money / concentrate your efforts on. There are quite a few excellent suggestions in various threads here on Agon and at AA made by people that have spent the time and money to learn the hard way. Let their experiences work for you and i think that you'll find that you are both happier and not quite as poor as others that aren't quite as open to suggestion. Sean
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slappy OP
903 posts
 
Thanks Sean, however, i think i have made my mind up, because i think i have the perfect solution for an AV rack

Get a bunch of paint-mixers and place the audio equipment into the clamps of these babys and turn em on!

they will be shaken so violently that no airborne vibrations will make any difference!:)

HAHAHAHAHAHAHAHAHAHAHAHA

just kiddin!
viggen
838 posts
 
Hey Sean,

The purpose of understanding natural resonance frequencies of different materials is so you can combine different materials to mechanically/sympathetically minimize vibration (instead of amplifying it.)

If you examine the Symposium shelves where it sandwiches materials of varied densities together, you'd see how this phenomenon works. Lexus does something similar with their car bodies and IBM does something like this with their high end server/storage cases.

With my speakers, I have good luck using the wood/graphite/granite to tailor the speaker to sound the way I like it. This reduced a bit of boominess in the lows and LOTS of hashiness in the highs as well as expanding the soundstage.

So, when using your vibration measurement machine, try using it on a combination of materials such as rubber on wood or metal on marble etc, and, ofcourse, tune with your ears.
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