Author Topic: Turntable Wall Mount  (Read 37541 times)

Offline _Scotty_

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Re: Turntable Wall Mount
« Reply #45 on: February 22, 2012, 01:01:12 PM »
Bill what is under the floor in the room with the foot fall problem?
Scotty

Offline StereoNut

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Re: Turntable Wall Mount
« Reply #46 on: February 22, 2012, 01:32:37 PM »
Bill what is under the floor in the room with the foot fall problem?
Scotty

The room is 26' wide by 16' deep.  My stereo is on the longer (26') wall, almost centered L <> R.  The floor is ceramic tile set on a "mud" base with a plywood sub-floor.  Underneath that is a crawl-space.  I even had a buddy of mine stuff himself into the damned crawl-space and run a 4 x 4" halfway between the main center floor support (that's 8' out from the front wall) and the front of the room, across a 14 foot span that goes from just beyond my stereo rack on the left all the way across to just past my far right side speaker.  Even with that extra bracing (4' out from the front of the room towards the middle) horizontally under the floor joists, my tonearm STILL bounces!  :shock:

I thought everything would be taken care of, but the floor just has too much #@!$%&* "spring" to it!  :x
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Offline richidoo

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Re: Turntable Wall Mount
« Reply #47 on: February 22, 2012, 02:40:57 PM »
Excellent question Scotty. Wish I thought of that.  :duh

A screw jack post under the TT is all you need. They come in various nominal lengths and are adjustable over a range. Put it on a Dek-Block pier right on the dirt. Crank in 1/8" of lift, problem solved.  mfsoa uses these.

Here's one that uses your own 4x4 as column.
http://www.ellisok.com/ellisok/products_screwjacks.html#SJ4

Offline StereoNut

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Re: Turntable Wall Mount
« Reply #48 on: February 22, 2012, 04:46:13 PM »
I guess I should've explained my last post a little better.

The 14 foot long 4 x 4" that my buddy installed across the floor joists in the crawl-space at the front of the room is braced with vertical 4 x 4's jacked up underneath it, each supported at the base by a 1 foot square / 2" thick cement patio block.  (Oh, and by the way - the crawl-space has a 3" concrete scree coat covering the ground.  No exposed dirt.)  There are 4 of these 4 x 4" verticals, spaced evenly across that 14 foot 4 x 4" support.  And the damned floor STILL bounces!  :evil:

That's why this whole thing has me totally frustrated. :duh
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Offline richidoo

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Re: Turntable Wall Mount
« Reply #49 on: February 22, 2012, 05:24:25 PM »
How far away from the TT is the nearest jack post? It must be directly under the TT rack. The horizontal 4x4 is not rigid enough to stop micro-vibrations without support, it's just like the wooden floor structure, which easily vibrates.  The post under the TT needs to lift the house a small amount to pre-load the floor so that it can't move further upward with impulses. Then it can't move up and it can't move down.  You should be able to stomp on the floor above the post and feel/hear no low-frequency resonance.

Offline StereoNut

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Re: Turntable Wall Mount
« Reply #50 on: February 22, 2012, 07:01:22 PM »
How far away from the TT is the nearest jack post? It must be directly under the TT rack. The horizontal 4x4 is not rigid enough to stop micro-vibrations without support, it's just like the wooden floor structure, which easily vibrates.  The post under the TT needs to lift the house a small amount to pre-load the floor so that it can't move further upward with impulses. Then it can't move up and it can't move down.  You should be able to stomp on the floor above the post and feel/hear no low-frequency resonance.

It's very close to being right in front of the TT (L<>R) and about 2 feet in front of it.
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Offline richidoo

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Re: Turntable Wall Mount
« Reply #51 on: February 22, 2012, 08:02:28 PM »
Pisser! I can see why you're frustrated!! Can you try to crank in a couple more turns?  Just don't crack the plaster...   :rofl:

Offline StereoNut

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Re: Turntable Wall Mount
« Reply #52 on: February 23, 2012, 05:24:05 AM »
Pisser! I can see why you're frustrated!! Can you try to crank in a couple more turns?  Just don't crack the plaster...   :rofl:

Maybe I should just pull one of the air vents off of the foundation and have a cement truck come in and back-fill the whole damed crawl-space with 90 cubic yards of concrete...???  :shock:

That should do it!  :rofl: :rofl: :rofl:
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Offline BobM

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Re: Turntable Wall Mount
« Reply #53 on: February 23, 2012, 05:37:50 AM »
It certainly would alleviate the WAF for the wall mount shelf. I can hear it now ...

"But honey, that cement truck is out front because you didn't want me to ruin the paint job on the wall. I'm doing this for youuuuu."
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Offline tmazz

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Re: Turntable Wall Mount
« Reply #54 on: February 23, 2012, 05:42:51 AM »
It certainly would alleviate the WAF for the wall mount shelf. I can hear it now ...

"But honey, that cement truck is out front because you didn't want me to ruin the paint job on the wall. I'm doing this for youuuuu."


You've been there?    :rofl:
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Offline StereoNut

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Re: Turntable Wall Mount
« Reply #55 on: February 23, 2012, 05:53:48 AM »
You guys are too funny!  This is the most fun I've ever had in NOT solving a problem!  :thumb:
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Offline tmazz

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Re: Turntable Wall Mount
« Reply #56 on: February 23, 2012, 06:01:20 AM »
You guys are too funny!  This is the most fun I've ever had in NOT solving a problem!  :thumb:

Always glad to help.  :D
Remember, it's all about the music........

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Offline BobM

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Re: Turntable Wall Mount
« Reply #57 on: February 23, 2012, 07:46:34 AM »
I tend to agree with John. Your real problem is the Linn. You can still sell it for good $. Get yourself something less bouncy, and you will indeed have an improved sound as well (just ask rollo now that he's replaced his Linn).

Problem solved, you get new stuff to research, buy and play with, WAF is satisfied.
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Offline _Scotty_

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Re: Turntable Wall Mount
« Reply #58 on: February 23, 2012, 10:23:09 AM »
Bill as you may have noticed your Linn's suspension is not really isolating the table from vibration very effectively. You might try to re-tune the tables suspension to change its resonant frequency. The suspension may also be under-damped.
When you have an arm/cartridge resonant frequency that falls within the turntable suspension's resonant frequency range you can experience problems like you describe.
 As far as bracing up the floor goes, I would try placing my screw-jacks along a line perpendicular with the wall you would like to place your shelf on and also behind the wall clear to the other side of the house. You may also have better luck using a small hydraulic jack rated for several tons to raise the floor to allow placement of fixed bracing.
 The high dollar solution would be a Vibraplane isolation table.
Another possible solution would be to hang a maple cutting board from eye-bolts attached to the ceiling that is big enough to place the table on. It could be suspended using small diameter vinyl covered steel cables.
Scotty

Offline _Scotty_

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Re: Turntable Wall Mount
« Reply #59 on: February 23, 2012, 10:38:27 AM »
Bill, my apologies for not noticing the picture of your rack.
The first thought that came to mind after seeing this picture is, I wonder what would happen if I firmly attached the rack to the wall behind it. If the wall isn't actually moving up and down with the floor this might solve the problem.
 Elaborating on the solution, you might raise the rack off the floor a half an inch with soft rubber footers and secure it to the stud in the wall by drilling through the center bar in the rear and using several 1/4 inch lag screws. If the rack is now a 1/2 inch off the floor and virtually suspended from the wall behind it maybe the problem would go away.
Scotty  
« Last Edit: February 23, 2012, 10:58:14 AM by _Scotty_ »