Vibrations! Agh! Agh!

[ScooterMcTav]

So, I’m struggling with isolating my TT from vibrations being caused by my music and am looking for some DIY ideas.

Previously, my unsuspended TT (an Elipson Omega) sat on a wall shelf screwed into two wall studs. This sits roughly 3.5 feet above the floor, and is located between my fronts. The fronts are rear-ported Tannoy DC6T, sitting on felt pads to isolate them from the floor. The TT had two layers of Dynamat pads under each foot.

Lately, I noticed that when the volume came up, the woofer dance began. Although the TT appears to run quiet (the main reason for getting a new TT), there must be some sort of subsonic mumbo-jumbo going on that is causing this. Turning the bass dial down on my Anthem i225 certainly helps with the issue, but then makes the music suck. Cartridge is an AT VM95EN.

For S&G, I tried my Lenco L75 on the shelf with a Grado green, and the vibrations were worse, though the Grado certainly has a fatter bottom end than the AT on the Elipson.

So did some feel testing the other day, and can feel the vibrations in my wall as well as the shelf when the music is playing at even moderate volumes and with moderate bass. We’re not talking ear-bleed level volume either – just good listening volume.

The wall is an external wall (hence load bearing), and the floor is hardwood. I’m really surprised at the amount of vibration that was being conducted by the wall.

To try something different, I removed the shelf, and placed the TT on my media unit. On top of the unit, I made a six-layer sandwich of dynamat and 1/8” closed cell foam, placed the shelf on top, then added a square of magic eraser under each of the feet of the TT. This has minimized the vibration at the TT, but when my Mrs went stomping by, off jumped the needle. And then the dog went by, and the needle jumped again.

Aargh, I was reminded that the reason I went to the shelf was to insulate against stomping.

So, I’m at a bit of a crossroads. And since this is in my main living area, any suggestions must meet adequate levels of attractiveness as not to displease the Mrs.

A few things that I have not tried:

- Dynamat between the shelf bracket and the wall to reduce vibration into the bracket

- Dynamat between the shelf bracket and the shelf to reduce vibration on to the shelf

- Putting spikes on the speakers to decouple them from the floor better than the felt. Hate to do this as the tweeters are already high in these units, but what the hey

- Building some sort of board that is insulated from the wall, to which I attach the shelf brackets

Things I will not try:

- Listening to classic rock music without a proper amount of bass

- Turning the volume to “Yanni in the background” levels

I’m thinking I have to go back to the shelf, simply as I live with a family of unwashed, turntable insensitive stompers.

Any ideas other than the Dynamat and speaker spikes that anyone can recommend?

 

[oldman54]

Subsonic filter. Whatever you do with the wall shelf the screws will transfer vibrations. It's still your best bet. The KAB sub filter gets a lot of love but its $200. I use an fmod filter. They have different frequencies at 12db per octave but I like the 18db@37hz one. I don't notice any missing bass with it. It's about $35, other frequencies are like 17 each channel. They are line level, passive rca connected. I think the KAB crossover is 20hz if you need that bottom octave.

 

[AvFan]

I don't have wood floors but I still have speaker induced vibrations in the cabinet my TT sits on so I've tried two approaches:

Sandbags. I put four sandbags in a tray then placed a piece of plywood (that does not touch the sides of the tray) on the sandbags and the TT sat on the plywood. Sandbags are very effective at converting vibration to heat (think bench rest shooting). Here are some photos of this very effective isolation approach:







CLD Panel. A similar approach is to replace the sandbags with a CLD layering system of 1/2" MDF - 1/8" Aluminum - 1/2" MDF where these layers are held together with a 3M CLD tape. This sandwich rests on Sorbothane disks selected to be in the load range specified by Sorbothane. I used this approach when I replaced the solid cherry top of a new-to-me cabinet. Some photos of this approach:





There is more info on the latter vibration isolation system in this thread beginning on Post #793.

 

[ripblade]

Yes, put the TT back on the wall and install an isolation platform under it. The platform needs to be heavy and rigid, non resonant, like stone or thick hardwood maple. Under this you need something very squishy to absorb the vibes from the wall. Squash balls, partially inflated inner tube, sorbothane bushings (Vibrapods are ideal) or springs. Dynamat isn't compliant enough.

 

[justjed2]

Not sure if it's a thing anymore or not, but there was a time when people looking for isolation would hang their TTs from the ceiling, usually in some fancy macrame work and a board, or two.
I also seem to recall some discussion of whether a 3-point or 4-point support was most effective. Just a thought.

Isolation first. The KAB rumble filter is effective at controlling subsonics, and all but eliminates woofer pumping, but it is not a replacement for proper isolation.
It's just another tool to help rid the signal, and thus, the sound, of as much noise that isn't music as possible.

 

[Zygmo]

I have had the best luck with wall mounted shelves.

 

[AvFan]

@ScooterMcTav : I re-read your OP and that you have vibration in the wall your TT shelf is mounted to. I dealt with isolation of the TT but in your case isolation of the speakers from the floor and rest of your house might also help. I won't get rid of airborne induced vibration but the speaker cabinet vibrations won't make it into the structure. The methods I described above would work for the speakers but simple Sorbothane disks under the speakers should as well. Every little bit helps.

 

[sKiZo]

First things first ... make sure your table is perfectly level. If it's off, it will enhance any other problems.

That said, I use Vibrapod feet here. You can get those in different load ratings to match the weight of your table.

 

[doctor fuse]

1. Make a DIY tonearm fluid damper, out of household scraps of wire and plastic. It really helps with woofer pumping.
here is a good DIY guide:
http://www.enjoythemusic.com/magazine/bas/0809/
2. Try racquetballs as feet, under your turntable base. Either cut them in half, or drill holes in a board large enough for a bit of the ball to go through, so it can be stable. This really helps isolate my TTs.

After you do those two things, you should be able to crank the volume and not lower the bass! Rock on...

 

[Scramble]

I've been using a simple & cheap method for almost 20 years now. I have large floorstanders with big woofers & play them loud with vinyl & no vibrations come through my platform. It's 1/2" plexiglass cut to about 14" x 20" which is slightly larger than my TT. I use (4) 2" halfmoon Sorbothane feet. Get the plexi from your hardware store & the feet from eBay & you'll be in for under $80.

Also forget the Dynamat, that's for car interiors & keeping sound & exhaust heat out. Not needed for audio. You can buy sheets of Sorbothane from the Web. It's the best for isolation or even plain old rubber.

If your speakers have rear firing ports that wall mount isn't gonna help much. Ported speakers are not meant to be near the rear wall anyway but I'm a firm (pun intended) believer in sealed cabinets with tight & accurate bass.

 

[kirk57]

Not sure what kind of wall mounted shelf you are using, but the Target (UK) one I was using had upward facing spikes that the platform sat on.

Like this:

I used that is a pole-construction building (circa 1900) in Chicago and my girlfriend and I did a lot of dancing in that room and the suspended deck (Systemdek) never skipped.

The sandbox mentioned above is also a very easy DIY.
A box, some sand (I put the sand directly into the well sealed box) and a piece of wood on top.

 

[ScooterMcTav]

Thanks for the ideas folks.

Did a few things in the interim including spiking the speakers. This seems to have had the most immediate impact, as it decoupled the speakers from the floor, seriously reducing the vibrations transmitted to the wall.

Also used some closed cell foam on the bracket supports under the TT shelf (inert 1/2" MDF). These simple mods have removed a big chunk of the vibrations I've had, and have certainly reduced the woofer dancing.

Next on the list (likely this weekend) will be building a sandbox as suggested by AVFan, and sourcing some sorbothane online.

That being stated, I did play a warped record the other day, and have no ideas how to address this excursion except through a subsonic filter.

 

[AvFan]

Thanks for the ideas folks.

Did a few things in the interim including spiking the speakers. This seems to have had the most immediate impact, as it decoupled the speakers from the floor, seriously reducing the vibrations transmitted to the wall.

Also used some closed cell foam on the bracket supports under the TT shelf (inert 1/2" MDF). These simple mods have removed a big chunk of the vibrations I've had, and have certainly reduced the woofer dancing.

Next on the list (likely this weekend) will be building a sandbox as suggested by AVFan, and sourcing some sorbothane online.

That being stated, I did play a warped record the other day, and have no ideas how to address this excursion except through a subsonic filter.

It sounds like you are on the path to solving the TT vibration issues. Interesting that spiking the speakers improved the situation as spiking is generally thought to couple the item to what it is sitting on but if it is an improvement that is all that matters. I hope you can report back on the results of using the sandbox. Lastly, I was looking at your avatar and if it is your current setup I would suggest experimenting by moving the speakers away from the equipment rack if possible. Let us know how it all goes.