Decoupling turntables from floor vibrations

[Lee in Montreal]

Two weeks ago, I was at a friend's place and we mixed some music for his MixCloud channel. When I listened to it back at home, and with the heavy sub bass I have, I couldn't help notice all the thumping in the background. Yup. The needle was catching people walking around the room. Soft floor in an old appartment. So, I checked for some old drafts I did years ago. Added a few notes and sent the blueprint into production. Here's what I ended with. The basic idea is to decouple the Technics SL1200 from floor vibrations by using rubber bands. exactly what you could find in clubs and discos back in the 1970s and 1980s. I made a pair for my friend and another for myself as prototypes. I will spend some time experimenting with rubber bands, positionning and weight distribution. But at least, we can do some mixes at my buddy's place without having to care how heavy we walk.

[Ducatista47]

Ever wonder how those flimsy old Gerrard and Thorens transcripton TTs did it? They were used as intended, not like vinyl revivalists do it with add on expensive feet. They mounted them on large, very heavy blocks - not slabs - of granite. There are advantages to using commercial spaces to listen to music, strong floors being just one.

Nice, clever DIY to solve the lack of stone. Kudos!

[Allanvh5150]

It is pretty easy if you are on a ground floor. Pour a concrete base under the floor. Install a metal post with a top on it for the turntable and make sure where it passes through the floor, it doesn't touch. Nice, easy and cheap.

Allan.

[hjames]

It is pretty easy if you are on a ground floor.
Pour a concrete base under the floor.
Install a metal post with a top on it for the turntable and make sure where it passes through the floor, it doesn't touch.
Nice, easy and cheap.

Allan.

WOW - its easy - why hasn't everybody done this??

[Ducatista47]

It is pretty easy if you are on a ground floor. Pour a concrete base under the floor. Install a metal post with a top on it for the turntable and make sure where it passes through the floor, it doesn't touch. Nice, easy and cheap.

Allan.

The post has to be non resonant. Perhaps filled with concrete? People walking around is only one source of movement. I can tell you from running an 8 X 10 photo enlarger on a third floor of a commercial building in Chicago that vehicle traffic is much worse.

[Allanvh5150]

WOW - its easy - why hasn't everybody done this??

Oh dear, yet another snippy remark from Ms James...

[macaroonie]

Wall mounted shelf is a start , gets you off the floor. Sorbothane feet work well but not at low low frequencies.

Lee your metalwork is excellent as always , you want to have your rubber bands as boingy as possible. Not so stiff there is no give but not stretched up to their elastic limit..

Other cheapo mod with those Technics decks is to pack the cavities in the plastic mouldings , base and plinth body. Use any dead medium like blu tack , play dough.

Clean the main spindle bearing out till it is sterile and use a good moly oil or grease. As I recall the bottom of the bearing housing is open at the side , you may need to use a grease. This will drop the background noise floor.

Ah someone's been here before , Lee your machine shop could come up with one of these good ones eh ? 650 Ozzie Dollahz !!!!!!

http://www.audioasylum.com/cgi/vt.mp...&m=881627&VT=T




In simple terms there are all manner of resonances floating around in a turntable structure and any step you can take to minimize them is a step forwards.

[hjames]

It is pretty easy if you are on a ground floor. Pour a concrete base under the floor. Install a metal post with a top on it for the turntable and make sure where it passes through the floor, it doesn't touch. Nice, easy and cheap.

Allan.

WOW - its easy - why hasn't everybody done this??

Oh dear, yet another snippy remark from Ms James...

Was that snippy? Just a little, but it was an honest comment.
Let me break it all down for you then.

Building a concrete base under your house, cutting a hole in the floor, and putting a pole up through the floor
doesn't quite fit what I or most people might classify as "easy" - tho describing it sounds pretty easy.
I suppose it would depend on the caliber and design of your home.

I guess if your home has a crawl space underneath, it might be "somewhat easy" -
but it does seems like other approaches might better fit "easy".

Buying or building a base with elastic bands to float the table seems more like most people's definition of "easy" -
At least easier, compared to concrete work (most folks would think of that as hard work).

I kind of thought the original comment was fine, there was no mean spirit in it, and I was just trying to
avoid getting into a long off-tangent response and discussion - like you seem to want.

Frankly, I prefer Lee's or Macaroonie's approaches to yours ... and most folks would.



I seem to remember seeing Lee talking about ashtrays used with elastics in another thread -
he seems to have some genuinely great ideas to handle the problem.

http://www.audioheritage.org/vbullet...pension-thread

[gasfan]

Duck Seal was the premiere mastic putty solution way back when. It's that soft elastic putty they use for sealing the entrance holes for the refrigeration lines in the back of your frig. I stuffed a Technics TT with it. Instant Linn a la Red Green.

[macaroonie]

Duck Seal was the premiere mastic putty solution way back when. It's that soft elastic putty they use for sealing the entrance holes for the refrigeration lines in the back of your frig. I stuffed a Technics TT with it. Instant Linn a la Red Green.

That sounds just like the ticket. As long as it's a non setting compound. Window putty is no good as it sets hard.

[gasfan]

Stays the same forever.

[Mctwins]

Hallo!

Nice turntable

Is there no risk that the turntable will swing back and forth when touching the table by misstake. How is it attached to the feet? Can't see it on the pic.

But cool device thou.

[Mr. Widget]

Here's what I ended with. The basic idea is to decouple the Technics SL1200 from floor vibrations by using rubber bands. exactly what you could find in clubs and discos back in the 1970s and 1980s. I made a pair for my friend and another for myself as prototypes.

That isolation base is very nice looking… Beautiful enough that you should go to the trouble of finding the proper black O-rings that you can substitute for the rubber bands.


Widget

[Radley]

Back in the disco era of the 70's, Trocadero Transfer in San Francisco had their DJ booth on the second floor. Underneath all the finish work were two large pillars of concrete going down at least 25'. One for each turntable.

I also remember some guys building little square boxes with no top. They'd fill the boxes with sand and then place the cut out top on top of the sand upon which they'd sit their turntables. Very heavy but they'd be able to turn up the volume to club level.

Very nice millwork, Mr Lee. Is that from a CNC?

[NickH]

You want a base or plinth that's dead to resonance. Springy isn't as good. Granite also not a good since it rings like a bell. Silicone rubber is a better material to use as a damping medium. But honestly a heavy non resonances plinth is a really easy fix. I'm one of those guys with a flimsy thorens transcription table. Its mounted on a heavy laminated mdf plinth. I was lucky enough to have the use of a 50 ton present use to hold it together while the gorilla cured. Little bubbles in the poly foam glue helps to damp vibrations but big gaps create a reflections to it.


I've often thought about making plinths from a moderately high durometer resin with silicone rubber balls and tungsten balls mixed in it. Vacuum cast of course.

Slate is also good but there for guys with deeper pockets then me.

Nick