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. ;)

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC01998_zpscy44ekuv.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC01999_zpsn49jnh03.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC02001_zpstgpmeitp.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC02002_zpsvggpfinw.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC02003_zpsgscpomgs.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC02004_zpsn8wdoe2d.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC02005_zpsche0hwrs.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC02006_zpsvw0kc799.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC02007_zpse48lnkg5.jpg

[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??

:banana:

[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??

:banana:

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.mpl?f=vinyl&m=881627&VT=T

65291


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??

http://www.audioheritage.org/vbulletin/images/smilies/banana.gif

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/vbulletin/showthread.php?32833-Turntable-suspension-thread

http://farm5.static.flickr.com/4007/4190901485_c88f217643.jpg

[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

[Lee in Montreal]

There are indeed many ways to decouple a turntable from the floor vibrations. Making it simple is more difficult than making it complex. ;-)
Designing a new system is a very good intellectual exercise. It definitely turns me on. The system I drafted works. Now I have to rethink it and make it even simpler.

Lee

[gasfan]

Three feet?

[SEAWOLF97]

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.

I was in the darkroom on an Aircraft Carrier in a prior life ....When the catapult hits the stopping block during a launch, the whole ship shudders. If it happened during a print exposure , we just tossed it , knowing what the result would be.


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.
Nick

Mine is on a 18x25 slab of marble. Pretty dead, no ringing.

[Val33]

If you guys are in to the Technics 1210, you might like to look at 'The Art of Sound' forum, its UK based, but heavily biased to the Technics. Some of the mods are very interesting. http://theartofsound.net/forum/forumdisplay.php?46-The-Techiepedia

The normal isolation used here are Isonoes http://www.isonoe.com/products/audio-isolation-system/

Val

[macaroonie]

Just a point of info here , the sprung suspension turntables like AR , Thorens , Ariston , Linn and so on are very effective at isolating the playing mechanism from footfall and mechanical noise in the structureof the building. Why , because the sprung suspension is a high Q mechanical filter. It is crucial in all of these decks that the suspension is set correctly. You can read all about this all over the web esp about the Linn.
In a nutshell the springs must all work in unison to provide a single uniform resonance of the mechanical structure. Generally referred to as the ' bounce ' the sub chassis will have a movement, if agitated in any way that will resolve itself to a single motion up and down . Any sideways components of this movement , wiggles, or rubbing of the mechanism will defeat the effectiveness of the ' filter' ie short circuit.
In practice a properly adjusted sprung suspension deck will tolerate a significant fist thump ( a big one ) on the surface it is sitting on.

Internally all of these types of decks have a minimal chassis the sole purpose of which is to connect all the playing components together and at the same time to control the spurious resonances that are in the structure.
These resonances can be very very small indeed , coming from the needle/ arm , motor noise via the belt, spindle noise from the platter , ambient noise from the environment. Hi Fi is all about incremental improvements , any step forward is a good step no matter how small. It's surprising for example how nuch mush / background noise is generated by a less than good main bearing , or even dry lube or worn bearing surfaces. Sometimes just a good clean up and re lube is all it takes , just like cleaning your glasses ( drink or vision )
Some do this better than others needless to say.

Hope this helps a little.

[gferrell]

I hung an old Pioneer from the ceiling of my 1 story house about 35 years ago and it worked very well.

[stephane RAME]

http://images.junostatic.com/full/IS139223-01-01-BIG.jpg

Stéphane

[Lee in Montreal]

Yop. Seen that a while ago. Not as effective as rubber band suspension though.
Interestingly, years ago on a French DJ forum, I had discussed the principle of using rubber bands for suspending turntables and that it has been used for 4 decades in North America, and not a single DJ heard about the principle before. Back in the days, when a club would be built, it would use two layers of 3/4" plywood for the counter, and two square holes would be cut for the turntables. Hooks underneath to strap the rubber bands, and here you go. That was a common way to isolate the TTs from their environment.

[macaroonie]

The very expensive SME turntable uses elastic to suspend the playing chassis

65512

65514

[David Ketley]

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. ;)

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC01998_zpscy44ekuv.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC01999_zpsn49jnh03.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC02001_zpstgpmeitp.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC02002_zpsvggpfinw.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC02003_zpsgscpomgs.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC02004_zpsn8wdoe2d.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC02005_zpsche0hwrs.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC02006_zpsvw0kc799.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC02007_zpse48lnkg5.jpg
I think it is best to try and remove the turntable from the room if possible as even the best suspension will not isolate it sonically from the bass. I even do this with my CD player. I am amazed at the number of systems where the turntable is stuck in the middle of the speakers, surely the worst place possible?

[Lee in Montreal]

The problem I am working on to solve, is not the turntable being exposed to bass frequencies coming from speakers. It is undulations on the floor from people walking around. Mostly a problem in old houses and buildings and people walking heavily.

[gasfan]

I get it. It's really tough to cancel that kind of movement without introducing a more complex one. I think the best way to deal with that is simply to remove the tt from the source by hanging a shelf on the wall first, and then let your decoupling system do it's thing. Now all you need do is match compliance to vibration.

[Lee in Montreal]

I have developped the idea further and shall have something to show next week. I added a light subframe on which the TT can simply be bolted, or installed using the stock feet. I have reduced the height of the 8 pods from 3.5" to 1.5" to lower the overall height. e new subframe also allows to simplify the installation. Oh, and I have drafted a third version that is not as sexy looking but will do the same job. with less parts, and thefore cheaper to produce. ;-)

Lee

[SEAWOLF97]

My "daily driver" TT is isolated via ..

Double float system: The PL-530 Has a standard wood press board plinth base . And a steel sub- chassis. The tone arm connects to the subchassis. The subchassis is suspended from the plinth, along with the tone arm. All vibrations are absorbed twice, before they have a chance to spoil the record's tonal quality.

the platter is also on this steel sub-chassis. And with shock absorbing feet too, it works very well.

BUT, Lee's device sure is sexy. Need something better than rubber bands, they have a limited life (well,the ordinary ones)

[Lee in Montreal]

Need something better than rubber bands, they have a limited life (well,the ordinary ones)

One bag of 100 rubberbands for $1.50... Can't beat that for testing. Nonetheless I agree that something sexier is needed. I checked some large size o-rings but they seemed too stiff. I will investigate further after I have assembled the next version of the prototype.

BTW On the technical side, I found on my first attempt that when rubberbands are too soft, then the direct drive motor's impulsions will make the turntable oscilate radially. This greatly affects the sound. You can see the spots in the stroboscopic shake back and forth. But as soon as the bands are stiffened, the oscilation disapears. I think it is typical of a direct drive TT and that one driven by a strap shall not have that situation.

[Lee in Montreal]

Here's the lastest development. I'm quite happy on all aspects.

The base hasn't changed. Only the eights posts have been shortened by more than half.

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSCN5934_zps8fkav79o.jpg

The subframe can now easily be fitted.

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSCN5935_zpsitmmay4r.jpg

No particular skills required. Just hook the rubberbands.

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSCN5936_zps7lbpod99.jpg

Install the turntable on the subframe. You can use the original rubber feet.

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSCN5937_zpsnzwaw74y.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSCN5938_zpszuz585a8.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSCN5939_zpsh9nyeo5o.jpg

You can also lower the turntable by removing the rubber feet.

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSCN5941_zpswojzeiur.jpg

And install spacers and bolts between the subframe and the turntable. Sorry for the blurred picture.

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSCN5940_zpsuq0dofll.jpg

And voilà...

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSCN5942_zpswadmg8w3.jpg

The turntable is barely 1/2" (13mm) higher than stock.

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSCN5943_zpsgs74v4hg.jpg

[Lee in Montreal]

I could therefore shorten the posts by another 1/2" and the turntable would be at the exact stock height. Actually, if using only one rubberband instead of two, then the tiurntable lowers to stock height. And with the suspension being softer than with two rubberbands, it also lowers the frequency of resonance of the suspension. Now, as for using cheap rubberbands instead of classy viton O-rings, I will leave it to everyone to upgrade the suspension. DJs won't care ;-)

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSCN5944_zpsgokoozyy.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSCN5945_zpstmlesfir.jpg

Thanks very much for your attention ;-)

[SEAWOLF97]

that pup is getting nicer on each iteration :)

you're going to have a marketable product pretty soon.

when does the line start ??

[Lee in Montreal]

Now, with only one rubberband per corner.

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSCN5946_zps1znvmi5o.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSCN5947_zpsavr7vlqx.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSCN5948_zpsuplz040r.jpg

So. The dilemma is simple. With or without the original feet? If keeping the feet, then the subframe needs to be as shown above. One big costly craddle. If removing the feet, then the craddle can be replaced by four corners only, which greatly reduces production costs. At that point, more testing is needed to see if there's no adverse effect when removing the rubber feet.

[Lee in Montreal]

that pup is getting nicer on each iteration :)

you're going to have a marketable product pretty soon.

when does the line start ??

Thanks for the good word. I will test a pair myself and have a friend test another. Once my own testing is done, I will lend my own set to a record shop I know that has resonance problems when people walk near the turntables. Having the set displayed and tested in a well frequented record shop could help test the market and offer visibility. Then, I also need to consider how much it cost to produce, say, 50 units. Is it worth it? How much will people pay? Am I going to work for free, or even lose money? Then, what about making kits for other turntables, or maybe a universal non-SL1200 kit? Maybe if I wamt to be rich, I should produce expensive and esoteric interconnects instead... ;-)

One more feature I would like to add is the capacity to adjust the height of each corner, where rubberbands are hooked. Most likely for people who have an non-flat resting surface. I was thinking aluminum shims.

Turntables and vinyl are now very hip. So, maybe people will spend more than I think, just to farkle their turntable and impress their neighboor. ;-)

[SEAWOLF97]

well, Portland (where I am) has the highest number of record stores per capita in the USA , sooo .... an ideal place to have a beta tester. I know a volunteer here (you do too .. hint,hint :) )

[Lee in Montreal]

well, Portland (where I am) has the highest number of record stores per capita in the USA , sooo .... an ideal place to have a beta tester. I know a volunteer here (you do too .. hint,hint :) )

Do you have a record shop? ;-)

Lee

[Wagner]

Thanks for the good word. I will test a pair myself and have a friend test another. Once my own testing is done, I will lend my own set to a record shop I know that has resonance problems when people walk near the turntables. Having the set displayed and tested in a well frequented record shop could help test the market and offer visibility. Then, I also need to consider how much it cost to produce, say, 50 units. Is it worth it? How much will people pay? Am I going to work for free, or even lose money? Then, what about making kits for other turntables, or maybe a universal non-SL1200 kit? Maybe if I wamt to be rich, I should produce expensive and esoteric interconnects instead... ;-)

One more feature I would like to add is the capacity to adjust the height of each corner, where rubberbands are hooked. Most likely for people who have an non-flat resting surface. I was thinking aluminum shims.

Turntables and vinyl are now very hip. So, maybe people will spend more than I think, just to farkle their turntable and impress their neighboor. ;-)

Beautiful work friend; better yet, very ingenious solution

BUT, I would strongly suggest that you register a patient or some sort of "copy right" to protect yourself before you post too many more photos

That is how good I think this idea is; protect yourself (and I have been looking at turntable accessories/mods for a LONG time and have never seen anything like it) You've got a potential winner on your hands

Don't know how it works while you are still prototyping, but there are more than a few guys selling these sort of precision aftermarket metal bits, and have more than enough equipment to pull it off (take a look at all the sub-platter/drive pulley/counter weight/end stub guys there are out there selling these for the REGAs..........and all seem to be doing pretty damn good) Meaning: RIP YOU OFF

A suggestion? The table to target for this is/are the millions of REGAs out there; and NOBODY loves buying new metal upgrade bits for their tables more than REGA owners

Cut this for a REGA's dimensions and post it over at Steve Hoffman's site and you'd sell 500 of them in 6 months time (and that's just to the early adopters)

Only thing I don't like is the rubber bands part ("breakability"); the very practical flexibility to use an almost universal inventory of bands is a plus except for the fact that as of the past 10 years or so, rubber bands, like wood clothes pins are all shit (china china)

They all seem to break and turn sticky after only a few months nowadays (but I realize this is a prototype/in development stage item right now; "rubber bands" may not be the penultimate solution for the suspension)

Nice work and good luck; I think the idea is great

[Lee in Montreal]

Copyright and patents. Those are very expensive and so easy to go around. If somebody copies the design and changes a single bolt, and extends a measure by a millimter, the copyright doesn't hold anymore. The way around for a designer is to have a strong identity on a product. or make sure everyone understand he was the originator. That can be done thru branding and forum presence. I have already designed several dozen of auromotive-related products that I sell around the world. Ot doid happen that a couple of them got copied, but none sold very well because people knew they were copies and that the original one was mine. Not to mention that copies didn't work as well, or didn,T look as good as the original... ;-)

Nonetheless, your comment about Rega owner being keen to farkle their turntable is interisting. I was initially aiming at the DJs and vinyl collectors using SL 1200 Technics, but after a test I did yesterday, an imprevisible outcome came out. Let me explain.

My good old friend Denis was the first beta tester. I brought a flat-packed set and he assembled it himself. It was easy at that stage and my frienf DEnis is not necessarely technically gifted ;-). Then we installed it and we tested how isolated the TT was from the shelf. It was very conclusive. And we had two TTs to test. One with and another without the suspension. Then, my buddy told me he had the impression that the bass sounded better on the suspended TT. Honestly, I didn't notice it. I explained to him about placebo effects and psycho-acoustics. But he was a firm believer that the suspension improved the sound. Meh... I will let him believe this. I remember laughing, decades ago, when people were suspensding or fitting isolation cones under their CD player... To me it was oil snake. But maybe suspending a TT or a CD player improves the sound. And maybe that suspension kit can be used on a CD player too. But unless I can have data on that, I can hardly commit to support that pretention. My goal being to solve a real problem, nit just pretend and sell kits. I hate grey zones. ;-)

Gonna bring a demo kit on Saturday to that record store. I'll see what happens.

In regard of the Rega market, I sure am interested. If anyone can give me some info about dimensions, weight, how feet are distributed under the TT, etc. I suspect that at a mere 4.5kg weight (10lbs), the turntable must catch any vibration form the air ;-) Do people fill them with Play Doh to add mass?

And as for the rubberbands, I am 100% with all the comments mentionning how better a black suspension, using dedicated toroidal rings would be. But, I haven't found them yet. For sure they would be an improvement, at least visually.

[Lee in Montreal]

The next test I will be performing this weekend will be to place a turntable/suspension on a 12cft bass cabinet w/ JBL 2245 woofer playing only under 40Hz and powered by a bridged Yamaha PC2002 power amp. That cabinet sure generates vibrations on its surfaces. I will test how good at isolating the Technics from the surface vibrations that suspension is.

Lee

[macaroonie]

The Rega plinth used to be plain old particle board , nowadays it is likely to be MDF. No significant voids in it.

Dimensions: 17.5" (450mm) W by 4.5" (115mm) H by 14" (360mm) D (height includes dustcover, feet). ( Planar 3 )

As far as I can remember it has 3 feet , two at the front one central at the back. Not very compliant rubber.

This is a turntable that surely needs a helping hand. Wagner is bang on .

[Lee in Montreal]

The width of the Rega is exactly the same as the Sl1200 Mk2. The Sl1200 is just not as deep at 350mm. And obviously the location of the feet is different. I will see if I can find somebody local on which I can measure the mounting location of the three feet. Also, I grabbed some Nitrile o-rings this morning, made by Spaenaur. Sure they look good. But they don't offer the same compliance as the rubberbands. Compliance is what filters vibrations and oscilations ;-) They also don't filter as well as rubberbands. I shall get some new design mounting pods tomorrow. 1/2" shorter and a different design to "catch" the rubberband. No more bolt on top. I will update the set I lent to my friend with those. The pair that will be lent to the local record shop will have the updated posts too. I will also leave the four 6mm threaded holes on the base for people wanting to add spikes to the base, or rubber feet. I can see people adapting or modifying the suspenskit to their own taste/fantasy. ;-)

And back to those rubberbands, I am convinced they are the best tools for the job. ;-)

Lee

[SEAWOLF97]

instead of different devices for different models , just make a universal one with mounting
holes for the major TT's ..4 or 5 models , don't think that's enough to cause a "Swiss Cheese" effect. :)

Regas ? I've never seen one, but do see a lot of AR's & Technics & Philips & Pioneers and Denons ...
guess I don't run with the affluent gangs ..???

[Lee in Montreal]

instead of different devices for different models , just make a universal one with mounting
holes for the major TT's ..4 or 5 models , don't think that's enough to cause a "Swiss Cheese" effect. :)

Making a universal kit that allows no compromise is indeed the ideal solution. But sadly, something will be compromised somehow and somehwere. Per exemple, to fit a Rega TT, the kit must be deeper. Thefore, if fitting a shallower SL-1200, some space will wasted, and then people will start complaining the suspension takes up too much place. That being said, I am in favor of optimizing a design for each application. Production of that kit is pretty easy. Therefore it is not costly to produce several versions.

All that being said, comes another dilemma. How do I want to sell them? I am alresdy very busy designing andf selling my automotive line of products for BMW track/race cars. adding another line of products means more working making invoices, boxing and shipping. I suppose that a much younger and enterprising person would see the situation as favourable. It is. But I prefer to take my motorcycle and travel countries I don't know, or spend weeks in the desert. That means that as years go by, I will spend more time away from work, and enjoying every day of it... ;-) So, perhaps after those suspensions will have enough exposure, sales might be only thru wholesale. Selling 10 per 10 at a minimum and allowing 33% profit for the resellers.

Currently thinking of making a webpage to separate the audio from the automotive stuff. Nowadays. It might be as simple as creating a Facebook page. And it is totally free.

Lee

[Wagner]

The two most popular REGA platforms are the current "RP6" and the former "Planar" series (2&3)

The "RP6" demographic would prove to be the ideal target with which to test the waters; it is their "middle" deck and is EXTREMELY popular, even in light of the fact that it reportedly suffers many, (one is "many"; too much in my mind for a deck at this price point) and often, (as in many reports on-line) manufacturing flaws (ergo the extreme popularity of the aftermarket sub platters)

Regardless, once the stock REGA "feet" are removed, the deck should present a more shallow profile than the SL-1200 (although there is the stub of the bearing housing sticking out from the underside of the plinth as well as the more shallow plastic housing for the motor)

The Planar "25" as well as the Planar "9" have a wood trim surrounding the plinth which the standard Planar "3" does not; I do not currently have here at the house both of these models from which I could provide dimensions but I do currently have a "25" around here somewhere

Deeper and better bass? OF COURSE! Spread the word! Don't make the error of poo pooing that one my friend, otherwise, what's the point? (if you are interested in making money with this) :)

I stated I did not know the "ins and outs" of protecting your idea, and yes, I hear what you are saying. I am familiar with the "same but different" phenomena of skirting legality when it comes to (plagiarizing) manufactured goods.............my not so subtle inference was however that maybe a very plausible first step would be to not reveal so much of the specifics............by continuing to do so you might just not be the "first" to bring this idea to market, test or otherwise

As I understand things with some of the more successful REGA aftermarket outfitters, much of their product is made and delivered as demand dictates. Inventories are small, and with the bigger pieces, orders are taken until a target number is hit (to merit a production run) and the bits are made and shipped. Similar to what you are describing but without a "middle man" or distributor (the majority of the REGA bit guys maintain a standing exposure on ePay, but do take orders from fellow forum folks, the forum participation seeming to be a big part of their success). I'm rambling now; that would be all your business if you decided to pursue this.

All I am saying is that it is currently being done, more than a few individuals are doing quite well by it AND most importantly, I am convinced that your idea once polished would quickly find a market and sell briskly at first...............for how long who knows (history has shown, until the next "mouse trap" for deck isolation comes along) It is definitely a "flavor of the next couple of years" sort of thing.

Unfortunately even if the product does 100% of what it claims to do, this is often the case; I could see this idea making you a lot of money very quickly (sales in the 100s, possibly better) and then dying down to a rather modest, yet predictable stream (that inventory of 10 or so every 6 months would keep you covered)

I strongly suggest that you take a serious look at the Hoffman website; simply search REGA; you will need to view their enthusiasm over "tweeks" as a business person rather than an objective pragmatist, even though your product does work

As an additional benefit to you, the site enjoys a rather large Canadian population which wound surely make your life more simple with regards to shipping and customs (I know it can be costly for Canadians to order things from the United States)

My remarks regarding rubber bands had no bearing on their efficacy or their aesthetic...............it's just very difficult nowadays to find any that are worth a shit, to put it bluntly. I think their use is a marketing positive actually (again, if you could find a supply of any worth a shit) I do feel a more precision made "O"-ring however would allow for more precise tuning (which is going to be the "hot topic" on the boards as soon as you get one of these out there in the wild! ;))

Disregard all of my meddling/rambling if this wasn't even your goal in the first place

REGA's where the money is

Good luck with it

[Wagner]

Now, with only one rubberband per corner.

So. The dilemma is simple. With or without the original feet? If keeping the feet, then the subframe needs to be as shown above. One big costly craddle. If removing the feet, then the craddle can be replaced by four corners only, which greatly reduces production costs. At that point, more testing is needed to see if there's no adverse effect when removing the rubber feet.

Looks great

The "pro" for retaining the original feet is for leveling

Then there's the REGAs I have talked to death which require that the platform be level (the stock footers are not adjustable)

DJs may not be a critical, but still, any table needs to be as level as possible for optimum results

The "audiophiles" and those serious about Lp playback would insist on it, including those who use Technics tables; so at least as far as the SL-1200 series is concerned, allowing for the use of the stock, adjustable footers would be the ideal, especially as the arm on the Technics is a relative lightweight and the VTF settings are typically at the lower end of the range making the deck being level even more critical in allowing for any sort of decent tracking (as it is on all tables, but you get my point)

That's the only real rub with the rubber bands; the SL-1200 definitely has a heavy corner and a heavy "side" as well; the center of gravity hubbub could be problematic

[Lee in Montreal]

Looks great

The "pro" for retaining the original feet is for leveling

THis aspect has been adressed but knot shown in the pictures. The leveling can be done directly on the posts using aluminum shims. Those shims can be slid between the rubberband and the top of the post. That bolt on top has disapeared in the newest design. It is replaced by a fixed reduction in the machined post's diameter.

Lee

[gasfan]

What about using 'inner tube' material? From bicycle to utility to automotive. Nice flat surface stamped out to shape. You could keep the bolts. High quality rubber, various thickness available. Holes punched in the bands and retained between washers.

[Wagner]

THis aspect has been adressed but knot shown in the pictures. The leveling can be done directly on the posts using aluminum shims. Those shims can be slid between the rubberband and the top of the post. That bolt on top has disapeared in the newest design. It is replaced by a fixed reduction in the machined post's diameter.

Lee
Understood; I also realize that you are refining the design
Please do NOT think that I am kibitzing or trying to tell you "what to do" in any way
I was only offering observations based on what I could see
I admire your skill and I am envious of your resources

[Lee in Montreal]

1 month testing in a record shop with a dozen DJs. They will try the feel, and how much compliance works best in the rubberbands. Will they prefer 2 or 3 bands? Doubleor triple pass? What about those who scratch? Will it be too compliant? if they stiffen-up the suspension, then how good is the vibration filtering?

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC02966_zps8fzzcsbe.jpg

With the revised posts

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC02967_zpsf5rdbrcj.jpg

[SEAWOLF97]

I use those heavy "Live Strong" type rubber wrist bands for locking down the brake levers
on my bikes ...the distance needed on your device looks about right for them.

1/2 inch wide , colorful and I've NEVER had one break

[Lee in Montreal]

Definitely one option to tink of. They can be customizd/branded too. I don't know how stiff or compiant they are, so, ordering a few units for testing will be needed... ;-)

http://www.jordanmarketing.com/images/Customized_Silicone_Bracelets.jpg

http://www.printmylogo.com/bracelets/awrenessbracflyer.jpg

[Lee in Montreal]

Actually, I had a couple of those silicone wristbands around. Not mine, my girfriend's. The initial deflection/stretch is fine, but it maxes out very quickly. It lacks compliance and elasticity. It won't be suitable. They have the same characteristics as the o-rings I tested.

Lee

[Wagner]

I think the dampening properties of the "rubber", no matter how compliant (or not) will prove superior in performance to the stock footers

The rubber isn't going to transfer any energy, not at any frequency that's going to disturb a turntable

I've made isolation mats by sandwiching a sheet of Styrofoam between a door mat made of recycled tires; it worked well (but yes, it would transfer energy as it was still on a flat surface ultimately coupled to the floor)

I suspended my deck with fishing lures (the fine steel cable type for deep sea fishing) when I live in a condo (made of crap)

Worked well in a room where heaving breathing in the direction of the floor would upset a tonearm (I had two small children at the time as well)

Any rubber would be superior I would think (and give you the desired results), regardless of how much "stretch" it demonstrated

[grumpy]

Might think of adding some non-contact rubber bumpers or between-towers loose cable
as a safety net for broken bands... they'd do or add nothing otherwise.

[Lee in Montreal]

Might think of adding some non-contact rubber bumpers or between-towers loose cable
as a safety net for broken bands... they'd do or add nothing otherwise.

Each corner uses two rubberbands, or even three for stiffer setting. If one band breaks, you still have another to catch. And if two bands break, the three other corners are still holding the turntable.

[grumpy]

Just an overly conservative thought :) nice looking implementation.

[Wagner]

Might think of adding some non-contact rubber bumpers or between-towers loose cable
as a safety net for broken bands... they'd do or add nothing otherwise.

I concur

[macaroonie]

3mm Bungee cord might do the trick for the bouncy bit. Not quite sure how you would make a tidy joint.

[Lee in Montreal]

The more it goes, the more I find that rubberbands are the way to go. Sorry guys ;-) You can use two or three rubberbands according to your compliance preferences. Rubberbands can be installed indifferent configurations. Straight "O" or twisted as an "8", which slightly affects their compliance. Or use less ruberbands, but tripple pass them instead of a simple double pas. Rubberbands can also be bought for $1.00 a hundred units... Easily replaceable and dirt cheap. I am sure that many will try alternate solutions but will return to the rubberbands. Back in the days, we wouldn't change them often. They'd last 3, 4 years. And that's in a smokey bar environment. Also, the bases already have four 6mm threaded holes near the corners. Those can accept extra feet. Either aftermarket stainless steel/rubber feet (supplied in kits and designed to keep from scratching that delicate lacquered audio furniture) or Technic's own SL1200 rubber feet. People can even fit stainless spikes if they want. The options are endless. Thise suspension will serve a clear vibration-cancelling purpose, but will also allow the user to play and customize its supension to his/her own individual tastes.

http://images.junostatic.com/full/IS235242-01-01-BIG.jpg

http://ecx.images-amazon.com/images/I/415T1RPGIDL._SX342_.jpg

[Lee in Montreal]

Development has evolved into 3 versions for 3 budgets. The version with base and subframe is definitely way too expensive to produce and will be costly to retail in its actual form. But it will remain available for those with deeper pockets. I have developped three alternatives that are equally sexy. The cheapest one being $100.00usd

Four sets of the initial version are currently being tested. Will need two more beta testers for the next generation. Must have SL1200 TTs and preferably a nicely set-up system. Not one put together on a kitchen counter ;-) And preferably people suffering from floor vibration problems. When I see people bolting frames to the wall thinking it will solve the problem, it makes me dizzy... :D

[Wagner]

When I see people bolting frames to the wall thinking it will solve the problem, it makes me dizzy... :D

Cannot imagine why? The practice solves many problems and solves them very well, especially when augmented with any sort of secondary isolation

[Lee in Montreal]

Cannot imagine why? The practice solves many problems and solves them very well, especially when augmented with any sort of secondary isolation


Wall is attached to the floor. Vibrations from the floor are transmitted to the wall. Then somebody slams a door. Oscilations will reach the turntable from the wall. Wall vibrates from low bass thumping. Then thean reach the frame.

Lee

[Wagner]

Wall is attached to the floor. Vibrations from the floor are transmitted to the wall. Then somebody slams a door. Oscilations will reach the turntable from the wall. Wall vibrates from low bass thumping. Then thean reach the frame.

Lee
Did NOT say or imply that a wall shelf was the penultimate solution for turntable isolation

I also thought I was clear when I said shelves were a good approach, when AUGMENTED with secondary isolation

AND assuming the installation is an intelligently done one (you don't bolt the steel frame directly to the sheet rock for example) I use heavy neoprene insulators you can pick up at any good hardware store and fuel injection hose cut to length through the frame where the mounting hardware passes; the shelf structure itself never comes into direct contact with the wall

A shelf will/can be installed to put a turntable at a good working height as well and doesn't require another piece of furniture or equipment rack to employ (again, freeing up floor space to be better used in smallish rooms) A well mounted shelf will also get a deck out of the "line of fire"

Where practical, a well designed and properly mounted wall shelf for a turntable is as valid a solution as your creation; in fact, the two could be used in tandem and I would venture to suggest with excellent results

Your reaction to their use, that it makes you "dizzy" was a bit over the top, ergo my post; again, I never said it was the complete and final solution or a competing solution with your idea

I have used wall shelves for years and when combined with good secondary isolation or footers works just fine, and once leveled it stays that way (I have also made 100s of Lp to tape transfers with no ill effects of transient pollution or impulse noise in the noise floor, none that was audible anyway and I am running some very light trackers at times

If one lives in a building constructed so poorly as what you propose, then any table weighing in at more than 10 lbs is going to be swinging the breeze on those rubber bands; you've got to put your creation on SOME flat surface now don't you?

And obviously my comments apply to permanent/semi-permanent installations; your device lends itself well to applications requiring portability

[Lee in Montreal]

The past weeks were spent simplifying the idea in order to lower production and shipping costs.

The base frame has disapeared. Replaced by two shapes of feet. Tetrapod (left) and tripod (right). The tetrapod is more stable at the moment. The tetrapod will have four rubber pads underneath and the tripod will have wide stainless/rubber feet which shall increase stability. I will chose one or another. The subframe itself has been beefed-up and is now thicker.

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC03028_zpsgu2dut0h.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC03024_zpsw9zchfqa.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC03023_zpstynsnnu3.jpg

The original Technics rubber feet can be removed and replaced by those. It lowers the turntable. Reduces costs and will most likely appeal to clubs. All they will have to do for an install is to get those flat feet and screw hooks under the "counter". works at home too.

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC03031_zpsv5adjzge.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC03025_zpsz1bsxcpc.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC03026_zpswzpzugge.jpg

The posts have been redesigned too.

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC03030_zps1o3to70q.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC03029_zpspxmddvc4.jpg

[Wagner]

Keep in mind that the 6mm threaded inserts tearing out/coming out of the rubberized bottoms of SL-1200s (later models) seems to be a problem for some reason (never could figure that one out for certain, how this is done; only know that it seems to be a common failure)

Lateral/stress on the horizontal plane?

The simplified hook replacements for the footers may not work (well) on all decks; don't know if the lateral (angled leverage) stress now applied by their use will exacerbate this "phenomena" over the long haul or not?
Don't know how they can be "pulled out" without damaging the hole to some degree?

From "KAB"'s site:
SL1200 Stock footers do a good job overall of isolation and offer an easy way to level the turntable.
Time proven design of spring loaded elastomer damped suspension with 6M threaded stud. They do wear out over time though and can lose their "as new" height. so it is best to replace tired old footers when this happens.
KAB also has the threaded insert which goes into the rubber base. Sometimes in rough handling these pullout and go missing.

https://www.kabusa.com/GIF/insert.jpg

[svollmer]

I was one of Lee’s beta testers. Lee was kind enough to send me one of his isolation bases along with hardware, accessories, and rubber bands. Below is my experience with his device.

My Setup:
Technics SL1200 MkII Turntable
Audio Technica AT120E Cartridge
Creek OBH-15 Phono Preamp
Mark Levinson 380S Preamp
Mark Levinson 332 Power Amp
Legacy Focus Loudspeakers
Four DIY 2245H Subs
Audio Control Richter Scale III Crossover (set at 40Hz)
DIY Maple Butcher Block Equipment Rack

Background:
I listen to most of my music from CD’s. But, I also enjoy listening to records, especially the ones that have never been issued on CD or are now too rare and expensive to purchase on CD. I would call my turntable setup as “nice functionality.” It’s certainly not extravagant or expensive, but it’s competent. I grew up with Technics turntables and when I had a chance to purchase a brand new SL1200 a few years ago, I jumped on it. When playing records, I’ve noticed that the Technics has a quieter background with the dust cover off. I can also hear a clear “boom” through the speakers if I wrap my knuckles on the butcher block stand or even if I just tap my finger on it. However, when records are playing, I’ve never noticed low frequency feedback coming through the speakers. So, I always assumed the butcher block stand was strong enough to isolate the TT from acoustic vibrations even though my light strikes on it from my hand produced noises.

Assembly:
Assembling Lee’s isolator was easy and straight forward. I chose to use the tripod feet only because I liked the look of them better than the tetrapod feet. The machining on all the parts was very nice. Lee has continued to refine and improve the design. The feet in my kit came with flat head Allen screws to attach the posts and the bases were machined so the Allen screws sit flush after installation. You can see in the picture that it’s flush on the bottom. I placed beer coasters under each base. The posts were machined very nicely and certainly do not look like a DIY project. I chose to use two rubber bands per foot. I tried three, but they seemed too rigid to me.

Impressions:
All I was hoping for with the isolation base was that it would reduce the microphonic sounds that I regularly heard if it picked up or placed objects on the butcher block near the turntable. It certainly did that. With the turntable not spinning and the tonearm down on a record, I tapped on butcher block with and without the isolation base. The sounds picked up by the TT were greatly reduced with the isolation base. What I didn’t expect was an improvement in the overall bass quality in recordings. It’s not that I heard “more” bass with the platform; I heard bass that was more taught and defined. It wasn’t miraculously better, but it was better. It’s possible that the reduction in microphonic pickup while a record was playing was reduced (even though I hadn’t noticed it before) and that led to the impression of tighter bass.

One observation I had was when I accidentally bumped my rack with my leg. The side-to-side energy I induced into the rack was reproduced by the isolation base as the turntable gently rocked from side-to-side on the rubber bands until the energy dissipated. The caused the tonearm to gently skip across the record. So it seems that the isolation base is very good at reducing vertical (up and down) energy and vibrations, but doesn’t reduce lateral, or side-to-side energy. But, I found a fix for that; I didn’t bump the rack on the side again! 

Value:
I recall in an earlier post Lee saying the target price would be around $100. For what you get and for the quality of the pieces, I think that’s a very fair price. Compared with all the other accessories one sees in the high end world at shockingly high prices, I’d say this accessory is a bargain. At the above price, I would purchase one.

The suggestions I have for Lee are purely aesthetic. If there is a possibility of anodizing them black, some people may prefer that as it would make them more invisible, depending on the neighboring surface, equipment, etc. If there are black rubber bands available (I recall Lee ruling out O-rings), that might be a nice change too. I’m fine with the regular rubber bands as they are functional, but some may feel reluctant to have rubber bands in their high-dollar rig. Also, if this goes into production, it will need to be packaged properly. It doesn’t have to be exorbitant, like some interconnect cables, but it should reflect how nice this is and have “branding”.

Overall, I would say Lee has a great product here and I think he wouldn’t have much trouble getting it into the retail accessory market. I bet many of the online turntable and accessory dealers would be happy to add it to their offerings. Great job Lee!

Steve

[svollmer]

A couple pictures from my setup.

[Lee in Montreal]

Thanks Steve for the report.

The parts you received for testing are pre-production and the surfaces aren't finished. On the end product, the aluminum would be anodized. I will probably offer black and clear anodize.

About the shape of the corner bases. One is tripod and the other is tetrapod. I recognize that the tripod looks very nice, but sadly it is not as stable as the tetrapod. So, if I have to chose between form and function, I tend to pick function. Hence the final kit will use the tetrapods seen on the left. The tripod could be used if the inner pod is bolted/screwed. One change I was intending to perform on the posts was to make them perhaps a 1/4" taller to accomodate people fitting softer rubberbands. The bands being softer, the turntable will be lower. Tell me what you think.

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC03028_zpsgu2dut0h.jpg

About filtering the vibrations
Filtering vibrations is one thing for which the kit is designed. But filtering movements such as in hitting the rack is another. ;-) It would require longer distance between the rubberband pick-up points, and way softer rubberbands. The softer the suspension, the lower the frequency it filters. Then, if the suspension becomes very, very soft, many people will have a hard time handling the stylus without shaking the turntable. It's all about compromise.

Options
I supplied Steve with a few optional components. The two styles of pods are one option. But it also came with "hooks" and spacers that bolt in place of the rubber feet. THose were perhaps intended for fixed installations where people cut square holes on a counter, lay rubberbands and put the TT on top. That way, the turntable ends pretty much flush with the counter which is usually made of two layers of 1" birch.

Or it can be used at home, without the subframe.

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC03031_zpsv5adjzge.jpg

http://img.photobucket.com/albums/v668/Lee_Vuong/The%20Parts%20Factory/DSC03026_zpswzpzugge.jpg

The thin alu spacers I mentionned in the previous paragraph can also be used if bolting the turntable to the subframe. That is by removing the original rubber feet. The prupose is to get a lower turntable. Am I also reducing some vibration filtering that came from the rubber feet? Not necessarely I think. That's because the rubberbands filter at a lower frequency than the rubber feet. Maybe Steve can test that. ;-)

[Sean Dab]

I'm so in need of these!

73143

73144

As you can see, our setup is resting on a deck with tons of movement. Was debating on hanging the whole rig but now I think the best bet is to float the turntables and use cutouts with rubber suspension. Hardware available? The hook / feet replacement hardware is the ticket :)

Thanks, Sean / Dj Dab