[neobop]

seems like the screws would provide the needed coupling.

i have a thin and quite firm strip of cork (cut from sheet of gasket material) between my headshell and the tonearm.
not because i think it helps with sound, i don't think i noticed a difference with or without, but because the spacer gets my tonearm in a good sweet spot for me to adjust the VTA.
if i had a plane that i could run my armboad through i'd just do that a few times and lose that cork spacer...

This is a spacer between your cart and the headshell?

What kind of table and arm? Maybe the armboard could be lowered or a mat used to effectively do the same thing.
neo

[bastlnut]

hallo,

i like to use stuff between cartridge and headshell, but never anything that corrupts the structural integrity of the union.
i used lead sheeting material until it was not availabe anymore.
now i hammer fishing sinkers (weights) flat and then rub then plan so it will not change the geometry.
i still have a Grado mounting plate with tip toes for the F1+ cartridge i had.
i have made a few based on the principal and really can not tell the difference between tip toes and lead sheets.
i also like polypropylene at 1mm and 2mm thick.
sometimes 2mm acrylic glass is the best material to use.

personally, i think the headshell is the 2nd most important part of any tonearm.....the bearing is far and away the most important.
if one looks at modern day tonearms they are mostly made with a fixed headshell.
the stand-fest integrity of the the cartridge mounting has taken priority over convenience.
Graham has it right with swapping entire arm-wands.
Graham also does something clever by machining a recess into the middle of the headshell and placing a damping circle of foam rubber there to damp the connection of the headshell to the cartridge.
early tonearm designs used a rider or carrier to connect the cartridge to the headshell,
this allowed flexibility and damping the connection in the process.
Thorens always used plastic spacers for VTA but also for damping the interface of cartridge and headshell.

there are many headshells that have 2 pins to firmly press the headshell onto the bayonet fitting on the tonearm.
the problem here is that many bayonets are not aligned with the armwand and so are not offering a 90° surface for the headshell to connect to!
i can not tell you how many tonearms i have had to align the headshell bayonet to 90°!!!!!!

many tonearms are poorly designed and use pressed fittings!
tonearm resonances follow straight lines like water and do not like to move off at an angle.
these are all design parameters that must be integrated in a tonearm design.
Grado uses Wood as the material they use for the cartridge body, wood is a very good material to use to damp resonances.
stone as well as it uses mass as a damping material.
it seems to me, many times,  that  the cartridge needs to compensate the weaknesses of the tonearm.
this is probably the biggest reason that i find tonearms to be the most important item in a vinyl set up.

regards,
bas

[BaMorin]

Ha!  Lurne happens to have a degree in physics. All that stuff about the center of gravity an ellipsoid of inertia, is the real deal.

neo

Wasn't the "perfessor" i was refering to Neo..........I was refering to the "perfessor of physics" from a previous "life".........remember?  if he couldn't finger it out with the greek alphabet......it didn't happen.
You didn't hear it..........it was mystics.......etc   

[neobop]

On page 2 of the Stereophile interview, he was asked about platter design. He talked about making the platter out of a sandwich of methacrylate and lead. An 8mm thick piece of lead was used between 2 slices of methacrylate. The vibrations reflected back to the cartridge were timed so they would not be coincident. This was compared to a room where there are standing waves.

I've found platters and mats made out of methacrylate to be far superior to any other. This is not the same as acrylic. Rubber mats tend to overdamp. Sometimes this is preferable to audible rumble or the mechanical impedance of a metal platter. Goldmund used to sell a separate mat that could be used on other platters. These go for lots of money these days. Now, apparently you can have one made to order.
http://www.appliedfidelity.com/

I agree with Bas about the critical role of the arm and cart/arm interface. A clear path for dissipating vibrations is necessary for best performance. Maybe this stuff is in the realm of diminishing returns, depending on your equipment. But not for me. Once you're used to a certain level of performance, it's hard to compromise. While I can listen to an inexpensive system (or my own) and appreciate it for what it is, or the performance I'm listening to, it's not the same as high res. You don't have to get elitist to make significant improvements sometimes. If you are planning to upgrade, try to get out and hear really good tables and familiarize yourself with the differences.
neo

[bastlnut]

hallo again,

i have 2 of the Goldmund Relief mats, and yes they make a huge differnce.
nothing better that i have found. the last one i found for sale was sold for $800 i think.
i am not sure that the Applied fidelity mat is of the same material.
there is a newer material that is making the rounds in the turntable world that is similar to Methacrylate material.
it is POM which is a short name for Polyoxymethylene.
here is the Wikipedia page for it......
http://en.wikipedia.org/wiki/Polyoxymethylene

i have a Lurné TT and a couple of his tonearms, all unipivot.
he really is a master at his art!

regards,
bas

[jmpiwonka]

This is a spacer between your cart and the headshell?

What kind of table and arm? Maybe the armboard could be lowered or a mat used to effectively do the same thing.
neo

yes. about 1-2mm of a firm cork material.

it's an empire with a sumiko ft-3 arm.

[Photon46]

I've had very good results with this thin vibration damping material from SmallParts.com. I used a pad between either my Grado Sonata or Garrott Optim FGS and VPI unipivot arm with obvious good effect.  It's tough as rhino hide to cut, so you'll need a very sharp X-Acto knife and small drill bit to start the holes for the mounting hole slots you'll cut. Since upgrading my turntable & tonearm (Acoustic Signature Final Tool & Audiomods tonearm,) I've not taken the time to see how the vibration damping pad affects this combo.

http://www.smallparts.com/vibration-damping-sheet-040-thickness/dp/B0015RVDOO/ref=sr_1_4?sr=1-4&qid=1302823618

[neobop]

hallo again,

i have 2 of the Goldmund Relief mats, and yes they make a huge differnce.
nothing better that i have found. the last one i found for sale was sold for $800 i think.
i am not sure that the Applied fidelity mat is of the same material.
there is a newer material that is making the rounds in the turntable world that is similar to Methacrylate material.
it is POM which is a short name for Polyoxymethylene.
here is the Wikipedia page for it......
http://en.wikipedia.org/wiki/Polyoxymethylene

i have a Lurné TT and a couple of his tonearms, all unipivot.
he really is a master at his art!

regards,
bas

Actually we used to call methacrylate, delrin. Delrin is DuPont's trade name for POM. The stuff is very similar. Some of these TT companies won't say exactly what they use for their platter or mat. I'm pretty sure they buy it in slabs and machine it.
neo

[neobop]

yes. about 1-2mm of a firm cork material.

it's an empire with a sumiko ft-3 arm.

I thought the Empire tables had a hole cut in the plinth, with no armboard.

It would be easier to stick with what you're doing now if 2mm is enough. You could always get a thicker mat. I know Herbie sells lots of different thicknesses. It might be better if you don't use 2 mats, and just get 1 in the thickness you need. Make sure your spindle is tall enough to accommodate.
neo

[neobop]

I've had very good results with this thin vibration damping material from SmallParts.com. I used a pad between either my Grado Sonata or Garrott Optim FGS and VPI unipivot arm with obvious good effect.  It's tough as rhino hide to cut, so you'll need a very sharp X-Acto knife and small drill bit to start the holes for the mounting hole slots you'll cut. Since upgrading my turntable & tonearm (Acoustic Signature Final Tool & Audiomods tonearm,) I've not taken the time to see how the vibration damping pad affects this combo.

http://www.smallparts.com/vibration-damping-sheet-040-thickness/dp/B0015RVDOO/ref=sr_1_4?sr=1-4&qid=1302823618

Photon,
Thanks for that link. That's a cool store. I was browsing around there, and look what I found:
http://www.smallparts.com/small-parts-acetal-sheet-black/dp/B003SLEZPE/ref=sr_1_6?sr=1-6&qid=1302861856

It's hard to know whether a particular arm/cart would be better damped or coupled. Sometimes you just have to try it. In this case I suspect the JMW might benefit from damping, but I don't really know.
neo

[dlaloum]

This is a fascinating topic...

and applies to plinth, arm, headshell, and cartridge... (not to mention platform, rack, speakers etc...).

Also differs for different materials (of any of the components) not to mention connection methods....

The possible permutations and combinations are (needless to say) endless.

Any one solution could work for one setup, and fail for a seemingly identical setup - perhaps the platform is different, or a differing cartridge; or maybe one example is using stainless screws vs aluminium in the other...

All you can do is hear people's suggestions and experiment.... (argh!)

A simple suggestion from Van Alstine (circa late 70's I think - article in BAS Speaker) - a 1/4" dot of modelling clay/plasticine, at the back of the headshell (behind the cartridge, under the leads)

Plasticine tends to damp vibrations between 300 and 3000Hz...

Also the same dot on the arm - preferably on a resonant node for maximum effect.

Lots of people use a stethoscope to listen for vibrations on their setup - truly the perfect hobby for people suffering from OCD.

bye for now

David

[dlaloum]

couple more things...

Delrin is often mistaken (or generically named) "plastic"

My Revox TT therefore has a "plastic" tonearm...

Other high tech materials including carbon fibre, delrin, etc... are also commonly used for various parts (platter, plinth, arm, headshell) - and later derided for being "plastic".

I have some plastic headshells that sound very good (actual material name unknown) - some carbon fibre ADC's, etc...

Acrylic has also proved itself in use for various TT components - and even basic thermoplastic has its benefits...

With regards to elastomers and headshells, the Denon aluminium headshells have a piece of rubber stuff stuck on the inside at the back (same place proposed by Van Alstine for plasticine dots)

Audio Technica LS10 headshell has a hollow along the top filled with a strip of a similar rubbery material (toped with a glued on thin metalic layer)

A number of my "plastic" headshells have a copper layer on the underside - it is not clear what it is glued to the plastic with (but a small amount of elastomer glue, 1mm thick would result in a CLD - constrained layer damping - design)

Just a bunch of observations on what is out there...
bye for now

David

[jmpiwonka]

I thought the Empire tables had a hole cut in the plinth, with no armboard.

It would be easier to stick with what you're doing now if 2mm is enough. You could always get a thicker mat. I know Herbie sells lots of different thicknesses. It might be better if you don't use 2 mats, and just get 1 in the thickness you need. Make sure your spindle is tall enough to accommodate.
neo

you are right about the hole in the plinth
the platter is so tall though, that i had to make an armboard to get the tonearm up high enough to get in the proper vta range

[Photon46]

Speaking of Empire turntables and vibration.... I had an Empire 598III for many, many years and one tweak that really took it's performance up a notch was to install Black Diamond Racing carbon fiber feet in the plinth. I drilled three vertical holes in the upright MDF framing members, two in back and one in front. Then I coated the inside of the drill holes with epoxy and inserted threaded brass rod coated with grease. When the epoxy had set up, I unscrewed the threaded rods and then had threaded, epoxy reinforced mdf walls. I installed brass rods and the BDR footers and set everything up on a maple block plinth. The results were a much better performing turntable that was very close in performance to a stock original version VPI Scout.

[jmpiwonka]

Speaking of Empire turntables and vibration.... I had an Empire 598III for many, many years and one tweak that really took it's performance up a notch was to install Black Diamond Racing carbon fiber feet in the plinth. I drilled three vertical holes in the upright MDF framing members, two in back and one in front. Then I coated the inside of the drill holes with epoxy and inserted threaded brass rod coated with grease. When the epoxy had set up, I unscrewed the threaded rods and then had threaded, epoxy reinforced mdf walls. I installed brass rods and the BDR footers and set everything up on a maple block plinth. The results were a much better performing turntable that was very close in performance to a stock original version VPI Scout.

yeah i have my 208 on some metal feet
thought i'd go back to more original looking and some real solid rubber feet
screwed them to the bottom
all my treble disappeared

took those rubber feet back off and my table still sits on those metal feet...

[neobop]

You can get large tiptoes that come with a 6mm threaded bolt in the top and threaded inserts that you mount in the bottom of your base. You have to drill a hole deep enough so that it will accept the entire height of the bolt. You then epoxy the insert in place.

BTW, for those who have Japanese tables, most have 6mm bolts attached to the top of stock rubber feet. You should be able to substitute something like this with no problem. Some Sonys have 8mm bolts, and some others might have different sizes. Check first, if you're substituting.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=240-698

For a couple of my tables I bought 2" bolts and nuts that thread right in. You have to grind off the head of the bolt to make a spike. The nut is used as a jam to keep it stable. The Denon had cutouts where the nut fit right in. You usually have to keep the spikes all the way up to keep it stable, so level the board or whatever your table is mounted on.
neo

[DaveyW]

yeah i have my 208 on some metal feet
thought i'd go back to more original looking and some real solid rubber feet
screwed them to the bottom
all my treble disappeared

took those rubber feet back off and my table still sits on those metal feet...

I removed the pretty ordinary stiff rubber feet from my Sondek and now sit the whole thing on two layers of foam rubber carpet underlay like this.



The shelf that this in turn sits on is also isolated using a further couple of inserts.

Originally, with the volume turned up (even on a solid concrete floor) if I gently touched the arm board and arm pivot, I could feel both vibrating with an accompanied muddying of the sound.

The vibration was completely elliminated with the application of the underlay.
In this case I witnessed no negative effects in tonal character, just a cleaning up in detail at higher volumes.

I remain very happy with this low cost isolation solution.
Cheers
Dave

[neobop]

The diversity of solutions is really interesting. There are multiple challenges and everyone's situation is somewhat unique. Apart from stability considerations and vibration dissipation from the tonearm, acoustic feedback can make a mess of the sound. I think acoustic feedback is the primary cause of woofer pumping. The natural inclination might be to look at arm/cart low frequency resonance. That could be a factor, but mechanical shock from the plinth or platter is more likely, IMO.

Obviously, any kind of shock that can be transmitted to the cart is a problem and a solution isn't always straightforward. To mass couple/decouple, or damp? In general, I think damping will tend to minimize the amplitude of of resonances just as fluid damping of a tonearm does with a cart. Over-damping considerations are probably similar, I think. Mass coupling your table to it's mounting board can work, but won't prevent physical shock in the first place. If your mounting scheme isn't stable, then what's the point?

Many of us are familiar with solutions for dealing with the  hollow cavity of plinths, like the JVC thread recently. The plinth is like a drum and not only transmits impacting sound pressure waves, it actually amplifies them. The top plate of many of these decks is nothing but a thin piece of wood, and makes a good drum head. The bottom is usually even thinner, like a 1/8" piece of masonite. If it has holes, they don't fix it - more like tune it like bass reflex port(s). Filling it with clay removes the volume from the hollow box and damps the impact of any physical shock. It also adds structural rigidity. I advocate using braces wherever possible just like in a speaker cabinet. If you can make the top plate more rigid, it will be even better.

Mass is often an underrated aspect. That's why lead and sand help so much with vibration dissipation and/or isolation. Lead as a material isn't all that great at preventing the transmission of vibrations. But the weight of lead will tend to turn vibrations into heat and add stability. Combine the very low resonant frequency with that of another material, and you often wind up with much better acoustic cancelling properties. Solutions aren't always revealed by testing vibration transmission of two combined materials with an accelerometer.  Why? Because of the amplitude of the vibrations. Touch a vibrating tuning fork to block of granite and see what happens. By the same token, even if you have a 200lb turntable plinth and the whole thing wobbles on the stand.....
neo

[BaMorin]

BTW, for those who have Japanese tables, most have 6mm bolts attached to the top of stock rubber feet. You should be able to substitute something like this with no problem. Some Sonys have 8mm bolts, and some others might have different sizes. Check first, if you're substituting.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=240-698

I had a set of feet from a Sony PS-X7.......like the mat that came with the table, they are silicone filled bladders. 8mm X 1.25 pitch.  Just happend to be what my Sonographe feet had. The Sonographe had hard plastic disks for feet. It also had a very diffuse bottom end sound. The inclusion of the sony feet brought the mid-bass to low bass into focus.

[Wayner]

The Sony PS-X5, PS-X6 and PS-X7 all have the same footers, and they are very effective. Once in awhile, a set will be on eBay, if your looking.

Wayner