Damping Platter With Liquid Latex

[Ldg]

therefore the normalising is for visual comparison only

I see. And the purpose of the plot is for......visual comparison. Look, it is simply the best way to present such things. So long, CS.

[Eoin]

ld, you've got some great scientific and mathematical knowledge here so please continue to contribute. This is a learning forum for me and debate and argument can help.

I think you've got the wrong end of the stick slightly on the normalisation issue though here with respect to damping.

Chaps I want specifically to reduce motor vibrations from propogating through the deck. Cats, I thought I'd understood that your measurements suggest that damping is unlikely to be effective in preventing this. Have I misunderstood? Are you saying a layer of nuplast and a steel sandwich below would work? This is not too hard to make.

[cats squirrel]

Hi Eoin,

the original poster was talking about damping his platter, something which he was having trouble with, as I've tried to illustrate.

if you have noises coming from your deck plate, the best place to start the remediation is either with the noise source (the motor, so probably not possible) or the deck plate. Although damping the platter will reduce the ringing (if it rings) and reduce the transmission of noise, as you have a suspended deck, much more mass is going to be a problem. My suggestion is that you damp the deck plate, either by being a bit clever and incorporate cld or composite structures, or by simply adding damping such as plasticine and the like.

The best thing would be a new deck plate made of a material that has good intrinsic damping, but if you can't manage that, then apply as much damping material as possible, the thicker the better.

One thing you mentioned up thread was the fact that I was showing plots of materials being struck, whereas a motor has continuous input. Yes, a real problem, but the same rationale still applies. And please don't think you can over-damp these things, its just not possible (with anything I have measured).

Now I really must go to bed, as I've stubbed my toe three times on the Lenco platter I put under the desk, thank goodness it was damped!

If you give me the dimensions of the deck plate (including thickness), I'll calculate the loss for a sandwich design (assuming a flat rectangular plate!).

[Ldg]

CS, there's a post in the 'Support' section of the forum that defines rules for commercial members. Right up front it states :

...... it should be noted that self-promotion or advertising in any form is strictly prohibited and the following rules have been devised to preserve the non-commercial nature of the forum.

CS, it turns out that your website linked in your signature advertises 'catodamp5', inc pricing, apparently your own product. So you have a commercial interest in promoting that product. And your posts advising of its specific 'virtues', (and in large quantities !) I find objectionable, and I believe busts forum non-commercial rules.

For all I know, it tastes great on toast too. But at minimum, you should have declared your interests, IMO. I think if you read those rules, you'll see the problem.

[cats squirrel]

if I have broken any rules, I'm sure I will be told so by the relevant people. But there is no product, there is only 500g of the stuff (presently lining a platter), hardly a salable product! (and the give away is the price it's in $!). And one would think the best place to 'push' my 'product' would be on my web site, as you will see, there is no mention of it, neither on the forum.

The website actually says it is not available, and the red and blue doesn't' even exist. It was supposed to be tongue-in-cheek', I mean, 'catodamp5', what a stupid name.

I mentioned 'catodamp5' because that is what I used, just as I mentioned plasticine and 'Newplast', because that is what I have used.

As for you fixing my calculations, how do you work that one out. Do you have access to my spreadsheets? I noticed an answer you gave was different to one I had worked out as a sanity check. When I checked my source, I noticed it was missing a short line over the square root sign, which made the results tend to 0.4 instead of 2, a bit like compression. Re-assessing the equation got me to where it is now.

If you think you had an input in that, I thank you, there was no intention of 'kippering' you, whatever that means.

You seem to have a problem mate, a huge chip on your shoulder, maybe a chill pill will help. I don't mind heated debate, you are obviously passionate about the subject, and I applaud it, but please don't be antagonistic. It doesn't help your case.

[mattlynch]

hi again jbonner,
not sure if it would work given the clearance issues with the pulley but how about buying a sheet of sorbothane and sticking it to the underside of the platter , should be easy to work with and its available with adhesive backing,
just a thought

cats , can you offer possible explanation for the complete loss of sound staging ,dynamics and sparkle in the sound of my old thorens td160 when i used dynamat on the subchassis,plinth , platter and exterior of the platter bearing, the sound only came back to life after i removed almost all of it with only a little left between arm mounting and platter bearing on the sub chassis and a single wrap on the bearing well, all the rest was removed, its always left me puzzled when so many recommend heavy use of damping.
all the best,
matt

[Ldg]

Just being public spirited. Because I know I would always like someone to point out, when reading advice, of potential declarable interests. And giving you the opportunity to fix the problem any way you wish, CS, without wasting JaS' time.

the sound only came back to life after i removed almost all of it with only a little left between arm mounting and platter bearing on the sub chassis and a single wrap on the bearing well, all the rest was removed, its always left me puzzled when so many recommend heavy use of damping

I think perhaps that's easy to explain, mattlynch. There was a certain added colouration that you found attractive, that was removed by damping ? Some like the TT to be 'musical' in itself, some prefer it not to participate......well not that one can ever get there, but you get my point. Random changes are just that. You don't know what you're going to get.

[cats squirrel]

Hi Matt,

I know what you are alluding to, the belief that one can 'damp the life out of the music'. Many have stated this, whether they have experienced something like this, or just repeating hearsay.

I wonder, in these circumstances, what really is going on. I do not believe that anything we do underneath the stylus (meaning the mat, platter and deck) can damp the stylus from doing its job. This is evidenced by looking at clicks produced by scratches on records, where rise times are unabated.

I have come to the conclusion that what you have got rid of when damping is (nearly) all the vibrations that are not part of the original recorded signal, originating from the deck, seismic and aerial intrusions. When these vibrations are damped to oblivion, what is left is what is on the record.

This argument then assumes that what people have been used to is an augmented rendition, added vibrations and harmonics, producing exaggerated bass and/or treble, and reverberation, and a little distortion. Get rid of all that, and one is left with the naked truth. And sometimes it is boring, like the original.

I have just put a recently bought cartridge in a highly modified arm I rebuilt, and listened to some Bach piano concerti. I thought, that sounds just like an ordinary piano, no flashing lights and whistles, no over blown bass or tinkling treble that seems to pervade cd's. Sometimes, when all is stripped bare, we don't like the result.

People I converse with who have tried to banish extraneous noise seem to like the 'stripped bare' sound. Others may prefer the bells and whistle approach.

[mattlynch]

hi cats,
thankyou far taking the time to share that,
although i didn't like the fully damped approach myself i did find a couple of recordings that were previously very brash became very listenable when lots of damping was present on the td160, of course the dm101 is a very different animal and i am wondering how it will respond to the OP's experiments,
all the best,
matt

[Ldg]

the belief that one can 'damp the life out of the music'. Many have stated this, whether they have experienced something like this, or just repeating hearsay..........sometimes, when all is stripped bare, we don't like the result

It's a great divide. Not just philosophical, but in preference and taste.

Various descriptions, such as 'life', or "complete loss of sound staging ,dynamics and sparkle in the sound", mark that some (or even most) people simply find certain extras attractive. On assumption that vibration damping subtracts extras far more than it affects original programme material, which seems true enough for these purposes.

Plenty of studio effects exploit the psycho-acoustics of such things, of course.

Then TTs, arms, even cartridges that have high reputation might have got where they are today by Darwinian selection principles. i.e. being both good at what they basically do, and having selective 'augmentations' that prove popular. ie people positively prefer how they self resonate, and therefore sound. Being mechanical devices, all such augmentations must arise through vibrations, of course.

My personal preference for critical playback listening is to attempt to perceive as little augmentation as possible. Philosophically, I suppose that is most people's goal too. But, being at least partly psycho-acoustic, the means to that end is plainly not universal. Personally, I find that easiest when pretty much all is as dead as its possible to be.

I think it was mattlynch who posted a question on another thread as to whether one would add damping to a Dunlop guitar? By analogy, the TT being an instrument. I thought at the time, this is the crux issue of a great divide. Rodrigo by Yepes, or with a hint of Dunlop ? Which is 'correct' and which do you 'prefer' ? Not always the same answer, and knowing that can be quite insightful.

General platter/plinth damping influences this, of course.

[missan]

Good points LD.
To a large extent we initially always prefer what we are used to. What our experience are.
Most of us are not used to playing on inert equipments, so it´s also much of a cultural thing what we initially prefer.
missan

[mattlynch]

hi gents,
i fully agree, although i dont know where the guitar thing came from 'lucky dog',,, the thing i was getting at here was that the td160 acted in this way when heavily damped and perhaps thorens got it right ,the metallic particle sheet thorens used for the bub chassis was already dead as a dodo when struck and was pretty trick stuff and far more advanced than say the sheet steel linn used in early sondeks, i use quite heavily damped rega arms in a large self damping plinth structure and its great at high volumes but unattractive at lower volumes,
are we actually fixing problems with equipment that the maker missed or are we tuning to personal taste ?
the makers of the logic dm101 must have spent some considerable time tuning the deck to give the best they could get from it ,but that is to their ears and with equipment they had at the time, did they deliberately leave in some of those extraneous resonances because they sounded good to the ear even at the cost of ultimate fidelity,
to put into a few words, the manufacturers tuned the product to get a good ,likeable product, a bit of fine tuning can be good but mostly i have found a little is often more than 'more'


if i had a dm101 spare to experiment with i would get the underside of the sub chassis machined in the same fashion as the linn keel or limm sub platter and do the same to the platter rather than mess about with adding energy storing substances ,hence my earlier comment of using easily removable substances ,
i look forward to the OP's results.
all the best ,
matt

[jimg]

After all that most interesting stuff, to answer your query i have used only an extra felt mat on top of the bonded one and found that this is a definite improvement. Also if you peruse the manufacturers set up instructions, available in the manuals archive, Logic offered this when the deck was bought new. Other mats may also offer an improvment but you would have to buy or borrow to find out. As with the early Systemdek and a few others many mats do not work to well with a fixed felt one. I recently bought a Japanese deck with a nice cork mat which is quite heavy so i may try that.
Jim

[Eoin]

There's lots of VTA adjustment available on my arm so what I might try is a felt mat on top of the rubber one.