What are good turntable acoustic damping materials

Bright Star Audio,

Please enlighten me without too much tech talk regarding these words you posted above:

"Felt will damp some ringing and resonances present in the structure of the Thorens but it will not be as effective as more absorptive materials (that are typically more massive). The objective is to convert the mechanical vibration to another form of energy that will not affect the musical signal. Converting the mechanical vibration to thermal energy (heat) is very effective if the transfer is done as efficiently and quickly as possible."

My simple mind tells me that a suspension attempts to isolate the record surface/stylus from vibration and the felt mat is just an extension of that design philosophy. By using an absorptive mat aren't we more or less coupling the record to the suspension and thus defeating the principles of the design? Or, do you know of a mat that acts on absorption without transfering energy back to the platter?

If you know of such a device I would be happy to audition one and write a review. Another question. Are you saying that the platters from either a Thorens or a Linn actually ring? Having owned both brands of turntables in my nearly 40 years of spinning vinyl I've never heard any ringing.

Thanks.

Barry, I have absolutely nothing against intelligent use of damping. But given that perfection is not possible in this world, at any price, do we really want to highlight any weaknesses a turntable must have by over-application of damping? In other words, if a "lesser" 'table sounds greatly musical because (like the LS3/5A which used an entertaining boost to better convey rhythm and the illusion of bass) it has a resonance somewhere which is musically satisfying, then do we really want to wipe out this musical resonance? This is with the understanding that no amount of damping will make a Thorens TD160 Super a Walker Proscenium, and it is foolish to try, as one simply ends up with a lesser Proscenium, but without that entertaining extra "bounce" a classic 'table may have, being it's sole advantage over more "neutral" designs. I've read a large amount of material on damping over the decades and have used and experimented with all kinds of materials and continue to do so, and agree with you entirely that damping has several beneficial effects. But these improvements must not sacrifice the essential musicality or "magic" of a design in the doing, or we end up with a "neutral" piece (and this neutrality may itself be a colouration) which simply falls musically flat. What profits it a man to gain the world and lose his soul? Similarly, what profits it an audiophile to gain neutrality and lose the music? Do we want to wipe out the resonances of a Stradivarius to make it more neutral? Sometimes certain resonances enhance the music, while others detract. The secret in damping a record player is to find which spots can be damped without sacrificing the music, and to leave the design "strengths" alone, knowing that the 'table will never be "perfect". With this in mind, I advise Faradayblue to get to know his player before he embarks on modifications. For instance I own a TD160 MKII and a Maplenoll. The Thorens will never equal the Maplenoll in terms of all those audiophile strengths we seek, but the Thorens does have an entertaining musicality about it which I quite like, this particular quality being superior to the Maplenoll on strictly musical/entertaining grounds. I will tweak it, but also be very careful not to wipe out this ingredient. Intelligent application of damping in a world where technical perfection is not possible, but poetic perfection can be attained: the Stradivarius.

Hi Johnnantais,

Your comment about damping killing the dynamics of the turntable prompts me to respond.

I assume that you’ve had a previous experience where you’ve added damping to a component and have heard a seeming reduction in dynamics or an altering of the frequency response that might be described as a dulling or a more lifeless effect. Please allow me to present a scenario that might shed some light on your experience.

Let’s say we have a turntable that, because of the materials used in its construction and its configuration, adds a 4 dB boost at 1000 Hz caused by resonance as the result of vibration (I’m using an exaggerated amount of boost to illustrate my point). This boost not only affects the frequency response but also the amplitude response and phase response. Frequency, amplitude and phase are all inter-related and changing any one of them affects the other two. The uncorrupted relationship between the three is critical for all areas of performance. When the relationship is disturbed by vibration, the sonic results include (but are not limited to) bloating of certain instruments due to increases in certain portions of the frequency response, exaggerated dynamics because the bloating is more evident as the volume of the system increases during peaks and an increase in the size of the soundstage BEYOND what is contained in the recording due to random out of phase artifacts.

In many other respects this turntable does provide good performance (deep bass, stable platter rotation, etc) and it has actually received good reviews in the magazines by reviewers that have not measured the turntable but have just placed in their reference systems and have written about their impressions. We read the reviews and go out, buy the turntable and place it into our audio system. In fact, we also buy a new tonearm, upgrade the cartridge and get new tubes for our amp around the same time. We place the TT in our system and like the many good qualities that have been described in the reviews. We do hear somewhat more presence in the midrange than our old turntable (the 4 dB boost at 1000 Hz) but figure we have to let the new cartridge break in. In some respects we actually like that little bit of extra presence in the mids and think that maybe our old tubes must have lost a little in the mids over time and these new ones have revitalized things.

After a few weeks the cartridge has broken in and we like the new turntable and we make further changes in the system over time. Increasingly though, that extra midrange boost is a little annoying so we try a few different cables between the preamp and amp, we fool around with VTA and azimuth, change the speaker position and add some room treatment panels. We have now made the midrange boost disappear.

We start reading about how vibration in a system can change the sound so we decide to really tweak out our turntable and get rid of any vestiges of vibration contamination by damping every part of the turntable. We are very careful, however, not to change the tuned suspension of the TT.

We sit back to listen and like a number of improvements the damping has brought about but find the midrange to be rather lifeless and feel like there is less dynamic range than there was before.

Hmmmm. What is really going on? What has happened is that we have finally (with the chassis damping) removed the original problem and the 4 dB boost at 1000 Hz. Subjectively, however, we have caused a DECREASE at 1000 Hz by 4 dB and don’t like the results.

Well, you might say, what’s the difference if we decrease the 4 dB boost through damping or through changing components and set up procedures? We’ll still end up with a pretty flat response, won’t we? And we won’t have that feeling of restricted dynamics and lifelessness if we accomplish it through the changing components / set up (CC/SU) route. The problem with that line of reasoning is that the CC/SU route has addressed the symptoms of the problem not the cause. Removing the cause more clearly shows that the CC/SU route has diminished the midrange response and dynamics – not the damping.

For a much more thorough discussion on this topic please see my thread “Damping Vibration – Friend or Foe?” at http://forum.audiogon.com/cgi-bin/fr.pl?ymisc&1078727040&openusid&zzBright_star_audio&4&5#Bright_star_audio

Best,

Barry

Hi Faradayblue,

Any condition that a turntable exhibits that alters the signal the cartridge is retrieving from the record is a detriment and takes us further away from reproducing the sound of the music as it has been captured by the recording team. Unwanted vibration and resonance surely causes a change to the signal and should therefore be eliminated as much as possible.

Felt will damp some ringing and resonances present in the structure of the Thorens but it will not be as effective as more absorptive materials (that are typically more massive). The objective is to convert the mechanical vibration to another form of energy that will not affect the musical signal. Converting the mechanical vibration to thermal energy (heat) is very effective if the transfer is done as efficiently and quickly as possible.

I do agree with Lugnut that you must be careful not to alter the original tuning of the suspension system in a turntable that suspends the plinth with a compliant spring or supports the plinth with a compliant spring. Adding mass to the plinth will change the resonance frequency of the suspension system which the turntable’s designer has optimized (hopefully correctly). If you do add more mass to the plinth, you can change the springs which comprise the suspension system to compensate.

If the outside frame of the turntable is vibrating or resonating, steps should be taken to eliminate that vibration as much as possible.

Best,

Barry

Faradayblue, I know of only two Mission tonearms: one was slim and was the 774, the other was massive - much more "chunky" than a Rega for instance - and was called the Mechanic. The slim one was considered good, and with MMs such as the Grados for instance, are sonically superior to the Regas, MMs in general (and in my own experience/experiments) preferring lower-mass arms, regardless of what the manufacturers say (these same manufacturers feel compelled to write that their designs prefer medium or high-mass tonearms because apart from the Morch that's prety well all there is these days!). As far as MCs go, then the Regas probably have it, though this isn't certain. If it is the large, chunky piece of business, then this is the legendary Mechanic which I would give my eyeteeth to have, a superb tonearm which you should keep, assuming the bearings have not been damaged. At best, have it re-wired by the folk at Incognito.

The tonearm that came with the tt is manufactured by Mission Electronics. I know very little about this arm, please see my other thread on this subject. I'll leave it on for now. It also came with quite a heavy rubber after market mat, a "Unitronics Strobo-Mat". Regarding cartridges and cables, I'll initially swap the Benz Micro Silver and the Cardas Golden Cross from my TD 166 Mk II. I'll take your advise and listen to the table as is, for now.

Suspension tables may not respond favorably to additional dampening. IMO, based on listening tests my LP12 didn't like a non-felt mat or the use of a clamp. Dampening the motor housing may provide some benefit but I have yet to try it but plan to. Geez, I'm probably going to take a hit on this, but those tables that over-use lead don't get my toe tapping in spite of some benefits such as a blacker background. There is an eBay seller that has a number of dampening devices for a Linn that seem interesting. I'd love to read an Audiogon review of his products. I'm also anxious to read what Bright Star Audio has to say. I've got an open mind on this topic.

Faradayblue, tread very carefully in "improving" the TD160 Super, as it incorporated many of the tweaks - damping materials and so forth - that were being used at the time. Over-damping will kill the dynamics of the 'table, lead sheet being especially dangerous in this regard. You should set up the 'table first and live with it for a while before attempting any mods, as only in this way will you know whether something is an actual improvement or not. Have you upgraded the tonearm (what is it, by the way?) or cartridge (ditto) yet? These are safer improvements until you get a handle on the 'table's strengths, so you can make wise decisions when you are ready to tackle the issue of changing the design somewhat. Here's a good source of info on mods popular at the time, complete with articles and so forth: http://www.theanalogdept.com/thorens_td_160_dept_.htm. An excellent website with reams of material.

The TD 160 Super (1980s vintage) included damping material from the manufacturer. The internal sheet metal surfaces are covered in felt sheet. My question is whether newer materials perform better at damping/absorbing vibrations.

Hi Faradayblue,

What portions of the Thorens do you wish to damp?

Best Regards,

Barry Kohan

Discalimer: I am a amnufacturer of vibration control products.