ack's system - end of round 1

[ack]

Ack, are you checking the table plinth for level, or the platter? Do they match? I used to have a Zoethecus rack and abandoned it in favor of something much more solid. At the time I simply put shims under the shelf supports to level each individual shelf. If your floor underneath is uneven, why not just put a hard shim under your rack footers so that the rack itself and the individual shelves are level and be done with it? Then you could screw down your VPI footers. I would want to remove all of those washers and tighten the feet as much as possible for as solid a connection as possible so that internal vibrations drain away from the plinth. However, by putting the spikes up on dampening material, the vibrations are probably remaining in the footer/plinth structure anyway. Have you tried a rigid coupling of your turntable to the Zoethecus top shelf or to what looks like a marble slab?

I did not know that your VPI turntable is suspended. Or are you saying it acts like it is suspended because of the compliant rubber under each footer? Could you describe the suspension system and what specifically you do not like about it? I don't see how the leveling of the footers relates to your aversion to suspended turntables? I don't follow your conclusion or why you are constantly adjusting your table's feet? Is the level really changing that much over time? That's a lot of washers jammed in there. And could you further explain why you now don't like suspended turntables as a class? The Kronos, TechDas, SME are all suspended. Do they have these issues that you don't like or is it just about the implementation of your specific VPI turntable, which admittedly, I don't really understand?

Regarding your Isodamp, have you considered separating your electrical panel from its support structure with a layer of Isodamp to reduce vibrations? I don't know if this would violate local codes, but it might reduce noise in your power delivery system. I don't know if anyone has tried such a thing, but given your willingness to experiment with Isodamp, I thought I would throw out the idea to see what you think.

The Isodamp in the amp fins looks good and I bet the ringing has really decreased? Do you hear a difference? My Pass amps suffer from the same issue.

The VPI is not a suspended design. I no longer care for suspended designs like the ones you listed, because they have the same issues (to one degree or another) as the VPI with loose feet. I now like solid structures. Regarding checking for level, the only place it matters is at the platter; my floor is not flat, hence the need to adjust the feet (always been the case), and I don't really like shims. And yes, I have obviously experimented with and without the dampening materials underneath the feet, and that's how I arrived at that isolation solution.

The Isodamp between the fins makes a profound difference at loud volumes, as I posted earlier - also, a simple flick with a fingernail before and after confirms the fins are now dead; you should try it on your Pass.

 

[PeterA]

The VPI is not a suspended design. I no longer care for suspended designs like the ones you listed, because they have the same issues (to one degree or another) as the VPI with loose feet. I now like solid structures. Regarding checking for level, the only place it matters is at the platter; my floor is not flat, hence the need to adjust the feet (always been the case), and I don't really like shims. And yes, I have obviously experimented with and without the dampening materials underneath the feet, and that's how I arrived at that isolation solution.

The Isodamp between the fins makes a profound difference at loud volumes, as I posted earlier - also, a simple flick with a fingernail before and after confirms the fins are now dead; you should try it on your Pass.

Thanks, I now understand. You think the loose feet on your unsuspended VPI table have a similar sonic effect as the suspensions do on the TechDAS, Kronos and SME turntables. I have listened to my SME turntable with the suspension locked down and the Vibraplane deflated. The structure was completely solid. I preferred the sound of the suspension and isolation in place.

I still think making your VPI footers as solid as possible by tightly coupling them to the plinth by removing the washers and screwing them down making contact and then leveling either the marble slab or the rack shelf itself might provide better sonics. Perhaps those washers are adding something you like to the sound. On the other hand, if you keep needing to add washers because your floor moves some every year, then you must find the most practical solution, and adding washers may be it.

I did try your scraps of Isodamp between my Pass heatsinks. Yes, they reduced vibrations just like placing them on the top plates did. Not completely, but much less audible when tapped. They were very effective without being under any pressure or load. However, I did not have them long enough to experiment with sonic effects from the listening seat. I've tried to remove resonances from the rest of the room, so I might give that another try on my amps. I have found in some other cases, that overdampening things does not always lead to better sonics. Experimentation is the only way to know. I think often we just change the resonant frequency of whatever it is we are dampening, and sometimes the change is for the better, and other times it is for the worse. I overdamped my SME arm once but using the damping trough and it sucked the life out of the music. No good.

Anyway, it is fun to read about your experiments and modifications.

 

[ack]

Thanks, I now understand. You assume the loose feet on your unsuspended VPI table have the same sonic effect as the suspensions do on the TechDAS, Kronos and SME turntables, although they have solid feet and very different suspension designs from each other. I have not heard the owners of those tables describe these problems, but maybe they are there. I have listened to my SME turntable with the suspension locked down and the Vibraplane deflated. The structure was completely solid. I preferred the sound of the suspension and isolation in place.

Keep in mind that "assume" and "same sonic effect" are your words, not mine. Rather, the way to read what I said is that, what I hear in suspended designs is AS IF something is loose, similar to but not the "same" as the loose VPI feet. Said otherwise, I'd rather start with a solid design and isolate it with various means, rather than go for suspended designs and take it from there. If I had your turntable, I would lock down the suspension and experiment with solid isolation underneath it, like HRS products.

On the other hand, if you keep needing to add washers because your floor moves some every year, then you must find the most practical solution, and adding washers may be it.

BTW, no one said my floor moves every year, and that I have to keep adding washers. Rather, the table's feet have always been uneven because of the uneven floor. Without the washers, you might see a bit of the bare set screw, and that's where the instability comes from (frankly, there is also a soft cushioning material, so the screw is not really visible with it; VPI provides it for better visuals; in the picture, it's bulging out now). The bottom line is that the total height per VPI foot is still the same as before. A better solution might be to remove VPI's cushion and black washer plus my washers, and use a nut instead to lock down each foot.

I did try your scraps of Isodamp between my Pass heatsinks. Yes, they reduced vibrations just like placing them on the top plates did. Not completely, but much less audible when tapped. They were very effective without being under any pressure or load. However, I did not have them long enough to experiment with sonic effects from the listening seat. I've tried to remove resonances from the rest of the room, so I might give that another try on my amps. I have found in some other cases, that overdampening things does not always lead to better sonics. Experimentation is the only way to know. I think often we just change the resonant frequency of whatever it is we are dampening, and sometimes the change is for the better, and other times it is for the worse. I overdamped my SME arm once and it sucked the life out of the music. No good.

The resonant frequency changes as a result of mass and shape (the Spectral fin shape is just not good, if not horrible); dampening material can also affect that, but it also dampens.


EDIT: I had easily demonstrated to Al a while ago the differences between the HDCD Janaki vs the LP, playing them in parallel, and the latter was markedly softer. Not anymore.

 

[PeterA]

Yes, I had presumed too much so I was editing my post while you must have been composing yours. You will see that my post is different from the quotes you pulled out in an earlier version. I apologize for my haste in posting and for my presumptions.

Here's a rather boring picture of my VPI's feet - I have to raise the back a little in order for the table to be flat (uneveness in the floor underneath):

So for years, I was simply adjusting the feet, as anyone would, by unscrewing them, and said feet would be a bit loose after a certain point.

I was also hasty it seems in reading what you wrote here as meaning for years you were simply adjusting the feet. Perhaps you meant that your floor is uneven and you adjusted them once and then for years you wondered about the sound of the loose footers. That makes much more sense. I had read your words to mean that your floor moved over time because you were adjusting your feet for years. My mistake.

Rather, the way to read what I said is that, what I hear in suspended designs is AS IF something is loose, similar to but not the "same" as the loose VPI feet. Said otherwise, I'd rather start with a solid design and isolate it with various means, rather than go for suspended designs and take it from there. If I had your turntable, I would lock down the suspension and experiment with solid isolation underneath it, like HRS products.

I suppose if I wanted a solid turntable, I would have kept my old SME Model 10 or bought an unsuspended alternative. My suspended larger model SME sounds much better. I don't know what owners of TechDAS and Kronos would think about disabling there suspensions because they sound "as if" something is loose. Rockitman's suspended TechDAS is the most solid and quiet turntable I have ever hears. Spooky quiet. I suppose his new 500 lb unsuspended American Sound table sets a new standard for "solid".

Anyway, this is about your thread and the many modifications you are making to improve the sound of your components. Sorry to distract from that theme by discussing SME suspensions and air isolation. Solid, rigid and massive is certainly a different approach.

 

[ack]

One thing I don't think anyone can deny is that, in a suspended turntable, the top plate is floating to one degree or another, no?

 

[ack]

Credits and attributions - or why audiophile communities are so great

It's been about 10 years since I started seriously modifying my equipment, starting with the speakers I think, but the last 18 months or so have been really intense, if these pages don't make it obvious. This last round started when Goodwin's would not let me borrow the 4000SV when I wanted, at which point I started seriously looking at the Alpha circuitboard - their loss really, and not mine, 'cause in the end I ended up with better and sensational digital sound.

During the course, there is no telling how many times I've played the same material over and over again, to the point I've gotten sick of it myself. At the same time, many people have been instrumental here in me getting better sound, so this is a tribute to the wider audiophile community:

1) My family: you have made no comments on the sound, you have no idea what I am doing, but your patience and support is immeasurable! Best of all, you have no idea what my handle is on this board. I assure you, though, the spelling is correct, WBF and not WTF.

2) The Boston group: many comments have been right on, the latest being a few weeks ago when you said there was a thinness to the sound; well, that was a bit intentional with lower bass output due to the turntable issues I was having and the loose feet. I reworked the crossover and subwoofer to some incredible results, now that the sources are probably at their top. I have been fighting bass integration for many years, but at least I have the privilege of tuning the crossover to the room

3) All posters in this thread, for a variety of comments: ayreman for the subwoofer help (indeed, post-mods, I ended up crossing over higher at 28Hz, and the low notes are oh-so tight); marty for calling out my insanity and confirming that cable networks do indeed need shielding; microstrip for a variety of comments (BTW, do folks really know what a microstrip is???); Mike Lavigne for comments on generalizations, but I gotta tell you all again, digital volume controls really suck and I can go into all the technical details if anyone cares; kingsrule and other critics who think we are a bunch of narcissists, but deep down, I know you are a good man - BTW, you were right, I am using bananas in production, and you are looking at the subwoofer cables connected to the amps (the real speaker cables are spades); Steve Williams for an incredible demo at his place, from which I learned so much; Myles Astor for another incredible demo two Christmases ago, and I gotta tell ya, I finally got the flamenco dancer to really shake that stomping platform on my Pepe Romero Flamenco CD, like that LP you played for me at your place; BMCG, daveyf and others for following and encouraging this insanity; mdp632 and others like you who have jumped on the Spectral platform and are oh so happy; Dave from Switzerland for our private discussions; and everyone else who reads these pages and shakes his/her head. I apologize if I missed anyone!

And now some lessons learned - and feel free to disagree:

1) Noise is everywhere, mechanical or electronic, and a real killjoy. This aspect does not get the attention it deserves by some manufacturers
2) I would not be doing what I am doing if I were not very familiar with live performances, which had me looking for the missing information that I knew ought to be there in the recording and should be presented to me. Real live performances are the only true reference
3) Mechanical grounding is paramount to turntable performance; arm stability and so many other parameters are incredibly important, even the cartridge-to-arm coupling
4) If anyone ever had any doubt, power supply quality is tantamount
5) Crossover parts and design: unless you try it, you probably won't believe how much better speakers can sound
6) So far, I have no reason to part with electrostatics, and it will probably be very costly to do so
7) RBCD can indeed sound like excellent analog, no BS; D2D, though, still rules in here
8) There is always room for improvement

And with that, on to better things!

-ack

 

[Uk Paul / Z:Axis Audio]

Nice post and I couldn't agree more with you ack! You have come a long long way since those days on ML discussing inductors.. Well done.. P

 

[PeterA]

One thing I don't think anyone can deny is that, in a suspended turntable, the top plate is floating to one degree or another, no?

Could you please be more specific about what you mean by top plate?

 

[ack]

The top plinth hosting the platter. SME and others like it try to load with mass in order to minimize this floating, but at the end of the day, there is no solid mechanical ground.

 

[Mdp632]

Thanks for the mention ack. I’m enjoying my Spectral gear immensely. Your posts and our exchanges were instrumental to me pursuing spectral. I’ve found that the products make a statement only about themselves.

Everyone has different tastes but , I’ll say this as a digital only person if Spectral released a Dac with the SV technology . I would order it before even listening to it. I’ve never been able to say that about another audio product in my life .



Now I can understand why the waiting period to get a pair of the 500s is approaching two years.

 

[PeterA]

The top plinth hosting the platter. SME and others like it try to load with mass in order to minimize this floating, but at the end of the day, there is no solid mechanical ground.

I may be completely wrong about this but are you maintaining a mechanical ground with the use of that compliant material under your motor and turntable footers? Aren't spikes meant to couple the component to ground and provide a path for vibrations to exit? Does that rubber help or hurt in this regard? Where do those internally generated vibrations traveling down your arm tube, arm board, plinth and platter bearing go if they can't leave the structure? What about a mechanical ground for the American Sound platter which floats on a layer of air? Do you feel the Kronos, TechDAS, EMT, SMEs and all suspended turntables are flawed in this regard, and if so, how do you account for people enjoying the sound of these tables?

This is a pretty interesting topic. You should start a dedicated thread on the subject.

View attachment 38454

 

[ack]

To make a long story short, I feel the mechanical ground is most important when it comes to the arm assembly. As such, and depending on the implementation, a floating platter could be fine, ditto for a pneumatically suspended one or similar. But if a platter were to float, then I would say it’d better be a really heavy one. In other words, I really like the AS 2000 design and similar ones with detached arm assemblies/towers, where the arm at least is mechanically grounded on hard isolation surfaces like HRS.

So I suppose we should make a distinction between suspended turntables - where the platter and arm assembly float - vs suspended-platter designs, vs unsuspended designs

 

[PeterA]

To make a long story short, I feel the mechanical ground is most important when it comes to the arm assembly. As such, and depending on the implementation, a floating platter could be fine, ditto for a pneumatically suspended one or similar. But if a platter were to float, then I would say it’d better be a really heavy one. In other words, I really like the AS 2000 design and similar ones with detached arm assemblies/towers, where the arm at least is mechanically grounded on hard isolation surfaces like HRS.

So I suppose we should make a distinction between suspended turntables - where the platter and arm assembly float - vs suspended-platter designs, vs unsuspended designs

Yes, this is a fascinating topic: grounding or isolation, or some combination. This is precisely why I asked you to define what you mean by "float". Your arm assembly seems mechanically grounded to your VPI constrained layer plinth, but that plinth is then decoupled from ground because it is supported by your spike footers which then rest on compliant rubber. It seems to me that if the arm assembly being grounded is what is important, then the Kronos/TechDAS/SME all have arm assemblies that are grounded more or less like the one on your VPI. That is, they are rigidly connected to a heavy chassis/plinth that is then suspended/isolated by air, or rubber.

The top chassis/platter/armboard of my SME at more than 50lbs weighs about the same as your entire VPI table. The SME is hanging on rubber isolation bands and your VPI is resting on a rubber interface to the rack shelf. You suggested that I lock down the suspension of my SME. I tried that and it does not sound as good. I don't see how you can define the VPI as a grounded design and then declare that you no longer like suspended turntable designs because they sound "as if" or similar to, or to one degree or another, like your turntable does when the footers are loose. You break the ground with your Isodamp, cork, and black rubber interfaces. From the looks of the designs, it seems that your VPI is really not that different from the suspended top plates of those other brands, at least by overall mass and rigid arm/armboard/plinth/chassis assemblies. What happens below is not that different either given that you have chose to decouple your table from ground with the rubber under the footers.

Vinyl is so incredibly complex and frustrating, but also very rewarding. The picture below shows a very thin layer of sorbothane in the shape of a T placed between the cartridge and the headshell. The results are immediately noticeable as further clarity and articulation in the highs, with noticeably less edginess. A simple tap on the headshell with a metal object results in a duller thump, with less high frequency content and ringing. The screws already use plastic washers. The real problem with this presumably easy tweak was re-aligning the cartridge - what a pain. I have not noticed any drop in dynamics or bass performance, and VTF was only affected by 0.1g, easily compensated.

View attachment 37377

You also seem to break the mechanical ground of your cartridge by placing a T shaped layer of sorbothane between it and your tonearm headshell. If you prefer the sonic result, it is not because of mechanical grounding giving the vibrations a path to follow away from the stylus/vinyl interface, but rather you are decoupling the two, isolating the cartridge where the vibrations will remain because they have no where to go. Now, perhaps that sorbothane at the headshell prevents arm vibrations from reaching the cartridge and that would be a good thing. It is a little bit difficult to know what is happening at your cartridge/headshell connection, but it is not a rigid mechanical ground connection. This is a case where your ears tell you what sounds better than simply making assumptions about what might work better in theory.

Congratulations for improving the sound of your VPI through your extensive modifications to the original arm and table design. I just don't think they are because of improving mechanical grounding paths. I did the same with my SME by placing the whole assembly on an air isolation platform. This prevents low frequency floor borne vibrations from entering the table system and is certainly a modification to the original design, but it is no different from a good rack/support system. The SME engineers did a fairly good job, it seems, of rigidly coupling certain parts of the system and then isolating other parts like the motor and two chassis from each other and also providing a very hard ball bearing mechanical grounding path at the footers for the motor vibrations via the lower chassis to exit the system. These footers are directly coupled to 285 pounds of steel below them because of the hard ball bearings under the footers.

You are right to focus on these kinds of things with your turntable. Mass loading and mechanical grounding versus floating and isolation and some combination with grounding are critical to the performance of a turntable/arm/cartridge system. And there are many different approaches to successful designs, from the light weight Monoco to the ultra heave American Sound, and countless table designs in between.

Your system thread is a good place to describe what you are experimenting with.

 

[ack]

Yes, this is a fascinating topic: grounding or isolation, or some combination. This is precisely why I asked you to define what you mean by "float". Your arm assembly seems mechanically grounded to your VPI constrained layer plinth, but that plinth is then decoupled from ground because it is supported by your spike footers which then rest on compliant rubber. It seems to me that if the arm assembly being grounded is what is important, then the Kronos/TechDAS/SME all have arm assemblies that are grounded more or less like the one on your VPI. That is, they are rigidly connected to a heavy chassis/plinth that is then suspended/isolated by air, or rubber.

There is a fundamental difference with what I am doing and what SME is doing - your upper plinth is floating on the horizontal plane (and what I don't like) and less so in the vertical, and my entire table is not in either plane (therefore, not suspended), by sheer virtue of the thick and inflexible (therefore, NON-compliant) isolation. Mechanical ground does not imply total lack of isolation and a straight unimpeded path to the floor; so I feel one is OK as long as we impede vertical and horizontal floating and provide some isolation; therefore, isolation platforms like HRS provide ample mechanical grounding and some isolation.

You suggested that I lock down the suspension of my SME. I tried that and it does not sound as good.

What I suggested is to lock down your suspension AND isolate with something like an HRS platform underneath the entire turntable - huge difference - as I don't think the pneumatic platform provides enough of a mechanical ground; post 623: "If I had your turntable, I would lock down the suspension and experiment with solid isolation underneath it, like HRS products."

 

[PeterA]

Thanks for the clarification. There are many successful solutions to turntable design. Good luck with your modifications and I'm glad you are hearing results. I enjoy reading your system thread and learning about your progress.

 

[ack]

There are many successful solutions to turntable design

Yes, each with its own strengths and weaknesses. The issue of mechanical grounding is very important to me, and again, using certain elastomers in the chain does not preclude one from achieving adequate mechanical ground. Case in point, the elastomers in the stylus suspension, at the very beginning of the entire chain - are they precluding proper mechanical ground? Absolutely not; they are very much non-compliant.

 

[PeterA]

Yes, each with its own strengths and weaknesses. The issue of mechanical grounding is very important to me, and again, using certain elastomers in the chain does not preclude one from achieving adequate mechanical ground. Case in point, the elastomers in the stylus suspension, at the very beginning of the entire chain - are they precluding proper mechanical ground? Absolutely not; they are very much non-compliant.

Ack, you did not answer my question about how the T shaped pad of Sorbothane between your cartridge and your tonearm headshell maintains a mechanical ground for the vibrations occurring within your cartridge. This is an area that SME looked into very seriously. You did say that you feel the arm is a more vital area of concern for mechanical grounding, but the cartridge is at the location of signal generation. Could you address the mechanical ground at the cartridge/headshell interface or do you not think this is important?

The Sorbothane pad is compliant, at least I presume it is, because you mentioned how difficult it was to align your cartridge after the installation of that pad. One benefit I suppose is azimuth adjustment by playing with the mounting screw tension.

EDIT: From your photo, it does not look as if the VPI headshell rotates, so how do you adjust for azimuth? Also, I seem to remember from somewhere that the A90 cartridge has three tiny bumps on the top surface for better contact with the headshell. Is this the case, and if it is, you seem to be defeating this feature, though as you write, if it sounds better with the modification, that is more important. Could you clarify?

 

[ack]

Ack, you did not answer my question about how the T shaped pad of Sorbothane between your cartridge and your tonearm headshell maintains a mechanical ground for the vibrations occurring within your cartridge. This is an area that SME looked into very seriously. You did say that you feel the arm is a more vital area of concern for mechanical grounding, but the cartridge is at the location of signal generation. Could you address the mechanical ground at the cartridge/headshell interface or do you not think this is important?

The Sorbothane pad is compliant, at least I presume it is, because you mentioned how difficult it was to align your cartridge after the installation of that pad. One benefit I suppose is azimuth adjustment by playing with the mounting screw tension.

EDIT: From your photo, it does not look as if the VPI headshell rotates, so how do you adjust for azimuth? Also, I seem to remember from somewhere that the A90 cartridge has three tiny bumps on the top surface for better contact with the headshell. Is this the case, and if it is, you seem to be defeating this feature, though as you write, if it sounds better with the modification, that is more important. Could you clarify?

I already answered your question: certain polymers are non-compliant; the sorbothane between the cart and headshell is so thin and so squished that's it's almost not there and rendered very much non-compiant - it's probably a hair's thickness - the stylus's suspension is definitely the only compliant part of the chain. Azimuth is achieved in this arm by rotating the counter-weight, though with the A90, the construction is so perfect (what Ortofon is so renowned for) that I never had to (unlike the Dynavector before it). And indeed, the A90 has three contact areas, and yes, I am defeating that to better results because of the ringing in the arm, nothing to do with the design of the cartridge.

 

[PeterA]

I already answered your question: certain polymers are non-compliant; the sorbothane between the cart and headshell is so thin and so squished that's it's almost not there and rendered very much non-compiant - it's probably a hair's thickness - the stylus's suspension is definitely the only compliant part of the chain. Azimuth is achieved in this arm by rotating the counter-weight, though with the A90, the construction is so perfect (what Ortofon is so renowned for) that I never had to (unlike the Dynavector before it). And indeed, the A90 has three contact areas, and yes, I am defeating that to better results because of the ringing in the arm, nothing to do with the design of the cartridge.

Vinyl is so incredibly complex and frustrating, but also very rewarding. The picture below shows a very thin layer of sorbothane in the shape of a T placed between the cartridge and the headshell. The results are immediately noticeable as further clarity and articulation in the highs, with noticeably less edginess. A simple tap on the headshell with a metal object results in a duller thump, with less high frequency content and ringing. The screws already use plastic washers. The real problem with this presumably easy tweak was re-aligning the cartridge - what a pain. I have not noticed any drop in dynamics or bass performance, and VTF was only affected by 0.1g, easily compensated.

View attachment 37377

Thanks Ack. I went all the way back to page 48, post 478, to find your original photograph of the sorbothane at the cartridge. It is indeed thin, slightly thicker than the cartridge lead wires, judging from the image. Could you indulge me to clarify this mechanical ground issue a bit more?

The Sorbothane polymer is essentially non-compliant because of how thin it is and how tightly it is compressed between the cartridge and headshell by the pressure of the mounting screws. It maintains the mechanical ground of the cartridge to the headshell because it is a non compliant polymer. Yet, the ringing noticed when tapping the headshell with a metal object is less, so you must be dampening either the resonances in the headshell, the tonearm, or some combination of the two. Presumably, the vibrations which cause the ringing are no longer reaching the cartridge, or at least not to the same extent as they once were, which results in better overall sound.

Are you saying that this ringing from the arm/headshell is being attenuated by the Sorbothane and not reaching the cartridge AND that the cartridge is mechanically grounded to the headshell? If so, then this would be similar to your solution at the turntable footers to support shelf interface. You said that the turntable is mechanically grounded but I presume the Isodamp/cork etc prevents some floor born vibrations from entering the turntable system.

What I do not understand is that I always though mechanical grounding is meant to provide a pathway for resonances/energy to travel along and away from sensitive parts. Are you saying that some resonances are traveling along the mechanical grounding pathway
from the cartridge to the headshell and tonearm and that other vibrations from the tonearm and headshell are not traveling to the cartrdige? If this is the case, then you are essentially placing a one way filter in that location which allows some vibrations to pass but not others. Is that correct?

 

[ack]

Thanks Ack. I went all the way back to page 48, post 478, to find your original photograph of the sorbothane at the cartridge. It is indeed thin, slightly thicker than the cartridge lead wires, judging from the image. Could you indulge me to clarify this mechanical ground issue a bit more?

What you see is the Sorbothane part that's bulging out; therefore, the contact area is even thinner than what you see - in fact, I removed it to examine it back then, and the compression markings make it almost semi-transparent - it is that thin. I experimented with two thicknesses, and settled for the thickest. BTW, I highly recommend such experimentations in your own system as well.

The Sorbothane polymer is essentially non-compliant because of how thin it is and how tightly it is compressed between the cartridge and headshell by the pressure of the mounting screws. It maintains the mechanical ground of the cartridge to the headshell because it is a non compliant polymer. Yet, the ringing noticed when tapping the headshell with a metal object is less, so you must be dampening either the resonances in the headshell, the tonearm, or some combination of the two. Presumably, the vibrations which cause the ringing are no longer reaching the cartridge, or at least not to the same extent as they once were, which results in better overall sound.

Correct; even the slightest bit of Sorbothane can have a positive effect, while effectively still maintaining solid contact.

Are you saying that this ringing from the arm/headshell is being attenuated by the Sorbothane and not reaching the cartridge AND that the cartridge is mechanically grounded to the headshell? If so, then this would be similar to your solution at the turntable footers to support shelf interface. You said that the turntable is mechanically grounded but I presume the Isodamp/cork etc prevents some floor born vibrations from entering the turntable system.

Yes, that's what I am saying. And yes, I am sure some floor-borne vibrations are absorbed (easy to confirm by tapping underneath the granite) and some are still reaching the 'table. I am more concerned about dissipating air-borne vibrations, though. There is no perfect solution, but I do feel a mechanical ground for the arm assembly is paramount, but I also have to admit, at the same time this raises some more interesting questions, like: what about air-bearing arms???? The two Air Tangent I have heard in the past, I was unable to properly assess because of the immense rumble from the platter...

What I do not understand is that I always though mechanical grounding is meant to provide a pathway for resonances/energy to travel along and away from sensitive parts.

Impossible to have it go one way AND still have a meaningful mechanical ground.

Are you saying that some resonances are traveling along the mechanical grounding pathway
from the cartridge to the headshell and tonearm and that other vibrations from the tonearm and headshell are not traveling to the cartrdige? If this is the case, then you are essentially placing a one way filter in that location which allows some vibrations to pass but not others. Is that correct?

See above; the only way to have an effective one-way filter is via a pneumatic platform (and even that is relative), but then you lose the true mechanical ground, and in that case, manufacturers mass-load to simulate such a ground, but I just don't think it's as effective, and it shows in bass performance. This is why I suggested to try locking down your suspension and then isolating with a non-compliant platform like HRS (which is effectively what I am simulating in my set-up; BTW, the HRS platforms have a separate cutout for external motors, effectively also what I am doing).

BTW, your magnesium armwand probably has one of the most effective absorptive properties, and wonder why not so many manufacturers use this metal - beats me.