Eminent Technology ET-2 Tonearm Owners
Chris, after looking at your picture (thanks) and after thinking about it further, would placing multiple magnets in a straight line not cause the damping to vary as the spindle "sees" additional magnets as it moves toward the rear? What I plan on trying is one single magnet on either side of the manifold, as close as possible to the manifold. Regards. |
Frogman - I have been thinking about that too. Since that pic I have them on top of one another in one pillar. Will try that out. My TT setup does not allow for magnets on both sides as the arm is on a pillar. Look forward to your observations with them on both sides. Richard, Dover, others - based on your experience if only using the magnets on the counterweight side of the manifold - can u tell me what the most effective arrangement was. I will try various arrangement as well as one larger magnet instead of few smaller ones. |
Chris Yes various magnets tried in..,...completely original ET2 , ET2 with fixed counterweight. My manifold with and without lead slug. All iterations also tried at wand and counterweight end. ( not both ends simultaneously ) All tests done at 12 psi Dover, for a given resonant system, all else being equal, addition of mass will lower the resonant frequency and reduce the amplitude of this resonance. I had a dual manifold arm on the drawing board well before I rebuilt the ET. Feel free to check with RW for confirmation. I currently have a pseudo active dampening/mass system in the early stages of development. It doesn't use mags or conventional feedback and IMO it is elegant in its simplicity. If it works it would eliminate the lead weight. And to miss quote the Bard just a little...... Thou doth protest too much, methinks |
Richardkrebs Thou doth protest too much, methinksAbout what exactly. You raised the issue of bearing stability and the placement of magnets. The mass you have added to the bearing tube destabilizes the air bearing. My question to you as to whether you have measured the reduction in dynamic stiffness in the air bearing as a consequence of your modification and how you intend to remedy this remains unanswered. You encourage people to try your modifications. These modifications could damage expensive cartridges and records. Are you inferring that these concerns about your modifications should not be raised. |
Dover Adding mass to the spindle helps to stabilize it. To repeat, for a given resonant system, extra mass lowers the resonant frequency and reduces the amplitude of this resonance. This is F=ma again. Force the same, Mass up, means acceleration must go down. I agree that adding too much mass is potentially a problem. Where we disagree is at what point this extra mass becomes a problem. Pivoted arms, as seen by the cantilever, have high effective mass due to the head shell offset. Yet nobody seems to worry about this. I would also suggest that anti skate is significantly more dileterious to the cartridges health. Placement of magnets..... Below the bearings natural resonant frequency, it is effectively loose, above it is nearly rigid. So the thought experiment is where is it best to place a restriction to movement which creates a pivot point in order to minimize unwanted movement of the wand. If the mag is placed wand end, the bearing clearance allows wand movement at frequencies below natural resonance but not as much as when the mag is placed at the counterweight end. This is not a bearing stability issue, it is just optimizing the bearing geometery. Like I said this the same principle employed with inverted bearings in TTs. |
Yeah I got all that the first time. We'll never agree on the added mass approach. But anyone trying it should check their cantilever deflection on eccentric records to ensure the cartridge can cope. I'm sceptical on the degree of movement in the bearing, but if there is movement then stylus drag will pull the bearing tube forward on that side of the air manifold. IMPORTANT NOTE for Frogman/Chris What folk need to know is that if you use 2 magnets either side of the tube ( forming an eddy current clamp ), the dampening will increase disproportionately. I have seen controlled studies where dampening of unwanted energy has reduced by 80+% with 2 magnets either side of a beam instead of 1. You place the magnets S-N Beam N-S Your ultimate solution if you want maximum dampening would be 4 magnets, 2 pairs either side of the manifold in the "S-N Beam N-S configuration". I could argue that if you use 2 magnets in a clamp arrangement, you might be better off clamping the counterweight end and letting the stylus drag of the wand pull that end of the bearing tube against the bearing wall naturally. That way you dont have conflicting forces created by the eddy currents and stylus drag fighting on the wand side. When positioning magnets for eddy current dampening, closer is not always better, the magnetism has nodes that vary up and down with distance. |
Playing with magnets. From yesterday the pic shows two magnet setups The top setup is superior. Three on top of one another not alongside each other closer to the spindle. Dover will try the Eddy magnetic clamp later today. It is just 9am here Sunday right now. If you look at the bottom pic you can see I do not have alot of space to work with for two magnets either side of spindle. I will clamp a small platform there with some blue tac today to allow me to put two magnets up closer to the spindle and on either side of it. Will pick up some square magnets today to give the S-N Beam N-S ------O---------- Beam/Spindle S || N--N || S---- Magnets Being an IT guy I hope you are impressed with my illustration. I took a cue from you. Cheers |
Dover Ok wanted to get this out so excuse any errors. here is the temporary setup pic (lower one) showing the same pole magnets providing eddy currents from both sides of the spindle. The Blue tac marks the north poles of the magnets. Will be making the magnet platform out of something else. Here is what I did today instead of house chores. Went and picked up a package of the magnets you see in the pic. There are 8 in a pack for $3.00. Thin rectangular pieces. I took two – put a string between them – let the opposite poles hold the string. I then let it hang very gently so one of the sides pointed north. Either it remains as north or it started turning to get to north. I marked the north poles with the blue tack you can see. I guess you can see I like this blue tack stuff. I cut a temporary piece of wood high enough to just clear the spindle and placed the two magnetic pieces on wood. The magnets could fit just below the spindle right now if I slid them across. With this setup then could be raised and placed on either side of the spindle too. Dover The distance that can be seen between them in the pic; is the minimal amount allowed in this setup. Any closer and the magnet pieces with the same pole magnetic repulsion start pushing each other off the wood. Sort of like my twins - sorry had to throw that in. They are just resting on the wood. This is how my TT works – magnetic repulsion - that produces levitation. So all of this feels like I am playing on home turf. Impressions - To describe what I hear would be just another opinion and I am no good at describing sound. Plus all our setups are different. So lets use a car analogy again. You can buy cars that have buttons that give you sport – normal – and cushy suspensions. You push the button to select the ride type based on road conditions. The different LP/Records being the different roads here. What if a car was made that did the switching for you automatically. If the road got worse or changed to gravel, the suspension changes on its own and cushions it. The resulting ride would be quieter and smoother and you can hear yourself talking with the other passengers better. Thats more of the sense I am getting with this setup. Records are quieter, highs more refined similar to past magnet damping, but now it seems more consistent/stable. This is only based on 6 or 7 familiar lps. All ET2 tonearms owners should try this. If you have some records that are more off center, sound more splashy to you then others - try them first. Once I have settled into the sound I will make a pillar for the other side to hold two similar magnets at the start of the manifold and listen again. Frogman looking forward to your impressions as well as others that try it. Richard – I know you tried many variations of magnetic damping. Did you try this same pole magnet clamping style ? Early on but am not able to detect any eccentricity or excitement in the spindle yet. Music seems to be very controlled, stable. ET 2.5 spindle 19 psi. Thanks for the suggestion Dover. Cheers |
Good work, Chris. I look forward to trying the magnetic clamp arrangement, and will post my impressions. So far, we are hearing similar effects with the two different arrangements that we have used. I do get the strong feeling that my current arrangement does not fully exploit the potential of this tweak. Well, I guess that loose floor molding is going to have to wait; darn! ;-) |
Dover - I always thought shagging around with the system was housework Dover – What is your definition of shagging. If you mean ‘experimenting’, its a release for me along with a couple other hobbies from staring at a screen for 30+ years in IT. The problem is when I get on to something I disappear. I promised my wife yesterday if she let me play with some magnets I would watch the Oscars with her. Re: The Oscars - She thinks I am like the guy in Silver Linings. I saw it a month ago – some parts hit home. I tell her my meds are the music, running ...and a little red wine. Out of interest do you run your Verdier with or without the ball inserted? My opinion on the setup ball was expressed here. setup ball |
Ketchup Ketchup – the way I used the three magnets in a row the effect was very subtle, so too hard to answer the question sorry. In a tower three on top of one another the effect is more noticeable in system. My spindle is sitting high compared to where the magnets are when in a row. I will say lack of knowledge about the magnets prevented me from experimenting further. The discussion here and the experience with the Dynavector arm made me want to experiment. |
Dover/Richard/Frogman and others trying the magnets. Another short listening session today then I had to head out for the evening. My impressions are mixed now. Not sure what to think. I really feel with myself, when tweaking like this what I can hear can depend alot on my mood going in, and how the day went. This is why multiple sessions are required for me over time. I have added more magnet slivers (4) to each side. Will have a few more listening sessions this week. Richard/Dover I used to enjoy “shagging” fly balls during practice playing baseball when I was younger. Cheers |
I have finished testing Dover's mag configuration on my modified ET2, along with individual mags independantly at either end. This has been the most extensive test I have done with magnets, spanning 3 nights of listening. The results were consistent and largely the same for all mag configurations. Differences being the degree of change. I used both weak fridge magnets and what I believe to be strong neo magnets. Test records were.. Corelli, Harmonia Mundi 7014, track 1 Oscar Peterson Trio, We get requests, Analogue productions V/V6-8606 track, You look good to me. Saint-Saens, Respighi, Proprius 7857, track 3 The descriptions here are all referenced to no magnents, being the control example. All changes noted were minor but repeatable over the three nights and were present with both magnet strenghts. With the magnets in this is what I heard.... Corelli. The harpsichord notes lost some of their attach. The spaces between the individual instruments of the orchestra was reduced with the sound stage being compressed laterally and front to back. The piece begins with a series of very short movements, each stopping abruptly allowing the sound to decay naturally into the hall. The tail of this decay was shortened. Oscar Peterson. This track begins with a bowed bass followed by the piano and drums, it steadily builds to become quite loud by track end. The effect is dramatic. The bowed bass had less bite. Less slip stick of the bow on the strings. Ray Browns usual muttering as he plays is less apparent. Less space between instruments and smaller sound stage. The build up to the final notes was diminished. Saint-Saens. The singer uses vibrato to good effect adding interest to this piece. This vibrato was rounded, smearing her voice. An aside is the airconditioning that can be heard on this track. It rumbles along beneath her voice. With the mags in place this becomes more of a low frequency hum. Sound stage and hall cues were diminished. With all iterations, there was a fog added, this covered up low level detail. There was also a slight feeling of unease, a tension which by the third night had become annoying. The greatest negative change was with the 4 strong magnets, becoming less of a problem as I reduced strength and number. All of these differences were slight, but it is the litle bits that make this hobby of ours interesting. For those of you who may be interested in adding mass. I would bring your attention to Morch's latest arm which uses massive weights to increase horizontal mass. On their web site it does not say what these weights are made out of, but brass or stainless steel would be reasonable asumptions. Extra weight like this would dwarf the 30 or so grams I have added to my ET. An appology. Some of you have contacted me via my Technics upgrade web page krebsupgrade.com While I can see the mail, I cannot at this time open them or send replies. I will get it fixed asap. |
Richardkrebs, I have finished testing Dover's mag configuration on my modified ET2 For the record you have NOT tested my ( Dover's ) configuration at all. You have only tested magnetic dampening in the context of your own reconfigured version of the ET2. Your added lead mass has pushed the operating parameters of your ET2 outside of the original design. Your ET2 is set up completely differently to mine in that : You have rigidly coupled the counterweight to the arm. You have added lead mass to your bearing tube. You have added lead mass to the headshell. You have increased the horizontal mass significantly over the standard arm. The configuration I use is: Decoupled counterweight in the horizontal mode ( spring bypassed ) Lightened tonearm Minimal magnetic dampening The level of actual magnetic dampening I use is as follows : Shure V15VMR - 1 cupboard door magnet under the bearing tube at counterweight end Koetsu Black - 1 cupboard door magnet as above Madrigal Carnegie Model One - 1 cupboard door magnet as above Denon 103 Garrott ( Aluminium/Boron hybrid cantilever/Weinz Parabolic diamond ) - none Yet again, and you seem to do this with monotonous regularity, you misrepresent statements and arguments in order to justify your own point of view. For those of you who may be interested in adding mass. I would bring your attention to Morch's latest arm which uses massive weights to increase horizontal mass. On their web site it does not say what these weights are made out of, but brass or stainless steel would be reasonable asumptions. Extra weight like this would dwarf the 30 or so grams I have added to my ET. Your argument is wrong. The Morch arm is a pivoted tonearm. The ET2 is an airbearing tangential arm. The Morch applies its mass at the rotational pivot point. You have added lead mass to your ET2 at 3 points - the headshell, the bearing tube and the counterweight. One needs to understand the physics as it applies to Linear Dynamics versus Rotational Dynamics. The added mass under these different conditions will have quantitatively different outcomes. You don't appear to have considered this at all. Furthermore, the Morch website confirms my earlier statement that added mass, magnetic dampening and fluid dampening are not the same yet you contend that they are. Morch state on their website that mass increases inertia and has no dampening properties as I explained to you earlier. Morch use silicon fluid to dampen the motion in addition the added mass weights, again, which only increase inertia. Your earlier contention that added lead mass is the same as fluid or magnetic dampening is incorrect. Again I caution readers that adding lead mass in the manner advocated by Richardkrebs could potentially lead to cartridge and record damage when playing most records which are eccentric. Why ? Because the added lead mass is loading up the cantilever. |
Dover please re read my opening sentence. "I have finished testing Dover's mag configuration on my modified ET2" This clearly states that my ET is modified as anyone reading this thread recently would know. My testing was done in that context. That fact is obvious. The Dover Mag dampening test was as you proposed to Chris and that he asked me to try. I also took the opportunity to revisit earlier versions with strong and weak magnets independantly each end. I have not said that mass, mag dampening and fluid dampening are the same other than that they all resist motion and that this resistance increass with frequency. The Morch adds what appears to be considerable mass at a radius out from the pivot point. In so doing they have made a flywheel. Lateral movement of the cantilever mounted on a pivoted arm tries to rotate the arm about this pivot point. This added mass, flywheel, serves to resist this rotation tending to keep the cartridge still, a desirable trait. As viewed by the cantilever this is no different to me adding mass in the linear plane to the ET. Adding too much mass would result in unwanted cantilever movement due to record hole out of center problems. We agree on this, as you say it would load up the cantilever, but Morch with their flywheel do not appear to have reached that point nor have I with my arm. |
Dover – I really do wish you had your ET2 up and running. The detail you remember is impressive. Richard - that was a really nice post on your findings. Thank you for taking the time to do this. Your attention to detail is very evident as well. BTW - Your recommendation for the ground on my second regulator has helped - thank you. Also I found the “Why do we listen to music” on your website very informative. No affiliation to you or your site. I want to ask (anyone) when we talk about dampening .... Does damping not mean - reduce, diminish, dull - to a point that reduces some of “vinyl’s nasties”, caused mostly in this case with the ET2 tonearm – the off center hole - but we want to do this without taking away too much from the music itself ? The effects of the magnets (small ones) so far to me is very subtle. Have not tried stronger neo magnets. I am not able to put magnets at both end of the manifold as my ET2 is on a pillar that only allows magnets at one end. Is the effect of the magnets in my case subtle because, imo, I do not play really eccentric records. Or does the small amount of movement we are talking about even matter ? Richard/Dover - would not significant movement in the ET2 spindle be required, to induce more than a subtle effect with eddy currents when using smaller magnets as I have been using on a stock spindle ? I will say it can sound a little “nicer’ sometimes with the magnets on some lps. Lps are engineered all differently. On others the effect is very small if at all. There however seems to be more background/ambient info without magnets on those lps that I did notice a difference. I refer back to the car shock absorber analogy. So does this not imply - trying to get the setup done right first - before you add any kind of dampening effect - even the oil trough ? IMO - The good thing here is any ET2 owner can try these magnets very easily and decide for themselves. Hope we get more impressions from others. I got a response back from Bruce that he is travelling. I did ask him about the manifold shims, and will also ask about his opinion on adding weight in the spindle itself - even if only 30 gms. Very intriguing |
Richardkrebs para 1 - not obvious to everyone. You are testing the effect of magnetic damping with an ET2 with rigid counterweight and high mass. Chris has been testing magnetic damping with partially decoupled counterweight and no added mass as has Frogman. I have not said that mass, mag damping and fluid damping are the same other than that they all resist motion and that this resistance increass with frequency. This simplistic view fails to differentiate between inertia and damping of motion. During the course of this debate over the last few weeks you dont seem to comprehend the difference between inertia and damping of motion. Inertia is the resistance to a change in its state of motion or rest. When you add lead to your ET tonearm you increase inertia. By increasing inertia the cantilever will flex more on eccentric records. Damping is the retardation of motion once the movement has commenced. This means the cartridge can move straight away with an eccentric record, which results in minimal flex in the cantilever, and less distortion, but eddy currents generated by the motion of the arm relative to the magnet retards the oscillation of the arm and cartridge. Adding lead mass creates higher inertia but does NOT retard motion. Magnetic dampening has lower inertia and dampens motion. I repeat again that the lead mass that you have added puts more load on the cantilever when the arm tries to move to accommodate an eccentric record. Furthermore, with the higher mass of the added lead, when the arm moves there is more momentum, there is no control over this mass, and there is no damping of motion to minimize overshoot as the arm tries to correct. As viewed by the cantilever this is no different to me adding mass in the linear plane to the ET. Again - a very simplistic view of the world. Pivoted arms have tracking error and offset angle. The physics is quite different to that of a linear arm. Adding mass but Morch with their flywheel do not appear to have reached that point nor have I with my arm.This is an assumption and speculative. I could just as easily surmise that the Morch arm is so thin and lacking in structural integrity that it needs added mass and fluid dampening to control energy and resonances in the arm generated by a good moving coil cartridge. Conventional mathematics says that adding mass to a flywheel, not only increases inertia, but it is harder to slow down. You are making the problem of navigating an eccentric record bigger than it needs to be. |
Hi Chris - Yes I have a good memory. When we first imported a pile of ET2's we had in the shop an ET1. There was a big debate at the time that the ET2 had less bottom end than the ET1. The ET1 has a fixed counterweight. My business partner preferred the counterweight bolted up as per the ET1, but I found that gave a one note bottom end, lacking speed and articulation. I experimented with the counterweight coupling and other ET2 mods quite extensively not only with a variety of TT's including Sota Star Vacuum, Townsend Rock, Roksan, Oracle and Final Audio TT, but also a variety of speakers including Martin Logan CLS, Apogees, Proac EBS, Proac Tablettes, Duntech's, vintage Tannoy Monitor Golds and many others - over the last 30 years. Also have run the ET2 specifically with a wide variety of cartridges including Madrigal Carnegie, various Koetsu's, Van den hul Grashopper, Shinnon Red, Sumiko Talismans/Virtuoso's, Shure V15VMR, Denon 103 Garrott, Benz Reference and many others I've long forgotten. I have also seen enough off centre cantilevers to last a lifetime from the misapplication of both tangential and pivoted arms. |
Dover As you said we will never agree on this. The difference is that I have tried both light and heavy ETs. As far as I can tell, I am the only one who has done that. If so, I am the only person here who can speak with any authority on the subject. People are free to try, it is entirely their choice. Install an alternate cheap cartridge, play a record you don't like, if you are that worried about damage to same. Your scaremongering may have dissuaded people from trying a simple reversible mod, which is a pity since we could have advanced the collective knowledge of this diverse group. And isn't that exactly what these forums are for? |
“para 1 - not obvious to everyone.” Why not, there are only 2 words to understand: ‘modified ET2.’ “Adding lead mass creates higher inertia but does NOT retard motion.” Yes it does, more energy is required to activate the system. You’re banging on about lead mass and inertia as though it is a random activity. Required mass (and its related inertia) will be cartridge specific, so isn’t it simplistic to state or imply that no mass should be added to an ET. |
Thank you Chris, Dover, Richard, and all for the fascinating data, opinions, and food for thought. I continue to enjoy the, admittedly, subtle effects of using a single weak magnet with my ET. I can't claim to understand the physics involved well enough to give a thorough explanation of what happened in my particular case, but I have to concur with Dover about the concerns over added mass. In my case, it was not mass in the spindle, but a case of too much mass at the "headshell" and cartridge itself. A few years ago I managed to destroy the suspension on one of my VDH cartridges by applying too many bits of Blu-tac to a "naked" MC1, and to the top of the headshell in an attempt to dampen a cartridge that sounded overly aggressive in the highs. It worked to smooth out the ragged highs, but within days, experienced a collapsed suspension. The cartridge was properly balanced and setup at the appropriate VTF. ****Does damping not mean - reduce, diminish, dull - to a point that reduces some of “vinyl’s nasties”, caused mostly in this case with the ET2 tonearm – the off center hole - but we want to do this without taking away too much from the music itself ?**** -Chris In the endless debate about wether footers, pads, etc. have a beneficial effect on music playback accuracy, I have always contended that, in absolute terms, it is not possible to overdamp a component's resonances by adding mass. Added mass can only be a good thing; in theory. While it may be possible to tweak the resonances to suit a particular system or listener's tastes, eliminating/controlling resonances can only be a good thing for a component's electrical performance, if not it's role in a given "system" (including the listener's ears) which is functioning in the electrical domain. But, it seems to me that in the case of a tonearm, we are not talking about simple resonances, but how added or removed mass affects the movement and stability-in-motion of the arm/cantilever "system". Sorry for possibly stating the obvious, but it helps me to make better sense of all this. Thanks again for a most interesting discussion. |
Frogman. I enjoyed your post, thankyou. How much blutac did you add to the headshell? By way of comparison I have added a net 0.77gm to the headshell of the ET2. (Lead in, teflon out.) Not a lot of extra weight. On damping... If it is not meant to move, make sure it doesn't. To everyone..I'm sure that you have experienced this. Last night's listening was great. All the planets seemed to align. So what causes this? Clean power? Just the right room temp, humidity? My own state of mind? Off topic, I know, but I am curious to read your views on this. thanks Richard. |
Hi Frogman, Thanks for the feedback. You have highlighted the nub of the issue in your last few sentences - when the arm moves laterally to accommodate eccentric records it becomes very complex. In addition to the bearing tube moving back and forth we have - 1. The arm mass pushing the cantilever back and forth through its pivot point 2. The counterweight, if partially decoupled with a spring, starts to oscillate as the bearing tube moves back and forth. My approach to the problem has 3 elements all of which work together - 1. Lighten the arm to minimize resistance to lateral movement. Remove any soft spongy material - shrink wrap/foam if using the old aluminum arm tube. 2. TOTALLY decouple the counterweight ( no spring, no fixed coupling ) 3. Minimal magnetic damping Counterweight Set Up In my view fixed, coupled counterweight is wrong because it adds inertia, a resistance to any correction for eccentric records. I also think a spring is suboptimal, because although by tuning it we get a lower resistance, and maybe better bottom end on round records, on eccentric records the in and out motion means the counterweight will oscillate and feed back into the bearing tube, affecting its horizontal stability. I would surmise that when you tune the spring, you are probably synchronizing the motion of the counterweight with the arm motion to minimise these conflicting forces. This will vary with the cartridge compliance and how eccentric the record is. With both coupling and spring ( partial coupling ) the arm movement is inhibited – causing cantilever flex that is disconsonant with the music. The key question is - What do we want the counterweight to do on eccentric records ? The answer in my view is nothing. We want it to continue to load the tracking force. We want it to remain absolutely still horizontally whilst the arm moves in and out so it does not inhibit the arm movement. ( we don’t want the tail wagging the dog ). Think of a hinged counterweight, rigid vertically, but free to move so that when the arm moves the counterweight stays still. My solution was to remove the spring action by loosening off the end cap such that the counterweight beam just flopped at a touch; then inserted teflon wedges loosely either side of the spring to provide the tiniest dampening of that I could apply. The combination of the "floppy" counterweight in the horizontal direction and minimal magnetic dampening gave me the best result – very quick bottom end. A bass drum has harmonics and overtones up in to the high frequencies – the highs tell you how a drum is hit – so for me I trade off a little bottom end weight for accurate, clean and extended high frequencies. Funnily enough this approach gives me the quickest and most tuneful bass. How much magnetic damping to apply ? My experience is as little as possible. What I have found is that I set the amount effectively by tuning the bass for optimum speed. Remember that the eccentric arm movement is affecting all frequencies. The dampening will affect all frequencies. My view is that if you use too much magnetic dampening you will stiffen up the bottom end, but at a cost over over dampening the high frequencies. That’s why I was interested in Chris testing the eddy clamp – which I suspect is just too much. I wanted to clarify that for me the use of minimal magnetic damping goes hand in hand with how I set the counterweight up and the low mass/minimal resistance. |
Here is Bruce's opinion on using ET2 manifold shims
Richard, Dover, others ? When Bruce says: “science of resonance in a phonograph tonearm would first involve a measurement to prove something exists.” Curious if magnetic and mass damping, and any of its effects can be measured other than just by listening ? Have you done it? |
Chris - No I dont have the equipment, but Martin Colloms did in a Hifi News review years ago ( 1985, I think ). He measured the resonances before and after the air bearing and compared them to ascertain how the air bearing dealt with such. Typically you would use an accelerometer placed on either the arm or bearing housing to measure these. If my memory serves me well the resonance profile remained in tact, in other words even though the resonance is passing through air and rubber, it went through almost unhindered. By the way - another little tweak for you - I decoupled the rotating arm lift from its bracket using teflon washers/spacers, another small audible improvement. |
RichardKrebs Richard your NZ last night is my yesterday still.... I believe in the one and almighty, and in the things that are out of my control. He giveth and taketh away. Yes I am talking about the local hydro company. This is an audio gear site. I was very aware of the power limitations I had, and their effect on my systems in the big dense city. I feel kind of blessed now that I live in a rural area with an abundance of clean, raw power. Sometimes on a few occasions there is not enough (hot humid july/aug nights). Other nights, more often, there is too much above 120v. When the number on the gauge reads between a certain range I have come to know that good things can happen. It then depends on my own mood. Humidity helps. There is more grain in the music for me when the power reads above 120v. Looking forward to converting my table to battery soon. All Power Conditioners I have tried made the bears sound pleasant but like they were on meds. No thank you for the amps. The OTL's coming have their own line conditioners designed for them. |
Chris Yes when you talk to Dover and I you are conversing with the future. I agree with you. Clean power and I think that we should not underestimate the effect of our own state of mind. I think that every professional reviewer should prefix their review with..., Today I feel..., or over the period of this review this was my general state of mind. BTs comments are interesting. I know the effect of the shims and grub screws. It is definitely positive. As in the drive thread, I believe that there should be nothing soft in the loop between LP around to cartridge. The o'rings are quite soft. My testing, with and without the bearing sleeve clamped seems to support that view. |
Yes when you talk to Dover and I you are conversing with the future. Richard/Dover – have you figured out a way to tell me how the stock markets will open in Toronto or New York ? Small correction to my previous post. humidity is good I have found for vinyl (as we deal with static), but not good for ESL’s especially my Quads which are very sensitive to levels. They like it really dry. So its like being between a rock and a hard place in a way. Still Quad 57 and 63 are designed differently. Some info I got from a respected rebuilder - The 63 panels will be destroyed soon if placed in rooms with high humidity. Not as hardy as the 57’s – now there’s an oxymoron for you. The Acoustats do not seem affected by humidity – are they like Hercules of ESL’s ? Both in their ability to withstand conditions over time and accept wattage without problems. Wondering if this is due to the amount of space between the mylar? Cheers |
The base of the ET2 is mounted with one bolt and has 3 grub screw spikes for proper leveling on any surface or armboard. We have discussed removing the aluminium shim. If your worried about marring your surface, Dover had mentioned filing down the grub screw points. Can the bracket be improved or .......removed...? Another material? It is the part that holds all of the goods. Cheers |
I have been researching possible bearings for a new Arm and I came across the Kuzma web site and the Airline Arm. This appears to be unique in using a porous material rather than multiple drilled holes like the ET. It also has a sliding sleeve instead of the sliding spindle of the ET Wow this is a spectacular looking arm which is definately on my wish list. This brings me to the subject of horizontal effective mass again. I asked them for this figure for the Airline. It is probably not appropriate for me to publish this here, since it was a private conversation and the number is not shown in their specs. But I can say that it is higher than my heavy modified ET2 arm. We went on to talk about potential problems with cantiliver flex. His response was the resonant frequency due to the combination of a typical low compliance cartridge and horizontal effective mass was in the region of 2.5 -3.5 hz.(this has been published by them elsewhere), this is well above the 0.55 or 0.75 hz for 33 or 45 rpm eccentric records. Therefore the cartridge does not "see" this movement. He directed me to a video of the arm and cartridge tracking the lead out grooves with a oscillation amplitude of 12mm. See www.Kuzma.si ,tech support,tech info, Airline video. This Video was posted by them to allay fears of cartridge damage due to high horizontal mass. This arm is amongst the best currently available. It has a large differential between its vert and horizontal effective mass figures and does not appear to be a cartridge killer. I'm sure you will agree that this motion is violent and way beyond what any record eccentricity would produce. He assures me that there is no problem with the cantilever under these extreme circumstances. I want one. |
Richardkrebs I have queries regarding your claims re the Kuzma air bearing tonearm. This appears to be unique in using a porous material rather than multiple drilled holes like the ET.This is not correct. The ET has a captured air bearing with a continuous air gap between bearing spindle and manifold. We went on to talk about potential problems with cantiliver flex. His response was the resonant frequency due to the combination of a typical low compliance cartridge and horizontal effective mass was in the region of 2.5 -3.5 hz.(this has been published by them elsewhere), this is well above the 0.55 or 0.75 hz for 33 or 45 rpm eccentric records. Therefore the cartridge does not "see" this movement. This defies basic physics. Any lateral force on the stylus forces the cantilever to flex laterally, until the resistance of the cantilever to movement meets or exceeds that of the arm, at which point the arm must follow. More mass in the arm = more inertia in the arm = more flex in the cantilever. This Video was posted by them to allay fears of cartridge damage due to high horizontal mass. The video does not show the cantilever. Proof of the above assertions is not demonstrated. As regards the best available, what other arms have you auditioned to draw this conclusion. If you are talking air bearing arms - where have you considered the dynamic stiffness of the air bearing. Although the Kuzma runs 60psi into porous tube versus the ET2 at 19psi into captured air bearing, the psi alone does not determine the dynamic stiffness. Some other factors you need to consider are : The hole sizes The flow of air The surface area of the bearing etc The ET2 also has a wider manifold. If we assume for arguments sake the air bearings are of equal dynamic stiffness, the ET2 will be inherently more stable than the Kuzma. He assures me that there is no problem with the cantilever under these extreme circumstances. This is an inadequate response. To support your contention that adding mass has no deleterious effect, which cartridge designers have you sought an opinion as to loading up the cantilever in the manner you continue to advocate in this thread ? Bruce Thigpen's patents clearly outline the benefits of the decoupled counterweight and lower mass. |
Dover. You need to research the difference between the two air bearing types. The Kuzma is unusual in its choice of bearing construction. So how am I wrong in my statement that the use of porous material appears to be unique? This in no way detracts from the ET2 bearing. I was just showing that other options are out there. At frequencies below resonance the cantilever is free to push the mass of the arm sideways. This does not defy physics, it is physics. In other words the cartridge suspension is stiff enough to accelerate the arm mass sideways. Think of a tension spring with a weight suspended at one end. This combination will have a resonant frequency. If you hold the spring end opposite to the weight and move it up and down at a frequency below resonance the weight will move up and down in sync with your movement. The spring will NOT stretch as a result of this movememt. No, the video does not show the cantilever, that is why I asked him if it was a problem. I have to take his word on this that it is not, and resonance formula back him up. Further this confirms what I see when my arm is tracking eccentric records. I repeat the video is shown specifically to allay fears of problems due to high horizontal mass. |
The Kuzma is unusual in its choice of bearing construction………… the use of porous material appears to be unique? In his review on the Kuzma Airline, Michael Fremer also mentioned that the Airline use porous material in the airbearing, while the older, but similar designed, Rockport 6000 utilized a groove-compensated bearing, which has lateral grooves in the bearing wall. He went on to comment that due to the difference in the bearing design, the much higher air-pressure used in the Airline didn’t necessary mean its bearing was stiffer. It is also interesting to note that the arm on the Walker Proscenium turntable shares a similar design with the ET2, but using a fixed counterweight and much higher pressure at 45psi. I believe Lloyd Walker is well known as a fanatic tweaker, who would not stop to squeeze out the last bit of performance from his turntable. So, why would he not use the decouple counterweight design (if he sees any advantage in it), or is that patented by ET? |
