Eminent Technology ET-2 Tonearm Owners
Where are you? What mods have you done ?
I have been using these ET2's for over 9 years now.
I am still figuring them out and learning from them. They can be modified in so many ways. Bruce Thigpen laid down the GENIUS behind this tonearm over 20 years ago. Some of you have owned them for over 20 years !
Tell us your secrets.
New owners – what questions do you have ?
We may even be able to coax Bruce to post here. :^)
There are so many modifications that can be done.
Dressing of the wire with this arm is critical to get optimum sonics along with proper counterweight setup.
Let me start it off.
Please tell us what you have found to be the best wire for the ET-2 tonearm ? One that is pliable/doesn’t crink or curl. Whats the best way of dressing it so it doesn’t impact the arm. Through the spindle - Over the manifold - Below manifold ? What have you come up with ?
Showing 50 responses by dover
Richardkrebs, With all due respect the sonic signature of the different materials you outline are meaningless unless the rest of the system is described at the time of testing. For example it might well have been that the system was slow and the concrete, whilst sounding hard, may have been showing up coloration elsewhere. I see very little science and no concrete evidence to support your observations. Furthermore, it is well known that the geometry of the original Hadcock 228 was in fact incorrect and if you had built an arm to that geometry then I'm surprised you could not hear the high tracking error and distortion. Specifically the offset angle was incorrect and this was remedied with the release of the 242 in recent years. |
08-21-13: Ct0517Dgarretson is not comparing the ET2 & Kuzma. His post is quite clear - it is a report on the effect of running the Terminator with different horizontal effective masses. At no point in his post is he comparing the ET2 and Kuzma tonearms. |
Hi Richardkrebs 10-03-13: RichardkrebsI imagine it might be a bit challenging producing these parts for a DIY enthusiast. Given you have access to CNC machines and a fully qualified engineer at your workplace who could design something for you, it surprises me given your criticisms of the ET design in this thread. There are companies that can design and fabricate these components for you. Here is a link to a company that could do the engineering design and fabrication... http://www.dovermotion.com Cheers |
09-16-13: Ct0517 1. The "included angle" has nothing to do with VTA. The included angle of 90 degrees is the angle between the 2 45 degree walls of the groove. ( 45+45=90 ). In theory if the cutterhead is set up with an error of say 5 degree in the "included angle" then you would possibly need to adjust azimuth. 2. One of the fundamental problems is that the cutter moves in a fixed plane, whereas the stylus moves in an arc about the cantilever pivot, and therefore all cartridges with a conventional cantilever produce distortion. The notable exceptions are the Decca London Cartridges and the original Ikeda cartridges both of which do not have cantilevers and therefore these are the only cartridges that do not have this distortion built in. I own the Ikeda and have personally set up around 20 Decca's over the years. The speed, lower distortion and lack of phase and time smear with these cartridges is superior to anything else for the reasons outlined in the 1st sentence of this paragraph. 3. Cutterhead angles are a minefield as they varied historically over the years and different cutting lathes were set up with different cutting angles. There was a standardisation of sorts in the 60's but bear in mind the US settled on 15 degrees +-5 degrees and the Europeans settled on 20 degrees +-5 degrees. The actual cutting angle used would also depend on how the engineer sets the equipment up and that is unpredictable. Springback is a common problem when cutting and this will alter depending on the composition and quality of the lacquers used ( they are soft ). Temperature is a big factor and if the lacquers have been stored at room temperature, as opposed to the recommended cool room temperatures, then often engineers would alter the cutting angle to get a clean cut due to the changing properties of the lacquers at different temperatures. A few points to note : Increasing the room temperature by 5 degrees F or approx 3 degrees C will lower the tracking angle by approx 1 degree. Increasing the tracking weight by 0.1g will result in a lowering of the tracking angle by approx 1.5 degree A spherical stylus profile will help to reduce these distortions in points 2 & 3 above. If you add lead mass to the ET2 and remove the decoupled counterweight, as suggested earlier in this thread, then VTA doesn't matter as the increased distortion from a tracking angle error of +-5 degrees is almost certainly significantly less than the distortions introduced by the addition of lead mass and removal of the decoupled counterweight. For ET2 aficionados, with a conventional cartridge that uses a cantilever, the combination of tangential tracking and a spherical stylus would minimise distortions due to VTA issues. I have run the Denon 103 which although not the ultimate in transparency, produced very good timing and coherence. The EMT TSD15 with spherical tip option would be an interesting cartridge to try. |
Ct0517.. Increasing the room temperature by 5 degrees F ( 3 C ) is enough to soften the rubber suspension in the cartridge and drop the VTA by 1 degree. I would assume by the time you have finished a session you will have softened up the suspension and this may explain some of what you hear. Where you live it is quite easy to experiment - start with a cold room and warm it up, or put a lamp over the cartridge so the heat is localised. You will hear quite a difference - as the cartridge reaches optimum temperature the sound opens up and becomes more natural, as you overheat the cartridge the sound will literally go gluggy. What I have experienced is some cartridges mistrack on a seasonal basis (winter vs summer) here in NZ even though the temperature swings are not large, eg the Shelters. The Benz's generally spec out the optimum temperature and humidity ranges in their cartridge packaging. |
10-28-13: Ct0517Economics 101 - from my university days - If one were to put a value on the time spent trawling the net for a second hand arm wand, one would find that it is indeed more economic to simply purchase a new Magnesium wand direct from Eminent Technology. According to my last correspondence with Bruce a few months ago, they were still available, albeit there is no lead filled version for those who ill advisedly continue to attempt to make a Kuzma out of an ET. |
Dave/Frogman - Interesting your comments on going back to the aluminium arm with MM's. With my aluminium arm I removed the heat shrink and internal foam. This yielded a lighter sound, but cleaner, clearer and less smear with both high and low compliance cartridges -Shure V15Vmr/Denon 103/Carnegie/Koetsu Black. I also removed the soft teflon from the headshell and epoxied in a piece of carbon fiber. If you dont mind butchering your arm tube a little all you do is prise open the end, the teflon will pull straight out if you can get a good grip on it with some long nose pliers. Then just cut and insert the carbon fiber with epoxy and clamp the headshell up in a vice. In my view with the low compliance cartridges tweaking the spring counterweight set up is plenty sufficient to get the optimum without having to add mass to the arm tube. I had no tracking problems with low compliance cartirdges in my lightened aluminium armtube. Follow the instructions on counterweight position, ie low mass further out and tuning. When you go to 2 or 3 springs you are increasing the mechanical coupling of the mass of the counterweight and the cartridge sees more horizontal mass. I still prefer decoupling the spring by loosening the end cap and using teflon wedges to dampen the swinging counterweight motion even with low compliance cartridges. Frogman you reported hearing more bass notes when you loosened the end cap off. Any update on this ? |
11-28-13: RichardkrebsThis seemingly innocuous statement requires careful examination as it continues the flawed thinking espoused earlier in this thread. If the goal were to keep the cartridge still, then one would never reach the end of the record. The record groove is not a straight line; it is a spiral with a decreasing radius that requires the cartridge to move to the center of the record as it plays. Furthermore if the record is not perfectly centered, even by 0.01mm, then the cartridge is required to move in and out from the center approximately 660 times for a standard 33rpm record at Industry Standard or 0dB (20 minutes of music). This means that the arm will reverse direction 1320 times within approximately 20 minutes of music. (Is anyone here still of the view that adding lead mass to an ET2 that is reversing direction 1320 times per side of a record is a good idea?) There are two goals which are in conflict with each other - 1. To ensure that the cartridge maintains a constant relationship with the groove the cartridge will be constantly moving to align itself with the groove. 2. To ensure that the recovery of as much information as possible which would suggest keeping the cartridge as still as possible. On the one hand we want the cartridge to maintain a position that at all times it aligns the cantilever pivot point to the center of the groove. In order to achieve this, the cartridge must be able to move laterally freely and unimpeded whilst playing. Any addition of mass or "apparent" mass by adding lead, stiffening the counterweight spring or adding fluid damping will increase the inertia and will reduce the ability of the cartridge to maintain the correct alignment with the groove instantaneously. The increased inertia will introduce lag to the response time of the cartridge tracing the groove and increase cantilever flex and distortion. Some may not hear this effect, but it is there and is readily apparent in a resolving system with good fundamental timing. If you want to hear the concept proposed by Richardkrebs that the cartridge should remain still here is a link to the Transcriptors Transcriber. This turntable has a fixed arm which tracks linearly by holding the cartridge still while moving the platter underneath. http://www.youtube.com/watch?v=IQ_r0Vk9Ct8 Have a listen. This set up has more WOW (as in pitch variation) than a wind up gramophone on its last legs. This is the sound you will end up with if you add enough lead, fluid damping and/or remove the counterweight spring as has been suggested. As Frogman has confirmed with his experiments - when he decouples the spring and lowers the apparent mass, he gets a quicker and more tuneful bass response. Less weighty but better timing. The use of fluid damping may ameliorate a resonance issue with some particular arm/cartridge combinations, but it comes at the cost of compromising the ability of the cartridge to follow the groove by increasing the resistance to tangential movement - it slugs the sound. A better solution is to ensure that arm/cartridge resonances are minimised such that fluid damping is not required. I would also point out, since someone mentioned the Townsend Rock, I sold several of these when I was an importer/retailer in the 80’s. The use of fluid damping in this TT killed the sound so much, that cartridge differences were nullified. For example, one customer could not hear the difference between a Madrigal Carnegie and a Koetsu Red. I also ran an ET2 on the Townsend Rock for a while, with a Shure V15Vmr and can assure you the sound was much improved in speed, timing, articulation and transparency without fluid damping. Having dealt with Max Townshend directly, I should point out that Max’s reference cartridge, at the time he designed the Rock and the fluid damping mechanism, was the London Decca Gold cartridge, a poorly constructed cartridge with no cantilever and notorious for it’s poor tracking ability. It was in this context that he came up with the trough design. |
Dlcockrum Yes I agree that damping may be required in some cases, and that running the paddle at the surface would be best. That is how I set the paddle with the Townsend TT. However, the application of damping should be a last resort. In my experience many folk have applied damping to cure a "resonance" that has resulted from poor set up eg VTA, tracking force, etc and could have been removed by careful set up and in the case of the ET tuning.. I have used electromagnetic damping on my ET2 as discussed earlier in this thread. The damping is created by eddy currents which are only generated when the arm moves relative to the magnet. I have run the ET2 for 25 years and found that the higher compliance cartirdges such as my Shure V15vmr benefitted most from electromagnetic damping. With lower compliance cartridges such as Madrigal Carnegie, Koetsu, Denon 103 and Benz Micro fluid damping slugs the sound in my experience. Bear in mind that I run a decoupled counterweight assembly rather than a sprung counterweight - this has the advantage of keeping the ET2 horizontal mass as low as possible. As your friend Frogman has found, running the counterweight decoupled has produced quicker, more transparent bottom end in his system.The set up procedure he described above is the same as I have used. A little history here - If you read Bruces manual and patents he starts with a low mass arm, and then brings the effective horizontal mass up very gently by providing variable spring rates on the decoupled counterweight. This is formulated to keep the differential resonances between horizontal and vertical in sync with the compliance of the cartridge and the Q of the system. The Q is related to the dampening of the oscillation - the use of magnetic dampening will shift this slightly. Very small adjustments can give quite dramatic changes to the sound, especially in speed, transparency and articulation. Krebs approach has been to load up his ET2 with 30+ grams of lead. He has also removed the decoupling spring from the I beam. Effectively he has added some 60g to the horizontal mass of the ET2. It is no wonder that he has changed his mind after 20 years and is now using fluid damping. Mass increases inertia and has no dampening properties. The high horizontal mass he is running has increased the side forces on the cantilever by over 300% when the arm moves back and forth increasing cantilever flex and distortion. Quote from Thigpen If the weight is coupled the system resonant frequency would be extremely low, a resonant frequency at 3Hz with a significant rise in response (6-12dB) results, which would affect tracking slightly because of the asymmetric position of the cantilever, we opt for splitting the horizontal resonance frequency into two points and lowering the "Q" which improves tracking. I note that DGarretson has been experimenting with his Terminator tonearm. The Terminator in standard form has a much higher horizontal effective mass than the ET. DGarretson has reduced the horizontal mass quite substantially by reproducing some of the parts and yielded significant improvements. |
Richardkrebs and readers of this thread, My apologies to all for not having responded earlier, neurosurgery has precedence. Richardkrebs has been advocating changes to the ET2 that include adding mass and removing the patented decoupled counterweight. These suggested changes take the ET2 outside of its designed operating parameters. In February Richardkrebs promulgated a theory that adding 30g+ of lead to the ET2. He also advocated removing the decoupled counterweight and changing it to a fixed counterweight assembly. He claimed that this was a big improvement on the performance of the ET2 with low compliance cartridges. Richardkrebs claimed to be the only authority on adding lead mass to the ET2. Richardkrebs claimed that adding lead mass and removing the decoupling gave a flat frequency response in his listening room. To recap… Richardkrebs on adding mass: 02-15-13: RichardkrebsNOTE : This post demonstrates a lack of understanding. Removing the decoupling of the counterweight also increases that horizontal mass that the cartridge sees and therefore the total increase in mass would exceed the 30g claimed. 03-04-13: RichardkrebsRichardkrebs now claims that he has NOT added 30g off mass after all, and that his arm is close to the standard weight. 12-09-13: RichardkrebsIt would appear that the sonic benefits Richardkrebs proclaimed, accompanied by much mathematical conjecture over the past 10 months, are not attributable to adding lead mass as Richardkrebs claimed, and that the benefits of adding lead mass, if any, exist only in his head, in theory, as they have not in fact been trialed. With regard to the Morch analogy, this is speculation and assumptive on his part by his own admission. Rotational inertia is quite different to linear inertia and I’m not sure how one could possibly use a pivoted arm model to explain the forces involved in a linear tracking tonearm. For what its worth, I too have experimented with lead mass. I made a lead slug, 25mm long and fitting the ID of the ET2 as per Richardkrebs suggestion. Excluding the string and glue, the mass varied from 26gm to 34gm depending on how tight the slug was wound. Richardkrebs now claims that his arm is only 7gm heavier than standard. I cannot replicate his new claim of a mass differential of 7g with the size of lead slug he advocated. 05-15-13: RichardkrebsClearly Richardkrebs calculations were incorrect since he has not added anywhere near the amount of lead mass that he believed he had. Richardkrebs on removing the patented decoupling system on the counterweight: 03-25-13: RichardkrebsFrom Richardkrebs posts it would appear that he removed the decoupling spring, but did not understand the implications. Bruce’s testing on the Eminent Technology website demonstrates a rise in low frequency resonances if the decoupling is removed. Despite this Richardkrebs clearly states that he disagrees with Bruces ET2 design goals of maintaining a low horizontal mass and using a bifurcated spring to split the resonant frequencies to minimize resonant peaks in the low frequencies. Here is an extract from Bruce’s patent on the ET2. The damped leaf spring 39 is oriented so as to allow horizontal motion but prevent vertical motion, i.e., decoupling, of the counterweight arm 37 and counterweights 38. Decoupling is necessary to reduce the effective mass seen by the cartridge 36 in the horizontal plane which allows the use of high compliance cartridges 36. The stiffness of the damped leaf spring 39 can be increased to allow higher horizontal mass to match low compliance cartridges 36. The damper material for the leaf spring 39 can be an elastomer. Damping provides the desirable quality of little or no rise in amplitude at resonance horizontally. Also separate horizontal and vertical resonant frequencies can be achieved by decoupling only in one plane of motion.Removal of the spring decoupling will increase the resonant peak – Bruce measures 6db plus. If you go though the Shure white papers on low frequency resonance, they confirm this – they measure resonant peaks of 6-20db that increase motion 2 to 10 times. From the Shure white papers - what happens at the resonance frequency? One important characteristic of resonance is that motions are magnified considerably, in this case, typically from 2 to 10 times. Clearly the removal of the decoupling has negative impacts on both tracking and increased distortion in amplifiers and speakers from the infrasonic distortion generated by the cartridge/arm resonance. Use of Fluid Damping Again there are more contradictions in Richardkrebs posts - 02-18-13: Richardkrebs Richardkrebs on Stiffness of the Air Bearing 04-21-13: Richardkrebs This is a very good example of conflating physics and mathematics. Frogman, Ct0517, DGarretson, Slaw, myself and many others hear significant differences in performance when adjusting the air pressure on the ET2. Having studied structural, mechanical and materials engineering and physics at university, my view is that altering the air pressure will alter the performance of the arm – either altering the rigidity and/or altering the resonances within the air bearing. I quote Ralph Karsten of Atmasphere producer of valve amplifiers, and who has considerable experience producing and cutting records. 01-17-12: AtmasphereWhen I questioned the stiffness of the bearing in relation to the added mass Richardkrebs advocates, he responded - 03-19-13: RichardkrebsAnd yet now he says he is running 18psi. 11-05-13: RichardkrebsIn summary then, despite having owned the ET2 for over 25 years, it would appear that since February this year - Richardkrebs has advocated adding lots of lead mass, and claimed many benefits, but now claims that his ET2 arm mass is close to standard. Richardkrebs has proclaimed that Bruce’s decoupled counterweight is not a good idea, and stated in April that putting the arm back to standard will degrade the sound. Now, in December, Richardkrebs is not sure and is going to retrial the decoupled counterweight. For 25 years, Richardkrebs eschewed fluid damping, but now believes it is of benefit. Richardkrebs claims the ET2 air bearing is rigid at audio frequencies and 12psi was the optimum air pressure for his set up, having carefully calculated Q. Now he has moved up to 18psi without an explanation. These contradictions outlined above, demonstrate a lack of scientific rigour in testing and set up. It is not an approach that one would recommend. It would appear that Richardkrebs has much work to do to determine the optimum set up for his ET2. My suggestion would be for him to put his arm back to standard and set it up as per Bruce Thigpens’ ET2 manual, assuming he now has some understanding of how it works. For your reference here are links to the Manuals and Patent http://www.patexia.com/us-patents/04628500 http://www.eminent-tech.com/main.html Seasons greetings to all.. Dover |
01-28-14: RichardkrebsYet again you have misquoted me. I said that your arm is 300% heavier than standard based on the information you provided. You claimed that you had added 30g of lead mass to the 25g spindle and that you had converted the decoupled counterweight (30g+) to a fixed counterweight. 01-28-14: RichardkrebsSo now you have contradicted yourself and agree that the decoupling reduces the effective mass. This means that based on your assertion that you added 30g of lead to your arm and removed the decoupling then you have indeed increased the effective mass by 300% or thereabouts. 01-28-14: RichardkrebsYou now concede that fixing the counterweight will generate bloated bass as documented on Bruce Thigpens website. Since you also have acknowledged that fixing the counterweight increases the effective mass above FR, then fixing the counterweight will have deleterious effects on bass, midrange, treble - where the music is. 01-28-14: RichardkrebsThis is a terrible solution. You are proposing to run the arm at air pressures below the air bearings design parameters and/or increase resistance to lateral motion by putting tension on the lead out wires. Others on this thread including Frogman, Slaw, Ct0517 have reported significant improvements in sound quality by increasing the operating pressure and reducing any drag added by the lead out wires. You are proposing the opposite. Most systems with a reasonable level of resolution are capable of demonstrating the effects of increasing horizontal effective mass. 01-28-14: RichardkrebsYou have misunderstood BT's testing protocols and conclusions. BT says "the ET2 with a damping trough will exhibit almost perfect low frequency phase response". He is referring to a standard ET2 that has not had lead mass added and has not had the decoupling removed. It should be noted that the damping paddle is designed to provide dampening in the vertical plane, but less so in the horizontal plane. This is why it is wide and thin. The fluid damping is designed to address record groove irregularities which cause scrubbing and oscillation as the stylus tracks. This is documented on BT's website and is also documented in the Shure white papers on trackability. In summary the changes you have made to your ET2 including adding mass and removing the decoupling are contrary to the fundamental design principles and advantages of the ET2 and should be discarded. |
Richardkrebs I did not say that the mass of your arm is “300% heavier at these frequencies”. I have said that your horizontal effective mass is 300% heavier than standard. Your arm is 300% heavier than standard. You added 30g of lead and removing the decoupled counterweight increases effective horizontal mass above FR. These 2 changes have increased the horizontal effective mass of your arm by some 300%. Since the removal of the decoupling increases the horizontal effective mass above FR - FR for most systems would be below 10hz, then we can say that the increase in horizontal effective mass of some 300% will affect all reproduction above 10hz. As far as below FR goes, your argument is the cantilever does not flex below FR. I dont agree with this as confirmed by Bruce Thigpen in his correspondence. I have seen cantilevers flex on eccentric records and will post a video at some stage. However the cantilever and suspension still see this mass. As far as the damping paddle goes, Bruce Thigpen provides this option for the standard ET2. Thigpen does not sell an ET2 with a fixed counterweight and 30g of added lead. Your claims that one can achieve a flat response in the bass with a fixed counterweight and 30g of added lead mass are not supported by any testing. |
For those who desire the best and the perfect match for the ET2, there is a rare opportunity to purchase a Kondo Ginga TT for sale here on audiogon. The Kondo Ginga is a derivative of my Final Audio Parthenon which is now unobtainable. In addition the Final Audio Parthenon has adjustable torque control of the motor and the SPZ base. I would expect however that the Kondo Ginga would be very close to the Final Audio Parthenon in offering unparallelled performance and resolution. Having used the ET2 for a number of years with my Final Audio Parthenon, this combination is unsurpassed. http://app.audiogon.com/listings/turntables-turntable-ginga-kondo-ginga-2014-02-05-analog-italy-irwin-oh Disclaimer : I have no relationship with the vendor who is unknown to me. |
Richardkrebs, From your explanation I conclude that you are putting an argument forward that the more components that are in the process that are inherently unstable, then based on mathematical probability you are suggesting that this may increase the efficacy of the air flow. You might like to research chaos theory. Another solution may be to use a rigid tube, but put lots of pins through the tube - if you do the calculations and modelling, it would be possible to have a totally chaotic air flow rather than patterns of eddies, which may be preferable. Last year you said that the ET2 air bearing is rigid. I assume since you now claim that you can hear a difference with different pumps and air supply configurations, that you would now concede that the air bearing is not rigid. I have studied engineering including fluid dynamics and the way I view the ET2 is that the air bearing is not rigid, and what you are doing with all this experimenting on air pumps and tubing is in fact minimising instability within the bearing. That is why you hear a difference. I note that you are now running 17psi whereas previously you said that 12psi was optimum ( and that your arm was perfectly rigid ). Can you explain why you have changed your view. Have you removed the lead and put your arm back to standard with the decoupled counterweight put back in now ? |
06-04-14: RichardkrebsRichardkrebs, your interpretation of Bruces email is interesting. Could you explain what you think happens when there are supply pressure irregularities. Conventional air bearing theory is that the dynamic stiffness of the bearing will be affected by the air pressure and the surface area of the bearing and other factors. Are you suggesting that the large diameter bearing tube upgrade and high pressure manifolds have no benefit and that users would be better off attending to supply pressure irregularities ? This would be a game changer for most participants on the thread if it were true. Are you using the 2.5 manifold and bearing tube or are you using the high pressure manifold on an ET2 ?? or are you using the original manifold on an ET2 ?? By the way, I agree with Bruce's observations - traditional tonearms with gimbal bearings are prone to chatter and noise, and the offset tracking angle introduces a raft of conflicting forces on both the cantilever and bearings. Notwithstanding that a unipivot is another story.. |
I also happen to believe based on my compressors versus current setup from years ago, that there are advantages in a constant air psi being delivered by a quality pump versus a cycling off and on compressor which is like letting air out of a balloon slowly.I tend to agree, would you want a phono stage with a constantly changing input impedance. I wondered if anyone here has investigated the use of variable speed/variable capacity rotary air pumps to provide a balanced load and eliminate the pulsed air supply endemic in piston type pumps as used in most of the compressors mentioned in this thread ? |
Ct0517, As you know the ET2 is a very tweakable arm. I run slightly higher torque settings on the 4 arc bolts and for this reason I loosen them slightly before adjusting VTA. Your analogy of car wheels is rather odd. In over 35 years of running the ET2 the arc block is still original and in pristine condition. I did have some customers who managed to break and grind down arc blocks by over tightening and trying to adjust VTA whilst overtightened and indeed one customer who managed to break 3 cartridges mounted on their ET2 back in the day, despite adding copious amounts of mass... |
Merry Xmas to all. Richard - congrats on the new ET2. Are you going to mass this year ? Ct0517 - when I do VTA adjustments I always loosen the 4 bolts slightly to release pressure on the arc block, and then retorque. Indeed if you loosen the bolts too much alignment goes out, but you can loosen them slightly whilst arm is mounted if you are careful. By the way in your original post you suggest using the short end of the allen key - in fact using the long end in the cap screw, and turning the short end to turn will put less torque on the bolt. |
Bigalt - In your methodology for levelling the arm the stylus has friction or resistance imparted even by the smooth record. A better way to check the level of the bearing tube (and the efficacy of the lead out wires ) is to add enough mass or move the counterweight to zero the tracking force. That way you can check that the arm is not running away in one direction, and if you tap gently you can double check the resulting movement is equal in both directions. Or buy an accurate digital level, you don't need an audiophile one ( usually overpriced ) buy an engineers digital level from an engineering supplier. |
Frogman - You have alluded to an attribute of the ET2 that has not really been recognised in this thread. In my view the ET2, due to the lack of offset angle tracking error and variable side forces, has better timing than pivoted arms, particularly with cartridges with conventional cantilevers. The proviso here is that the decoupled counterweight has been tuned to ensure that resonances are not interfering with the "timing". The suggestion to remove the decoupled counterweight by richardkrebs earlier in this thread will impair timing and rhythm - I have tested this myself - it is easy to hear. Correct reproduction of fundamentals and harmonics is a prime requisite for accurate music reproduction, and that includes rhythm and timing. Of course eccentric records cause timing problems with a conventional cantilever with any arm. Contrary to some views on this thread, the ET2 is the easiest arm in the world to set up correctly. It is one of the few arms in the world that provides for levelling in all directions. The lack of offset angle, tracking error and the elimination of anti skate adjustment ( which can never be perfect ) is a big advantage for the ET2. Just look at the number of posts and misunderstanding of anti skate. Azimuth adjustment is missing on many arms. The ET2 manual is sufficient to correctly set up this arm. When I bought my first ET2 30 years ago - I read the manual, installed the arm, reread bits of the manual to check that I'd completed the install correctly - all completed in half a day. The various mods - rewiring, electromagnetic damping, trialling fixed vs decoupled counterweight, trialling running 0.5mm overhang ad infinitum were all completed within months of ownership. It does not take rocket science to set this arm up, simply read the manual and pay careful attention to detail. The explanations of tuning this arm and the supporting test data on Bruce's ET2 Website are one of the best in the business. Here is a quote from Thom Mackris of Galibier Turntables - 04-03-10: Thom_mackris The most valuable discussions in this thread for me have been the discussions on air supply and seeing how others have set up their air supplies and pressures. |
Frogman - One interesting experience I had years ago was when a friend played a Phillips reissue of a Mercury Living Presence recording that I had. I could not believe it was the same recording, the reissue being very slow and ponderous. After investigation the only difference was that the tonal balance had been altered in the reissue. In terms of correct tonal balance I only use MIT Oracle cabling in my system - the gains in accurate fundamentals and harmonics over other cables ( assuming you have a decent system to start with ) are evident to my ears. Here is a very interesting video on the subject - https://www.youtube.com/watch?v=bgK87tmRVeY |
Shubert - I had an Audiomods tonearm with the VTA adjuster on a Verdier briefly a while ago and was quite impressed albeit with a Moving Magnet cartridge. Very easy to set up and adjust, same mounting as a Rega/Origin Live and reasonably priced. When I had an hiatus from the ET2 due to springy wooden floors and the difficulty of wall mounting a 125kg turntable I decided to go to a unipivot, the rationale being that the unipivot bearing has much lower friction than conventional gimbal arms and would be the next best option. I had had unipivots before and they have good pace and timing in my view compared to gimbal bearing arms. Purchased a Naim Aro and can happily live with that as well as the ET2. Funnily enough Martin Colloms used the Aro on his Linn for the same reason - unipivots are less susceptible footfalls on sprung floors. |
Frogman - that was one point I was going to mention that has not been covered, the tightening of the 4 bolts on the manifold. I tried one bolt tighter than the rest to get a single point ground effect, but ultimately came to the same conclusion as you, evenly and not too tight. Re the cabling, my ultimate set up had the armwire running straight from the wand to a teflon block on the side of the tt plinth midway along the arm travel, ie centered. But I also turned my preamp sideways and backed it up to the deck so I only needed 6" of cable from tt to pre. I simply soldered the arm wire straight into the phono cable. The whole loom was probably not much more than 14". For some customers I would install phono inputs on the side of the preamp, if the phono was situated on the left, so they could put the preamp next to the tt and run super short looms. In my own instance 6" of raw MIT cable beats 1m of MIT Oracle ( and probably any other phono cable out there ) easily in this application. The best wire I found was a silk ofc litz, preferred to stock, Vdh silver & cardas. |
06-25-13: RichardkrebsRichardkrebs The fact that they are advertised as having your US$800 upgrade says otherwise. I quote from the published advertisements here in New zealand - The Technics SP 10 MK II has had the Richard Krebs US $800 upgrade.I was advised that they had your upgrade and at no time was the word mule or prototype mentioned. Your explanation conflicts with both the advertising and the descriptions given to me by the retailers. Your post of 06-24-13 accused me of making untrue statements. You owe me an apology. |
Chris/Richard As per my earlier post, both an oil trough and a magnet impose a resistance to lateral movement as seen by the cantilever. They behave much like weight in the lateral plane. I have simply used weight alone. This is incorrect. This is like comparing apples, oranges and pears. Magnetic dampening will vary with the speed of horizontal motion whereas the added mass approach is simply increasing static inertia considerably. The resultant behavior from an additional horizontal force will be quite different. Same for fluid dampening. In terms of sound - with magnetic dampening I have gotten increased cartridge output, which indicates that the cartridge is losing less energy due to micro vibrations being damped. By contrast with all fluid dampening I hear a loss of speed, focus and detail. Dynavector also concur with this view in their discussion of their tonearm design. Despite the high horizontal mass they use eddy current dampening to reduce micro vibrations. In my view the ET2 is the best arm I've used. I changed to a Naim Aro due to problems with a sprung floor and growing tired of pumps, tanks and airhoses running through the house. The ET2 is out on loan, but at some stage it will come back. In engineering terms a unipivot is the most rigid bearing you can get. I chose the Aro because compared to the Graham of the day it had no arm tube dampening, the Graham arm tube was full of crap, and the bearing was the correct way up for energy dissipation to ground ( the Graham had what I call an upside down bearing, point up ). The sound of the Naim Aro is quick, lucid through the mids, excellent soundstage and very musical. The downside is that I believe it has a very narrow operating window in terms of cartridge compliance and mass. The Dynavector Nova 13D sounds excellent as does a Denon 103D. The Koetsu Black sounds awful, unstable in the bottom end. I recently purchased an FR64S to try with my Ikeda Kiwame - this arm is one of the best pivoted arms I have used and due to the detachable headshell I am currently running this so that I can play around with all my cartirdges - Ikeda Kiwame, Dynavector Nova 13D ( freshly rebuilt from the ground up by Dynavector Japan ), Koetsu Black and Denon 103D. No pivoted arm in my experience can match the transparency and presentation of the soundstage as well as the ET2 though. Furthermore as you will be aware, there is plenty of bottom end depth and speed if set up properly, despite reports to the contrary. |
Pegasus You don't get steel more elastic than with a perfectly pointed unipivot interface. Then think "it" as an elongated point and you see something like a short subminiature "string" at the end of the point - quite elastic, like a very small piece of microscopic harpsichord string. "Flatter" points like balls have much less of this, and make stiffer bearingsThanks for feedback - regards the above, this is one of the reasons I chose the Naim Aro as a second arm - it uses a radiused tip in a larger radius cup for the unipivot. |
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. |
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. |
Comparison of lateral forces on Kuzma/Terminator/ET2/ET2krebs For those who are interested in understanding the side forces on the cantilever : Force = mass x Acceleration, where acceleration = mass/(velocity squared) If the record is 12mm out of true, the arm travels 24mm in and out with each revolution, which takes 1.8 seconds. On an eccentric record the acceleration will be the same for each arm – 0.0024metres / (1.8 sec x 1.8sec) = 0.00074 metres per second squared The horizontal effective masses of the 3 arms mentioned in this thread are: Kuzma has been quoted as 100g Terminator 80g ET2 25g The force on the cantilever is as follows: Kuzma = 0.1kg x 0.00074m/s2 = 0.000074 Newtons Terminator = 0.08kg x 0.00074 m/s2 = 0.000059 Newtons ET2 = 0.025kg x 0.00074 m/s2 = 0.000018 Newtons Summarising then you can see that the increased mass of the Terminator and Kuzma arms increase the lateral forces on the cantilever by 300-400% over the ET2. Now Krebs has modified his ET2 by adding 30gm of lead to the spindle. This adds 30g to the effective mass of the ET2. Krebs also couples the counterweight ( no spring ) which adds another 30g to the horizontal effective mass. So Krebs has increased the horizontal mass of the original ET2 from 0.025kg to 0.085kg. The Krebs modifications have increased the lateral forces on the cantilever by over 300%. Furthermore he employs no dampening to control this mass and runs his ET2 at a lower pressure of only 12psi. The arm moves in and out every 1.8 seconds. This equates to a frequency of 100/1.8 = 55hz The resonant frequency of the unmodified ET2 is roughly 3.5 – 5hz. Krebs argument is and I quote: Below this resonant frequency the cartridge is able to move the arms weight, start it and stop it, without cantilever deflection. He is wrong. This statement defies basic physics. Below 0.55hz the cantilever WILL deflect on an eccentric record. I assume he has misunderstood the explanation given to him by Frank Kuzma, and seems unable to comprehend this. |
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. |
Richardkrebs Referring to your last post 03-12-13: responding to Dover. At frequencies below resonance the cantilever is free to push the mass of the arm sideways. This does not defy physics, it is physics.Correct In other words the cartridge suspension is stiff enough to accelerate the arm mass sideways. .That is an assumption that will depend on the compliance of the cartridge. If the compliance is low enough then possibly, but before the acceleration commences the cantilever will flex. You seem to be unaware that cantilevers are mounted in a rubber elastomer that is not rigid. 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. .A curious analogy, yet again, you compare apples and oranges. Your analogy compares 1. Holding the end of a spring with a fixed weight on the other end to 2. The stylus point sitting in a groove, not held, at the end of a cantilevered beam, at the other end of which is a rubber suspension ( not a spring ), and the other side of the suspension has a mass loading that is constrained at 90 degrees by the rigid air bearing some 6 inches away. Your analogy is a triumph of the imagination to consider these two scenarios in the same manner. Your discourse on resonant frequency is irrelevant. Quite frankly I cant be bothered doing the maths, but I defy anyone to show me a cantilever that does not flex when playing an eccentric record. This does indeed defy physics unless you have a cantilever that has zero compliance. No, the video does not show the cantilever, that is why I asked him if it was a problem.If you agree the video does not show the cantilever then why do you repeat the following statement that is misleading? I repeat the video is shown specifically to allay fears of problems due to high horizontal mass. . I assume from your lack of response that you have not sought any advice on this matter from any cartridge designers. I would have thought this was the first port of call for a thorough and complete understanding of the problems of navigating eccentric records. |
Richardkrebs OK now I understand where you are going wrong in your thinking. Shown here is a link to the Math on driven harmonic oscillators, a mathematical representation of an arm/ cartridge assembly. The arm/cartridge/record interface has 2 fulcrum points - The stylus point around which the cantilever pivots. The cantilever suspension point, about which the cantilever also pivots, but which is partially constrained by the rubber suspension damping. The forces involved are double ended - you have the groove applying a force to one end of the cantilever via the stylus. The other end of the cantilever has an restorative forces being applied from the arm motion. The 2 forces are not in sync because there is a suspension joint between the cantilever and the arm. Think of 2 people holding a pipe and each one trying to move it sideways out of sync with the other. That's what the cantilever experiences. The model you are working with is irrelevant. It is too simplistic. If you had studied mechanical engineering you would understand this better. if we take say 5 hz as the resonant frequency, we see that it will not be until we reach say 30hz before we have complete conversion into an output voltage. I dont think that this is desirable. This is the classic mistake made by an untrained ear. Let's add mass, lower the resonant frequency and we get more bottom end. Dont worry about the increase in distortion through the upperbass, midrange and top end from the cantilever being forced to deflect further. Richard, you have not answered the question posed in my earlier post.. Bruce Thigpen has confirmed that Richardkrebs assertion that ‘the cartridge is able to move the arms weight, start it and stop it, without cantilever deflection’ is wrong. The question I am still waiting for a response is: Does the cantilever deflect below resonance ? Just give me a straight answer - Yes or No |
Richardkrebs With regard to cantilever deflection on eccentric records, it is clear you are confused. Let me explain: Your original statements on this matter were and I quote 03-12-13: Richardkrebs Below this resonant frequency the cartridge is able to move the arms weight, start it and stop it, without cantilever deflection. I do not need to talk to cartridge manufacturers to confirm this. Do the math. 03-13-13: Richardkrebs What I have constantly said is that this force will not be enough to deflect the cantilever while tracing an eccentric record, provided the resonant frequency of the arm / cartridge system is above 0.55 hz for a 33 rpm and 0.75 hz for a 45 rpm record.[/quote] Now however your position is, and I quote from your post of 03-16-13: I see no movement with my cart tracking eccentric records and the math predicts none. However in absolute terms no one could say that there is zero deflection. Richard, you have made two conflicting statements in two consecutive sentences in your latest post of 03-16-13. Your first sentence states the maths predicts no cantilever deflection. Your next sentence contradicts that sentence and all your previous assertions for the past week or two and states that no one could say there is no deflection. Should readers of this thread take it that you now agree that Bruce Thigpen and I are correct and there is cantilever deflection below the resonant frequency. You were incorrect when you stated "Below this resonant frequency the cartridge is able to move the arms weight, start it and stop it, without cantilever deflection". |
Richardkrebs/John47 Quote from ET2 Manual – Bruce Thigpen P29 This is the exact opposite of what Richardkrebs continues to advocate. Richardkrebs is advocating increasing the horizontal inertia for low compliance cartridges – the opposite of what Thigpen recommends. Re the comments on the Kuzma There is a lack of comprehension of what is claimed with the Kuzma. Frank Kuzma is quoted as follows Horizontal disturbances of an eccentrically spinning record occur only at 0.55Hz or 0.75Hz (33rpm or 45rpm). This is well out of the Air Line tonearm's resonance in the horizontal plane, which is between 2 and 5Hz and does not cause problems tracking virtually all LPs.That is all he is saying. Kuzma does NOT say the cartridge does not see this resonance, it simply means that it does not cause problems tracking. This is because if the resonance of 0.55hz were within the tonearm resonance range the two resonances could at worst sum and “double up” which could cause tracking problems. I quote Bruce Thigpen the cartridge will "see" .55Hz mounted in any tonearm, more so in one with higher horizontal inertia Note that Thigpen says that the 0.55hz is seen “more so” with higher horizontal inertia. I would suggest this is one of the contributing reasons for Thigpen recommending a lower horizontal mass for low compliance cartridges. You continue to ignore Bruce Thigpens' recommendations based on the laws of physics and his extensive testing, because it would appear you do not grasp the physics and engineering principles involved. Unless you understand those principles then you are unable to understand what underpins Thigpens' and Kuzmas' comments and designs, and are speculating at best. |
Richardkrebs Astounding! After 25 years of tinkering with your ET2 tone arm, you now reveal in your recent posts that you have only just worked out how the arm works. Only now have you realized that the sprung I beam has a resonance and the tuning of the I beam and the number and position of lead weights used is critical to optimizing the performance of the ET2. This is clearly explained in the manual and was discussed at earlier on this thread.. Let me quote your recent posts: 03-19-13: Richardkrebs For the last 5 weeks I have been saying that you do not understand how this arm works. At the same time you have been promoting your modifications that include adding significant amounts of lead mass and removing the decoupling of the I beam which, I keep repeating, takes this arm out of its designed operating parameters. Your latest revelations make it clear that you have not understood the set up procedures described in the ET2 manual, nor do you understand their purpose and what principles they are based on. For this reason I would continue to caution readers that your advice on adding lead mass, M10 bolts and coupling the counterweight to the ET2 should be disregarded. |
Frogman, Thanks for the positive feedback. With regard to the loosened I beam this is where I got to: When I first imported the ET2 the spring was prone to coming off. If I recall correctly there used to be a little piece of dampening stuck to the spring. At that time if I recall correctly Bruce didn't have multiple springs, but offered springs with the dampening stuck to 1 side only or 2 sides. Basically I found the decoupled methodology I used by trial and error. I knew rigid coupling didn't work, because somebody told me it was better, I tried it and it was awful. At this point in time I was importing audio and had a shop full of high end TT's. We had Sota/ET2's combo's in three listening rooms with different gear, along with Oracles, Linn's, Pink Triangle's, Roksan's, Well Tempered's etc In the home system at that time I had the Denon 103 Garrott/ET2/Sota Vacuum - I played around with the looseness of the spring and noticed how changeable the sound was. So I went to 2 extremes – completely rigid, no good, then completely loose, way way better but not perfect. Then I just experimented from there,, started with a loose I beam, packed the spring either side with tiny lead shims to dampen the swing motion - results so so, then tried teflon shims - much better. The teflon shims either side of the spring in conjunction with the loosened end cap bolt gave a very smooth damped motion with the beam, so I stayed with these and then just slowly dialled the pressure up by slowly doing the end bolt up – listening as I went. The bass timing improved but at a point it lost timing, so I backed off slightly and hey presto. At the optimum bass speed/timing the I beam could move freely and very smoothly. A repeat of the procedure with other cartridges seemed to work consistently. In hindsight it looks like my treatment of the I beam is similar to Bruces and in keeping with the design parameters. My decoupling methodology dampens the I beam movement and most importantly leaves the frequency of the I beam motion very low below the horizontal frequency as outlined in the manual as one of the key design principles. In case there is any confusion I dont advocate reducing the arm mass substantially. I did remove the heatshrink and sponge foam from the arm wand because in my view soft dampening stores energy and releases it out of time with the music. |
Richardkrebs Further to the above, you conceded that after 25 years of owning and modifying your ET2, you did not understand how the I beam decoupling system worked until recently: 03-19-13: RichardkrebsThat means you added your lead mass and removed the decoupling of the the I beam without any understanding of how they were designed to work by your own admission. Clearly you have never heard your ET2 set up correctly as per the manual because you never understood how to tune the I beam and counterweights. This means that your comments on the merits or otherwise of your modifications are irrelevant to this discussion as you have never heard a standard arm set up correctly. It is a great pity you never heard my Sota/ET2/Denon set up correctly all those years ago as I believe you would have a different view today. |
Spock15 I currently own an ET2, Naim Aro & Hadcock unipivot and have just sold off my Bluenote Borromeo ( Titanium tubed unipivot ). I hear a crisper articulation of the leading edge with all three unipivots. It's not large. The Aro is better in this regard than the Bluenote & Hadcock. I do agree with you that effective mass, both horizontal and vertical contribute to the "squarewave". With regard to the high horizontal mass the standard ET2 has a very high horizontal effective mass as standard ( 25g plus the weight of the cartridge ) compared to a pivoted arm. Richardkrebs has advocated adding 60+g of horizontal mass by adding lead to the bearing spindle and removing the decoupling mechanism of the counterweight. With the ET2 the decoupling of the counterweight is part of the strategy to keep horizontal mass not too high. Bruce Thigpen has measured, not theorised, actually measured on the ET2 a 6-12db lift in bass response when increasing the horizontal effective mass by 30g ( removing the decoupling ). From what I have actually heard, in a real system, since I have owned an ET2 from the mid 80's, increasing the mass slugs the sound and robs the music of musical pace and timing. Most of the contributors on this thread ( Frogman, Slaw, Ct0517 & myself )have found big improvements when carefully tuning the decoupled counterweight, as predicted by Bruce's testing. By the way I still own a Dynavector 501 which has a very high horizontal effective mass, and whilst the bass is quite punchy, the musical timing, soundstaging, and resolution is well down on both my Naim Aro and Fidelity Research FR64S ( yes I own 2 of these as well ). |
05-15-13: Richardkrebs 05-16-13: RichardkrebsRichardkrebs, according to your own posts 05-15-13: Richardkrebs - There is a phase and amplitude problem at 3xFr 05-16-13: Richardkrebs - There isn't a problem at 3xFR Of course I agree with your first statement. The second is wrong. 05-15-13: RichardkrebsRichardkrebs your statement is misleading. Bruce added 18g of horizontal effective mass with the damping trough mechanism. You have added 62g of mass to your arm by adding lead and removing the decoupled counterweight. Assuming your example of 9g cartridge and 32g of counterweight plus your added lead of 30g then; The horizontal effective mass of the ET2 with damping trough is Std ET2 - 25+9+18=52g KREBS ET2 - 25+9+32+18+30=114g If you believe that you can increase the horizontal mass of the ET2 from 52g to 114g and get the same results as Bruce Thigpen, then that is where you are wrong. 05-15-13: RichardkrebsOk, so you disagree with me, then in the second sentence you agree with me. I'll take the second view. If the fundamental determinant is horizontal effective mass, why do you expect the same results as Bruce Thigpen when you have more than doubled the horizontal mass with your changes to your ET2. The other key issue with running high horizontal mass, far higher than recommended by Bruce Thigpen, is the increased tracking distortion that this causes. I quote from Bruce Thigpen: To reiterate, from my listening experience increasing the horizontal mass and removing the decoupling of the counterweight on the ET2 slugs the sound and the distortion can be clearly heard. |
05-17-13: Ct0517My local audio shop has been selling VPi’s for some years. In my experience if the arm is wobbling then it is either not set up correctly or perhaps the bearing needs checking. As a matter of interest, the Aro is inherently more stable than the VPI and most unipivots as the bearing is a radius tip sitting in a cup with a defined radius. This provides damping of around 2db, is a true mechanical ground and is self centering. With the VPi the tip is upside down – the cup sits on top of the tip, so it is less stable, and is not a true mechanical ground. Stereophile review ARO – June 1993I can run an extremely eccentric record or a warped record and the ARO remains incredibly stable – there is no wobble or change of azimuth when disturbed. |
John47, my name is Dover, not Utter Nonsense Dover. I have in fact studied engineering and English as well at university. Please see below the difference between “a” and “the” "a" [uh; when stressed ey] indefinite article 3.another; one typically resembling: a Cicero in eloquence; a Jonah. "the" [stressed th ee; unstressed before a consonant th uh; unstressed before a vowel th ee] definite article 1. (used, especially before a noun, with a specifying or particularizing effect, as opposed to the indefinite or generalizing force of the indefinite article a or an ): the book you gave me; Come into the house. 2. (used to mark a proper noun, natural phenomenon, ship, building, time, point of the compass, branch of endeavor, or field of study as something well-known or unique): the sun; the Alps; the Queen Elizabeth; the past; the West. So, in the context of a “resonant peak” “a” does not represent “the”. |
06-17-13: John47John47 - it would be helpful if you read my posts more carefully. This is precisely what I wrote - Back in December last year I posted a postulation that one could consider mounting the cartridge slightly forward of the tangent line. The theory is that if you are running at the tangent then there are no lateral forces on the stylus and it will “chatter”, slowly eroding the high frequency grooves over time.The postulation has nothing to do with the Audio article on timing differences - it is about possible tracking issues at tangent due to the lack of lateral forces on the cantilever. This is similar to olden days cars that had kingpins in the front steering - drive in a straight line and the wheels wobble, but as soon as you turn the steering wheel off centre, then the wheels stop wobbling and start tracking securely. The following paragraph on the timing differences between channels highlighted in the Audio article is a different issue, albeit one that has the same possible remedy of running forward of the tangent. So when you said I don't believe you "posted a postulation."you are wrong. |
Interesting comments on the Terminator linear tracking arm from Dgarretson on the MM thread who has fabricated a lightweight carriage from carbon finer instead of aluminium.... 08-16-13Just another reminder that the best place for adding lead mass is on the end of a fishing line. It has no place on the ET. |
RichardkrebsActually it is the tracking angle that propels the arm inwards, which is different from offset angle. The skating forces are proportional to the tracking angle and tracking force. With higher tracking forces the skating force reduces. It also reduces with longer arms due to the reduced tracking angle. If you are tracking from about 2.5g with a 12" arm the skating force becomes very small, and if the tonearm is designed with breakdown torque taken into account at this point it is possible to run a pivoted arm without anti skate. Stylus profile also impacts the skating force. Ladegaards theory ignores these causal factors and assumes no anti skate is applied, therefore it is a worst case scenario and improbable in reality.. Conversely on eccentric records the high horizontal mass of a linear tracking arm will create tracking distortion. Very few records are truly round, and increasing the mass with lead on a linear tracker will increase the inertia of the arm in the horizontal plane and increase distortion on eccentric records due to cantilever flex. Thigpens' recommendations are that with records with an eccentricity of 1/8" a low mass pivoted arm will be superior. Dgarretson - your listening experience that lower mass is giving superior results with the Terminator mirrors most ( actually all except for one ) of the users of the ET2 on this thread that have attained optimum sound quality from the correct application and tuning of the low mass/decoupled counterweight design parameters that the ET2 is based upon. |
12-04-13: John47Your analogy does not apply. The goals are quite different. If a record has a warp, for example, the goal is to measure the groove modulations, not the size of the warp in the record. If the cartridge is impeded from moving up and down with the warp, then the measurement of the groove modulation will be grossly inaccurate. This also applies with lateral motion. Loading the tonearm with mass, as Richardkrebs has advocated, increases inertia, and as the groove moves in and out, the increased resistance to lateral movement means that the cantilever will flex more and the measurement of the groove modulation will be impaired and inaccurate. This is the fundamental principle upon which Bruce designed the LOW mass, decoupled counterweight ET2. Richardkrebs in this thread has advocated converting this tonearm into a very HIGH Mass arm. He also advocates removing the decoupling. These alterations add 60g to the effective mass of his ET2, increasing inertia and resistance to lateral motion by over 300% compared to a standard ET2. These gross alterations will result in destroying the inherent advantages that the LOW mass ET2 offers in superior tracking and minimising distortion. Numorous contributors to this thread have found that setting the arm up as per Bruces recommendations produces superior sound which is clearly audible. |