12-09-13: Richardkrebs
Depending upon the counterweights used and the weight of the cartridge, this total can approach 100 grams. The same ball park as my arm. You have stated in earlier posts that you added 30g of lead to your ET2 plus lead to the headshell and replaced the original plastic counterweight beam with an M10 threaded rod. You have strongly advocated adding more mass to the ET2. It is simply not possible to add 30 plus grams of lead and arrive at the same net weight to an unmolested ET2. With my low compliance Denon 103 weighing 9 gms I could balance the ET2 with 35g at the counterweight giving a total mass of around 79 grams. ( That would be about 43 gms using your maths ). Re your comments on transmissibility - 03-14-13: Richardkrebs
Shown here is a link to the Math on driven harmonic oscillators, a mathematical representation of an arm/ cartridge assembly. It shows in both formula and graphical terms what I have been trying to say. The Math is a bit of a struggle but fortunately the graphs show the results.
en.wikipedia#Driven_harmonic_oscillators I have pointed out before, the model you refer to applies to a harmonic oscillator like a pendulum. You are incorrect if you think that this represents a cartridge. The arm/cartridge/record interface has 2 fulcrum points - The stylus point around which the cantilever pivots, constrained by the groove. 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 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. In order to conceptualise this, think of 2 people holding a pipe and each one trying to move it sideways out of sync with the other. That is what the cantilever experiences. It is not a pendulum and it is not a harmonic oscillator. The Wikipaedia example you have chosen does not apply. Rather than get lost in fanciful mathematics the bottom line is that the cantilever flexes when faced with an eccentric record, even more so with added lead mass. I quote Bruce Thigpen directly the cartridge will "see" .55Hz mounted in any tonearm, more so in one with higher horizontal inertia
I don't think Kuzma means the stylus does not deflect at all at .55Hz, that would defy physics Postulating that the cantilever does not flex with an eccentric record and that adding mass has no impact defies physics. |
Frogman, I had the luxury of having both the ET1 and ET2 in my showroom in the 80's mounted on a variety of turntables along with other top arms of the day such as SME V, Zeta, Alphason, Dynavector, Odyssey, Sumiko The Arm, Goldmund, Syrinx PU2/3, etc The ET1 had a bloated bass, slower and less tuneful than the ET2. The ET2 was clearly more transparent than the ET1 by a considerable margin. The improvements to the ET2 are as follows : Decoupled Counterweight - This offers 3 advantages. The decoupled counterweight reduces the horizontal mass The decoupled counterweight splits the low frequency fundamental resonance, which results in two peaks of lower amplitude, improving the LF performance as demonstrated in Thigpens testing. The decoupled counterweight provides the capability to tune the decoupling spring to the cartridge. The maths may be taxing for some, but the Thigpens ET site has documented test results demonstrating the advantage of the decoupled counterweight design. It is incomprehensible as to why any individual would ignore Thigpens test results and convert the ET2 back to the ET1 format in respect of the counterweight, unless their system does not have the resolution to take advantage of this patented decoupled counterweight design, which yields a quicker and more tuneful bass as you have found in your testing. Adjustable VTA that maintains correct position of the stylus The tower provides easy adjustment to ensure the level of the horizontal bearing is congruent to the platter surface. Here is a pic http://www.eminent-tech.com/history/modelone.jpg |
Richardkrebs,
You are wrong. You continue to put up an argument for adding lots of mass to the ET2 and removing the patented decoupling methodology of the counterweight. Your argument is based on a strawman hypothesis that only focuses of frequencies below FR. Bruce Thigpens exhaustive testing does not support your view. You continue to ignore what is happening above FR when the decoupling reduces the horizontal mass, and your horizontal effective mass is 300% higher than a standard ET2 ABOVE FR.
You claim that 300% higher horizontal mass above FR ( ABOVE FR ) and removing the decoupling is of no consequence. Bruce Thigpens testing that he has documented on his website clearly shows that you are wrong and the problems of increased resonance when the counterweight decoupling is removed are documented.
Your claim that high horizontal mass has no consequence suggests that Shure, Ortofon, David Fletcher ( of Sumiko ), Alisdair Aitken ( SME ), Bruce Thigpen and virtually every tonearm and cartridge manufacturer has got it wrong. Record grooves are cut at 45 degrees, both vertical and horizontal mass matter. You cannot increase horizontal mass ( ABOVE FR ) by 300% and expect no change.
In this thread Dgarretson has reduced the horizontal effective mass of his Terminator and yielded significant improvements in speed and resolution. Frogman has further decoupled his counterweight and yielded significant improvements in speed and resolution, more bass notes he says. I have tested fixed and decoupled counterweights some 30 years ago when the ET2 replaced the ET1, and yielded significant improvements with the decoupled counterweight even with very low compliance cartridges.
Bruce Thigpen has documented the problems of high horizontal mass as have Shure with their white papers on tracking.
None of your claims that a rigid counterweight and increased mass are supported by proper documented testing. Your argument is entirely based on theory, and it is flawed. Your maths that you quote continues to ignore the fact that the decoupled counterweight splits the fundamental resonant peak into 2 smaller peaks ( as demonstrated in the Stereophile review and Bruce Thigpens testing ) that has benefits of lowering distortion in the audible spectrum ( ABOVE FR ). You have used mathematical arguments that are not fully representative of the cartridge/arm resonant and tracking behaviour and are taken out of context.
I would suggest that you should buy a Kuzma arm which has been designed from the outset with a high Horizontal mass and has a fixed counterweight if you wish to throw away the advantages of the ET2 with its design goals of maintaining as low a mass as possible and minimising resonant peaks in the ultra low bass & minimising tracking distortion through the employment of the patented decoupled counterweight system.
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Frogman et al,
There are many reasons why different tubes will affect the sound.
Depending upon the velocity, the air is likely to flow chaotically, forming vortexes and eddies as it moves down the pipe, it is not necessarily laminar.
The geometry of the tube, the roughness of the tube walls, the elasticity of the tube and the purity of the air all affect flow and chaotic behaviour.
Furthermore, air is compressible, which affects flow. And finally as air flows, compresses or decompresses, it can change temperature which affects pressure and therefore flow.
Keeping the tube as straight as possible will reduce turbulence, just like an optical cable with digital - oh the irony.
It is quite complex.
As an aside I would have thought it would be advantageous to have a regulator at the end of the long tube, just prior to the arm, as the length of tube after the regulator will, if my rusty memory on fluid dynamics is working, drop the flow rate going into the bearing.
In other words if 2 of you had the same regulator and 40ft of tube, and one places the regulator at the start of the tube, and the other places the regulator at the end of the tube, then I would expect that you would end up with different flow rates into the bearing. I would at the very least expect a significant impact on the "sound" from where you position the final regulator in relation to the arm bearing.
Suggested music for AB testing - JS Bach Air on the G String : Zoltan Rozsnyai/Philharmonia Hungarica on M&K Realtime for the audiophiles, perhaps Malcolm Sargent/New Symphony Orchestra for the purists on HMV ( 78rpm of course ). |
Richardkrebs, On the one hand you say that the air bearing is rigid at audio frequencies, but now you speculate that the arm is prone to chatter due to "pressure irregularities". You also claim that the pressure irregularities are audible. The two theories are mutually exclusive - they cannot both be true. 06-06-14: Richardkrebs
If there are pulsations in the air stream this will be manifest as slightly different flow rates into the manifold and thus pressures seen by each of these holes and the flow rate thru them. This would cause the spindle to chatter. You do Bruce Thigpen a disservice. 06-04-14: Richardkrebs
Below is a copy of a mail I received from Bruce T many months ago.
The resonance of the air cavity is over 500Khz and does not manifest itself on the surface of the bearing, it is a well damped liquid bearing.
I used three measurement methods when developing the tonearm, accelerometers, strain gages, and the simplest and most effective was the use of a second tonearm to play parts of the tonearm under test while playing a record. Please advise what testing you have done that would confirm your theory. The ET2 manual clearly states that Bruce goes through a design process, supported by principles of physics and sound engineering, includes mathematical modeling, the production of prototypes and thorough documented testing before his products go to market. There is no speculation or guesswork involved. The ET2 has evolved from the 1st incarnation that utilized low pressure low flow bearing, then with the advent of customers using higher pressure pumps ( the WISA300 for example) Bruce redesigned the bearing for high pressure low flow air supplies. Bruce will also custom build for specific air pumps and provide advice on cartridge compatibility with each of the options. It is abundantly clear that each bearing has an intended set of parameters with regard to pressure and flow. You have discarded the original ET manifold housing, discarded the decoupled counterweight, discarded the horizontal moving mass targets that the ET design is predicated upon, and may well be running a pump that is not optimised with your particular bearing. Unless you can provide some documented testing as Bruce does on his website, your comments can only be described as speculative at best. |
Ketchup,
I have played with titanium components on the ET2 some years ago. I overhauled a company that manufactured custom wheelchairs, including custom titanium frames, with custom brackets to meet individuals needs. Unfortunately titanium is very brittle to machine, it shatters very easily and I think you will find it difficult. As an aside titanium tube is not rigid, you can actually bend it by hand, but it does have fantastic damping qualities. I have a titanium arm tube sitting around somewhere, but have not used it.
With regard to the aluminium one piece gooseneck, mine is the same as Krebs, and I use it in an ET2 & aluminium arm tube with both MC ( Carnegie, Koetsu, Denon 103 ) & MM ( Shure V15Vxmr with brush removed ). I have never had stridency from my ET2.
Bear in mind my ET2 aluminium arm tube has had the foam & shrink wrap removed, the teflon insert in the headshell removed and replaced with carbon fibre. I also run a loose decoupled counterweight ( tuned with teflon bushes ) that is much lossier than the standard spring for both MM & MC. Frogman has trialled this and attained the same benefits of quicker and more transparent bottom end ( literally more notes in his system ).
So my suggestion to Chris if he wants to run an MM in the ET2.5 with the aluminium gooseneck would be to try loosening off the counterweight nut and lower the overall horizontal mass ( above FR ). If you back the nut off and then dial it in slowly whilst listening to the changes you can tune the counterweight motion quite precisely, even more so if you put a tiny wedge either side of the spring to control the motion ( I used teflon ). |
Bigalt,
I run the wire straight out of the arm tube, looped under the bearing spindle/armlift rod to a teflon block on the the side of the TT (this is mounted behind the lift spindle and halfway along to minimise wire tension when playing. The wire does not enter the bearing spindle at all. I also use a silk insulated copper litz which is much less springy than the plastic/teflon insulated tonearm wires like Cardas etc.
There are no connectors at all between cartridge pins and RCA/phono connectors. If you back the preamp up to the side of the TT you can get the total loom down to around 16".
For maintenance all I have to do is unplug the phono and undo 1 screw holding the teflon block and the whole arm tube comes off complete with wiring loom and cartridge.
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06-04-15: Richardkrebs
Wouldnt your process potentially take the spindle out of parallel with the record surface?
This would mean that the tracking angle would change as the cartridge traverses the record. Richardkrebs, "tracking angle" does not apply to the ET2 as it is a tangential tracking tonearm. "Tracking angle" only applies to pivoted arms. The correct terminology if I interpret what you are trying to say is Azimuth may be out. It appears that you are suggesting Bigalts azimuth may be out, notwithstanding that if his platter is level, and he levels the arm, then assuming the wand is mounted correctly, it is not possible for the azimuth to be out, unless the stylus is not mounted in the cantilever correctly.. |
Pegasus - a few suggestions for hum
TT Checks :
Check the chassis/motor earthing on your SL1210- is it earthed to the wall ?
If so, then earthing to pre will create ground loop.
Check for continuity between TT earth and spindle to ensure platter is earthed. If not then there is an internal earth lead in the TT not connected.
Personally I've always got lowest noise by earthing the TT chassis/platter/motor through the power cable. If the TT chassis etc is earthed to the preamp you are putting noise into the phono ( assuming a single ended system ).
Arm Checks :
Unplug the phono cables/earths etc from the pre.
Check for continuity between your tonearm earth and the earth on your Decca phono cable with the arm not plugged into anything. If it is continuous then you will have an earth loop if you connect both the tonearm earth and signal cables to preamp. It is a long time since I had a Decca, but if I recall correctly some had the body and signal earth strapped at the cartridge end.
If the tonearm earth is truly separated electrically from the cartridge signal earths, then I would take the arm earth to the chassis and wall rather than the preamp. This is because any noise picked up by the tonearm earth would be dumped into the signal path in a single ended phono if you connect the tonearm earth to the phono pre.
ET2 Wiring :
My experience with single stranded silver wire was bad. Started picking up local radio stations and all sorts of rf. Twisting the wires helped but did not eliminate the rf.
I eliminated the rf completely by going to a silk copper litz wire. Even without twisting it in pairs there was no rf.
In both cases the wiring was continuous between cartridge and phono input.
Hope thats some help.
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Pegasus -
The copper litz I used was the same wire as used in the Sumiko headshell wires - each of the +R -R +L -L legs consisting of multi stranded litz - each strand within the bundle being individually insulated with silk. This ran from the cartridge pins to the side of the TT and was soldered directly into a very short pair of stripped ( unshielded ) MIT MI330- total loom was about 15" to phono. Also I did not have the arm grounded either. No hum or noise with Shure V15vxmr or various LOMC's. Like you I am not a fan of shielding signal wires where possible.
Is your TT chassis & platter grounded ? If so how ?
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Thread Drive
For those interested in thread drive I own and have owned both a Final Audio VTT1 thread drive and the Platine Verdier referred to above. My understanding from Final Audio's point of view is that the optimum pulley profile should be hemispherical concave for thread drive.
I found that the Final and Verdier incompatible as far as optimum thread selection. For the Final Audio I use a very fine braided suture silk thread from Davis & Geck - this has high tensile strength and good grip. This thread sounded awful on the Verdier. The Platine Verdier sounded much better with a larger diameter softer silk/linen thread. As an aside the rubber belt option for the Verdier is appalling- you can see the rubber belt drifting up and down the platter due to the fact that the rubber belt has large variations in its "round" profile.
Fwiw the Final Audio has an audibly superior motor drive system to the Verdier, much quieter, less noise and vastly superior in speed accuracy. I was easily able to prove this by running the Verdier Platter from the Final Audio motor drive. In the end I gave up on the Verdier, since the Final Audio is so much better the Verdier never got used.
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Ct0517
the other thing I want to mention is that pivot arms produce more resonance at the bearing. Bruce has actually measured this and documented it in the manual....
The most resonance can be heard in the bass.You need to get the bass right in any room. If someone wants to call this resonance - distortion - feel free. Air Bearing linear trackers produce less distortion - less resonance.
This statement is misleading. The primary reason Bruce's ET2 has lower resonance in the bass is due to the the fact that the horizontal effective mass of the ET2 and the Vertical effective mass of the ET2 are different, resulting in a lower resonance amplitude compared to a conventional pivoted arm in which the horizontal and vertical effective masses are coincidental and cumulative in amplitude. This is not necessarily true of all tangential trackers, it will depend on the design and mass distribution of each particular linear tracking arm. Secondly Bruce's patented decoupled counterweight system further lowers the horizontal effective mass through the use of a leaf spring which reduces the amplitude of the bass resonance. Reducing the bass resonance has significant advantages in reducing tracking distortion as confirmed in the 'Shure white papers' on tracking. There has been a suggestion by Richardkrebs earlier in this thread to remove the patented decoupled counterweight system from the ET2 - this suggestion defies physics, ignores Bruces extensive testing results and audibly degrades the sound as has been widely proven. |
Dear Chris,
It is presumptuous of you to assume I ran the Platine Verdierwith the ball inserted. I trailed both.
Really the essence of what I was saying is that the motor drive system is substandard. Furthermore the bearing tolerances are woeful and I would recommend the Callas kit if keeping it.
Fwiw I sold it to an SME20 owner who found it was an improvement over that TT, so it is not bad, but it is not reference quality.
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bh80231 I indeed have 2 aluminum wands and yes, running LOMC’s - Ortofon Quintet Black (boron cantilever), Ortofon Quintet Mono, and an AT33PTG/II.
I have had different wraps on them in the past, and stuffed foam inside too (what is your stance on that?), but they are naked now.
I have ordered my own sheet of CF wrap though, so am going to give that a try. bh80231 I stripped my aluminium wand of both the inside foam and also the heat shrink on the tube - at the time I was running both a low compliance Denon 103 Garrott ( boron cantilever/weinz tip ) and low to medium compliance Carnegie Model One. TT was Sota Star vacuum at that time. In both instances I got a lighter tonal balance but with more transparency. Overall I preferred the increased transparency over the slight lightening of balance. The other mod I did was to remove the teflon insert from the headshell part of the tube and replace it with a carbon fibre insert pressed and bonded in. This was worthwhile as well. |
Harry,
You place the magnet under the bearing spindle, right next to the manifold. You want the magnet close to and parallel to the arm tube ( if you are using say a cupboard door magnet ). If you place it on the side opposite to the cartridge end then it won't affect the cartridge signal at the end of play.
Cheers
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Chris/Harry Interesting Bruces comments. What was not imagined from using magnets for eddy current damping in my system was increased volume, I had to turn the volume down. I used cupboard door magnets - 2 in parallel underneath. Bear in mind the eddy currents are only induced when the arm moves - i.e. it only comes into effect with eccentric records. If the record is not eccentric then there would be no difference. Dynavector uses the same principle with their biaxial arms http://www.dynavector.com/products/tonearm/e_507mk2.html |
@vpi
I have found with the original aluminium arm that removing the internal foam and heat shrink improved transparency. I did this ins stages to verify each step. Ypou might want to try it.
I also opened up the cartridge end of the arm tube removed the spongy teflon insert and replaced it with a piece of carbon fibre - fixed with araldite and compression.This is relatively easy to do and again provided a good improvement.
Fyi years ago I had a Van den jul MC One -preferred it to the more expensive Grasshopper at the time. Verynice cartridge. It was more balanced and not as lean as some of the early Grasshoppers. |
Yes - I had rf issues with van den hul solid core silver.
Going back to copper litz fixed the problem ( and sounded better )
If you have the original wiring loom poor connections can be a source of rf - go through and clean all joints and resolder any dodgy looking soldered joints and check cartridge pin connections are nice and firm.
Failing that make sure that the wiring for each channel are a twisted pair - gently winding into a twisted pair +ve and -ve wires will help with the avoidance of rf.
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@nandric
I like disputes. Here is my ''first.''. This thread looks like Wittgenstein's ''phylosophical remarks'' He made about 10000 while an ''normal human'' can remember about 10. Keep inventing new upgrades...
If you want to do a case study in irrational logic and thinking read the posts from richardkrebs earlier in this thread - he argued for the best part of 12 months that adding 30g of lead to the ET2 was a good thing, presented fantastically illogical arguments and analogies for well over 6 months, almost daily. Anyone who disagreed with him was wrong. Eventually after about 18 months ( from memory ) he disclosed that he never added 30g of lead mass. ( or so he claimed ).
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@ct0517
And one of the best arms ever made regardless of price and most unfairly maligned.
It beggars belief that on audiogon there is so much misinformation on the ET2, when discussing tonearms in general, when the Eminent Technology website contains more testing and test data to support the design and substantiate their claims on performance than any other tonearm on the market.
It's sad that there is much to learn on the ET website even if your preference is a conventional pivoted arm that folk just cant be bothered to take advantage of Bruces formidable knowledge.
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@lewm
I am wondering why mounting a large weight close to the pivot point makes any difference as far as overcoming the air pressure and collapsing the air suspension ,
Because the air bearing carries the mass of the arm/cartridge/counterweight in total - If you have a larger counterweight that increases the total moving mass to above what the bearing has been designed for then it could collapse.
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