Thekong, Richard, I sometimes use brass weights (supplied by Thigpen) instead of, or in combination with, the usual lead weights. IMO, the concern is not so much the possibly inherently-different sound of something like brass as compared to lead, but the fact that using a material with a different density may necessitate placing it on a different spot along the I-beam, since as Dover points out:
****It is desirable in most cases ( low to medium compliance cartridges 5x10 dynes/cm – 20x10 dynes/cm ) to use the minimum number of weights, far out on the cantilever stem. This decreases the horizontal inertia of the tonearm while increasing its vertical inertia.****
In my case, the use of the supplied brass weights usually results in having to place the weights further in along the I-beam. In my set-up, this is usually not ideal, with inferior overall bass performance. I suppose that it would be possible to have the exact size of brass weight machined to match the weight, and hence placement, of the lead. But, that is not the case with the weights that Bruce sent me. |
Hi Thekong
Lead is also banned in Canada. Based on the shape and size of the ET2 counterweights here is an easy DIY alternative.
Go to any tire shop and pick up a couple of the lead weights that they use on wheel rims. They are of substantial size. They are easily snipped and the hole drilled to make any size weight you need. To get the nice square look as BT’s take them to a machine shop. Otherwise you could be up and running in the same day with the lead.
Nice speakers btw ! I am glad we have distance and a lot of water separating us otherwise I would be tempted to come over and ask to borrow them for a while.
Some more impressions.
The lead weight reminded me of something.
I “experimented” with a form of higher mass quite a while ago but only at the counterweight end. I had at the time email conversations with a couple of high profile Audigon members who were in this "lets add more weight to the counterweight camp” with their past experiences with the ET2 and ET 2.5. I really hope they see this post.
I added more weight to the counter weight end and tried to get as close to the spindle as I could. I found the sound seemed to get “bigger” each time I did it. It was addicting. I also did not have my Studer at the time for a reference point in my room for the sound. I made extra lead weights sourced from the tire shop I referenced above.
The horizontal mass of the arm may not have been seeing “some” of this extra weight as it was decoupled, but the air bearing spindle itself was. I talked to Bruce about this. Now lets imagine that he has heard every story you can probably think of in the last 20 + years from tweakers, hot rodders and experimenters of his tonearm. He was very clear to me. Try it and see...
So he encouraged me and said at some point I would affect the balance of the spindle, the air would not be able to sustain the spindle weight properly, and rumble would occur. something like that.
I never got as far as actual rumble occurring and then the light came on for me. The ET2 counterweight ” I” Beam is the most misunderstood part of this tonearm and the EASIEST to screw up. The ET2 arm comes with a set of lead weights along with a range described in the manual of the minimum and maximum cartridge weight they can counter. This range can be modified btw - but thats another discussion. How many of you have thought to yourselves, I don’t want to lose them. So lets put them all on the counterweight. Who hasn’t done this when you first started out with the ET2 ?
How many have even done it with a light MM cartridge?
NOW the really big question - imo.
How many Michael Fremer types (professional reviewers) have done the above - used all the weights when they were not needed ?
Has anyone ever read an ET2 review where a description of the weights (how many used/positioning on the I beam was actually described.
There positioning is as critical to the sound as the fine tuning adjustments made to the cartridge itself. Very sensitive. Without the knowledge about this ..
Well as noted in the previous posts from Dover the manual doesn’t say add extra weights like I was doing in the experiment. It says it is preferable to get as far out on the beam as you can. This implies less weight on the I beam itself as its intent is to be decoupled. Think about it – the weight is on a leaf spring. ITS A HORIZONTAL VERSION OF A CAR/TRUCK LEAF SPRING . Get that in your head and your home free with this tonearm – IMO.
So this Iight came on for me around the first couple of pages on this thread. Someone that calls himself Frogman reminded me.
Btw – I thought this person that calls himself Frogman was a scientist that spent his time where its wet; looking for Frogs. Monikers being what they are. Boy was I wrong !
Re-applying less weight further out on the beam; the tuneful bottom end returned with more speed and coherence. Similar wording to one of Dovers previous posts.
*********************************************************
Warning - The above post about adding "mass to the counterweight" does not relate to the mass spindle dampening being discussed. Persons reading this thread do so at their own risk.
********************************************************* |
Chris/Frogman -
Thanks for your feedback and comments. I was beginning tho think that analogue heaven consisted of only me and Bruce on a desert island.
I think the key point Chris as you have alluded to is that even if we assumed the Kuzma was the best arm in the world, adding substantive mass to the ET2 is wrong, it is taking it out of its design parameters. To accommodate the mass one would have to redesign the main air bearing and retune the Q of the total system. These factors are being completely ignored by the other folk.
Chris I note that you are also using the carbon fiber arm tube for high compliance cartridges and yet still finding the optimum is only 2 springs with the Benz. This does suggest to err on the more decoupled side of the ledger for LOMC's as well, the only downsides being possibly a fall off below 30hz.
I would be very surprised if many were getting below 30hz in a domestic environment, and if they were it would be unable to be controlled in that environment. To put it another way a roll off below 30hz I would see as an advantage in most domestic environments where room bass response is usually quite uneven and unpredictable. |
Further to the above post for those interested the weights of the arm options excluding the wire are: 13g ( Al) . 17g (Cf) & 19g for the heavy magnesium version. So Bruce has designed in only an additional 2-6g for MC's.
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03-13-13: Ct0517
The Rockport and Kuzma tubing makes me think of my past experiences with my VPI JMW 12 tonearm. That tonearm’s wires are used as its antiskating method. Their positioning pushes the tonearm back toward the outside.
Could the tubing being in a loop at the centre of the Rockport and Kuzma arm, be acting as a type of dampener for the arms motion in both directions ? 03-18-13 John47
Mr Kuzma replies to MF
[quote]"A question of damping..."
........ There is, in fact, a level of effective damping on the Air Line tonearm. The cantilever suspension, and the air supply tube add damping. Our choice was for either too little or adequate damping; we chose the latter. John47 - Thanks for confirming my assumptions with the Kuzma. Dover - My ET 2.5 has the CF armtube and was the one I referenced in my post with the Benz Micro. So many variables here. Plus the specs I listed are for the stock cartridge – it is now a Ruby cantilever SS retip. I have no idea if the specs were changed when it got retipped. Does anyone know what a Ruby cantilever does over the stock Benz Micro one ? The cartridge came with the VPI TNT I bought years ago, and it needed a retip when I purchased it so I never heard it in stock form. Richard – the triple leaf spring is tight but not 100% tight. It has a tiny bit of flex in it but you need to force it a little. If you hold it by the I Beam and shake it - it doesn't move. Still it is not as stiff as if you stuffed two toothpicks on either side. Cheers |
Re quality factor, Q. ... under, critically or overdamped systems, as they relate to the ET2. My running the arm at 12 psi is no accident. I addressed the Q factor of my arm years ago. And the bearing has no issues at all carrying the extra weight, even at this pressure.
I don't have any proof of this, it is just a recent thought. While higher or lower weight is obviously a factor, I think that the one leaf spring, two leaf spring plus number of weights thing, has probably a whole different set of cause and effect issues. So with reference to a rigid or sprung counterweight beam, it is probably an all or nothing event. In other words because we have the "potential" interaction of the swing frequency of the beam and the resonant frequency of the arm assembly, depending on the number of leaves and the number of lead weights used. It could be that tuning here with springs and weights (and their position) is at least partly to do with sorting this possible frequency interaction rather than just the weight or stiffness employed. Others may have already thought of this but, it is just an idea to put out there for comment. |
1986, June as I recall, my first ET.
In '78 whilst studying Engineering at University I learnt a fundamental law of physics.
Q : How do you titillate an ocelot.
A : You oscillate it's tit a lot.
We didn't have Wikipedia in those days.
|
Hi Dover- ... interesting post. thanks Wikipedia is ok ...Youtube can be effective too? I hate theory so the animation helps me alot; another reason I like posters here on the forum that talk to their direct experiences - not what if this or that. I am no physicist and I am bad at math to boot. I hate formulae. Btw – I have found myself the easiest what to find out about physics is to partake in a “hobby” that can kill you if you slip up. You learn really quick. Ever track a car ......around an oval track that kind of sort of resembles an lp ? |
Richard - re your last post. .....So with reference to a rigid or sprung counterweight beam, it is probably an all or nothing event. In other words because we have the "potential" interaction of the swing frequency of the beam and the resonant frequency of the arm assembly, depending on the number of leaves and the number of lead weights used. It could be that tuning here with springs and weights (and their position) is at least partly to do with sorting this possible frequency interaction rather than just the weight or stiffness employed. Others may have already thought of this but, it is just an idea to put out there for comment. Would not the rigid solution and the all or nothing event - be only applicable to a one cartridge guy and the specific cartridge cantilever needing to be – really stiff ? As an end user I feel with the sprung counterweight it allows me to use all of my cartridges. Just a thought. Also In your custom ET2 setup – are you able to use higher compliance cartridges if you remove the lead from the spindle ? or are there other factors like a custom manifold involved ? that keep you from using higher compliance cartridges – sonic preferences aside for the moment ? Cheers |
Chris - I assume you know the driving dogs are Kiwis ? NZSPA trained no less, here in Auckland. Not sure if they run ET's, but they demonstrate the benefits of high compliance. At the Engineering faculty I also remember Dr Fassbender, who had a fetish for experiments with rubber bands - http://www.youtube.com/watch?v=M0QShhpqtS8 |
Chris
I tune the arm with a set of different size weights. Don't know if manufactures of linear arms with fixed weight beams offer this, but it would make sense to do so.
Kuzma do suggest that their arm is most suitable for use with carts below a certain compliance. So they have considered this topic.
The weight I have added inside the spindle can be removed or adjusted in weight. No modification of the spindle is required.
The thought that there may be more going on with the decoupled counterweight was triggered by your post where you quoted BT where he said that the ibeam had a natural frequency of 2-5 hz.
This is close to the resonant frequency of the arm itself. This could have performance implications. |
Thanks for the info Richard. The thought that there may be more going on with the decoupled counterweight was triggered by your post where you quoted BT where he said that the ibeam had a natural frequency of 2-5 hz. The figure I quoted is from the manual and I believe it is for a stock single I Beam with the weights that are supplied with the stock ET2 tonearm - not the ET 2.5 – which we agree is a different animal with different resonances. I gotta believe that adding a leaf spring plus adding the ET 2.5 larger spindle changes things? I would need to confirm this with Bruce. |
Dover - if I may say - you come across as a real hard ass sometimes in your posts; but you have a very direct sense of humor. lmfao.
btw - what I just said my kids say to me alot. they unfortunately both being only 18 have not yet seen alot of my humor. I try to save it for you guys as I my wife just doesn't appreciate it either. This thread is 11 pages long now. She will never be able to trace back to what i am saying here.
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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
I don't have any proof of this, it is just a recent thought. While higher or lower weight is obviously a factor, I think that the one leaf spring, two leaf spring plus number of weights thing, has probably a whole different set of cause and effect issues. So with reference to a rigid or sprung counterweight beam, it is probably an all or nothing event. In other words because we have the "potential" interaction of the swing frequency of the beam and the resonant frequency of the arm assembly, depending on the number of leaves and the number of lead weights used. It could be that tuning here with springs and weights (and their position) is at least partly to do with sorting this possible frequency interaction rather than just the weight or stiffness employed. Others may have already thought of this but, it is just an idea to put out there for comment.
03-20-13: Richardkrebs
The thought that there may be more going on with the decoupled counterweight was triggered by your post where you quoted BT where he said that the ibeam had a natural frequency of 2-5 hz.
This is close to the resonant frequency of the arm itself. This could have performance implications. 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. |
Dover.
....Sigh.....
My comment re "All or nothing" was designed to open useful dialog on the subject. I was trying to be subtle.
So now, not so subtle..
Do you really think that it is a good idea to have a spring driven mass, ( cartridge and arm ) attached to a spring suspended mass ( ibeam and counterweight). Both with resonant frequencies in the same neighbourhood?
If you refer to the math and resonance graph I posted, it shows that this can be problematic. The two resonances need to be far away from each other to avoid any interaction. At best a good compromise can be achieved with adjustment of the parameters. I don't like compromises. Better to eliminate one of the compliant joints in the system completely.
As I have said earlier. If fixed, the counterweight beam must be very strong. I note that Kuzma also know this as the counterweight beam is substantial indeed. Three springs don't cut it.
It is no accident that other arm manufacturers have a rigid joint there....it simply sounds better.
I don't understand why you are so set on trying to stop people experimenting on this area of the arm. It will do no harm and at the very least add to our collective pool of knowledge. A big hand will not come out of the sky and squash anyone who deviates from the original design parameters, it will be a bit of fun and it may just bring the owner closer to the absolute joy of listening to music, which is what this hobby is all about.
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Put on your knitwear cardy so don't catch a cold, your thick lensed glasses so you don't fall, then pop out and replenish your Prozac.
Chris (such a lovely guy):
"You come across as a real hard ass .."
Acronym: PITA
BTW did Richardkrebs pick on you at preschool? |
Well I am not sure what to say now. I gotta admit that the folks from down under and specifically NZ, are not a subtle group by any means. You all seem to be in close proximity to one another? Can you by chance hear each others stereos when you turn them up ? BTW – Does Canadian Shania Twain still live in NZ ? I always had a crush on her. Richardkrebs
Do you really think that it is a good idea to have a spring driven mass, ( cartridge and arm ) attached to a spring suspended mass ( ibeam and counterweight). Both with resonant frequencies in the same neighbourhood? Chris,
You always want the horizontal natural frequency of the counterweight to be less than the cartridge/arm resonance, this is the case 98% of the time.
The natural frequency of the I-beam/leaf spring depends on the thickness of the spring, the amount of weight, and where the weight is on the beam. The natural frequency goes down as the weight moves further out on the beam which is where we want it to be.
brucet
************************************************************ Page 49 of the ET2 manual. LOW FREQUENCY RESONANCE MEASUREMENTS The curve below shows the typical response for the vertical resonance of the the tonearm. This was done with a medium-high compliance cartridge (30 x 10-6 cm/dyne) with a mass of 7 grams and two counterweights 15g + 15g. This counterweight combination gives a vertical effective mass for the tonearm of about 12 grams, which results in a resonant frequency of 6 hz (measured). Horizontally the resonant frequency will be much lower because of the tonearms higher mass (30grams). The horizontal resonant frequency is damped by the decoupling spring and is very well controlled. ************************************************************ Actual measurements and graphs for the above are also shown on page 49. Thoughts on the above ? At this rate we will probably have the whole ET2 manual on the thread by Christmas? My personal take on this as an amateur hobbyist. Bruce makes a lot of sense and has done the analysis and measurements to back it up. The ultimate test is "hearing is believing". My reference point for sound in my room is 15 IPS master tape dub. Both the MM 420str and MC Benc Micro that I discussed earlier play beautifully on my ET 2.5 with the CF armtube. I have the MM 420str on the ET 2.0 right now with aluminum armtube / other room and it sounds great there too. Each of us have different gear and rooms. We need to experiment with the different leaf springs to see what sounds best to us. But it is very obvious and clear to me that we should be trying to get *** AS FAR OUT ON THE I BEAM AS POSSIBLE - THIS IMPLIES THE LEAST AMOUNT OF WEIGHT ******* I haven’t tried a rigid counterweight with damping. If anyone would like to volunteer up a DL103 or similar low compliance cartridge I can give it a longer term try on the ET 2.0. If a good cheap DL103 pops up on the classified I can try to snap it up. I don't have a problem experimenting. Time permitting. Cheers |
As a New Zealander I would like to apologies for the behavior of Dover. It is a narrow country and this breeds narrow mindedness.
When I look at the pictures of RK's arm I do not see an ET2. It is something specifically crafted and tuned to his system. It is not a universal tonearm. A little bit like the highly modified ET1 that Lloyd Walker uses actually.
Nor for that matter is the ET2 a universal tonearm, as I can attest to from my experience of its truly poor performance in my system. Quite frankly it was clearly out performed by my humble G707 and has remained in the closet ever since.
Now that I am in the process of moving on from my LP12, I will give the ET2 a second chance. In doing this I will be applying a great deal of good advice from Dover, but when Richard gets off his backside and makes a decent new tonearm, you can bet I will be dumpster diving out the back of his place to score the discarded bits from his current arm.
What Bruce has created is a truly outstanding achievement, but here is the rub, in everything I have done with hifi, at no stage have measurements, be it mechanical, electrical, or acoustic, ever done anything but get me in the ballpark. Was is Saul Marantz who has been quoted as saying: "If it measures good and sounds bad, it is bad and if it measures bad and sounds good, you are measuring the wrong thing."
To get back on topic I will just say this. Neither of these guys have a clue. One uses a 'Japanese DD' turntable and one uses a Heath Robinson 'belt drive'. If they used a real turntable there would be much less of this idler bickering.
Ouch, just bit my tongue. Might have to move to Oz now to avoid getting lynched.
Best Regards
Grantn |
The discussions (arguments?) between Dover and Richard have been extremely thought-provoking; and very interesting to say the least. I think that the well-intended participants who look for complete harmony, agreement, and absence of confrontation run the risk of they, themselves, doing more to derail what has been one of the best threads on Agon than either of those two gentlemen. Personally, I don't feel Richard is owed an apology at all; certainly, not one instigated by someone on the periphery of these discussions. We all have different styles of communication, and when the issue is something that one feels passionate about, we throw the gloves off (well, we at least loosen the laces) and expect everyone to be a big boy. I have seen no profanity used; no personal attacks, certainly nothing that, at the very least, could not be up for interpretation.
I have found value in both participants' contributions, even if I don't agree (yet?) with all the pecifics about each of their respective stances re set-up of this arm. For instance, I am not yet convinced entirely that IN MY SYSTEM, going for the lightest weight/mass possible is the way to go. Yet, and speaking of loosening the laces, I decoupled (loosened) the I-beam yesterday, and lo-and-behold, on Donald Fagen's new release "Sunken Condos", what had previously been little more than amorphous low frequency energy suddenly became notes that I could discern the pitch of; completely the opposite of what I expected given my experience (extensive) experimenting with springs of different compliances (single, double, etc.), and the reason I had not tried it yet. Point is, let's all be big boys, try things and have a little more confidence in what we hear as being the right way to go. Dover and Richard please continue contributing to this thread.
Regards. |
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. |
Dover, thanks. It appears to me that re coupling/decoupling of the I-beam/weight we are dealing with two issues that, on the surface, may seem to be one and the same, but are actually two separate considerations. We have 1. the degree of coupling due to the stiffness of the spring, and 2. the degree of coupling due to how tightly the I-beam is secured to the arm. I make this distinction because, although I would have thought that the two are effectively the same, I am experiencing different and unexpected results from each approach. I suspect that each has different ramifications as concerns resonance, hence the very different results. As I mentioned above, I have almost always preferred (after much going back and forth) the double spring with most of the cartridges that I have used over the years; these, of every persuasion and compliance. The less compliant double spring usually yielding a more controlled, defined sound with tauter and faster bass. More compliant springs have produced sound that is generally fuller, but less-well defined; fuller mids and lows, but less-well integrated highs.
I usually approach system tuning with the idea that there is always a theoretical ideal, but a necessary practical compromise. I prefer fuller sounding tube amplification, so the perceived leaner sound of the double spring has suited my system well.
This leads me to the issue of perceived bass speed. This relates to (in my fairly non-technical mind, anyway) to the above issues and to the issue you brought up re energy storage of soft dampening. In my experience, perceived speed cannot be completely separated from perceived tonal balance. To be clear, for me speed refers to the ability of a component to let music (or, for the sake of this discussion, the bass range) move as it should; to allow it to swing, rock, crescendo, whatever, with the swagger that it does live. I have always found this aspect of reproduced sound to be THE most elusive of all. I have heard components that were unacceptably dark and excessively full sounding that let the music move as it should with great dynamic nuance; and others that were tight, defined, and sometimes too bright overall that sounded dead, as if the musicians were half-asleep. At the same time, since how a component handles the leading edge of transients has a profound influence on the perceived speed, a system tuned to the darker/fuller side of things can benefit (speed-wise) from a little help by way of what the double spring brings to the table.
A long-winded way of saying that I am a little mystified as to why the loosening the I-beam yields a superior result than simply using a more compliant spring. BTW, I am speaking strictly about bass performance; I need to spend more time, and experiment more in the ways that you suggest, to get a better handle on things.
Thanks again. |
Frogman
The less compliant double spring usually yielding a more controlled, defined sound with tauter and faster bass. More compliant springs have produced sound that is generally fuller, but less-well defined; fuller mids and lows, but less-well integrated highs. Frogman your observations mirror mine. Here are some personal impressions in my specific 2 rooms. BTW - Bruce has confirmed to me that adding a double spring raises the resonant frequency of the I Beam Counterweight. Two rooms set up with an ET2 and ET 2.5. First room The ET 2.5 is in a room with gear that I am able to pressurize easily and hear the bass nodes by walking around all on fours. I can locate where the bass is fullest and over powering. I can also find the spot where the nulls are. By experimenting over 19 years with multiple speakers I have found for this room only; the spots that give me minimal resonances at my listening chair, based on where I position the speakers. A key to my own audio madness 1) a dedicated room and 2) a listening chair that can be moved forward and backward multiple feet to adjust for soundstage/sweetspot differences between differently engineered music sources (whether they be on lp, cd, or tape) and different cartridges. Anyone that has ever heard a 420 str for the first time is aware of the stark differences in soundstage presentation it provides. I had to move my nearfield listening chair back a few feet from the first listen to the 420 str. What if your chair is up against wall..... I prefer the double spring in general in this first room. The bass is tighter as you say – mids and highs are clear, the bass nodes don’t last as long with the double spring. The triple spring was even more extreme in this regard. It became too lean however as I posted a couple of posts back. Second Room – much larger (adjacent to room one) An ET 2.0 setup with gear that provides for full sound through the mids and highs, but needs help with two subs for the lowest octave with certain music. They are Quad 57 speakers. I cannot pressurize this room no matter what I do – reason is - firstly the space is too big and open and 2) my wifes TV room is close to it above and adjacent to it a ways. :^( I prefer the single leaf spring in this second room. The bass is fuller as Frogman said, but in my case as the space is larger it allows IMO for bass waves to dissipate, not bounce around causing problems. This also means harder surfaces can be used in the room to allow for clearer highs. For me the room/space dictate our preferences above everything else. TORQUING OF THE ET2 LEAF SPRING USING DOVERS METHOD I untorqued the single leaf spring in room 2 last night per Dovers recent post and the sound seemed to get even more fuller. The change was noticeable. I will experiment more with this. Dover thanks for this detail it is really appreciated. Heath Robinson Belt Drive I really like Grantn's sense of humor :^) Welcome to the thread Grantn. I have learned alot from Richard and Dover in the last few weeks. Cheers Chris |
03-23-13: Gnnett
When I look at the pictures of RK's arm I do not see an ET2. It is something specifically crafted and tuned to his system. It is not a universal tonearm. A little bit like the highly modified ET1 that Lloyd Walker uses actually. Grantn – I thought your observation was a really interesting one. You mentioned the ET1. It has a very interesting history. As a reference point here I feel it is important to understand the transition from the ET1 to the ET2. Especially since we have been debating Rigid versus Sprung I Beams/Counterweights. ET1 - is Heavier and Rigid ET2 - Lighter and Sprung I skipped through the ET1 manual from Bruces’ site. Anyone interested in Tonearm Resonances and Testing of Resonances should see pages 49 and onward. It is much more detailed than the ET2 manual in this respect and the tests apply to all tonearms in general. So why did Bruce to go from an ET1 to an ET2. Do the design and specs themselves tell enough story? There are big differences between the ET1 and ET2. Actual tonearm tube/headshell weight is more on the ET1. The small counterweights on the ET1 are actually the large size on the ET2. The spindle weights are the same. ************************************************************ ET1 specs. Spindle Weight 14 grams Tonearm Tube Weight 14 grams / Headshell weight 5 grams Counterbalance Weight 15 grams small 30 grams large. ************************************************************ ET2 specs Spindle Weight 14 grams Tonearm Tube Weight 11 grams Counterbalance weights 5 grams small and 15 grams large. ************************************************************ Has anyone heard an ET1 versus ET2 ? Cheers Chris |
For me the room/space dictate our preferences above everything else. Just to be clear - my statement is very "biased" and it is based on my personal audio hobby experiences over the years. cheers |
My view on a stereo system is that it is just a machine. Actually lots of machines chained together to give an output based on inputs. As such it is logical and the output is predictable provided we have sufficient understanding of the machine. ( none of us have sufficient understanding )
What we are talking about here is a small part of the machine. The coupling, decoupling of a counterweight on a linear arm.
Frogman and Dover say that they prefer a loose connenction and one leaf spring.
Chris says that triple springs produce a sound that is too lean.
Rockport, Walker, Kuzma and I say that there should be no spring at all.
I believe ALL of the above statements as I think that they are actually saying the same thing along a continuum.
It all depends upon the voicing of your system and our biases, and we all have biases.
Also an improvement can actually sound worse as it can expose more clearly problems elsewhere in the machine chain. Sometimes when we open the window wider, we do not like what we see. We then need to work on the new "view" to correct a previously unseen problem. It does not mean that the original change was wrong
I have said that I don't think that it is a good idea to have a mass attached to two dissimilar springs who's resonances are in the same neighbourhood. The transmissibility graph I posted shows the potential nasty consequences of this. At least a 6 x seperation of the two resonant frequencies would a target.
Using one spring lightly coupled to the spindle pushes the resonant frequency down below the arms core resonance. This is good. (As Frogman points out, there may be other factors at play here with the loose screws.) Double or triple springs push the resonant frequency above the core resonance which is also good.
We have to be carefull when using stiffer springs that we don't move too close to the audio spectrum, since the same transmissibility graph data will bite us. We also have to be carefull that we do not go to low with lite springs since we get close to eccentricity frequencies again with possible nasty consequences. So what if we pushed the resonant frequency up above the audio spectrum. We have no risk of any of the issues I raise here.
My early fixed counterweight designs resonated somewhere in the midrange. It was easy to hear adding a nice, but not accurate bloom to voice and midrange instrumemts. If my system was not already "full" in this range I may have stopped experimenting, thinking that the arm was acurate. Increasing its rigidity more, pushed the resonance above the frequency of audibility. This is desirable and is the final logical progression to the tests that have been listed in this thread.
Gnnett. Do you live in AKL? It would be nice to meet. You can contact me directly via my web page if you wish. |
Richardkrebs: Yet again I have to address your gross assumptions and misunderstanding of the principles of the ET. Richardkrebs
Frogman and Dover say that they prefer a loose connenction and one leaf spring. Chris says that triple springs produce a sound that is too lean.
Rockport, Walker, Kuzma and I say that there should be no spring at all.
I believe ALL of the above statements as I think that they are actually saying the same thing along a continuum.
It all depends upon the voicing of your system and our biases, and we all have biases. This is absolute rubbish. You are implying that the decoupling and non-decoupling are both valid, when they are not. With the ET2, the outcomes are entirely different and Bruce Thigpen has tested and measured these. The decoupled methodology employed by Bruce Thigpen is designed to minimize horizontal inertia and ensure the resonance of the I beam and counterweight remains below the horizontal resonance of the arm. The rigid coupling of the I beam and counterweight that you advocate is contrary to these stated design goals. Your comment about voicing the system to biases is as presumptuous as it is incorrect. An experienced listener can hear changes in transient speed and accuracy of timbre and timing irrespective of the system. That is how a system should be tuned. Richardkrebs
Double or triple springs push the resonant frequency above the core resonance which is also good. Your statement contradicts research and testing by Bruce Thigpen, and I quote the following email from Bruce Thigpen published above: Bruce Thigpen
Chris,
You always want the horizontal natural frequency of the counterweight to be less than the cartridge/arm resonance, this is the case 98% of the time.
The natural frequency of the I-beam/leaf spring depends on the thickness of the spring, the amount of weight, and where the weight is on the beam. The natural frequency goes down as the weight moves further out on the beam which is where we want it to be.
brucet Richard, clearly you have not done any testing to support your guesswork, otherwise you would have found that 98% of the time you are wrong. If you bothered to read the manual you would see that the double spring is for low compliance cartridges and should be used with the minimum counterweight pushed further out on the I beam to position the resonance of the I beam and counterweight BELOW the horizontal resonance of the arm. Richardkrebs
I have said that I don't think that it is a good idea to have a mass attached to two dissimilar springs who's resonances are in the same neighbourhood. Again, if you bothered to read the manual and Bruce Thigpen’s website, the decoupled counterweight is designed precisely to achieve this. Furthermore on Bruce’s website he has provided extensive test results proving this. Richardkrebs
The transmissibility graph I posted shows the potential nasty consequences of this. I have already explained to you in great length that the mathematical model you refer to, "harmonic oscillators", which you pulled out of wikipedia, does not apply. Let me help you. Read my post of 03-14-13, the first sentence begins Dover
Richardkrebs
OK now I understand where you are going wrong in your thinking. Richardkrebs
At least a 6 x seperation of the two resonant frequencies would a target. Where did you pluck this number from? Why 6 times? Please don't use an incorrect mathematical model again when you attempt to explain. Richardkrebs
We also have to be carefull that we do not go to low with lite springs since we get close to eccentricity frequencies again with possible nasty consequences. Bruce has completed extensive testing and provided clear guidelines on the use of the light spring. He has calculated the resonances and provided extensive guidance. What testing have you done, or is this purely speculative guesswork on your part yet again. Richardkrebs
My early fixed counterweight designs resonated somewhere in the midrange.
Increasing its rigidity more, pushed the resonance above the frequency of audibility. Have you tested this? What resonant frequency did you measure? More guesswork? Richardkrebs
This is desirable and is the final logical progression to the tests that have been listed in this thread. You persist in arguing your unfounded case for fixing the counterweight. Arrant nonsense. To remind readers I repeat: The decoupled methodology employed by Bruce Thigpen is designed to minimize horizontal inertia and ensure the resonance of the I beam and counterweight remains below the horizontal resonance of the arm. The rigid coupling of the I beam and counterweight that you advocate is contrary to these stated design goals. Once again, we go round the block for the umpteenth time. Bruce Thigpen has calculated, tested and measured precisely the resonances of the decoupled I beam and counterweight with a wide variety of cartridges from low to medium to high compliance to determine the level of decoupling required to optimize the cartridges performance. How many times before you get that decoupling is an integral part of the ET2 design and how the arm is engineered to optimize performance. You are clearly out of your depth. You persist in misapplying physics and just don’t seem to be able to comprehend the design. Do you run your car on 3 wheels? You have resorted to implying that readers who have tried removing the decoupling and found it to be detrimental are either fixing up defects in their system or have biases. That is an arrogant assumption, and reflects poorly of your estimation of the contributors to this thread. |
Richardkrebs
My view on a stereo system is that it is just a machine. Actually lots of machines chained together to give an output based on inputs. As such it is logical and the output is predictable provided we have sufficient understanding of the machine. ( none of us have sufficient understanding ) Richard - from what I have learned about you, IMO you are one of the few in this hobby that can build and repair your own amps, preamps and TT’s, etc... Fair statement? As an amateur hobbyist I have my ears and memories of trial and error experiences. I agree with you that the actions and reactions that are happening are more predictable to a degree with some knowledge gained. I also agree that none of us have sufficient understanding. If anyone really did word would get around, and there would be a long audiophile line up at the persons door asking for help. Now consider this perspective. I refer to the Quad 57 speaker again just as an example. I have tried multiple amps with them (SS and Tube) out of curiosity; then one day after more research I discovered that Roger Modjeski designed his RM 10 amplifier around their specific needs. I already had his larger RM9 amp which I tried with them briefly, but was concerned about damaging them. Anyway cutting to the result - I now power them with an RM10 and could not be happier. So what I think I have based on what I hear is an amp whose outputs meet the specific needs of this unique speaker. There is a harmony and effortless sound that can be heard. Now consider this. I have placed these 57’s in 4 different rooms with identical gear in front of the Rm10 amp and the 57’s. One room had hardwood floors, one was tiled, 2 were carpeted. Some rooms had drapes, other s only drywall and some pictures. One had wood panelling on one side. Their dimensions all varied and two of them opened up into other rooms. Four different music perspectives resulted in the sounds as far as the music presentation goes. This was all with the same CD player. Now add in vinyl with all its variables to the mix...... The stereo system is a slave to the space/room -imo. Just to be clear here to the readers regarding my impressions I have given. We have been discussing refinements and tweaking for the ET2. In the last 10 years I have owned an ET2 and then added a ET 2.5. In stock form as designed – out of the box this tonearm remains my reference. And fwiw - The greatest sonic bump with the ET2 came for me, when I introduced air delivery with no (very little) resonance (at the pump) and 19 psi was achieved. The ET2 tonearm setup so far for me has been 40% actual tonearm setup fine tuning, and 60% air delivery tweaking. I am sure with the continued info from this thread it will become 50 – 50 soon. Cheers |
Dover.
:Yes the outcomes are entirely different if the counterweight is fixed....so.
:We have established that it will not be the end of the world for the cartridge if the horizontal mass is increased, this by reference to other arms that are heavy.
:Countary to stated design goals yes.....so.
:While BT designed the cw arm to swing at frequencies below the core arm frequency, it does not neccesariy prove that using 2 springs will result in that criteria being met. It is almost certain that the use of three springs, as Chris did will push the frequency above core.
:I know that BT designed the arm to have the two spring systems, Cart and Counterweight. I just don't think that it is a good idea because they talk to eachother. Has anyone thought about why the CW spring(s) and their damping are so fussy to set up?
:Yes I pulled the resonance graph and math from the net. This because it explains the effects more clearly than the literature we regularly refer to here at my work. Those readers that understand the math will know why I chose a 6 times multiplier.
:My prime reason for fixing the counterweight is to restore the full bass drive. You have in an earlier post talked about not needing response below 30hz and that response in this region can be problematic, or words to that effect. I do want response in that range and yes it can be difficult to sort this area but with effort it can be done and the results are most rewarding.
:We are all biased, it is astonishingly arrogant to suggest that you are not.
Chris.
Agree the room is critical, same for the air feed.
|
ET 2.0 spindle versus ET 2.5 spindle I am focusing on the spindle /counterweight. I have some info to share. It can be difficult from pictures telling the differences between the ET 2.0 and 2.5. This makes it easier. Pictured is the ET 2.5 spindle Significant differences in weight and diameter. 19 gms ET 2.5 versus 11 gms ET 2.0. Chris,
About 19 grams with the aluminum inserts which are machined from bar stock. The 2.5 tubing has about the same wall thickness as the 2.0.
brucet Richard/Dover/theKong/Frogman others. I find this significant based on the recent damping conversations. I will have more information coming from Bruce when he has time to discuss. I feel this info will enlighten us. The only clue I have been given. "horizontal resonance to be above 2-3Hz but at least 4 to 5Hz below the vertical resonance" TWEAK I have also come up with something that I believe is significant as far as sonics are concerned and requires only a one minute adjustment. This is based on only one listening session but is so easy to try I had to share it. Loosen the end cap bolt (not the leaf spring bolt we have been discussing) just enough to lower the lead weights, so that they are positioned at the bottom half of the spindle; when looking at the arm from the gooseneck side. Once done tighten end cap again. This increases the VTF significantly. You will need to adjust by moving the lead farther out on the I Beam. A good thing. Cheers |
Loosen the end cap bolt (not the leaf spring bolt we have been discussing) just enough to lower the lead weights, so that they are positioned at the bottom half of the spindle; when looking at the arm from the gooseneck side. Hi Ct, In all the photos I have seen on the Walker turntable, the counterweight set-up was below horizontal. So, I suppose that is intentional and offers some advantages, at least in that design. I must apologize that due to my schedule, it will take me a while to have the time to do a thorough comparison on the counterweight set-ups in my system. I will report it here at once when I can complete the test! |
Chris, thanks for the tip. I will try it and report back. |
As we have been discussing the pros and cons of the decoupled counterweight on the ET, I have this question on my mind (admittedly a non-technical one) for a long time!
The ET uses leaf springs to decouple the counterweight so the arm doesn’t “see” the additional weight! To my thinking, this can only be possible if the counterweight actually doesn’t move during the initial movement (milliseconds?) of the arm, due to the compliance of the leaf spring. Then, after the arm has moved for a certain range, the counterweight would need to start “rebounding” to follow the arm.
If that is true, then would it create some delayed effect that could be detrimental to the tracking?
Or is my reasoning totally false? |
Thekong - yes you are correct. That "rebound" as you call it has a resonance. The idea behind the variable spring rate and shifting the position of the lead counterweight is to place that resonance below the horizontal resonance of the arm so that the 2 resonances ( arm and beam ) do not couple together to produce a large peak at the arms resonant frequency.
All tonearms will have a lift or peak in response at their natural frequency. The tuning with the I beam ( decoupled ) is designed to reduce this natural bass peak at the resonant frequency of the arm to produce a flat bass response. This is illustrated in the graphs on Bruce Thigpen's website where he has published some of his test results.
The idea behind loosening the I beam that I outlined in my earlier posts is to lower this "rebound" resonance, by allowing the I beam to swing freely and also keep the horizontal arm mass low. Some wag above says you get no response below 30hz but that is not correct. You get a low fall off in bass below 30hz.
Rigidly coupling the I beam will increase the bass, adding more bass lift at the resonant frequency and beyond. If you run 30 year old Acoustat 2+2's in a room barely 10ft x12ft, listening position 5 feet from the panels and you like humpa humpa one note bass, then that is your ideal solution. |
Hi Dover,
Thanks for the explanation, will certainly try all different set ups and see the difference myself! |
Hi theKong – answer to your question from Bruce. Thanks for that info as well Dover. Acoustats ? won't go there.
03-27-13: Thekong
As we have been discussing the pros and cons of the decoupled counterweight on the ET,
I have this question on my mind (admittedly a non-technical one) for a long time!
The ET uses leaf springs to decouple the counterweight so the arm doesn’t “see” the additional weight!
To my thinking, this can only be possible if the counterweight actually doesn’t move during the initial movement (milliseconds?) of the arm,
due to the compliance of the leaf spring.
Then, after the arm has moved for a certain range, the counterweight would need to start “rebounding” to follow the arm.
If that is true, then would it create some delayed effect that could be detrimental to the tracking?
Or is my reasoning totally false?
Thekong (Threads | Answers | This Thread)
********************************************************** Answer from Bruce. Chris,
The counterweight is decoupled in the horizontal plane so it only affects lateral motion of the tonearm. The counterweight always moves if the spindle is moving, it does not move at the same rate, the time constant is about 300 milliseconds. 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. The motion of the weight is damped so that it has a low "Q" resonance with a rise in response of about 3-4dB at 3hz and 2dB at 10-11Hz, these frequencies do not coincide with the vertical resonance.
More important than tracking, the intent was to reduce the modulation effects of low frequency energy (FM and AM) that increase distortion in the cartridge, amplification chain, and especially in the speakers woofer at a few Hz. I hope this helps.
brucet
Boy I wish I had someone like Bruce for when I go into these board meetings trying to sell services to CEO’s and CFO’s. You know the ones where they bring their own in house techies to the meetings to ask questions. Cheers |
Chris, your diligent follow up with Bruce Thigpen is much appreciated: 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.
More important than tracking, the intent was to reduce the modulation effects of low frequency energy (FM and AM) that increase distortion in the cartridge, Bruce Thigpen’s contribution affirm my statements over the past 7-8 weeks that Richardkrebs fixation with adding lead mass to the arm and coupling the I beam will increase distortion, affect tracking and produce an unnatural bass lift in response. My own analysis has long been based on a thorough understanding of the design principles and physics involved. It is disappointing that those who disagree, and clearly do not grasp the principles involved in this arm, have resorted to denial and personal attacks 03-04-13: Richardkrebs
Dover
Your scaremongering
03-17-13: Richardkrebs
Dover.
Hasn't this discussion run its course.
03-18-13: John47
Mr Dover’s bombastic contentions.
03-21-13: John47
Put on your knitwear cardy so don't catch a cold, your thick lensed glasses so you don't fall, then pop out and replenish your Prozac.
03-23-13: Gnnett
As a New Zealander I would like to apologies for the behavior of Dover. It is a narrow country and this breeds narrow mindedness. All too often denial and personal abuse is the last refuge of the desperate. Sadly those posters who are fixated with the idea of adding lead mass and removing the decoupling will continue to deny the science and exhaustive testing and measurements that underpin Bruce Thigpen’s design. If they prefer the sound of the arm set up incorrectly, there are clearly fundamental flaws in their system and they should look at the rest of their components and set up. This includes the environment in which they are listening. 03-04-13: Richardkrebs
Dover
I am the only person here who can speak with any authority on the subject. Richardkrebs, the ET2 is a brilliant design and deserves to be treated with respect. |
Frogman/theKong, others – regarding lowering the position of the lead weights.
Based on my own experiences, positioning the lead to be lower is not something imo, that any ET2, ET 2.5 owner is going to do naturally or instinctively. The reason being it is not as ergonomic. When you try it you will see it is easy to touch/scrap the plinth/armboard with the end of the I Beam, when you lift the arm at the end of a record. That is, if you have developed a habit like I have, of lifting the arm tube higher than required in protection of the stylus. This was an easy habit to break.
I talked to Bruce about it and he said multiple parameters get changed when doing this and that in general he's for an adjustment that results in an increase in VTF requiring the lead being moved further out on the I Beam. But we need to try it out in our rooms/gear. Look forward to both of your impressions when you get a chance to try it. I’ve had two positive listening sessions with now.
Cheers |
Dover...your diligent follow up with Bruce Thigpen is much appreciated Dover you’re welcome. I like to publish information for thought especially when it comes from a Subject Matter Expert (SME). Someone who by the way takes an interest in our activities and findings, and continues to experiment on his own. The info was not meant however to trigger any type of civil unrest with the NZ audio club. Fwiw - I have heard many stories of civil unrest from my Grandma and parents. In Canada I have seen civil unrest twice when Quebec decided to separate. Democracy prevailed. If democratic polls were held today I am not sure but I think the vote would be 2 – 2 or 3 – 1 against you. Good thing this is a hobby ? |
Chris - thanks - no war down here.
My motivation is to help people set their systems up correctly and learn more. We all learn from shared experiences. The debate over the past 7-8 weeks could have been much shorter had it not been inundated with junk science.
Richardkrebs, claims to be an authority, yet all the way through been belligerently dismissive of Bruce's recommended set up procedures and of the design principles that underpin this arm. Many of his arguments put forward were simply nonsense.
Everything I have said has since been verified by Bruce Thigpen's recent communications. The addition of lead mass and removal of the decoupling of the I beam will load the cantilever, increase distortion, and deliver a bloated bass response.
Would you have rather everyone who read this thread ignore Bruce's advice - add lead mass and bolt up their I beams as was suggested ad infinitum?
That, along with much uninformed comment, is an affront to the time and dedication that Bruce has put into this product. It is impossible not to have robust debate when basic scientific principles continue to be denied.
|
Dover.
To address the points raised.
Scaremongering.
This comment was posted in response to your claim that the weight of my arm was sufficient to cause damage to cartridges. You actively warned others against adding mass because of this belief. During the course of this discussion it emerged that the Kuzma is actually heavier than my arm.
While it is self evident that the forces seen by the cartridge will be higher with the Kuzma, you have posted zero evidence that these forces are sufficient to cause damage. The Kuzma has been around for long enough now for any problems of this nature to have surfaced.
Scaremongering....Absolutely.
My comment about being the only person who could speak with authority on the subject was referenced to the sound of my modified ET in its current form. That is a true statement.
It must have been 5 years since we heard each other's systems.
I have not commented on my impressions of yours because I assume that your system has improved since then and any comments I made would be out of date.
I would expect the same courtesy from you.
For the record. While the room is small, it is larger than you recall.
Re the acoustats, they may still look like 2+2s but that is where the similarity ends. Further someone once said something like. .. many a fine tune played on an old fiddle.
BTs letter is clear and well understood.
My position has always been that there are valid alternatives
Rockport, Walker, Kuzma. Just like Bruce, these arms are designed by people who are obsessive in their quest for ultra quality accurate record reproduction. The sales and reviews of these products would suggest that they have indeed achieved superlative results. With a design approach that you claim is fundamentally flawed.
Their designs are valid and I would say that it is l disingenuous on your part to suggest that the owners of these arms possess equipment that needs to be "looked at" , that they are all listening in comprised rooms and that they all prefer one note, excessive bass, along with the sound of miss tracking cartridges.
Yes the ET2 is a brilliant design. There are other brilliant designs |
Richardkrebs - So predictable. Yes there may be other brilliant designs, but the discussion is about the ET2, in case you've forgotten.
Yet again you just dont understand the physics.
You are trying to turn the ET2 into a home brew Kuzma, Rockport, or other design which have started with a different set of design parameters and operating assumptions completely - different masses involved, different bearings required, different air pressures required, forces will be seen by the arms differently and completely different set of resonances involved, all of which are fundamental to the performance of any of these arms.
You are tinkering around trying to convert a low mass tangential arm into a high mass tangential arm but have failed to address most of the queries I raised. You have provided some home grown theories and analogies that bear no resemblance to engineering science. You have provided no measurements of your system to support your assertions.
Bruce Thigpens documented design brief and extensive testing show that your approach is wrong in the context of the ET2 ( this thread is about the ET2 ).
I remind you that if you go back to my very first post after you described your lead footed home modified ET2 that my comments on increased distortion, increased cantilever flex, possible record damage from mis-tracking were all preceded with the words "on eccentric records" and I stand by that statement.
In your self taught engineering school of fabulosity do you understand what an eccentric record is?
Do I need to remind you of the laborious weeks of denial on your part that the cantilever does not see the side loads generated from an eccentric record, accompanied by much junk science subsequently refuted by Bruce Thigpen.
Do I need to remind you of the incorrect advice you gave to Thekong and then retracted when I pointed out your own self conflicting arguments, which you then retracted.
In a nutshell Richard you are telling Porsche drivers they can improve their car by converting it to a Hummer. If you prefer the Hummer, I have no issue with that. If you try to tell me that there are no consequences arising from this conversion then you are wrong - yet again. |
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: Richardkrebs
It could be that tuning here with springs and weights (and their position) is at least partly to do with sorting this possible frequency interaction rather than just the weight or stiffness employed.
03-20-13: Richardkrebs
The thought that there may be more going on with the decoupled counterweight was triggered by your post where you quoted BT where he said that the ibeam had a natural frequency of 2-5 hz.
This is close to the resonant frequency of the arm itself. This could have performance implications. That 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. |
Question regarding how the whole 'arm' structure/material and how it 'mates' with grounding, regarding tonearm wire?
Some arms are prewired with a 5 wire loom/ one lead specifically for ground. Why is this not needed/offered with the ET? How does magnesium serve as an electrical conduit? |
Hi Slaw,
The arm wand and bearing tube are ungrounded. I tried grounding the aluminium arm wand but couldn't hear any difference. I had a major problem with RF when using van den hul monocrystal silver wire, and went back to a stranded copper litz ( same as used in the old Sumiko PBT tonearm interface ) and had no RF problems whatsoever after that. My arm cable went from the wand straight into the phono on the side of the TT rather than through the bearing tube. If you are using the aluminium arm tube, running an electrical signal along a piece of aluminium can induce hysteresis distortion in the signal and maintaining a litz configuration would be desirable. |
Richardkrebs re your last post.
I believe we have something in common. In the contract work I specialise in I too am totally indispensable. Not only dozens but hundreds of employees world wide depend on my expertise. One mistake and a company could be bankrupted. Worse still, the New Zealand economy could collapse. Like you I also understand Q, and P that comes before it and R that comes after, and the other 22 letters of the alphabet too. Part time I moonlight as a neurosurgeon. My expertise in soldering gives me the manual dexterity to perform such delicate operations. It provides a diversion from responding to lunatics who post garbage on audio blogs. With your background in avionics, you would have become accomplished in soldering too. Perhaps you could apply one of your many talents to a part time career in neurosurgery. Just a thought. |
Hi Slaw – are you running an in room ET2 filter or pressure regulator ? I added a ground to the in room regulator at the suggestion of Richard. It seems to have helped. Recommend you give it a try. Hum Story and maybe a lesson. I am finishing the space in the adjacent basement area next to my main room. I noticed a hum coming from a certain area in the room near the ceiling by a light. Looking over I noticed a little transformer attached to the light base from the time the house was built. It was humming away – could be heard from a few feet away. I disconnected it and peace prevailed. The room is quiet now. My wife is not too happy because I have not yet reinstalled the wire to the back of the house like I said I would. I have discovered that I like not having a doorbell, and I told her there is a “door knocker” on the door. My kids are on my side on this one. But they are also the ones too lazy to get up and see who is at the door whenever anyone shows up. Now here is something I find interesting. Of the people that come to the door. No one appears to know what the obvious “in your face” door knocker is for anymore. They knock with their knuckles instead when they discover the push button doorbell doesn’t work. We have become a pushbutton society. My Lesson Learned. What if you have a system on a raised main floor, and the gear is sitting in a rack, or near the ground (amp/s) a foot or two from this humming transformer just below. Only a wood floor separates them. Dover was the noise from the silver wiring noticeable on your Final Audio or another TT ? 03-31-13: Dover
Richardkrebs re your last post.
I believe we have something in common. In the contract work I specialise in I too am totally indispensable. Dover/Richard, in my line of work (business continuity planning) one of the key objectives of every project for the consultants is to identify and eliminate as many SPF’s as possible. Single Points of Failure. By eliminate I mean an "action plan" for management to follow in a powerpoint or similar presentation. Richard, as an admirer of the Kuzma Airline tonearm; do you have any thoughts on Kuzma’s Top of the Line Version which comes with a Brass ArmpodHave you ever used, experimented with a armpod ? Cheers |
Dover-Chris, Thanks... I'm using a carbon fiber arm wand. My main concern in my upcoming tt design is the tonearm wire construction, and implementation. Some of you may remember, I have the AN wire in the wings, I'm not very confident on my skills as a small guage tonearm wire constructor. "Huh?" I've had several carts, throughout the years, mm & mc's, there is more noise associated with MM's. Should/could I try to run a ground from the armwand separately? My belief is that the CF armwand is a cf skin, on a magnesium or aluminum core??? The headshell is the same for all armwands??? |
A note.... the level of information and experience here is remarkable! I'm glad to be a recepient. Keep it coming.... |
Chris/Slaw - At the time I tried the van den hul the arm was mounted on a Roksan Xerxes. I was using a Shure V15Vmr so that could have been a contributing factor for picking up RF due to the higher impedance than a MC. Having said that, with litz wire there was no RF in the same situation. This suggests that even if you cant hear RF a litz wire will provide a lower noise floor. |
Hi, I hope that you all had a great Easter break with Family and Friends.
Chris. I don't have any first hand experience with arm pods. They tend to go against the grain so to speak, in the quest for absolute dimensional stability between platter and arm. That said it seems that there are many admirers of this approach and, other than to quote others, it would not be prudent for me to comment on the sound of something I have not personally heard.
Re arm wiring and earthing.
For anyone looking to earth the aluminium wand. Anodised al is an insulator so you would need to scratch thru this to bare metal. Something I would be reluctant to do.
Earthing the air stream should be done as close as possible to the arm. I have a pressure gauge close by and have grounded the metal part of this that protrudes into the air line. Simply cutting the hose and rejoining with an appropriately sized metal tube would do. Solder an earth wire to this. You can expect a quieter backdround and a good jump in transients.
I have been waiting for someone to run the arm wiring completely outside the wand and spindle. The results would be interesting, assuming that there are no RF issues.
Wouldn't look to pretty however. |
