Have filters and a pressure gauge, but not sure what a "regulator" is and locally what industry would be the best source for a suitable unit. Hi Grant - this picture shows a regulator (black top dial knob), moisture bulb and trap, pressure gauge They can be purchased separately or as a unit at any hydraulics place typically located in industrial areas. Total cost about $70 us dollars. The regulator allows you to dial the pressure down or up. The one in the picture is portable. You can hold it in your lap sitting in your sweet spot, and adjust the pressure up or down and hear how the music delivery is affected. You open the regulator by lifting up – turn clockwise and counter clockwise. When the music sounds best to you in your room – push it back in to lock – your done. As a kind of tune up I personally recommend anyone with an ET2 send alot more air than is needed to the tonearm so you can determine if you have any leaks from screws/bolts. This tonearm was meant to last forever – its industrial quality just like Bruce’s subwoofer :^) subwooferThe worst thing you can do is blow the tube off. Bruce Thigpen can also replace your low pressure manifold for a high pressure one. This changes out the manifold only – the spindle stays so you are left with a high pressure ET2 not a ET 2.5. I recommend emailing him to get the current price which is very reasonable. The high pressure manifold allows you to run low and high pressure with the ET2. Cheers |
The pump talk reminded me that Ketchup provided ET2 flow rates to us back in Nov - here is the link to his post which contains the information from his testing. Thx again Ketchup. ET2 Flow Rates |
Richard Krebs ET2 Setup (Custom) Richard Krebs ET2 setup pic 1Richard Krebs ET2 setup pic 2Hi Richard, if you are in a position to discuss many are probably wondering what I am right now from looking at these pictures. I have to ask if any of what we see can be duplicated, made again, or was it a one time effort of passion ? Not your typical counterweight setup ? If you are not in a position to discuss – understand - wonderful setup. Cheers Chris |
Chris, I was Googling images of "Garrard 301" and "ET-2" or something like that today and actually spotted another picture of Richards table. There are a few pictures here near the bottom of the thread. I have thought about making a new manifold housing for mine, but I eventually come to my senses and realize that I should just get the table up and running first! Anyway, can you believe that I can not find one photo of a Garrard 301 with an ET-2 or ET-2.5 arm? |
Chris
I built this version of the ET2 around 15 years ago. Drawings are long gone but it could be reverse engineered. The arm is optimized for low compliance carts. As you can see, just, from one of the pics Ketchup found, it has a fixed counterweight. I have a view on linear arms in that the rules for pivoted arms and effective horizontal mass do not apply. In fact I have added a lead slug inside the bearing spindle 25 mm long with its OD equalling the ID of the tube. This is glued in place halfway along its length. ( it can be removed if I go to high compliance carts)
This combined with the fixed counterweight means that the arm is HEAVY in the horizontal plane. I have tried magnetic dampening and oil troughs but prefer the pure mass approach. I run at around 12 psi, lower pressures may be problematic when adding so much mass.
On the magnetic dampening front the negative I heard was possibly caused by the induced circulating currents interfering with the cartridge output
The manifold and arm pillar are made from acrylic. Lead is inserted and epoxy glued inside these to sink energy. VTA is adjusted by a removable screw after loosening 4x M5 cap screws. Manifold and pillar are locked solid once these are tightened. The arm was designed with a lifter like the ET but I found a subtle improvement when this was removed. Same goes for the VTA adjustment screw. I. E in its operating form there are no bits to flop about. Arm pillar is fused to the plinth effectively making it one assembly.
Cartridge leads are single strand silver lightly twisted at about one turn per 8 mm. Continuous to the preamp
Big jumps in performance were the goose neck. (This was made from the same grade of aluminum as the wand.) The bracket that joins the wand to the spindle.
There are 2x M2 grub screws outboard of the bearing sleeve orings. These pass thru the manifold and contact the sleeve. Two small pieces of shim metal are inserted at 120 degree increments away from the grub screws. Once tightened the grub screws eliminate the compliance of the orings. There should be nothing soft in the loop between record and cartridge. This is a major improvement. There may be room on the standard manifold to do this but Beware anyone doing this it would be easy to break the manifold.
I use 2x 50 liter containers for the surge tanks. They are stuffed with long hair unspun wool to increase their effective volume. They are seperated by 6 meters of 1/4 hose entry and exit points are at opposite ends of these tanks.
Chris you have a regulator, water separator. It looks like it uses brass fittings and appears to be close to the arm. Try soldering a wire to the exit fitting and earthing this. I don't know why this works but it is possibly something to do with static electricity build up in the air stream.
On the topic of static electricity try rubbing the wand with AFC anti static foam cleanser. The stuff they use on photocopier glass.
Have removed the Teflon in the head shell and replaced with a square of 1/2 mm thick lead and superglued in place. Others have tried different materials here also with good results.
I have a new arm on the drawing board based on what I have learnt from this one. |
Hi Richard – thanks for joining the thread and Ketchup thanks for that link which shows better pictures. Richard - A lot to think about in your post thanks for sharing. I need to digest it some more. A few things that hit me immediately though. Big jumps in performance were the goose neck. This was made from the same grade of aluminum as the wand. The bracket that joins the wand to the spindle. I have always wondered about that Gooseneck – listed as the joint in the ET2 arm parts list. Before I ask Bruce if he can make a special run of aluminum ones for Et2 owners , do you have a source for making them ? If we asked ET2 owners here we could probably come up with a certain number of owners that would want to try an aluminum one? I know I would take two for the different size ET2 and ET 2.5 spindles. The manifold and arm pillar are made from acrylic. Lead is inserted and epoxy glued inside these to sink energy. VTA is adjusted by a removable screw after loosening 4x M5 cap screws. Manifold and pillar are locked solid once these are tightened.
Arm pillar is fused to the plinth effectively making it one assembly. I really like your custom arm as it is sleek and clean looking but that the adjustments have been eliminated that could cause movement. Very solid but you can still make VTA adjustments. Chris you have a regulator, water separator. It looks like it uses brass fittings and appears to be close to the arm. Try soldering a wire to the exit fitting and earthing this. I don't know why this works but it is possibly something to do with static electricity build up in the air stream.
On the topic of static electricity try rubbing the wand with AFC anti static foam cleanser. The stuff they use on photocopier glass. I am definitely going to try both of these ideas - thanks Have removed the Teflon in the head shell and replaced with a square of 1/2 mm thick lead and superglued in place. Others have tried different materials here also with good results. I have not got around to doing this. I remember Dover discussed doing this on his ET2 as well. Its a bit of a pain to remove that Teflon piece ? I have a new arm on the drawing board based on what I have learnt from this one. Richard - Will this custom arm be designed for a specific type of armboard / plinth, or will it be designed to be used with different armboards/surfaces ? Your counterweight is now fixed. I assume you are are not using the leaf spring? We have discussed the advantages of the single, double triple spring here. This would be a very interesting discussion plus the lead slug you mention. Cheers Chris |
Ketchup
Anyway, can you believe that I can not find one photo of a Garrard 301 with an ET-2 or ET-2.5 arm? Ketchup - Does a JN Lenco with an ET 2.5 count ? |
Richard,
It sounds like you have a lot of time into that arm. Very nice! A few months ago I took my ET 2.5 manifold out of the housing to give it a cleaning before I did the flow tests that Chris linked to above and to see how it's built. Upon reassembly, I saw how much give there is in the rubber o-rings and realized that the manifold is not rigidly mounted at all. I thought briefly about a way to stiffen the assembly.
It should be possible to insert three precision shims between the manifold and the manifold housing. They will probably have to be somewhere around .0005" oversized (or less) to get them in without deforming the manifold housing to the point of cracking. Once they're in, there should be no need for set screws which may be a problem for a stock housing. This is not for everyone as you will need a way to slowly creep up to your shim thickness a tenth of a thousandth of an inch at a time unless you happened to get lucky and already have the correct size shim.
Another option is to do what you did (or use three screws instead of one screw and two shims) but put the screw(s) on the inside of the o-rings. A little silicone on the threads may be enough to hold back the 15-20 psi.
Chris,
Nope! It’s got to be a 301 :) |
Richardkrebs Re: your ET2 mods. Here are a few points for you to consider. I have a view on linear arms in that the rules for pivoted arms and effective horizontal mass do not apply. In fact I have added a lead slug inside the bearing spindle 25 mm long…
This combined with the fixed counterweight means that the arm is HEAVY in the horizontal plane. This view is indeed strange. Many records are off centre. By increasing the horizontal mass of the arm significantly, when you play an eccentric record the increased resistance to motion from the additional mass will result in increased cantilever flex. On eccentric records your approach will result in phase anomalies during play back, increased record wear and probably cartridge damage in the long term. My ET2 has been lightened, no internal dampening, no external tube dampening, decoupled counterweight and have had no issues tracking low compliance cartridges, achieving extended bottom end with speed, articulation and accurate timbre. Magnetic dampening controls lateral motion on eccentric records. The arm is optimized for low compliance carts. As you can see, just, from one of the pics Ketchup found, it has a fixed counterweight. I have found the opposite. Using various Koetsu’s and a Denon 103 Garrott I found that there is an optimum decoupling point. Eliminating the decoupling resulted in more “apparent” bass but with less speed, articulation and timbre. In my decoupling methodology I used teflon pads either side of the spring with the end cap quite loose. This gave a soft lossy quality to the motion as opposed to springy. On the magnetic dampening front the negative I heard was possibly caused by the induced circulating currents interfering with the cartridge output I could not hear any distortions of this nature with the magnets located on the opposite side of the manifold from the cartridge wand and using copper litz arm wiring that exited before the gooseneck and straight into the phono 12” away. Cartridge leads are single strand silver lightly twisted at about one turn per 8 mm. Continuous to the preamp Highly prone to rf, might explain your perceived issues with magnetic dampening. Have removed the Teflon in the head shell and replaced with a square of 1/2 mm thick lead and super glued in place. With low compliance cartridges, there is significant energy generated for the arm to deal with. This energy needs to be wicked away from the cartridge and sunk to ground. To maximize this energy flow away from the cartridge materials should be used that that successively increase propagation speed heading towards ground. This encourages the energy flow away and minimizes reflection of energy back towards the cartridge. Inserting lead into the head shell creates an energy reservoir that will sink energy, but due to the softness of the lead some will be released back into the cartridge out of time with the music. The same argument applies to the use of a lead slug in the bearing tube. This causes smearing and loss of detail. I would not recommend the use of lead. One other question I have on your SP10mk3. You mentioned you are using an acrylic/lead/acrylic plinth. It appears from the photos that you have bolted the motor to the bottom piece of acrylic and the ET2 to the upper piece of acrylic, with the lead layer in between. If so this would compromise the loop rigidity between cartridge/arm/platter required for accurate playback. |
I'm bowing out, while whatever I offered, maybe, somewhat remembered. ( for what, that is for you to determine) Good luck to you all! .... remember the dragonplate... I'm not associated...> |
Ketchup
Yes your shim idea is a good one. I wonder if it would be possible to fashion tiny wedge shaped shims and push them in. Could maybe eliminate a bunch of trial and error with individual parallel shims.
And yes I agree, there is considerable compliance in the orings. Also in the original goose neck and arm pillar/ manifold interface.
Chris, yes I have the CAD CAM machines that could make the goose neck and a complete arm. ( excluding spindle and sleeve. ) It would however be costly due to the likely small runs.
The original Counter weight mechanism has been discarded. Adjustment is by means of two knurled discs, either side of the weight, on a M10 threaded rod. You can kinda see this in one of the pics Ketchup found.
Ref horizontal mass, I realize that this is controversial. I simply encourage those of you who feel the urge to try it. Particularly those of you that have full range systems. ( response into the lower 20s )
If we redefine horizontal effective mass as resistance to lateral acceleration we will see that magnetic and oil dampening are similar to " pure mass" all three options resist lateral movement and all three increase this resistance as the lateral movement increases in frequency.
All three impose lateral forces on the cantilever when the record hole is not centered.
The reason that I believe that the rules for horizontal effective mass are different for pivoted and linear arms is this.....
With a pivoted arm the horizontal effective mass in multiplied by the head shell offset. Only a percentage of the cantilevers lateral movement is resisted by the arms horizontal mass in trying to rotate the arm the rest of this movement is resisted by the cantilevers efforts trying to bend the arm tube itself. Linear arms do not impose the second characteristic on the cantilever. This I believe is one reason that the pivoted arm guys complain about a lack of gestalt from linear arms. We largely fix that with oil troughs or magnets. Pure mass is another option
Lead is strategically placed in an ascending hierarchy throughout the arm and TT itself. Tests with a number of soft and hard materials in the head shell and elsewhere convinced me that "local" sinks are beneficial.
While the magnetic dampening was an improvement over the oil trough, it was not as good as the recently added lead slug. It is speculation on my part why this is, but the induced currents seem to be a logical possibility. If they do exist, I suspect that they would be AF in nature, not RF.
I heard this, admittedly, small problem with the original arm wiring, OFC Litz headphone wire I then used and with the silver I now use.
Twisted pairs of wires are less susceptible to RF due to common mode rejection.
In my TT, the arm and motor are rigidly fixed to the same upper acrylic layer.
Dover, are you still running an ET2? |
Richardkrebs
With a pivoted arm the horizontal effective mass in multiplied by the head shell offset. Only a percentage of the cantilevers lateral movement is resisted by the arms horizontal mass in trying to rotate the arm the rest of this movement is resisted by the cantilevers efforts trying to bend the arm tube itself. Linear arms do not impose the second characteristic on the cantilever. This I believe is one reason that the pivoted arm guys complain about a lack of gestalt from linear arms. We largely fix that with oil troughs or magnets. Pure mass is another option Hi Richard – Have you actually measured these forces? I find it very interesting that what you say is supported by information I have from BT on actual testing that he has done with pivot and linear arms. His measurements found that this phenomena (horizontal effective mass, multiplied by the head shell offset and the resulting bending of the cantilever) produced a +6 to 12dB bump between 10-15 Hz versus flat response down to 5Hz (the ET-2). He also went on to say that “over the years these parameters have been mathematically analyzed and are well understood. There is an easy measurement to prove all of the above, it is called is wow and flutter. If you take the same turntable, put a straight line tonearm arm on it and a pivoted tonearm, both with the same cartridge, the straight line arm will exhibit about half the measured wow and flutter.” I have his summary findings on this if anyone is interested. Alot of his findings again are in his ET2 manual available publicly. Some of it was posted here already here already. Richard, Dover others ...... any comments on this very basic wow and flutter test ? |
Hi Chris - yes I agree with Thigpens comments, but I think Richardkrebs high mass approach throws away the advantage of the ET2 over other tangential arms, that is the light horizontal mass. The ET2 is less than 25gm compared to the 80g of the Terminator. The effective horizontal mass of the ET2 is even lower with a decoupled counterweight. The other problem with adding mass to the ET2 is that not all low compliance cartridges are created equal, as the compliance in the horizontal plane cannot be assumed to be the same. For example the Denon 103 is far more rigid in the horizontal mode than the Koetsu even though they are similar compliance vertically. |
Chris.
No I have not measured these forces and would be very interested to read Bruce's comments on same. I assume it is a big file, so can I ask you to email it to me at the contact address on my web page, if not too much trouble. Or if appropriate post it here.
As per my earlier post, both an oil trough and a magnet impose a resistance to lateral movement as seen by the cantilever. They behave much like weight in the lateral plane. I have simply used weight alone.
I did my initial tests on extra horozontal mass by disabelling the leaf springs on the counterweight beam and winding equal lengths of solder around the goose neck and counterweight assembly. This way I kept the lateral balance of the arm static. It didn't look pretty but was informative. I also tried this configuration with and without magnets.
I currently adjust for different cartridge compliances by using a range of counterweights.
Dover, I seem to remember from this thread or another that you no longer use an ET2. If so, we would be intereted in what you are currently using and any reasons for the change. As we all, I think, agree, the ET2 is pretty darn hard to beat. |
Hi Richard – email sent.
Where are my manners ? Do you want to try the 420str cartridge?
Your table and arm would need to be set up for the higher compliance.
I was all ready to send it to NZ anyway.
When you are done you can maybe pass it to Dover? I think Dover misplaced his ET2 - and I think it may have something to do with a drink called Slivovitz from Serbia. Maybe Nandric (Nikola) can provide more details on this.
Hopefully Dover gets it back soon
Glad you guys on the other end of the world have a sense of humor.
Cheers Chris |
Chris.
Thanks for the offer but I must respectifully decline. I am just dialing in my Shelter and newly renovated enlarged room. More distractions, while delightful, are unfortunately just too much for now.
re my building a new arm. The design would allow for bolting to a flat surface with three screws. Simalar to the ET. It has fully adjustable horizontal mass independant of the counterweight. I am struggling with the wand design at present, which is a little radical. While I can visualise it, I'm not sure I can build it. The whole project may founder on this. If I am to build a new arm, I want to be pretty sure it will be a step up from the present version.
Dover, what did you do, loose your ET2 in a drunken poker game or something? |
Chris/Richard As per my earlier post, both an oil trough and a magnet impose a resistance to lateral movement as seen by the cantilever. They behave much like weight in the lateral plane. I have simply used weight alone. This is incorrect. This is like comparing apples, oranges and pears. Magnetic dampening will vary with the speed of horizontal motion whereas the added mass approach is simply increasing static inertia considerably. The resultant behavior from an additional horizontal force will be quite different. Same for fluid dampening. In terms of sound - with magnetic dampening I have gotten increased cartridge output, which indicates that the cartridge is losing less energy due to micro vibrations being damped. By contrast with all fluid dampening I hear a loss of speed, focus and detail. Dynavector also concur with this view in their discussion of their tonearm design. Despite the high horizontal mass they use eddy current dampening to reduce micro vibrations. In my view the ET2 is the best arm I've used. I changed to a Naim Aro due to problems with a sprung floor and growing tired of pumps, tanks and airhoses running through the house. The ET2 is out on loan, but at some stage it will come back. In engineering terms a unipivot is the most rigid bearing you can get. I chose the Aro because compared to the Graham of the day it had no arm tube dampening, the Graham arm tube was full of crap, and the bearing was the correct way up for energy dissipation to ground ( the Graham had what I call an upside down bearing, point up ). The sound of the Naim Aro is quick, lucid through the mids, excellent soundstage and very musical. The downside is that I believe it has a very narrow operating window in terms of cartridge compliance and mass. The Dynavector Nova 13D sounds excellent as does a Denon 103D. The Koetsu Black sounds awful, unstable in the bottom end. I recently purchased an FR64S to try with my Ikeda Kiwame - this arm is one of the best pivoted arms I have used and due to the detachable headshell I am currently running this so that I can play around with all my cartirdges - Ikeda Kiwame, Dynavector Nova 13D ( freshly rebuilt from the ground up by Dynavector Japan ), Koetsu Black and Denon 103D. No pivoted arm in my experience can match the transparency and presentation of the soundstage as well as the ET2 though. Furthermore as you will be aware, there is plenty of bottom end depth and speed if set up properly, despite reports to the contrary. |
Dover, can you clarify a few points concerning the effective horizontal mass of ET? The manual states that it is 25-35gms. Is this the mass of the wand plus manifold tube, which is then increased by addition of up to 40gms in counterweights?
I understand that the mass of hanging decoupled counterweights behaves differently than fixed counterweights. It would be interesting to have the math on this horizontal pendulum effect. In any case, while the design may lower horizontal inertia to an extent, it will also contribute to horizontal inertia to an extent. I would imagine that the effective horizontal mass of the entire moving system is quite a bit higher than 35gm.
In the course of developing the predecessor of the Trans-Fi tonearm, Poul Ladegaard experimented with a pendulum counterweight. For whatever reason that feature was abandoned.
BTW, with a custom lightened CF slider and wand the horizontal mass of my Terminator totals 35gm. This includes custom front and rear wand counterweights designed to vary the wand's vertical effective mass. On my full-range system with a sub to 18Hz, the lighter horizontal assembly sounds better than the heavy one. Also, variations in vertical effective mass are more impactful than relatively large variations in horizontal mass.
Lots of variables. |
Dover.
Magnetic dampening will vary with the speed of horizontal motion..... so does pure mass. The formula F=Ma you quoted in another thread confirms this. Try shaking say a 1kg weight backwards and forwards at 0.55 hz (record hole centering error) and try again at 20 hz, (music). Much more force is required at the higher frequency. If this weren't the case, the R&D dollars speaker driver manufacturers spend on reducing the mass of the moving parts would be for nought. As I said earlier all three dampening methods increase in resistance with rising frequency of excitation.
That said, I agree with you, I do not like the effect of the oil trough.
To be clear, I do like, mostly, what magnetic dampening does. Further it is elegant and kinda cool, but I hear a slight negative which does not exist with the mass approach. As I said, I think that it is caused by induced currents circulating the spindle. Do you really want these currents anywhere near your delicate feed from the cartridge? I would be using mag dampening today if not for this slight negative.
Mag dampening increases cartridge output, yes agree, same holds for mass. My take on this is perhaps different to you. While is reduces micro vibrations which is a good thing, I think that the higher output is because the cartridge has more lateral resistance to work against because it cannot move the arm laterally as much. And move due to the cantilever tracing the groove it must, F=Ma again. More cantilever lateral movement equals more output.
Yes the Dynavector is an arm design that I have studied because it is unusual in using mass and magnetic dampening. But currents near the cartridge output?
Look, I don't actually care if people agree with me on this mass thing. I said earlier that it was contentious. Anyone with a full range system down to the 20s, might want to try it. They could well be surprised at what information is lurking in the grooves. |
Dgarretson
Dover, can you clarify a few points concerning the effective horizontal mass of ET? The manual states that it is 25-35gms. Is this the mass of the wand plus manifold tube, which is then increased by addition of up to 40gms in counterweights? Hi Dave Page 5 of manual – spindle weight (14 grams) tonearm tube weight (11 gms) plus the counterweights. To give you a reference point I am using one large and one small counterweight with the 420 str. That should be 20 gms. Page 9 ‘By decoupling the counterweights horizontally but not vertically, the mass of the counterweight is not seen by the cartridge above a certain frequency and is lowered. This allows use of heavier (more rigid) components in tonearm design with increasing effective mass. Decoupling mechanism is damped at a 2 – 5hz.” Maybe Dover, Richard or others can add more regarding the horizontal inertia. "lots of variables" YUP :^) Cheers |
but I hear a slight negative which does not exist with the mass approach. As I said, I think that it is caused by induced currents circulating the spindle. Hi Richard - Did you try the magnetic damping on belt drive or string drive as well ? Do you really want these currents anywhere near your delicate feed from the cartridge? Richard – in your opinion what would you consider as “near your delicate feed”. Reason I ask. The two little circle magnets I use with my ET 2.5 - the closest one is a good 7 or 8 inches away from where the wire exits the armtube – when at the the end of the record which is the worst case. I should note I am using copper on the ET 2.5 right now. I have silver on the ET 2.0 that is on a brass armpod. No room for trying magnets there. Looking at my analog gear its obvious I am not afraid of magnets. I know some who think magnets cause cancer. Can you give some details on how to go about making that lead slug for inside the spindle? Cheers Chris |
Chris.
While I have built a number of BD turntables, they all employed pivoted arms.
The eddy currents induced by the magnet are everywhere within the spindle since it is conductive, so having the magnets at the opposite end to the wand does not take them any further away from the cartridge signal. Therefore it is "near". The negative effect was apparent before and after I changed the goose neck to conductive aluminuium.
I made the internal slug by rolling up 1/2mm thick lead sheet strips. Cut to different widths. The roll OD was equal to just less than the ID of the spindle. Different widths gave me the ability to experiment with different weights.
A string was passed thru the center of this roll and thru 1/4" plastic tubes like that used for the air feed. String tied off one end and a length left at the other. The tubes were cut to length such that one tube protruded a few mm once the tube/lead/tube assembly was slid inside the spindle. Thus when the counter weight end cap was reinstalled it slightly compressed the tubes. Tubes were equal length to position the lead in the centre of the spindle. The pull string allowed the whole assembly to be removed.
Everything causes cancer. |
Chris
My apologies if this has already been covered in the thread, but can you tell us the sonic differences between the ET2 and ET2.5
Many thanks |
Richard, My ET 2.0 versus the ET 2.5 – both have high pressure manifolds. First an observation as I read what Ketchup and yourself said about the compliance in the air bearing spindle. Ketchup do you notice any difference in force required to move the spindle in your ET 2.0 and ET 2.5 with no air on? My ET 2.0 spindle can be forced through the manifold with no air. There is quite a bit of resistance but it can be done. This is normal according to Bruce. And its anodized coating prevents any damage. My ET 2.5 spindle will not move – it is really tight. There is not much movement at all without air. It has to be really forced. Bruce built it a few years ago for me. It was designed to run at 19 psi. Unlike my ET 2.0 which will run at 19psi and a low 3 psi as well, my ET 2.5 will start binding up if I drop the pressure – not sure what the actual PSI number is. The spindle starts resonating above a certain psi. We have discussed this here before. The consensus seems to be this PSI number varies just like our individual setups. For me its 19 psi and the reason I had the arm made for that psi. Richard as far as sonic differences with me. Let me use an analogy. We have all seen those graphs that show motor oil and the difference between lets say 5w30 and 10w30 motor oil at different temperatures. http://i36.photobucket.com/albums/e29/2002neonrt/35graph.jpgLets assume lower temperature represents lower compliance / heavier cartridges – that is the ET 2.5 5w30 and the ET 2.0 is 10w30. Both overlap and work well within a large range for both MM and MC. But when the setup is tweaked/improved I think the ET 2.0 works a tad better with MM and ET 2.5 with MC. Does that analogy make any sense? People assume the ET 2.5 is better because it is (.5) the next newer version. It depends. It came after so the obviously the parts themselves are newer but as far as sonics go ? well we know the smaller diameter 2.0 spindle according to Bruce resonates at 5-6 hz. The 2.5 resonates at 2-3 hz. The armtubes are the same as far as I know for both versions. Aluminum original one better with higher compliance, CF – middle ground – Magnesium – for really low compliance. This is the advice from Bruce with the testing he has done. The ET 2.5 sucks more air – has more volume. When they were in the same room I remember how the pressure gauge when I unplugged one for other would move by a few PSI. Ketchup’s graph shows this too. The ET 2.0 was around when vinyl was in its heyday along with MM cartridges. Then came MC cartridges and BT adjusted (I guess) to the time and introduced the 2.5 with its lower resonance. Just an opinion. If all things were the same – apples to apples - We know that will never happen. The ET 2.0 seems to handle a little better with lighter higher compliance MM’s. Like a lighter sportscar with great handling. But add a bigger motor to the sportscar (heavier MC/stiffer/lower compliance ) and I feel the ET 2.5 handles a little better. Bigger diameter spindle along with the lower resonance. A very rigid spindle to manifold coupling in my 2.5. The differences are not day and night. The MM 420str sounds great on the 2.5. Its just seems to be a little more ease on the 2.0. Bruce’s review of the 420str kind of confirmed this to me too. So I use MC on my 2.5 and MM on the 2.0. The rooms are adjacent to one another in the basement. Hope that helps. Richard you mentioned that you studied the Dynavector arm. Did you take any measurements of it - Impressions ? Cheers |
Chris. Thanks for the comparison notes. I now have a clear picture of the differences.
The Dynavector arms have always been fascinating to me due to their radical design. Magnetic dampening and for a pivoted arm the unusual idea of deliberately different effective mass in the vert and horiz planes. Both of these features being recently discussed in this thread.
Have only listened to 2 of these beautiful arms and in systems that I am unfamiliar, so cannot draw any concrete condclusions.
I have included a quote here from their manual on the 507 should anyone be interested.
• 3 Bi-axis inertia separation for accurate signal reproduction and superb tracking ability
"Bi-axis inertia separation" may sound complex but it simply refers to a tone arm having two arms which operate independently in the horizontal and vertical planes. In contrast, a conventional tonearm has only one arm which moves both horizontally and vertically. This is called a gimbal type tonearm and the inertia for both planes is the same.
The DV507 bi-axis tone arm has a large inertia for horizontal movement and a very small inertia for vertical movement. We shall now explain the reasons why this is advantageous.
It is well known that a cartridge generates an audio signal by the differential motion between the cantilever and the cartridge body. Consequently, if the supporting point of the cartridge (the tonearm) vibrates, the tonearm motion affects the audio signal.
In these conditions, the signal, which causes the tonearm to vibrate is of low frequency and large amplitude.
In the currently used 45-45 stereo record cutting procedure, low frequency signals are almost entirely recorded in a horizontal direction. This means that the low frequency signal, which can cause vibration in the tone arm, exists only as a horizontal force.
The tonearm therefore must have sufficient effective mass and rigidity in the horizontal plane in order to provide a stable platform for the cartridge.
On the other hand, for the mid to high frequencies, the effective mass of the tonearm should not be too large since the combined mass of the cartridge and the head shell need to be taken into account as well. In particular, where records have a warped surface, the vertical effective mass needs to be small enough to ensure a good tracking ability on such surfaces.
To summarise, the tone arm should have a large effective mass and enough damping in the horizontal plane and at the same time a small effective mass in the vertical plane.
These conditions are almost impossible to achieve with a tone arm of conventional design using a simple gimbal pivoting system. To solve the problem, Dynavector designed a bi-axis, inertia controlled tonearm where the shorter and lightweight vertical sub arm is placed at the end of the horizontal main arm. This is the special feature of our design. |
Richard, To take advantage of the Dynavector tonearm design wouldn't it require a cartridge with different compliance in the two planes? Otherwise wont only one plane will be optimized with the Dynavector arm? |
Richardkrebs/Chris :
Magnetic Dampening vs Mass.
I have been away on business and my responses have been brief. I can now expand on my previous comments.
With a lower mass the arm will move more rapidly initially to align with the eccentricity of the record, minimising cantilever flex.
The magnetic dampening only commences its action once the arm starts moving, and is proportional to the rate of movement. I should point out that the dampening is created by eddy currents which are only generated when the arm moves relative to the magnet.
By contrast, adding mass means the arm will not move until the driving force from the eccentricity is enough to overcome the higher inertia. This increased resistance to movement from the added mass means that the cartridge cantilever is forced to deflect to keep the stylus in the groove. This defeats the purpose and advantage of an air bearing tonearm - the uninhibited degree of freedom to accurately track the groove.
This higher mass is not dampening, it is increased inertia - a resistance to movement.
Magnetic dampening is dampening the arm motion once the arm has commenced movement.
I'll restate this :
Magnetic dampening allows the cartridge to move to the correct position in a damped fashion.
High mass means the arm wont initially move, inducing the cantilever to bend.
Any excessive cantilever deflection in a moving coil will result in phase anomalies as the coils attached to the cantilever are driven into a position where the response becomes non linear.
Furthermore, with the higher mass, once the arm starts moving, the lateral movement is undamped. Cartridge overshoot and more cantilever flex is inevitable.
With magnetic dampening the lateral movement of the arm is always damped when moving. |
Dover.
I pretty much agree with everything you say. Where we diverge is in the sublties. It is easy to add too much mass in the horizontal plane. I went there in my tests. The trick is finding a compromise point.
Dynavector put the reason for high horizontal mass far better than I could. I agree with their conclusions.
Sarcher30 Dynavector's quote covers their views on this.
Further, from memory, the ET in standard form has a horizontal to vertical effective mass ratio of around 6:1. So it is already a differential mass arm. It is just that in my view this ratio is not enough. As per before I don't care what people think about this, they are free to give it a go, or not.
Also as before, I like what Mag dampening does right, I just cannot put up with what it does wrong. |
“Magnetic dampening will vary with the speed of horizontal motion whereas the added mass approach is simply increasing static inertia considerably.”
"The magnetic dampening only commences its action once the arm starts moving, and is proportional to the rate of movement. I should point out that the dampening is created by eddy currents which are only generated when the arm moves relative to the magnet."
How was no static magnetic effect achieved: did you switch off the magnet? |
John47 - you misunderstand how it works. It is not magnetism that provides the dampening. It is the eddy currents created when the arm moves across the magnet. Read this http://en.wikipedia.org/wiki/Eddy_currentEddy currents (also called Foucault currents[1]) are electric currents induced within conductors by a changing magnetic field in the conductor. These circulating eddies of current have inductance and thus induce magnetic fields. These fields can cause repulsive, attractive,[2] propulsion, drag and heating effects. |
"you misunderstand how it works".
Not so.
Please reread my post.
I was referring specifically to the static effect - hold a magnet near apppropriate metal: does it have zero effect? |
Of course much more important is what effect do these eddy currents have - must have negative effects. Has it ever been objectified ? |
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First an observation as I read what Ketchup and yourself said about the compliance in the air bearing spindle.
Ketchup do you notice any difference in force required to move the spindle in your ET 2.0 and ET 2.5 with no air on?
My ET 2.0 spindle can be forced through the manifold with no air. There is quite a bit of resistance but it can be done. This is normal according to Bruce. And its anodized coating prevents any damage.
My ET 2.5 spindle will not move – it is really tight. There is not much movement at all without air. It has to be really forced. Chris, The compliance that Richard and I were talking about was in the o-rings between the manifold and the manifold housing. No matter how much air pressure you can get between the manifold and the spindle (making it very rigid), you will always have the squishy o-rings causing the spindle and manifold to move within the manifold housing. Not rigid = not good, hence the shims. Most other linear tracking, air bearing tonearms don't have o-rings to soften up the bearing. I believe that getting rid of this compliance may have a huge effect on performance as Richard suggested. I WILL be doing this after I get my system set up and I'm familiar with the sound without the shims. When I bought my ET-2.5 arm I actually did notice that it was a little difficult to move in the spindle with no air. I assumed that the spindle was out of round, but it worked fine with 1 psi in it when I did the air flow tests. Looking back at my notes from the air flow tests, I observed dragging at 1 psi with the ET-2 (set up on a TT with the arm wand, cartridge, and counterweight) but did not experience dragging with the ET-2.5 at 1 psi. The ET-2.5 setup did not have an arm wand or counterweight attached, though, so it's apples to oranges. The dragging with the ET-2 was most likely due to the added weight of the arm wand, cart., and counterweight. Also, I showed Bruce the results of my air flow tests and he said that both my ET-2 and ET-2.5 tonearms were set up for high pressure. I should have mentioned this earlier... |
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A real interesting read for me the last couple of days. Ketchup please keep us updated on those shims and I hope you get "one" of your arms up and running soon. Yes I was referring to the compliance between the “spindle and manifold” only. Sarcher30, John47 welcome to the thread. Excellent video link Ketchup. The ET2 tonearm no magnetic parts to be found anywhere on the tonearm itself. Put a magnet to it and find out for yourself. The cartridge itself, well don’t put a magnet there.....how close is ok or is it ? It got me curious. I hate unknowns. I have been reading both Richard and Dover’s positions on it. Have learned alot. I have something to share regarding these magnets, magnetism and it has to do with my Dynavector tonearm. I took one of the small circle magnets from the ET2.5 setup over to my Dynavector tonearm. What followed kind of reminded me of one of those horror movies –you know the one where the guy wakes up and finds himself magnetized in a kitchen; pots and pans, knives start flying towards him getting stuck on him as he ducks. ok - no pots and pans or knives here. But I did LOSE the magnet as it flew out of my hand. I had to search to find where it had lodged itself. Under one of the magnetic dampers near the DV505 base is where I found it. There is a little bolt (magnetic) on the left side of the main arm (as it has two arms). This is not shown on the tonearm diagram. Its helps with antiskating. As you get a few inches away from the post where the arm rests, the current draw is noticeable. The cartridge itself is about 6 inches away from this position which seems to be the last spot where a magnet field exists. On my ET2 arm the actual cartridge position because of it design is much further away. This got me curious so I sent an email to Masaaki at Dynavector asking about these magnetic levels. I’d like to say that Masaaki has to be one of the friendliest and knowledgeable audio people I have come across over the years in this hobby. Always responsive to my questions. I asked him for information about the “magnet force” levels on the Dynavector tonearm. His response. Hello Chris,
Unfortunately we cannot publish data of measured magnet current levels used the flux damper magnet in the DV505 tonearm. Only information is that the Magnetic flux density was multi-thousand gauss.
Thank you and best regards,
Masaaki
Dynavector
Multi – thousand gauss ? what does that mean ? Gauss Unit/Levels • 10−9–10−8 gauss – the magnetic field of the human brain • 0.31–0.58 gauss – the Earth's magnetic field at its surface • 25 gauss – the Earth's magnetic field in its core[3] • 50 gauss – a typical refrigerator magnet • 100 gauss – a small iron magnet • 2000 gauss – a small neodymium-iron-boron (NIB) magnet • 600-70,000 gauss – a medical magnetic resonance imaging machine • 1012–1013 gauss – the surface of a neutron star[4] • 4×1013 gauss – the quantum electrodynamic threshold • 1015 gauss – the magnetic field of some newly created magnetars[5] • 1017 gauss – the upper limit to neutron star magnetism; no known object in the universe can generate a stronger magnetic field[5] I am trying to figure out why Dynavector would use Gauss levels in the multi thousand range? Would they not have measured its affect on the phono signal ? From the DV505 manual - similar info to the previous posts. electro magnetic damper
This damper applies effect of eddy current, which is generated when conductor moves in magnetic field, and which obstructs conductor in motion. It has almost no damping effect on motion of non-vibrating tone arm, but is highly effective to vibration of arm, such as arm resonance. DV505 Manual Richard – can you tell us what type of magnetic damping you experimented with that led to your opinion of it? Position of the magnets relative to the arm, Gauss levels ? Dover - I believe you were using a fridge magnet ? which is about a gauss level of 50? Cheers |
Gentlemen, fantastic and very interesting reading over the last few days; thank you.
Dover, I want to try magnetic dampening. Could you please provide some more details about the positioning of the magnet for your magnetic dampening tweak? Did you place it between the manifold housing and the front edge of the tt, or between the manifold and the rear of the tt? Also, how did you orient the magnet's polarity? Does it matter?
Ketchup, I am intrigued by your idea of shims replacing the O rings in order to increase the rigidity of the bearing. I am confused however. Don't the O rings need to remain in place in order to keep air from leaking out of the manifold? What type of shim are you referring to, that is both very rigid and will seal the outer diameter of the manifold to the housing? Are you suggesting to place shims inside the manifold housing, between the OD of the manifold and the ID of the housing?
Chris, thanks again for starting what is currently, and without a doubt, the most interesting thread on the subject of LP playback on the 'Gon; IMHO.
Slaw, if you're still out there: what happened?
Regards to all |
Ketchup, I am intrigued by your idea of shims replacing the O rings in order to increase the rigidity of the bearing. I am confused however. Don't the O rings need to remain in place in order to keep air from leaking out of the manifold? What type of shim are you referring to, that is both very rigid and will seal the outer diameter of the manifold to the housing? Are you suggesting to place shims inside the manifold housing, between the OD of the manifold and the ID of the housing? Frogman, The shims will not replace the o-rings- they will be added to a completely stock, unmodified arm. The way the arm is built, there is about 3/16" of "free space" between the manifold and manifold housing before the o-rings. To illustrate what I mean: Cut a piece of paper into a thin strip 1/8" wide and an inch long. Slide the piece of paper into the gap between the manifold housing and the manifold. It should slide in about 3/16" before it hits the o-ring. That space is where the shims will go. Here's a photo of my ET-2.5 manifold that shows the 3/16" gap: ET-2.5 manifoldI like Richard's idea of making them tapered, but my OCD will have me constantly worrying that they have moved. A good compromise would be to make two of them non-tapered and make the third one tapered to apply the necessary force to lock the manifold in place. A small dab of silicone should hold the tapered shim in place and will be completely reversible. |
Frogman - I used a cupboard door magnet. It had a pair of magnetic plates implanted edge on. You see 2 parallel edges exposed in a plastic case. I placed these on the plinth, under the bearing tube with the edges in line with the bearing tube, next to the manifold, on the other side of the manifold from the cartridge. Like this ( looking down the bearing tube )
O bearing tube
!! magnet(s)
-- plinth
Note that my modified arm cable loom exits the arm wand in front of the bearing tube, it does not pass though the bearing tube. |
Very entertaining Chris, much mirth.
"I took one of the small circle magnets from the ET2.5 setup over to my Dynavector tonearm. What followed kind of reminded me of one of those horror movies –you know the one where the guy wakes up and finds himself magnetized in a kitchen; pots and pans, knives start flying towards him getting stuck on him as he ducks.
ok - no pots and pans or knives here. But I did LOSE the magnet as it flew out of my hand. I had to search to find where it had lodged itself." |
Chris
I initially used one fridge magnet then went to multiple fridge mags. Finally using Neodymium before abandoning the idea.
I tried first at the counterweight end then transferred to the wand end. There are differences. Now the reasons for that could be a whole new controversial discussion.
Frogman
As per an earlier post, when I rebuilt the manifold I used 2 shims and one grub screw arranged at 120 degree increments each end of the manifold. This allowed for tightening by doing up the grub screws. Do this on a standard manifold at your own risk
Ketchup
You got me running to the arm to check these little screws. Still tight after 15 years, phew.
So now some may be asking why I haven't cleaned the sleeve in 15 years.
Well, we do have very clean air here in NZ.
With the air pump running I break the air line next to my pressure gauge and squirt in CRC CO contact cleaner. Then reconnect.
I have previously placed paper towels at each end of the manifold. Then move the spindle back and fwd.
The cleaner is forced thru the sleeve and its tiny orifices. Leaving them to be nice and clean
I do this approximately every 6 months with positive results. |
Great thread and thank you to all that have contributed to this thread.
As a tangent tracking fan this ET thread is providing me with some very interesting viewpoint and insight on the working of this tonearm. |
Richardkrebs
Chris
I initially used one fridge magnet then went to multiple fridge mags. Finally using Neodymium before abandoning the idea.
I tried first at the counterweight end then transferred to the wand end. There are differences. Now the reasons for that could be a whole new controversial discussion.
Richard - We are all big boys here and we all know this hobby has a lot of controversy as it is based on preferences. Please do share the differences you found. |
Hi John47 :^) - raising fraternal twins can be entertaining too. My wife and I are into our 18th year of dealing with their demands in “stereo”. This hobby and a little sense of humor has helped me through it to this point. The twins have shaped my humor however – made it more cynical I think. My wife doesn’t care too much for it. She also doesn’t care for music above 70 db. Probably explains why I am here.
Rugyboogie - welcome to the thread. Am curious if you or other Kuzma Airline owners have ever considered any modifications to that tonearm?
Cheers |
Ct0517 - fyi
Magnets can be a little eccentric. On Richardkrebs deck they may prefer the wand end because they get a better view of the cantilever doing her one legged tantric yoga exercises. |
There is a sound engineering reason to put any mag dampening to be at the wand end of the spindle. Since the mag tends to resist spindle movement, it acts as a pivot for any non axial spindle motion
Since the cartridge is at the end of the wand and not at the end of the spindle, there is a force moment induced by stylus movement. The spindle can, at frequencies below the air bearing resonance point, move about this pivot point in a non axial manner.
Having this pivot point at the wand end causes less teter totter due to spindle sleeve clearance than would be the case if the pivot point was at the counterweight end. This benefit is clearly audible.
Exactly the same design feature is present in TT's with inverted main bearings.
Of course the mag is closer to the signal wires.
The choice is yours. |
Thanks Dover, Ketchup and Richard for addressing my concerns.
Well, I must admit I was somewhat skeptical about magnetic damping, but I am now convinced of the benefits. Some preliminary observations:
So far, I have used a single refrigerator magnet that conveniently detached itself from the back of a cooking timer. I glued this inch-squared flat magnet to a small block of glued layers of cork about the same size as the magnet. I situated it on the wand side of then arm pillar; frankly, only because I still have the damping trough attached to the pillar (with paddle disengaged). I plan on trying it on the other side, as well as trying other, more powerful magnets. The magnet is as close as possible to the spindle without touching it.
I listened to the same musical selections several times, with and without the magnet. The results are relatively subtle but unmistakable. There is a general "cleansing" of the sonic picture; as if a fine mist is removed. Bass definition is improved with an increase in one's ability to hear pitches in the bass; as opposed to simply low frequency energy. The highs gain a bit of refinement and sound slightly less ragged. On "The New Breed" from Donald Fagen's new release Sunken Condos, Walt Weiskopf plays both alto and tenor saxophones. Without the magnet, it is very difficult to hear when he plays alto vs tenor. With the magnet, more of each horn's individual character can be heard. Also, for an LP with otherwise very good sound, the bass, while being powerful and very well extended, has a strange "drummy" quality with less than good definition. The magnetic dampening brings a welcomed slight improvement in pitch definition. Curiously, the soundstage seems slightly smaller with the magnet; perhaps a result of the increase in control and definition. The differences are not earth-shaking by any means, but definitely worthwhile. I have not experienced increased volume; perhaps with the more powerful magnets.
Biggest surprise of all: record surface noise seems reduced. LP surfaces are quieter, and the loudest clicks and pops sound less obtrusive with a more subdued character.
More to follow. |
Richardkrebs -
I'm a little disappointed you dont think outside the box, or in this case arm.
What about running 2 ET bearings in a T bar configuration, armtube in the middle.
You like magnetic dampening but worry about the eddy current. Try standing on your head and thinking upside down. You dont have to use the bearing tube.
Why not use a magnet as a counterweight and an aluminium bar mounted on the plinth. Why not go the whole hog and put an accelerometer on the bearing housing, that way you can measure the resonance and employ electromagnetic dampening driven from a feedback loop and active servos to dial out the exact resonance.
What I do know is that added mass will have altered the dynamic stiffness of the bearing and the fundamental resonance. It will increase the instability in that air bearing. You are running 12psi - this is on the lower end of what most are running ET's. With the added mass you are increasing the very instability you are complaining about with the magnets.
Have you measured the dynamic stiffness and fundamental resonance after adding mass ?
Have you calculated how much you need to increase the pressure by to provide the same level of rigidity in the bearing as the standard arm ?
Have you measured the impact in the high frequencies of being able to achieve the same level of rigidity with less mass ?
When it comes to resonance mass is your enemy. Do you put lead in your gumboots for a smoother ride when you go tramping ?
Perhaps you should resign yourself and go to a unipivot. An air bearing will never be as rigid as a unipivot - you are losing so much of the leading edge of notes. That would solve all your anxieties and give you a whole new set of issues to fret upon.
PS The tantric yoga is no joke - stand on one leg, put the other to your ear, and you may hear a little more bottom end. |
Dover
PS The tantric yoga is no joke - stand on one leg, put the other to your ear, and you may hear a little more bottom end Well I have to say am very impressed with your flexibility Dover. I am very happy that I run every day for my health. But I can’t even touch my toes. I guess I should start Yoga..with my wife. Frogman – your observations are similar to mine and the reason I am still using the magnetic damping. Here is how I am currently set up. ET 2.5 Magnetic damping What is not obvious in the pic is that there is actually over one inch of clearance between surface and spindle when it comes across. Can the positioning be improved ? Will try three on top of one another. I just placed three for even distribution as the spindle comes across. I am assuming placing any magnets directly under the manifold will have a reduced effect ? I could try this with the ET 2.0. Home depot has a large selection of various magnets. http://www.homedepot.com/webapp/catalog/servlet/Search?storeId=10051&langId=-1&catalogId=10053&keyword=magnets&Ns=None&Ntpr=1&Ntpc=1&selectedCatgry=Search+AllMy wire exists at the armtube. After getting the Dynavector gauss level info about using thousands of gauss in their tonearm – these 50 (approximate) gauss magnets seem harmless enough ? Many variables here including air psi. Different PSI’s do affect how the spindle reacts based on my direct experience and discussed here already. Eddy Current with a floating modelMy experience with the stock ET2 and 2.5 spindles – I am no scientist – is the higher the PSI the less force required with magnets and the smoother (the motion will be). I use 19 PSI. The ease with which the spindle goes through the manifold at higher PSI is obvious. Try 3 psi and 20 psi to prove this. I have also said this before here - When my cartridge is raised and at rest – at 19 psi - I can blow on it and it will shoot across the top of the LP. Also whether it is a 2.5 or 2.0 spindle. I would assume that the 2.0 spindle being smaller reacts more to less magnets? But the differences could be subtle? Richard – did you have the lead slug in your spindle when you were using the magnets and was it at 12 PSI? Cheers |
I think the home depot link blew the last post up like that.:^( Just want to clarify when I said. Richard – did you have the lead slug in your spindle when you were using the magnets and was it at 12 PSI? I want to recognize that you are running a custom setup spindle/manifold. My experiences have been with stock spindles 2.5 and 2.0. Still - I assume you tried magnetic damping with the lead slug and without ? Cheers |
