Eminent Technology ET-2 Tonearm Owners
Chris, Funny, this morning I happened to see the post where I got the Phoenix Wire idea from. It came from Oilmanmojo here: New Maplenoll Ariadne owner needing advice He gives another source for wire- A-M Systems |
Oilmanmojo, Thanks a lot for posting about your tonearm wire. I just want to get something straight, though. You said you bought 0.015", 0.010", 0.005" diameter wire from A-M Systems. In your system page, you mentioned using 0.003" wire in your tonearm tube. Did you also use 0.003" wire? That must have been even more difficult to solder than the 0.005" wire. |
The whole paragraph from page 9 of the manual: "The effective mass of the arm horizontally is equal to the sum of its component parts. (It does not pivot) It needs to be as light as possible for low mass, however, making the arm too light sacrifices rigidity. By decoupling the counterweight system horizontally, but not vertically, the mass of the counterweight is not seen by the cartridge above a certain frequency and is lowered. This allows the use of heavier (more rigid) components in the tonearm design without increasing the effective mass." He is, indeed, talking about the rigidity of the tonearm parts. Throwing weight at the I-beam near the spindle pivot does not increase the arms rigidity. |
it needs to be as light as possible for low mass, however, making the arm too light sacrifices rigidity. I think what he's talking about here is the construction of the arm itself. If you make the arm too light by making the spindle wall thinner and the arm wand thinner, for example, the arm will loose rigidity. I do not believe the comment has anything to do with the position and number of counterweights, but I need to read the manual again to fully understand what is discussed in that section. Are any of you able to update your virtual system now? I want to add my new air compressor, but when I log in to my account it says there is no system saved, even though I can view the thread. |
Ct0517, good info. What I would like to know is how to inspect a manifold to determine what pressure it's set up for. I would guess that things like the spindle/manifold clearances and capillary size would need to be measured. Did Bruce mention how to determine this? Maybe he could let us know the specs that he built the to for different pressures. |
Philcoffino, Is it a Delphi? I have an ET-2 on my Delphi, but don't experience that problem. You might want to check to make sure that your platter is perfectly level. If it's not, when the cartridge gets near the end of an LP, the platter will become even slightly more un-level and cause even more acceleration of the arm as it nears the end of the LP. Also make sure to see if you have the maximum amount of space between the joint and the manifold housing when the cartridge it at the very end of the runout groove. I have heard (no idea how true it is) that if they get too close, the air coming out of the manifold can push against the joint and cause the arm to "bounce" back across the LP. Maybe its just the joint coming in contact with the manifold and bouncing back, I don't know. Either way, you never want the joint to come in contact with the manifold. You want some buffer distance there. Before your arm rebounds, does the joint contact the manifold? Have you ever watched it? |
Frogman, I couldn't agree more. I just assumed that his arm was perfectly parallel with his platter's surface! Philcoffino, If it's not, make that adjustment first, then level your suspension with the oracle gauge to make sure that your aluminum plinth is parallel to the acrylic plinth. After that's perfect, use the arm as a level and level it by adjusting the spikes under your Oracle. |
Regarding changing the cartridge with the air pump on- I made a simple latch that locks the cueing shift to the cueing eccentric when you don't want the arm to move around on you. Using the latch with the pump on when changing cartridges eliminates any wear to the spindle or bearing while also eliminating cartridge damage. The spindle, at least, is hard anodized, but it's good piece of mind to always have the pump running when moving the arm... even the slightest bit. |
You can’t put wear on the ET2 spindle or bearing. The spindle can only be damaged by driving over it with your car. I realize that moving the spindle back and forth in the manifold feels “very wrong” and “rough” without the pump. It feels like you are damaging something. But you are not hurting anything and actually helping it if you can believe it. You are actually encouraged to do this a little on new arms to help them settle in. If the spindle is so indestructible and tough, how can simply moving the spindle with no air benefit? The clearances between the spindle and manifold are set at the factory. You do not want to change the clearances. The arm is ready to go out of the box and requires no additional "fitting" by moving the spindle by the customer. That would be a poor design. I will be happy to eat my words if you can provide some proof that moving the spindle with no air does any good. Did Bruce say this to you? |
I just finished a flow rate test to see how much air my ET2 and ET2.5 arms flow at various pressures with different pumps (Wisa and ET/Takatsuki). I'm also going to do the test with an unlimited supply of air (60 gallon air compressor) from 1 psi to about 15 psi (the maximum pressure that the air flow calibrator can take). My setup was: Pump>Bios Defender 510M air flow calibrator>Parker air pressure regulator>Tonearm. I tested each arm/pump combo from 1 psi to the maximum pressure that the pumps would provide. Results can be found here: Flow rate chart The results suggest that the Takatsuki pump flows more air into each arm at equal PSI, but can not provide the PSI that the Wisa can. The results also show that the ET2.5 is less of a restriction to the pumps than the ET2. It flows a larger volume of air at a lower pressure. These results may not apply to all tonearms. As I understand it, Bruce customized some arms for use with specific pumps. |
I just did the tests with a 60 gallon air compressor from 2 to 14 psi. The setup was: 60 gallon air compressor @ 120 psi>water separator/filter (5.0 micron)>pressure regulator @ 25 psi>coalescing filter (.01 micron)>pressure regulator>Defender 510M air flow calibrator>tonearm. I updated the chart with the new data: Flow rate chart |
Ketchup, thanks for sharing the data. The question then becomes: how do the different flow rates affect the sound when PSI remains the same? Did you notice differences in the sound with different pumps with the regulator allowing the same PSI? Frogman, There was no listening done during these tests. I barely had enough time to complete the tests as is and my ET-2.5 is not even mounted on a turntable. I have the data now, though, so listening tests should be possible down the road. |
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? |
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 :) |
John, The spindle's material is aluminum. It is not magnetic, in that it is not attracted by magnets, but it is affected by eddy currents. This video should help: http://www.youtube.com/watch?v=H31K9qcmeMU |
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 manifold I 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. |
The Kuzma looks like a nice arm, but one thing that always made me scratch my head is the air supply tube. We ET-2 owners pay so much attention to tonearm wire routing. What about that stiff plastic tubing on the Kuzma? It seems like it would have a huge effect on the arm's movement even if both of the fittings swiveled. Does anyone know any details about the tube's fittings or if it hinders the arm's movement? |
Dover, I would also love to see some pictures. Why did you remove the foam from the aluminum arm tube, and could you detect a difference? I just got my vinyl rig up and running but the tweaker in me is already thinking about the next move. I'm currently using an ET-2 with the aluminum arm tube and a Denon DL-103R. I think the Denon would work better with the higher mass magnesium arm wand, which I have on an unused ET-2.5. Does anyone have any experience with the Denon DL-103 on both the aluminum and magnesium arm wands? It's too bad the forum is so archaic. This might have been covered in this thread already, but it's virtually impossible to search it. |
Bigalt, What you want to do is put a straight edge on top of your platter, parallel with the tonearm spindle. Then, adjust the tonearm so the spindle is perfectly parallel with the straight edge. Just use your eyes. You may have to play with the lighting on the straight edge (use a flashlight at different angles) until you can see both the top of the straight edge and top of the spindle. This will get the spindle much more parallel to the platter than any other method. Most levels, digital protractors, etc. are not accurate at all. Now, do not ever touch the adjustment screws on the post. Once the spindle is parallel with the platter it will never need to be touched. Now all you do is simply level the TT until tonearm does not drift in or out. The problem with your method is that you do not know that your platter is perfectly level to begin with. Care to share how you are determing that? |
Slaw, Maybe I'm misunderstanding you, but why not do that with no LP on the platter? This way you are lining the spindle up with a precision machined surface (the platter). Vinyl is far from precise with all the warps and what-not. The stylus does not have to be in the groove for this part of the set up. |
Bigalt, Another problem with your method is that, because the post adjustment has three screws, when you are "leveling" the tonearm as you do, you are also messing with how vertical the post is. It should be perpendicular with the TT platter when viewed from the front of the TT. These parameters need to be set up and locked in. It's not something that you should ever adjust, unless you feel that they might have went out of adjustment over time. |
Hello, I currently own an ET-2 and an ET-2.5 tonearm. My ET-2, which I bought used, came with a Wisa air pump and Airtech surge tank and my ET-2.5 came with an ET branded Takatsuki pump (also bought used). My ET-2 has an aluminum arm wand and my ET-2 has the magnesium arm wand. I don’t know if my ET-2 is the low pressure or high pressure version. As I understand it, there were two linear tracking arms offered by ET. The ET-2 and the ET-2.5. The ET-2 had a smaller OD (outside diameter) spindle and a smaller ID (inside diameter) manifold than the ET-2.5. There was a high pressure manifold option for the ET-2 that had reduced air bearing clearances (.0007" less ID to the manifold according to this Stereophile article). All ET-2.5 arms were the high pressure version (thanks for that bit of info, Ct0517). There are also three arm wands available- the original aluminum, magnesium, and carbon fiber. Were there any arms with the ET-2.5 designation? My ET-2.5 says ET-2 on it, but it’s clearly the larger manifold and spindle. I have always assumed that all ET-2.5s just used ET-2 bearing housings. If that’s true, none have the ET-2.5 designation. Anyone? There are two things that set the ET arms apart from others, in my opinion. The first is the arc block or VTA block as stated in the parts list on ETs website here. The arc block is the post that the bearing housing rides up and down on during VTA adjustment. Its purpose is to keep overhang exactly the same as VTA is adjusted by not only moving the bearing housing up and down, but in an arc. Do any other linear tracking tonearms have this feature? The other feature is the decoupling of the counterweights from the spindle. The I-beam connects the weights to the spindle. The I-beam is connected to the spindle by a thin piece of metal situated vertically. This lets the spindle move side to side as the cartridge follows an off centered LP without even moving the tonearm weights. This results in a much lower horizontal effective mass. Do any other linear tracking tonearms have that feature? |
Ketchup – I had a look at your setup. You have done some really interesting stuff too in your system. You have gone in front of the manifold with the wiring. You were considering some new medical wire ? .003" in diameter with .001" thick teflon insulation. Do you have the details on it? Chris, I don't know exactly what wire I'm using right now as it came with my tonearm, but I think it's some kind of van den Hul wire. It's solid core, silver in color, with clear insulation that might be Teflon. The wire enters a tube that I added to my arm wand immediately behind the cartridge pins. From there, it loops over the platter and enters a Teflon tube that runs to my phono preamp. A copper braided shield covers the Teflon tube between the end of the "loop" and the phono preamp. The copper braid is grounded at the preamp. The four individual wires are separated from each other where they are exposed in the loop. This arrangement had the least effect on tonearm movement. The tonearm leads are soldered directly to the Lundahl step up transformers in my phono preamp. No RCA connectors are used. I should take a better photo of the wiring to show exactly what's going on. As you mentioned, I would like to try some smaller diameter silver wire with even thinner insulation. Phoenix Wire has a lot of wire that would probably work for us. I doubt Teflon insulation over 0.001" is necessary, but I'm only guessing. I wonder what minimum gauge wire can we get away with using in this application. Phoenix Wire claims that no order is too small, but if there's a price break for larger quantities, I'd be interested in going in on an order with some of you guys if we can all agree on the wire specs. |
Dover, When you mentioned removing the heat shrink from the arm tube, which arm tube were you talking about? My aluminum tube does not have any on it, but I also have what I think is the heavy magnesium tube (it's definitely not the aluminum or carbon fiber tube, and I'm not sure if they ever made a lightweight magnesium tube). When I got it, it had heat shrink on it, but I did not know if it was factory installed or not. It was a little damaged, so I took it completely off. What benefit did you see by removing the heat shrink? What did the metal beneath the heat shrink look like? Mine is a dull, gray color with a pretty rough surface finish, close to what 100 or 80 grit sandpaper would give. Here's a photo and a diagram of the magnesium arm wand. http://www.eminent-tech.com/25%20magnesium%20arm%20wand.html http://www.eminent-tech.com/magarmtube.html Also, how did you remove the teflon "filler" in the headshell? I assume your talking about the white material inside the arm tube where it's squished together where the cartridge mounts. What did you do, buy a sheet of carbon fiber and cut and file it until it fit in the slot? What benefit did you see from doing this? Thanks a lot. |
First an observation as I read what Ketchup and yourself said about the compliance in the air bearing spindle. 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... |
Wisa pump isolation o-ring info here: https://forum.audiogon.com/discussions/wisa-audio-pump-for-et2-tonearm/post?postid=1681632#1681632 |
Hi Chris, They "wear out" due to age. They get hard and crack. Putting the pump in another room is the easiest way to mitigate vibrations. An even better way is to use a large air compressor to get rid or the air pulses, but that's a different matter altogether. The info in the link above is for someone wanting to bring their pump back to factory configuration and operation. |
@forrestc thanks for the info. I may have to pick up an aluminum goose neck, especially because it sounds like I might not need to go through with a cart alignment after installing it. I just finished up a painstaking alignment and don't want to have to do it again for a very long time! Have you always fun 18psi? How much better is it than low pressure? I'm now running 5 psi with my ET2. I have a shop compressor all plumbed up to deliver dry air, but I wasn't going to try it until I put my ET2.5 on. Now I'm wondering if I should just go for it with my ET2 and forget about the ET2.5 for now. |
My reasoning for weighing the magnesium and aluminum arm wands is that I just removed my aluminum arm wand to install a magnesium arm wand. The heavier magnesium arm wand should be a better match for my low compliance cartridge. Does anyone know what kind of adhesive is used to attach the metal leaf spring to the I beam? |
@ct0517 I'm sure it's somewhere buried in this thread, but how long is the long I-beam? I have one that's 60mm and one that's 70mm. Is there one that's longer than 70mm? |
With the stylus down, how is everyone's I-beam angled? Is it perfectly horizontal or a little down at the counterweight end? I have the long I-beam and the counterweight end is currently a little lower than the spindle end, but I really don't see a reason to not adjust the I-beam so it's horizontal. |
The key to using a shop compressor is to have a large enough tank for at least one listening session. I can listen to LPs for days with one fill of my 60 gallon tank. It's the most quiet air source you can possibly have and there's no need for a surge tank. I waited years to connect it to my tonearm, and once I did, I felt stupid for not doing it sooner. |
