this is usually a result when the teflon pin is worn on the bottom plate allowing a little flutter. This can be exaggerated with a slightly out of balance lead platter. I wrestled with this issue on my first maplenoll ariadne reference (white one with 40 lb platter) because of shipping damage and the worn pin. it is very difficult to find replacement parts for this so i ended up making a replacement. The platter balance is not as critical but for flawless performance is does help. I had the platter turned by a machine shop and balanced. Then repainted with a good grade of acrylic paint. The bottom pin can be pressed out and replaced but you must remove the plate using the three bolts. You can buy stock rods of teflon that will perfectly fit into the bottom plate then machine top so that it fits snug into the brass sleeve in the top airbearing plate. Carefully lube the brass sleeve with the supplied lube or high grade graphite grease. it sounds very difficult but its not really that tough if you are a little handy. I got pretty good at this while getting that table perfected. after that one, i moved up the the ariadne signature (beast of a table with a 90-100 lb platter). i currently own 3 maplelnolls including a heavily modified apollo that was the precursor to lloyd walker's current table. This one was modified by him and has an external drive vs the one attached to the plinth. the VTA adjustment is an engineering marvel.
Back to your other question. Yes on both accounts and yes on leveling the arm. Not sure about what model you have but i am a firm believer in getting base perfectly level. Usually the platter air bearing bottom plate is level, but if not, you will have a level base and the platter is slightly off. this can result in the platter bottoming out as it rotates and force higher pressure on the platter thus robbing vital air pressure to the arm. check them both. I spent a lot of time getting level right on platter. you will know you have it right when you spin by hand (with air on but belt not hooked up) and the platter spins for 3 or 4 minutes. You have not mentioned the arm so I am assuming its properly tuned and does not create a problem. If you level properly, provide clean, consistent pressure the the arm and platter, the maplenolls will produce some of the sweetest sound you will ever hear from a table in this price range.
I sent in a detailed response last nite, not sure what happened but in a nutshell, one significant possibility for your problem is a worn centering pin (teflon) on the bottom base plate of the air bearing. I had a similar problem that i corrected by replacing that pin. If the moderator does not release the my response, you can PM me and i will help you diagnose the table to see if that is the problem
Thank you for your kind response. Am I correct that a proper, unworn, center pin allows no side-to-side movement when fitted to the opening of the top plate? Or, does the pin act as a centering point and the spinning lead platter completely floats with no contact between pin and top plate? I hope this is understandable.
Great question and hopefully i can answer correctly. The centering pin (teflon i believe is the material if i remember lloyd right), serves the purpose of ensuring as the platter floats on the air between the plates (very small clearances) that it stays centered and does not move side to side as the platter turns. Remember the belt will put a slight force on the platter so sufficient friction exists to spin the platter. This means the platter pulls slightly towards the pulley attached to the motor. Now if the pin is slightly worn, but the platter is perfectly level and balanced, no major problem because the force is parallel to the platter and does not cause wobble. But if the platter is not perfectly balanced, then as the heavy side spins, the clearance will be lower on that side versus the light side. Again if the center pin is perfect, and the imbalance is low, then you do not see much if any deflection because the imbalance is just offset by a little friction on the pin. Since teflon has very low frictional properties, you do not see much impact. in fact you will be able to determine this if you carefully reduce the platter air pressure just to the platter just rubs. I found that if you listen carefully the imbalance will be an rhythmic sound and not continuous. if the platter is perfectly balanced the sound will be continuous. I know this sounds a little black magic but it works. If the platter is off balance you compensate by adding more air pressure which lifts the platter a little higher thus offsetting the imbalance Again you will see this by looking at the top of the spindle. It wobbles.
Now there is one other possibility and that is the spindle is bent slightly. If that is the case, the spindle will wobble but your tone arm will not move up and down. Look at it carefully. You also can get a carpenter square to determine if the spindle is bent.
hope this helps
I believe I can have a friend make a replacement center pin for me. I also think I can find a Teflon rod at US Plastics. I've recently replaced the belt and the increased pulling has caused the side-to-side movement to be more apparent. I have noticed the periodic rubbing when the air pressure is reduced. I don't have a source to balance the platter, unfortunately. I have read the owner's manual and have "trued" the top plate's spindle by lightly tapping on it. I finally have a good source of high enough air pressure. So the centering pin is the last hurdle.
Thank you, very much, for the information.
If you have a good machine shop where u live they may do it for u. Good luck and let me know how it comes out
My friend did a great job and made a couple of center pins that fit perfectly. Now I want to clean some of the lower platter mounting parts and touch up the paint around the mounting area. I try and restore as much as possible when things are torn apart. My friend thought that the upper and lower plates might have been made of magnesium. They have a very smooth surface where they touch when no air is between them.
Excellent. You should see the difference pretty quick. Couple of points. As you reassemble, please note the bottom plate has the holes that are threaded. As you probably figured out, the long bolt screws into these. Not sure if they are sealed on the bearing surface side but the three tables i have all are sealed. If they are sealed, i would just tighten until they are hand tight. Not sure if you have the white table (lot of plywood that is sealed on sides and top with white corian or the grey table (mostly corian though i believe there is a plywood core. The white table is a little tougher to deal with because with 20 year old plywood, it can be a little brittle. There is a string online where a fellow maplenoll owner completely refurbished the white one and sealed the plywood exposed surfaces with a pliable material that hardened similar to corian. The grey signature table is a lot easier to deal with.
Concerning the material, it is an alloy that i believe has some aluminum and magnesium but it is a special alloy that could be highly polished to extreme tolerances. I have been warned by several experts that you want to leave it alone and do not try to alter it. It is very hard but brittle and was specially polished and each of the plates were matched. I have a few spare platters and spindles that i purchased from the guy i got my ariadne signature. One of those platters is ruined where a person tried to polish it to "improve" it. I know anything can be polished with the right materials but i am a firm believer in leaving that to people who understand how to handle this material. My understanding is that Dilger had a number of these plates made and that was one of the "expensive" components that made the table pretty expensive at the time. i have been very successful just cleaning about every 6 months with an alcohol pad and very soft microfiber cloth. By the way, make sure you put a little lube (the blue stuff if it was provided) in the brass fitting that the teflon pin fits in.
I am excited to hear how this works out for you.
Thanks, again, for your helpful comments, Oilman. I also have the Ariande Signature so the base seems to be a "sandwich" of lead and synthetic countertop material. The long threaded screws seem to only thread so far into the lower platter plate, but I'll heed your recommendations. I cleaned up the thin washers that go underneath the rubber grommets they were stained pretty heavily. Then I'll touch up the black paint above and below the platter support surfaces.
I agree the platter air bearing surfaces should be cleaned only, the material seems already nice and smooth and most importantly flat. I've read about adding another bearing opening to produce a more even lift, but I don't feel I want to tackle that.
I've pretty much done all of the other cosmetic things I wanted to do. Now all that's left is the tonearm rewire, measure the total tonearm moving mass and put it back together and run a few tests.
Some designs do have multiple air ports on the bearing plate but since this design has the air port in middle (not quite center though) adding a second port does not impact the balance as the air pressure is developed in this section and lifts the platter evenly. If the air port was actually on the bearing surface, then you would need several. On the air spindle, it is actually set up with multiple orifices that introduce the air to the spindle. This is to exert an equal pressure on all side of the spindle to get it to float. That is why its critical to keep the pressure high to the arm relative to the platter
Ah, the Maplenoll magic is back! Everything is setup and working beautifully. I have a few more minor things to do, but what great sound this table can produce! Thanks for your generous help, Oilman.
Thanks for the feedback. Glad the pin suggestion helped. As you said, a magical table