RichardKrebs
It shows all over again that the arm is very sensitive to the quality of the air supply.
Richard - obvious agreement from me. I got sidetracked for a number of years (elapsed time) in my Audiophile phase PUMP journeys.
Where does one stop ? It can be addicting. I did learn a lot about how different pump technologies work though.
********************************************
I think it is worth noting for newer readers, a couple important thread quotes from Bruce on Air Supply and Setting Manifold PSI Values.
1) Air Supply (Quality - PSI and Mositure/Dirt)
Bruce Thigpen
More than air pressure, the air supply will change the sound of the tonearm. if it is bad, allowing pressure pulsations to enter the manifold. Increasing pressure slightly and a big enough surge tank are the best things that could be added to the tonearm in terms of performance.
The key words to me from Bruce is increase pressure slightly, and it implies one knows what PSI your ET2 manifold was built for. If someone buys an ET2 on the used market we have discussed here how to find out the PSI/Bar it was designed for. As a guideline if a regular manifold - 3 psi. If a High Pressure manifold 8-10 psi unless it was a Custom Build. Once consistent PSI is achieved (think pulsations), the big other factor is moisture and dirt.
What helped me understand how important this moisture and dirt were, was to think about air brush painting and what happens if dirt/moisture get in the air line for the person doing the spraying. Now I don't air brush myself but there are many air brush painting forums to get an understanding.
For me personally.
My Timeter pump is designed for keeping people/patients comfortable. It therefore has controls that allow me to vary the moisture being sent out as it has an integral drying system. The pump is affected by humidity and going from very dry winter air, to humid spring/summer air forces me to make pump adjustments to the level of drying.
I have found in my room on a few occasions during the season change from winter to spring (going dry to humid) I could have been listening to digital for a while, then switched to vinyl, the system itself is warmed up; at times the vinyl sounded wrong. Almost how reproduced music in a room can sound with cold solid state gear if you know what I mean. When the music sounds like this, it makes me think of wires and the gear. Not the music at all.
Going to the pump I notice the dryness level needle has dropped some so I need to crank up the dryness factor a bit on the pump. So the PSI was just fine but there was some moisture in the air line - it affected the sound. And this is moisture "vapor" that is hard to be trapped by filters. Again the air brush forums help to get an understanding of this. Our audio expectation is nice music we enjoy. Their expectation is the finish on their painted product. Its all visual. For those running with tanks of compressed air - don't forget to drain the water in the tank before using (bringing the tank to its PSI level). My Timeter Aridyne pump is tankless.
The fact of the matter is if you live in a hot, humid place (I wish I was there now) you will have more challenges with air supply than the guy in a drier, colder environment. So many environmental factors can affect the sound that are never discussed on Audiophile forums.
2) Setting the Manifold PSI on ET 2.0 and 2.5 for specific customer requirements.
In the past customers have had Bruce design the manifold PSI for their pump's specific requirements. This is discussed on the Eminent Technology website when one is looking to buy the tonearm, as the pump system is not supplied with tonearm when you purchase it.
Bruce Thigpen
The pressure drop across the set screws define the restoring force and part of the stiffness of the air bearing.
The tolerance between the Manifold Inner Diameter and the Spindle Outer Diameter determines the lifting pressure as a function of flow rate through the set screw. Without a restoring force or pressure drop across the set screw, the bearing will lock up, so you always need a higher air pressure in the manifold housing as compared to the pressure at the surface of the spindle.
The high pressure manifolds have a slightly tighter tolerance between the spindle and manifold, they also use a set screw with more plating to restrict the air flow around the threads to create the increased pressure drop (the difference between the pressure in the manifold housing and the pressure at the surface of the spindle).
It does not hurt to slide the spindle in the manifold bore without air, the resistance you feel may be the surface finish roughness on the hard coat anodizing as well as tolerance.
I hope this helps, thank you very much.
-brucet
************************************************
Fnding the ET2 Yellow Sticky Thread Posts.
Here's the ET2 thread Yellow Sticky for the setting of manifold PSI values
https://forum.audiogon.com/discussions/eminent-technology-et-2-tonearm-owners/post?highlight=et2%2By... The new Audiogon system allows one to find the Yellow Sticky Posts on this ET2 thread easily now.
Just enter Yellow Sticky in the forums search field.
