A few comments about the offered arms:
- the ET one is a good choice for a low to medium compliance cartridge, usually a MC. I think the bearing was almost (?) as high quality as the "low pressure" ET2 bearing. The bearing (and the headshell / arm / bearing connection) is less stiff than the ET 2.5 though.
The main advantage of the ET 2 and ET 2.5 is that they are more adaptable (than most any arm on the market except the Mörch).
- Surge tank: My Airtech tanks end caps broke during a long time of being stored away. My replacement was a standard HDPE gasoline tank, 10l (ca. 2 gallons) with two 5mm holes drilled in the screw cap, with silicone tubing entering each hole, one with a short piece entering the tank, one with a long piece touching the "floor". The tank is filled with polyacryl wool for damping. The seam of screw cap / tubing then is "glued" with hot glue. This stays air tight since 10-15 years, and i's cost were almost nothing.
- My original ET pump with ET 2 arm gave ca. 0.25 to 0.3 Bar. With the improved tightness of the ET2.5 air bearing I'd expect 0.4 Bar. This is at least enough for a (well) "working" bearing. My high pressure manifold still runs at 0.15 Bar - much better than the original "low pressure" ET 2 bearing!
- the ET one is a good choice for a low to medium compliance cartridge, usually a MC. I think the bearing was almost (?) as high quality as the "low pressure" ET2 bearing. The bearing (and the headshell / arm / bearing connection) is less stiff than the ET 2.5 though.
The main advantage of the ET 2 and ET 2.5 is that they are more adaptable (than most any arm on the market except the Mörch).
- Surge tank: My Airtech tanks end caps broke during a long time of being stored away. My replacement was a standard HDPE gasoline tank, 10l (ca. 2 gallons) with two 5mm holes drilled in the screw cap, with silicone tubing entering each hole, one with a short piece entering the tank, one with a long piece touching the "floor". The tank is filled with polyacryl wool for damping. The seam of screw cap / tubing then is "glued" with hot glue. This stays air tight since 10-15 years, and i's cost were almost nothing.
- My original ET pump with ET 2 arm gave ca. 0.25 to 0.3 Bar. With the improved tightness of the ET2.5 air bearing I'd expect 0.4 Bar. This is at least enough for a (well) "working" bearing. My high pressure manifold still runs at 0.15 Bar - much better than the original "low pressure" ET 2 bearing!