Eminent Technology ET-2 Tonearm Owners

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?

Mods for ET2
Removed heatshrink from arm tube
Removed foam from arm tube
Removed teflon filler from headshell and replaced with carbon fibre
Had stiffer bracket that joins armtube to bearing tube manufactured
Replaced wire with van den hul silver - hello radio campus ( rf )
Replaced wire with copper litz from Sumiko tonearm box, hung below pivot and soldered directly into MIT cable approx 2' behind the bearing tube in the centre of the range of movement
Placed small cupboard door magnet under bearing tube - this provides electromagnetic dampening on eccentric records.

All of these were good improvements. I have found any sort of dampening other than the magnetic described slugs the sound.

Oh and using an isolation transformer on the air pumps, running 2 air pumps out of phase to double the airflow and surge tanks.

I still have the original 2.0, but plan to upgrade to the 2.5 manifold soon. I run Discovery wire from the cartridge pins, looped over the top and directly into my Herron Phono stage via Eichmann plugs. That was the single most noticeable cable change I've ever made. I have Fo.Q tape in a couple of places on it, including along the I Beam. I have a Lyra Delos on it. I adjust VTA on almost every record I play, to the extent that I'm looking to get Bruce to replace the worn out arc bloc. I don't know how folks can live with one VTA setting, given the difference in vinyl thicknesses, and variations within a thickness. I've had mine for about 15 years.

Dover, what was involved in having a custom armtube bracket made? That sounds like a good mod.