Eminent Technology ET-2 Tonearm Owners

John
The owners I have talked with before this thread started used to use bubble levels. If one really wants to find out the wiring effect (push and / or pull)... set the arm up without the wiring. Then add the wiring in and find out the truth. This is how I do regular setup. If one were a wire loom swapper kind of audiophile - which I am not. It would take all of 10 minutes to swap out entire wire looms using the wiring layout I am using.

As far as PSI - people should be using the PSI designed for the manifold by Bruce. If someone picks up a used ET2 and this is unknown - we have discussed the process on how to determine the PSI. If anyone wants to rehash, then lets rehash. Higher PSI won’t harm things unless you go over 19 psi. We can discuss why this is too if someone wants. There is a reason Bruce designed my ET 2.5 for 19 PSI.

With that it bears repeating that if someone is using higher PSI and it sounds better, it is likely because;

1) air flow quality is better over the previous pump - not because of the higher PSI.
2) your manifold capillaries are partially clogged.

If using the original pump on a stock ET2 - the pump may be producing PSI but it is unlikely the diaphragm is in spec. Air flow quality suffers.

The ET2 is like an Olympic runner when it comes to good air flow. The better the flow, the better the operation, and therefore the sound. If we analyze how other air bearing tonearms work, it is really quite fascinating (to me), how different each design is.

Cheers Chris

Regarding pumps and pressure:
a) Back in the 80's I found that the WISA 300 "high pressure" model (of which I bought several, directly from the company) was a single membrane pump, not a double one like the original HiBlow. My high pressure WISA model dropped in actual measured pressure level at the arm below the HiBlow, and had a high variation of pressure (mains frequency) - and the needle vibrated. This resulted in a "homeopathic 50Hz drone" that subjectively gave more, but a slihtly tubbier bass - this was *with* a ca. 7.5l tank.
b) I then chained two HiBlow pumps, ie. I hot-glued a piece of silicon tube to the inlet of one pump and to the outlet of the other pump. This resulted in (if I remember correctly) ca. 0.45 Bar (6.5 psi?). Three pumps were around 0.6 Bar, all this sounded very good, and was more silent  than a WISA pump. The HiBlow has a surprisingly steady flow and it's limitation can be surmounted by chaining two or three. On the ET 2's "normal" low pressure bearing the two HiBlows were a remarkable improvement.

^^

"This resulted in a homeopathic 50Hz drone"

’8^0

If one wants to hear if their pump is introducing noise.
Ensure your setup is good before attempting this.
With the air pump ON and system on mute, lower the ET2 onto a "STILL" record.
Now turn OFF the air pump, and unmute the system.
Have your friend now turn ON the air pump, while you listen close to the speaker.
Ensure your setup is good before attempting.

This is indeed the way I tested this. Stylus in groove, platter stationary, pump running, phono gain turned up. In this test the HiBlow was audibly quieter than *my* WISA 300 high pressure.

I use two wisa pumps working out of phase with each other in parallel, two large surge tanks in series with a small surge tank made from a plastic radio control gas tank, sitting a few feet from the ET-2. When I did the above test, it was complete silence with and without the pumps on. -Guess my pumps are different?
-John