Eminent Technology ET-2 Tonearm Owners

Frogman - I think this the 4 th time you have made me spit up coffee on my keyboard.

Q: How can one tell that the floor of the stage is level?

A: The viola player is drooling out of both sides of his mouth.

What happens to the poor guy when the stage is tilted back a bit ?

maybe I don't want to know...

Hi All.

I have been experimenting with the air supply again. This after earlier experiments implied that the output pressure from the regulators I am using oscillate around their setting.

The change I made was simple taking a few minutes but furnished a worthwhile improvement.

initial setup was... Compressor, inbuilt regulator, 6feet soft PVC tube, 1/4" needle valve vented to atmosphere (barely open), second regulator water trap, 30feet soft PVC tube, arm.

The new configuration places the needle valve immediately after the second regulator. The theory being that both regulators are unstable and bleeding some air to atmosphere via a non compensated needle valve will smooth the regulator perturbations in the air stream to the arm. I had to increase the setting on the second regulator a tiny amount to bring the pressure seen by the arm back up to the pre change figure.

The hissing of the needle valve is not an issue since this setup is in another room.

The result is an increase in "tightness" notes are more visceral and solid. Soundstage larger in all directions, greater differentiation of the sound between records and individual tracks of the same record . An agreeable result.

All testing was done with the compressor cycled off.

*** YELLOW STICKY FOR ET2 THREAD MARK - AIR SUPPLY ***

A series of posts to help me and others find stuff here - just working with the system !

This one focused on Air Supply/Manifold/Air Bearing Spindle
ET2.0 (.5) Motto
Better the air supply "AT THE PSI AS DESIGNED FOR THE MANIFOLD IN USE" and the ET 2.0 (.5) just keeps sounding better.

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.

Firstly let me say I believe Bruce has created a real monster with this air bearing manifold/spindle design. Truly excellent results with a stock setup for music lovers to enjoy their records at 3 psi with the base ET2. This can be the end of the story, and it is for most. That's real life.
Lets recognize this for a moment before non-ET2 readers here think all ET2'ers are like us. I am sure in the thread views that there are many ET2'ers who have been enjoying their records in stock ET2 setup for years, that get quite the chuckle every now and then here with our adventures. Cool...enjoy..... I hope they approve of Dorothy. Boy I am mellowing as I age....

Unfortunately the changes with improvement of air supply is very addictive. I went personally through 6 pump systems. I am very very happy to report that I am a music lover again and pleased with what I am hearing. But its funny that all those experiments even though years ago are still fresh in my mind. We have all heard about Audiophiles going down deep rabbit holes with tweaks. Well this is about air lifting the music up to the ...... (use your own word to describe)

So some ET2 Secrets revealed.
I dug up a few emails with Bruce relating to Air Supply delivery that explain the above better - hopefully this is helpful, informative and illuminating to everyone. Maybe grab a coffee or "other" drink before reading. All emails cut down for brevity.

This first one I asked just yesterday - RK's post inspired me. The others are from early this year and previous years.

ME

Hello Bruce - assuming a setup like this.

pump /surge tank --- 100 feet of air line ---- ET2

Is it not better to have the moisture /dirt trap plus a second regulator as close to the ET2 for air supply quality ?

Chris,

I would put the pressure gauge/filter within 5 feet of the tonearm only so I could monitor the input pressure and the quality of the filter. After the air travels through a long length of small diameter air line the flow should be very smooth. To verify if the air flow is smooth, listen to the output of the air hose, if you hear any humming in the air flow then it is not a good air supply.

- brucet

ME
If we use my ET 2.5 as an example that you set up specifically for 19 psi which is your optimum design setting for your tonearm. A continuous 19 psi air flow is sent in. Can we assume the spindle uses all 19 psi to work optimally (or is it a percentage of this amount)

Bruce
The manifold is optimized for the design pressure, the pressure at the surface of the spindle is a percentage of the inlet measurement, this is by design. The ET2 uses roughly half of the air to allow the spindle to work properly ? The supporting force is the surface area of the bearing times the pressure at the surface of the bearing

ME
So allowing air to escape around the edges of the manifold as more is pumped in ? is this a captured air bearing system ?

Bruce
Yes it is captured.

ME
Hi Bruce - so to be clear - for example in the normal design of the base ET2 at 3 psi.
Air continually goes in at 3 psi - circles the spindle "captured bearing" and escapes out the sides of the manifold, as more air is pumped in? This is by design.

Bruce
correct

ME

If someone has a 20 year old stock ET2 manifold designed for about 3 psi and decides to pump in 12-15 or more PSI
the extra air will just escape around the edges of the manifold and at a rate that can be heard ?

Bruce

The extra air will escape, but the rate of escape will not be that large from an operational point of view, but the escaping air is usually audible which causes one problem and the air can cause a push back at the extremes of travel.

So there you have it. The ET 2.0 (.5) design is meant to bleed around the manifold. Now what happens then if someone mods their arm and adds shims to the ends of the manifold as has been discussed here ? Does this not block the air from bleeding as designed? IMO this would change the design substantially. This would also mean that any observations in regards to changes to air supply, most likely will apply to that setup only, and not a stock ET2 manifold setup ? I have not added shims and am just visualizing this. This is my opinion and I don't feel I need to ask Bruce on this one. Does anyone disagree ? Richard I bring this up as you are using shims ?

Another Fact revealed. This one is on page 3 of the manual. .

From Manual - Page 3
The large surface area of the air bearing uses some of the tightest tolerances in tonearm manufacturing today, and is much more rigid at audio frequencies than metal bearings.

Whenever I read that someone increased the PSI and it sounded better, some "Audiophiles" would say the bearing is not rigid. THIS IS TOTAL NONSENSE. It is not that the bearing is not rigid; its because by happening to increase the PSI with the pump in question, the user actually bettered the air supply coming in, with that respective pump. How many of us are pump experts ? How much do you really know about your pump? if that person had used a better pump same PSI the sonics would have also improved.
Its about better air supply.

My Pump - Timeter Aridyne Compressor

How Aridyne’s Dry Compressed Air Movement Works

This is what happens when I flick the switch.

First, air is drawn through the air pump inlet filter. Then it is pulled into the pump where the pistons pressurize it to 80 psi and push it forward through the Teflon® lined high pressure hose that is reinforced with braided stainless steel. At this point the temperature of the compressed air is approximately 300 F.
Then compressed air flows through the copper coils where it is cooled to room temperature. During cooling,
moisture in the air begins to condense. The cooled air moves to the water trap where the condensation is rained
out and collected. This moisture that is collected in the water trap is continuously drained through the nylon tube
to the water collection tray where it evaporates.
Next the air is decompressed to 55 psi by the secondary regulator. After this decompression the small amount of
remaining moisture is so dispersed throughout the expanded volume that the dew point of the air is several
degrees below room temperature. In the Aridyne Air Compressor this dew point depression can range from 3
to 10 F.

All of the above with the flick of a switch. Turnkey. I do need to train my new puppy on how to flick the switch. From this point the air is regulated down to 19 and sent down 100 feet of tubing - some of it coiled up. The ET2 likes dry Arizona air. Its been said here before.

I also happen to believe based on my compressors versus current setup from years ago, that there are advantages in a constant air psi being delivered by a quality pump versus a cycling off and on compressor which is like letting air out of a balloon slowly. This constant controlled air psi from a pump is how air is delivered for patients in hospitals. That's another discussion !

Now a question for long time ET2'ers using original manifolds. Some over 20 years old. When is the last time you checked the condition of your capillaries? Are the manifold inlets at 50-60-70 80% of what they should be? If not 100% you will be using more PSI to drive the arm because they are partially clogged and not getting the performance they were designed for. This is another reason some say the sound got better with more PSI. Clean them per the manual instructions.

lastly - someone advised me of a poster, a respected professional reviewer who has posted on Whats Best Forum saying he used 50 psi with his ET2 for it to sound its best. First as mentioned above the design limitation is 19 PSI. Don't take my word for it - Ask Bruce yourself. When I read stuff like this, I make like a deer in the headlights on the other side of my screen. I wonder what he really hears, and what else is in his audio chain to cause this. I try to stay within the design parameters for all the gear I own. This is another clue imo that you are a music lover first.

My experiences have been increase the quality of the air supply and the sounds gets better - every time.

I hope this was helpful.

More secrets revealed coming up. The title of the next post?

"Why does the action of my ET2 VTA, resemble me Coming Out Of A Brothel at 2:00 am"

The dirty secret is finally revealed......

"Why does the action of my ET2 VTA, resemble me Coming Out Of A Brothel at 2:00 am"

lol. Can't wait to read that one.

Chris.
You must have time on your hands to produce such a lengthy thoughtful tome.

I read it multiple times to try to get inside what you were saying. I think that you take BTs comments to mean that the o'rings will leak if a low pressure manifold is over pressured? I don't think that this is what he means.
I suggest that BT adjusts the arm design pressure by manipulating the clearance between the spindle OD and manifold ID and/or the way the capillaries are set up.
The push back at end of travel he talks about is due to excessive air flow exiting the gap between spindle and manifold bush, not due to the o'rings leaking.

The shims I have added are in the gap between the manifold outer plastic shell and inner aluminium bushing. This is the gap where the o'rings sit. The 2 shims about 2x3x**mm thick, each end, are spaced at 120 degree increments. Completing the circle at 120 degrees each end is one M2 grub screw. It is gently tightened to make a solid mechanical link between the manifold outer shell and the inner bush.

One would not consider removing the main arm to TT plinth mounting bolt and gluing the arm to the plinth with say rubber discs spacers in place of the three pointed screws, since this would be introducing a compliant joint between the arm and TT. But this is exactly what the o'rings do. They are a compliant joint.

The positive benefits of adding the shims and grub screws is unambiguous.

cheers.