Eminent Technology ET-2 Tonearm Owners

Hi Chris,

Thank you so much for the comprehensive response. Very helpful.

I shamelessly stole the TNT thread drive mod (all the way down to using unwaxed dental floss) from your posts here. BIG improvement!

Ditto for the second low pressure regulator that I installed behind the table (stole it from your posts). There is only 2 feet of 1/8" tubing and a check valve between this regulator and the arm, so all pressures quoted in my posts are essentially "at the arm".

My compressor is the Medo AC0910. Compared to the AC0110, the 0910 puts out a lot more air volume at higher pressures and has a higher max operating pressure (21.4psi vs 17.1psi for the 0110). Frogman uses the 0910 and says that it does a great job with this HP 2.0 bearing at 17psi. The compressor sits in my DIY baffle box in a closet about 12 feet from my listening position. Can't hear it there. The first regulator/filter and 4 foot long 4" PVC surge tank are in the closet as well.

I just did the Pump test. Turned the preamp volume up way beyond normal listening levels and put my ear close to the midrange drivers. No added noise at 3.5psi, but I hear a slight hissing sound from the midrange drivers starting at 5psi and increasing slightly in volume at 7psi. The noise does not pulse, but is a smooth and faint sound of air flow. Sounds a bit like tube rush. The noise does not seem to increase as I move up from 7psi to 17psi. I can't really hear it at my listening positions at max listening volume, but I think your point is that if I can hear it, it is affecting the performance of the arm. Any suggestions on how to reduce/eliminate this (may be solved with the HP manifold)?

Agree that the air bladders are, and have always been, a PITA. I recently called VPI about the leakage issue and they sent me some modified round rubber bushings to place around the outside of the schrader valve so that it seals the metal cap to the corner pods. Seems to be working great so far.

The AT616s are so cool looking on your TNT. I saw a set on "that auction site" for 400 bills. They show some deformation on the top. For that price, I would want an audible improvement over the air bladders in addition to eliminating the aggravation of maintaining level. Any opinion on that?

Thanks again, Chris.

Best,
Dave

Any suggestions on how to reduce/eliminate this (may be solved with the HP manifold)?

Dave - just so we understand.
so no noise in your system with NO pump on - stylus in groove - and the preamp volume high.
this is with a stock ET2 which is designed to work at about 3 psi.
When you turn the pump on there is no noise in your midrange driver up to 3.5 psi,
So we can assume the ET2 with your pump works well to 3.5 as designed ?
In fact it is quiet to just under 5 psi. So all is good.

but at 5 psi you start to hear what sounds like air (like tube rush) in your midrange driver.
It is not a mechanical piston type noise, or drone like noise - it is the sound of air - maybe like air escaping ?
It gets louder to 7 psi and then stays the same to 17 psi.
I would think if it was mechanical / piston problem it would maybe be heard at the lower pressure too. Maybe the hydraulic guys? can chime in - Richard ?

try something - with your system on mute and the ET2 raised and at rest.
crank the PSI up all the way to 21 and put your ear right next to the ET2 manifold- do u hear any sounds like a balloon with a leak ?
If yes is there air coming from a bolt ?
Try wiggling the tube at the input nozzle around. It would be shame if a great pump system and that connection at the plug is not tight.
If there is a leak at the plug - pull the plastic out - cut an inch off so the plastic is tight and fresh - re-insert. Is there significant air coming from the manifold where the spindle enters and exits? You will feel the air coming out with your finger near both ends.

With the info you provided it sounds to me like the HP manifold would fix this as its lungs are designed to inhale the higher PSI.

Frogman uses the 0910 and says that it does a great job with this HP 2.0 bearing at 17psi.

Frogman provides clear support for the HP ET2 model with the same pump.

It is very easy to spend other peoples money :^)

Since you are hearing benefits of the higher pressure - but you have a stock ET2 it makes sense to me to do it, if you feel its worth it? Bruce charges a reasonable amount for both upgrades ? Making the ET2 HP or by using his magic to transform the ET 2.0 into the 2.5 HP. As you said this would take a few weeks.

Some input from the others?

I recently called VPI about the leakage issue and they sent me some modified round rubber bushings to place around the outside of the schrader valve so that it seals the metal cap to the corner pods. Seems to be working great so far.

What a great service company. I bet they didn't charge you for those either, and if they did a very nominal charge.

I saw a set on "that auction site" for 400 bills. They show some deformation on the top. For that price, I would want an audible improvement over the air bladders in addition to eliminating the aggravation of maintaining level. Any opinion on that?

http://www.ebay.ca/itm/Audio-Technica-AT616-Pneumatic-Suspension-Audio-Insulator-4-pcs-/321244326789

Probably 500 by the time they get to you.
I don't know what to say - everything in this crazy hobby just keeps going up in price.
What you see in the picture may be marks only and not an actual indent.
The seller can verify this.
Sounds like your VPI fix is working so I would hold off. I'd put money into the manifold ?

Chris

HI CHRIS - ANSWERS IN CAPITALS BELOW:

Dave - just so we understand.
so no noise in your system with NO pump on - stylus in groove - and the preamp volume high. RIGHT
this is with a stock ET2 which is designed to work at about 3 psi. RIGHT
When you turn the pump on there is no noise in your midrange driver up to 3.5 psi, RIGHT
So we can assume the ET2 with your pump works well to 3.5 as designed ? YES
In fact it is quiet to just under 5 psi. So all is good.

but at 5 psi you start to hear what sounds like air (like tube rush) in your midrange driver. YES
It is not a mechanical piston type noise, or drone like noise - it is the sound of air - maybe like air escaping ?

NOT MECHANICAL OR PISTON NOISE OR DRONING, JUST THE SOUND OF AIR, LIKE AIR ESCAPING. SIMILAR TO THE AIR SOUND YOU HEAR WHEN INFLATING CAR TIRES FROM AN AIR TANK WITH NO COMPRESSOR, BUT SOFTER.

It gets louder to 7 psi and then stays the same to 17 psi. RIGHT. MAYBE SLIGHTLY LOUDER AS PRESSURE IS INCREASED.

try something - with your system on mute and the ET2 raised and at rest.
crank the PSI up all the way to 21 and put your ear right next to the ET2 manifold- do u hear any sounds like a balloon with a leak ?

DID THIS AND FOUND OUT THAT THE AIR INLET NOZZLE WAS LOOSE WHERE IT SCREWS INTO THE ARM HOUSING. HAD TO TURN IT 180 DEGREES TO TIGHTEN. NOW AIRLINE FORMS A U-CURVE BETWEEN ARMBOARD HOLE AND INLET NIPPLE. LOOKS FUNNY BUT WORKS. NO MORE AIR LEAK THERE. WILL ASK BRUCE ABOUT THIS.

If yes is there air coming from a bolt ?

I STILL HEAR A VERY,VERY FAINT AIR NOISE FROM AROUND THE BEARING AREA. TIGHTENED BOTTOM VTA ADJUSTMENT BOLTS TO SEE IF ANY EFFECT , BUT NONE. CHECKED OTHER BOLTS QUICKLY. I BELIEVE THE REMAINING AIR NOISE IS COMING FROM THE BEARING ITSELF, BUT IMPOSSIBLE TO TELL FOR SURE.

Try wiggling the tube at the input nozzle around. It would be shame if a great pump system and that connection at the plug is not tight. If there is a leak at the plug - pull the plastic out - cut an inch off so the plastic is tight and fresh - re-insert. TUBE WAS TIGHT BUT NOZZLE WAS LOOSE - SEE ABOVE.

Is there significant air coming from the manifold where the spindle enters and exits? You will feel the air coming out with your finger near both ends. NONE DETECTABLE AT ~3PSI BUT DEFINITELY FEEL AIR ESCAPING AT EITHER END OF THE BEARING HOUSING AT 7+psi - MORE AS AIR PRESSURE IS INCREASED, BUT NO "KICKBACK" OF ARM AT END OF TRAVEL AS OTHERS HAVE REPORTED.

With the info you provided it sounds to me like the HP manifold would fix this as its lungs are designed to inhale the higher PSI. SURE HOPE SO!

Frogman uses the 0910 and says that it does a great job with this HP 2.0 bearing at 17psi.

Frogman provides clear support for the HP ET2 model with the same pump.

It is very easy to spend other peoples money :^)

FROGMAN IS AWESOME!

Since you are hearing benefits of the higher pressure - but you have a stock ET2 it makes sense to me to do it, if you feel its worth it? Bruce charges a reasonable amount for both upgrades ? Making the ET2 HP or by using his magic to transform the ET 2.0 into the 2.5 HP. As you said this would take a few weeks. I WILL CALL BRUCE TOMORROW TO CONFIRM THAT MY ORDER IS STILL IN QUEUE. SURE WOULD BE GREAT IF HE MAGICALLY FOUND A 2.5 BEARING ;^)

Some input from the others?

I recently called VPI about the leakage issue and they sent me some modified round rubber bushings to place around the outside of the schrader valve so that it seals the metal cap to the corner pods. Seems to be working great so far.

What a great service company. I bet they didn't charge you for those either, and if they did a very nominal charge.

THEY CHARGED $2.50 FOR A SET OF FOUR. ALSO GOT NICE PLUGS TO FILL THE HOLES IN THE TNT'S PLINTH WHERE THE TRI-PULLEYS WERE FOR $5 EACH.

I saw a set on "that auction site" for 400 bills. They show some deformation on the top. For that price, I would want an audible improvement over the air bladders in addition to eliminating the aggravation of maintaining level. Any opinion on that?

http://www.ebay.ca/itm/Audio-Technica-AT616-Pneumatic-Suspension-Audio-Insulator-4-pcs-/321244326789

THAT'S THEM

Probably 500 by the time they get to you.
I don't know what to say - everything in this crazy hobby just keeps going up in price.
What you see in the picture may be marks only and not an actual indent.
The seller can verify this.
Sounds like your VPI fix is working so I would hold off. I'd put money into the manifold ? RIGHT. MAYBE ALSO A NEW AUDIO NOTE WIRE LOOM PER FROGMAN. MY AYRE PHONOLINEPREAMP HAS XLR INPUTS FOR THE PHONO STAGE. WOULD LIKE TO GET THE BENEFIT OF THE DIFFERENTIALLY BALANCED CIRCUITRY AND ELIMINATE THE RCA TO XLR ADAPTERS I AM USING NOW AS WELL AS THE ARMWAND PLUG, ET RCA JACKS AND INTERCONNECTS (ALTHOUGH THEY ARE VERY GOOD ONES).

THANKS CHRIS! MUCH APPRECIATED.

DAVE

Re "escaping air". Even with the HP bearing/manifold there will be air escaping from the ends of the bearing. In my case you hear it only when the arm is at either end of its "trajectory"; and certainly cannot be heard when music is playing. IOW, you hear the air when it escapes and then has either the rear end cap or front elbow to make contact with. In general, the sound of a small amount of air escaping is normal, subtle, and should not be surprising. Chris is correct about the issue of pressure at the pump vs that at the arm, but the Medo 0910 is conservatively rated and actually outputs closer to 30 psi, so achieving 17-19 at the arm should not be difficult. Dave, you will be very pleased with the HP manifold and Medo; it is not a subtle difference. Keep us posted.

Air escaping from the bearing can cause subtler damage by modulating the arm wand and stylus. This may be a necessary evil in any air bearing design... Doubtless the effect can be mitigated by reducing air gap tolerance or with arm wand damping. I suspect that the Kumza Airline has a particularly close gap, as it is designed for higher pressure 60 psi operation. At CES I asked F. Kumza about this. He replied that as the technology is well proven in industrial instruments in microscopic applications, it should be good enough for audio.

Trans-Fi/Ladegaard is the only air tonearm that I know of that doesn't use a captured air bearing. Air escapes freely all around the bearing. With this design the lowest possible air pressure that floats the bearing(about 1 psi)sounds best. A different approach.