Eminent Technology ET-2 Tonearm Owners

HF Dover.
Compressor is a piston type, which one would think would produce a pulsating air flow. Certainly the piston type loaner they gave me failed the Chris T noise test. The difference this time around is as follows. I'm using two regulators in series. I have a small restrictor between them, ( a trick we sometimes use for low pressure pilot hydraulics). The tank is a little larger. Its set/ reset pressures are much higher 120/80 psi v/s 60/40 psi.
I said earlier that it turned back on too frequently at around every 7 mins. When it does turn on, it only runs for approx 10 seconds. Obviously a larger tank will not only increase the rest time but also increase this on time. I could lower the reset pressure, giving a longer rest time, but there would be a corresponding increase in run time so don't plan to do this since the compressor is acoustically noisy. This can't be heard in the listening room but can in other parts of the house. Also I suspect that the regulators are more stable with a high delta P, contributing to the smooth air flow. This is certainly the case with hydraulic regulators.

Hello fellow ET owners! I recently resurrected my TNT/ET Two (2.0) rig and thanks to this thread and a lot of advice and encouragement from Frogman, the sound quality is now the best I have heard from my system:

Dave's system

After converting the TNT to thread drive and eliminating the tri-pulley system, I made a 2 spring I-beam and moved the weight way out on the I-beam (past 6). All three of these tweaks made a significant improvement in sound quality and it was all free!

I then started working toward improving the air supply to the arm. I was using a WISA 300 and the ET pump together out-of-phase into a makeshift surge tank (could not find the old Airtech in the attic). On Frogman’s recommendation, I build a 4ft long 4” PVC surge tank and bought a Medo AC0910 compressor. Assembled two regulator/filter units, a standard pressure one between the Medo and the surge tank and a second low pressure unit right before the arm. Also built a DIY baffle box to reduce the noise from the Medo. Made it quieter than the WISA. Pics of most of this are at the link above. One other improvement was adding a high-quality check valve under the table just before the arm. I read about this on another thread and it really makes a significant difference in sound quality, similar in magnitude to adding the bigger surge tank.

Called Bruce about a HP manifold for the 2.0 (no more 2.5’s available) and he said it would take about 3 weeks to make one for me, so I am now experimenting with the new air rig and the standard 2.0 manifold. Started at 5psi at the arm. Good improvement over the old WISA/ET pump setup (~3psi at the arm). Went to 7 psi, not much difference from 5psi. Then cranked it up to 12psi. Blacker background, tighter and more tuneful bass, but maybe not quite as open in the highs as at 7psi (only slightly less open, if at all). Perhaps it is just smoother, eliminating some arm resonance occurring at the lower pressure that I mistook for open-ness…

I was wondering if anyone has experience with even higher pressures with the stock 2.0 manifold? I think 12psi is probably pushing it, so thought I would ask here before going higher. From my reading of this thread, it seems that most of you have reached a pressure “threshold” where the sound quality starts to fall off. What exactly do you hear when this happens?

I really like this thread and all suggestions will be appreciated.

Thanks again to Frogman for his excellent tutelage and encouragement.

Dave

I have not used the low pressure bearing with anything other than the stock pump and then the Wisa, which Bruce considers "high-pressure". I know that he feels that the arm with regular bearing performs best with lower pressure, but like you, I experienced considerably better sound with the Wisa's higher pressure with regular bearing. When I later upgraded to the HP bearing it worked well with the Wisa, but nothing like the large jump in performance that I experienced with the move to the Medo compressor (+\- 30 PSI). Welcome to the thread.

Thanks Frogman. I did experiment with higher pressures (15-17 psi) over the last couple days and my ears are telling me that sonic differences between 5psi and 12psi are very subtle and I really can't discern any improvement above 12psi. Maybe that's why Herb Wolfe (Airtech Audio) chose 12 psi for his WISA upgrade way back when (before the HP manifold was available)...

I was reading back through this thread tonight and found this:

01-19-12: Apbiii
...My arm is a very early version, so certainly not optimized for higher pressure, and I can feel the air escaping at 19 psi but I can't hear it yet. I have not tried to determine if it introduces significant horizontal force. As I stated in my post I could hear some of the life or vibrancy go out of the music when I increased the pressure...

and this:

01-20-12: Apbiii
...Frogman the change in sound with changing pressure was fairly subtle prior to the suspension change and since the change is essentially nonexistent...

Seems to confirm what I am hearing with the stock manifold. Can't wait to get the HP manifold.

While reading through the thread, I took a look at Ct0517's system(s). Holy cow! That's some serious gear. I was especially stoked to see his TNT setup with the Audio Technica A616 footers:

>http://cgim.audiogon.com/i/vs/i/f/1366420145.jpg


I have come to terms with idiosyncrasies of the VPI air bladders, but I sure would like to find some of those feet. Would be interested in hearing Ct0517's impressions of the TNT with and without the AT616s.

Best,
Dave

Hi Dave

After converting the TNT to thread drive and eliminating the tri-pulley system, I made a 2 spring I-beam and moved the weight way out on the I-beam (past 6). All three of these tweaks made a significant improvement in sound quality and it was all free!

You gotta love that. For me improving sound for nothing is the best "lasting" feeling in this hobby. Its a special feeling imo when you discover something on your own. I guess because I want to know why it works. It needs to be repeatable and when reversed, should bring things back to where you were.

I was wondering if anyone has experience with even higher pressures with the stock 2.0 manifold? I think 12psi is probably pushing it, so thought I would ask here before going higher.

When you refer to PSI are you referring to the PSI at the pump itself or at the ET2 arm ?

Reason I ask - the MEDO AC0110 pumps that I have owned in the past all lose some psi along the way. They deliver 12 at the pump itself pump but about 7-8 PSI at the actual arm.

From my reading of this thread, it seems that most of you have reached a pressure “threshold” where the sound quality starts to fall off. What exactly do you hear when this happens?

01-19-12: Apbiii
...My arm is a very early version, so certainly not optimized for higher pressure, and I can feel the air escaping at 19 psi but I can't hear it yet. I have not tried to determine if it introduces significant horizontal force. As I stated in my post I could hear some of the life or vibrancy go out of the music when I increased the pressure...

"Some of the life or vibrancy go out of the music"

imo these are very good and effective words by Archie of what happens - "life and vibrancy" I wonder if he is still around ?

Someone asked me about this on my system blog. This was part of my response.

"So to answer your question based on my experience. If too much air is put through and starts affecting the spindle the actual spindle will start resonating. The detail in the music will start blurring. Its kind of like when your stylus gets a little dirt on it if you are lazy to clean it. I take notice of it from familiar recordings - something is amiss or off and you clean the stylus. Likewise sonically the music sounds thinner, leaner with less information. imo - this is how you will know what pressure psi your system can handle based on your own system / room."

So I think we are all saying similar things as to what we hear.

Now here is something to think about.

IMO outside of our own room/gear tuning, the "PSI threshold" itself for each of our systems is determined as a result of two separate things but both need each other to work.

The pump delivery system itself and the ET2, 2.5 spindle starting to vibrate/resonate.

Both the pump system and the ET2 and ET2.5 can be at varying stages of setup and condition with each of us. Consider someone using a 20 year old ET2 that has never been cleaned out or has leaking air around it; over a newer one, maybe a new Et 2.5 that Bruce just delivered to someone. The beauty here is that the older one is easily cleaned and air leaks tightened and brought up to spec again.

The pumps are the real moving targets here as we all use different pump setups.

I am willing to bet 100 Canadian dollars if you asked Bruce in the last 20 years of the ET2, ET2.5; if there was one thing he could change he would say something about having more control over the pump systems that people have used.

We can help to assess how much the PUMP is contributing to the PSI threshold with the PUMP test.

Have you tried the Pump Test yet Dave ?

This requires the help of a friend.

*****************************************************
Turn your system on and place it on mute at lowest volume.
With your ET2 setup properly (level and balanced) and NO air on - lower the stylus onto a lead in groove.
Again with NO Air on - unmute the system and start raising the volume.
Keep going till you reach the level on your dials that represents high volume in your room.
Your room has now become a listening chamber for your system and gear and more importantly - NO PUMP.
Its isolated and not a factor yet.
If all is well to this point,
with the stylus acting like a stethoscope in that groove, go up to one of your speakers and wait there.
Tell your friend to go turn your pump on while you keep your ear up close to the speaker.
*****************************************************
What do you hear when your friend turns the pump on ?
Have your friend turn it off and on again.

If you are hearing any noise at all, the pumps air delivery is not optimized and is sending nasties to your ET2.
The noise is putting a layer in the music.
This is also affecting the PSI you can run with your ET2.
It is my opinion that improving the air delivery should allow you to reach the best PSI threshold for your room/gear with the high pressure manifold ET2 or ET2.5 and gain benefits.

I am not a scientist. I am hobbyist, I trust my ears and I base this on my personal experience.

Very Important
For anyone reading that is a new ET2 user do not attempt the above test until you are familiar with the ET2, it is setup properly, level and balanced.

A while back I went on a mission for a few years with pumps. I ended up with the Aridyne timeter medical pump that is used for patient respiration. You flick a switch to turn on and off. It dumps moisture at the pump just like a cars AC system. These are purchased on ebay cheaply but required being picked up. They do require a separate room as they are around 60 db as far as how loud they are when you stand next to them.

I have come to terms with idiosyncrasies of the VPI air bladders, but I sure would like to find some of those feet. Would be interested in hearing Ct0517's impressions of the TNT with and without the AT616s.

Regarding the TNT

As with noise above being the resonance vibration hobby it is - I have always found consistent results whenever we are able to remove "noise or structure feedback" from entering our system/gear. The result being more music comes through for us. We have all experienced this sensation and it generates the same kind of comments on the forums -

"I did not realize the "noise" was there until it was removed"

The TNT and thread - congratulations for implementing this! this was a biggie for me. A sort of analog revelation.

http://cgim.audiogon.com/i/vs/i/f/1366420145.jpg

If you read my system blog thread, the thread controlled with the SDS controller, truly elevated the performance of the TNT.

Air bladders like the VPI legs work but keeping them inflated and level can be a PITA and as we know out of level is disaster for an air bearing tonearm. I found the Pneumatic AT616 footers insulate and decouple really well, but where they supersede others is that they have a smooth and excellent leveling system - and once set - don't go out of level. The Verdier also has a pneumatic suspension.

Welcome to the thread Dave.
Very nice setup btw. I wish everyone here could post virtual systems.
sorry for the long post and any errors.
Cheers Chris