Eminent Technology ET-2 Tonearm Owners

Ct0517: Regarding my arm and for which pressure it was designed.... I found a receipt stating "high pressure manifold", remember, this was way back when this option was first introduced. This and the fact that I am getting optimum sound from exactly 18.5psi, to me, confirms the fact that what I'm hearing correlates to this discussion.
Again, FWIW.

Richardkrebs: My "low cost" way to smooth out air pulses to null and at the same time trap any and all moisture has seemingly been lost in this thread. For around $100 one can have it all in a small package, low maintainence, HIGH performance in an "all-in-one" product. The Motorguard filter... the M-30 & M-60, I use the M-30 in my stereo system as it comes with a mounting bracket and readily accepts the fittings we normally use in this application. If one wants to investigate there are user forums one can search on line. I highly recommend it!

Ct0517: (While you all are on compressors),I finally took my Jun-Air to be repaired. I am excited about it's return and my thought to add the ability to expand it's capacity by way of an extra air tank. By the way, it's a 6-25 not a 16-25 as I mistakenly wrote earlier.

Frogman & Ct0517: I feel the need to admit the fact I was wrong. Early on in this thread, there was a discussion regarding the sonics of "The Nightfly" lp. I've been modifying my wall panels and decided to replay this lp. My verdict is while it's obviously a digital recording, I can now listen to it and enjoy! Ahhh! CT0517, you were right, it was my room.

Richardkrebs
I did not say that the mass of your arm is “300% heavier at these frequencies”. I have said that your horizontal effective mass is 300% heavier than standard.

Your arm is 300% heavier than standard. You added 30g of lead and removing the decoupled counterweight increases effective horizontal mass above FR. These 2 changes have increased the horizontal effective mass of your arm by some 300%.

Since the removal of the decoupling increases the horizontal effective mass above FR - FR for most systems would be below 10hz, then we can say that the increase in horizontal effective mass of some 300% will affect all reproduction above 10hz.

As far as below FR goes, your argument is the cantilever does not flex below FR. I dont agree with this as confirmed by Bruce Thigpen in his correspondence. I have seen cantilevers flex on eccentric records and will post a video at some stage.

However the cantilever and suspension still see this mass.

As far as the damping paddle goes, Bruce Thigpen provides this option for the standard ET2. Thigpen does not sell an ET2 with a fixed counterweight and 30g of added lead. Your claims that one can achieve a flat response in the bass with a fixed counterweight and 30g of added lead mass are not supported by any testing.

****Chris has taught me the extreme importance of the air supply. A good smooth source of air lifts the arms performance considerably. ****

Completely agree; and analogous (pun intended) to the importance of good clean (smooth) power for our electronics.

Greg.

Good luck with the pump rebuild.
Chris has taught me the extreme importance of the air supply. A good smooth source of air lifts the arms performance considerably.

Hi Greg

I looked at it again and see that the pump has just come loose from the springs. The intermediate shelf looks solid and the springs are still attached there. What I can see of the spring mounts on the pump look ok too.

I suspect it was banged around or dropped and that pulled the pump loose from the springs... and then it was banged around a lot afterwards to nearly pulverize the plastic housing.

that is a little better news. the shipper must have had the thing close to upside down at one point for it to come off one of the springs? That Timeter pump hanging in its enclosure, reminds me of the pics and videos I have seen in the past of those eccentric vinyl guys (women audiophiles would never do this ?) who hang their entire turntables from the ceiling beams with long thick cables for isolation and to avoid vibrations. Thats the idea here as well and the first time of I have ever seen a motor mounted this way.

Look forward to hearing your progress with it. Cheers

Dover.
"yet again you miss quote me"
I think not. See your post 03-13-13. Where you go to great lengths to show, incorrectly, that when tracing eccentric records, my arm is 300% heavier than a standard ET2.
The leaf spring is inactive at eccentric record frequencies. ALL ET2's and my arm are of similar effective mass as seen by the cartridge under these conditions.

I am on record stating the clear superiority of the oil trough over my previous low pressure damping method.

Dover
"provide damping in the vertical plane and less in the horizontal"
Wrong. A quote from the oil trough manual "The design of the paddle and its position mean that it will be much more effective for damping horizontal resonances than vertical"
This is a simple paddle shape and lever effect. The arm has no leverage over the oil paddle in the horizontal plane but has the full length of the arm wand in the vertical. The target is horizontal damping. This is why BT publishes the before and after responses of horizontal resonance. Where the nasty high Q resonant peak is effectively eliminated.

Frogman.

If you are using a low compliance cartridge, have you tried a properly stiff fixed counterweight with an oil trough fitted? Disabling the leaf spring(s), say by wedging match sticks in the gaps, gives a hint at the effect, but the counterweight I beam is too flexible (it was never designed to be stiff) to show the true differences.

Thanks for the comments. I had forgotten that the ET1's counterweight arrangement was not decoupled. While I can't speak to why the reviewers that I mentioned considered the weightier bass of the 1 to be "superior", I do agree with Dover that, based on my experimentation, decoupling the counter weight wand does result in bass that is more tuneful and correctly speedy than with more direct coupling.

01-28-14: Richardkrebs
Dover.
Up till recently you have been telling us all repeatedly that the counterweight decoupling spring is active at eccentric record frequencies and that at these frequencies my arm is up to 300% heavier than a standard ET2. We now all know that you are wrong

Yet again you have misquoted me.
I said that your arm is 300% heavier than standard based on the information you provided. You claimed that you had added 30g of lead mass to the 25g spindle and that you had converted the decoupled counterweight (30g+) to a fixed counterweight.

01-28-14: Richardkrebs
The math which proves this effect, below FR, shows that above FR the decoupling spring is active and it dramatically reduces the arms effective mass.

So now you have contradicted yourself and agree that the decoupling reduces the effective mass. This means that based on your assertion that you added 30g of lead to your arm and removed the decoupling then you have indeed increased the effective mass by 300% or thereabouts.

01-28-14: Richardkrebs
If we fix the counterweight, to push FR below the danger zone, we unfortunately get a big, high Q peak at FR. Exactly what the leaf spring fixes for us. So there is a conundrum here. Live without the last bit of bass extension or fix the counterweight and experience bloated bass performance, not due to excessive bass but due to the FM phase problems propagating up from FR into the audible spectrum. On the bloated bass topic we agree.

You now concede that fixing the counterweight will generate bloated bass as documented on Bruce Thigpens website. Since you also have acknowledged that fixing the counterweight increases the effective mass above FR, then fixing the counterweight will have deleterious effects on bass, midrange, treble - where the music is.

01-28-14: Richardkrebs
But there are solutions to this. Run the arm at pressures below design and dress the lead out wires to resist lateral movement. Not a very elegant solution but it kinda works.

This is a terrible solution. You are proposing to run the arm at air pressures below the air bearings design parameters and/or increase resistance to lateral motion by putting tension on the lead out wires.
Others on this thread including Frogman, Slaw, Ct0517 have reported significant improvements in sound quality by increasing the operating pressure and reducing any drag added by the lead out wires. You are proposing the opposite. Most systems with a reasonable level of resolution are capable of demonstrating the effects of increasing horizontal effective mass.

01-28-14: Richardkrebs
Or far more effective, ran at design pressures and use an oil trough. See BT's test data on this where he uses his arm "set up so that a high amplitude Q existed" (a fixed counterweight exhibits a high Q) and then adds the oil trough. The resultant response graph he publishes in the oil trough manual, shows a critically damped system with zero resonant peak and importantly he mentions "the ET2 with a damping trough will exhibit almost perfect low frequency phase response"
No more bloated bass and with full LF extension. Lovely.

You have misunderstood BT's testing protocols and conclusions.
BT says "the ET2 with a damping trough will exhibit almost perfect low frequency phase response". He is referring to a standard ET2 that has not had lead mass added and has not had the decoupling removed. It should be noted that the damping paddle is designed to provide dampening in the vertical plane, but less so in the horizontal plane. This is why it is wide and thin. The fluid damping is designed to address record groove irregularities which cause scrubbing and oscillation as the stylus tracks. This is documented on BT's website and is also documented in the Shure white papers on trackability.

In summary the changes you have made to your ET2 including adding mass and removing the decoupling are contrary to the fundamental design principles and advantages of the ET2 and should be discarded.

Dover.

Up till recently you have been telling us all repeatedly that the counterweight decoupling spring is active at eccentric record frequencies and that at these frequencies my arm is up to 300% heavier than a standard ET2. We now all know that you are wrong and that the spring is in fact rigid at this low frequency making the effective mass seen by the cart in standard ET2's in the same ball park as my arm with a fixed counterweight.
The math which proves this effect, below FR, shows that above FR the decoupling spring is active and it dramatically reduces the arms effective mass. This is a brilliant solution if you are using a high compliance cartridge. But this same math shows that if the FR is around 7Hz or above, we get bass attenuation. Low compliance carts will exhibit a FR in this danger zone of 7Hz and above. If we fix the counterweight, to push FR below the danger zone, we unfortunately get a big, high Q peak at FR. Exactly what the leaf spring fixes for us. So there is a conundrum here. Live without the last bit of bass extension or fix the counterweight and experience bloated bass performance, not due to excessive bass but due to the FM phase problems propagating up from FR into the audible spectrum. On the bloated bass topic we agree.

But there are solutions to this. Run the arm at pressures below design and dress the lead out wires to resist lateral movement. Not a very elegant solution but it kinda works. Or far more effective, ran at design pressures and use an oil trough. See BT's test data on this where he uses his arm "set up so that a high amplitude Q existed" (a fixed counterweight exhibits a high Q) and then adds the oil trough. The resultant response graph he publishes in the oil trough manual, shows a critically damped system with zero resonant peak and importantly he mentions "the ET2 with a damping trough will exhibit almost perfect low frequency phase response"
No more bloated bass and with full LF extension. Lovely.

Frogman,
I had the luxury of having both the ET1 and ET2 in my showroom in the 80's mounted on a variety of turntables along with other top arms of the day such as SME V, Zeta, Alphason, Dynavector, Odyssey, Sumiko The Arm, Goldmund, Syrinx PU2/3, etc
The ET1 had a bloated bass, slower and less tuneful than the ET2.
The ET2 was clearly more transparent than the ET1 by a considerable margin.

The improvements to the ET2 are as follows :

Decoupled Counterweight - This offers 3 advantages.
The decoupled counterweight reduces the horizontal mass
The decoupled counterweight splits the low frequency fundamental resonance, which results in two peaks of lower amplitude, improving the LF performance as demonstrated in Thigpens testing.
The decoupled counterweight provides the capability to tune the decoupling spring to the cartridge.

The maths may be taxing for some, but the Thigpens ET site has documented test results demonstrating the advantage of the decoupled counterweight design. It is incomprehensible as to why any individual would ignore Thigpens test results and convert the ET2 back to the ET1 format in respect of the counterweight, unless their system does not have the resolution to take advantage of this patented decoupled counterweight design, which yields a quicker and more tuneful bass as you have found in your testing.

Adjustable VTA that maintains correct position of the stylus

The tower provides easy adjustment to ensure the level of the horizontal bearing is congruent to the platter surface.

Here is a pic
http://www.eminent-tech.com/history/modelone.jpg

Frogman.

Look to the other end of the arm and compare the counterweight attachment. If you are using a low compliance cart on an ET2, this is the main cause of diminished bass extension. Calculate your FR using the ET2 manual formula. Around 7Hz or above and you are missing the lowest registers. The math on this is very clear.
Further the quite flexible goose neck and arm pillar on the ET2 don't help.

I remember very clearly that one of the things that reviewers seemed to agree on when comparing the newly released ET2 to the ET1 was the more powerful and more extended bass performance of the ET1. This was described as the one area where the original bested the 2. I would be particularly interested in how the arm wand attached to the bearing tube in the ET1; amount of decoupling and any other physical differences between the two arms that might contribute to this difference. Thanks.

LOL.

I'll try to respond to the ET-I vs II in more detail later this week... bottom line, I really liked the way the air bearing and arm base mounted mechanically on the ET-I and have always thought that upgrading the arm-spindle, arm-headshell, and cartridge interfaces while retaining the ability to adjust VTA and the secure bearing mounting might have made a more rigid arm.

Back on the pump, I looked at it again and see that the pump has just come loose from the springs. The intermediate shelf looks solid and the springs are still attached there. What I can see of the spring mounts on the pump look ok too.

I suspect it was banged around or dropped and that pulled the pump loose from the springs... and then it was banged around a lot afterwards to nearly pulverize the plastic housing.

I really have to pull on some rubber gloves and scrape-out all the remaining sound-deadening foam, then use lacquer thinner to remove the residue in the pump compartment as it is very gooey and sticky (and hard to clean off). It may be a few weeks before I can get to that... need to be able to do it outside and during the day in the light. But only after I do that will I be able to see the full condition.

Again, I appreciate your help and suggestions, especially on the checkout and the info for getting another regulator (I have confirmed the one I already have IS a Schrader Bellows, but again, I need a 2nd one).

One other area where you could assist... you linked to a composite picture above. One section showed the opened pump compartment. I've downloaded it, but it is pretty low-res and I can't enlarge it to see more details. Can you send me the hi-res version of that picture via email? I'll contact you by the A-Gon system to provide my email.

Again, many, many thanks!

Greg in Mississippi

Greg - the current pump issues aside.

I not only have 2 ET, but started with an ET-I back in the day!

Holy Moly !

you are in a very unique position.

This thread is at well over quarter million views. I am sure many would probably like to hear the differences you experienced between the two. I know I would !

when u have some time ....

Cheers

(that broke to pieces on hours)

should be (that broke to pieces on yours)- wish there was a way to edit.

Greg -
I get ebay alerts on the Timeter as I am always on the lookout for a second one.
The link you posted - I remember that one and thinking - man that is rough.
For the shelf the motor hangs off to rot to the point that it came loose and it banged around makes me wonder what type of environment it was kept it and whether it was left in the rain for some time.
Water under the bridge now - no use thinking about - this is what I would do.

I'm assuming the motor and fan still operate ?
Remove all insulation as you say.
Put in another shelf (it slides in and out easy enough) and remount the hanging motor.
Once this is complete and this part is very important.
Get an empty regular hand size water bottle.
Fill 1/3 with CLR. insert the water/moisture spring loaded exhaust nozzle into the bottle.
Leave overnight.
Next day you will see what kind of environment it was run in by how much crud gets dislodged into the container.
Remove the bottle and cap it for reuse later.
Start it up and the pump will blow the remainder of the crud out through the nozzle if any remains.
The pump will now purr better and run cooler if the nozzle was partially clogged. Turn it on and see how hot the motor gets.
It is hot to touch normally. Make sure there is no obstruction on the bottom under the fan.
The air exits from the bottom.
The housing shape above the motor (that broke to pieces on hours) helps the air run through shelf opening and by the motor - there are wide slots on the top of the upside down half bowl shape to help with this. By removing the insulation you will also have helped cooling as well I believe.
Let me know how you make out.

I looked a little more tonight and it is much worse than I thought... not un-recoverable, but needing a LOT more TLC than I expected knowing that it does run and produce pressure.

First the sound-absorbing foam has REALLY deteriorated. In the bottom, it is gooey & sticky & will be a real pain to get out and off all of the components there.

In the top, it is crumbly... will be easy to remove, just probably dusty.

Then the pump not only has broken loose, but has banged around a good bit and what I believe is part of the plastic housing or trim around it has broken into medium to small bits... of course, all imbedded in the foam.

I need to clean the foam out and off the pump and other internal components and take stock of whether that destroyed housing is a critical part of the pump's function (I suspect it helps in cooling the pump) and whether I need to replace it. Good thing is that I think I see the motor mounts (looks like they were not part of that housing) and if they are not sound, the pump has a standard mounting flange... I can always put it on a piece of MDF and mount that to the springs

And then the whole thing probably needs a rebuild.

Well, MUCH more work than I planned and expected, but that it runs means there is still hope.

It looks like the motor broke loose and banged around a long time ago, given how the pieces of the broken housing are distributed through the foam fragments. Shipping probably didn't help, but I doubt this much damage was caused in just one trip.

Greg in Mississippi

Thx for the info and legwork. That'll be very helpful.

I pulled the fitting off the top outlet and will try a few possible options this afternoon.

One thought... is it better to run the 50psi into a surge, then regulate it down, or regulate first, then surge tank? I have a couple of heavy-wall PVC pipe surge tanks and did have them upstream of a regulator in the past, so they can take the pressure.

Yah, I do already have a regulator, but I'm planning to setup both arms in separate systems and will want a 2nd one. I prefer to have the regulator near enough to the system where I can see it and adjust if needed. So I'll use the contacts you sent to get the 2nd one.

On the pump being ugly, I wasn't joking... it had seen some use, see here: http://www.ebay.com/itm/330896465118?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649 .

I found the maintenance manual and opened it up... all of the sound-deadening foam is crumbling, need to find replacement. And the pump may not be fully secured on its mounts... will look at it closer this weekend and start some R&R on it.

I not only have 2 ET, but started with an ET-I back in the day! When I got that, I knew I had the arm I'd die with!

Greg in Mississippi

Thx for the info and legwork. That'll be very helpful.

I pulled the fitting off the top outlet and will try a few possible options this afternoon.

One thought... is it better to run the 50psi into a surge, then regulate it down, or regulate first, then surge tank? I have a couple of heavy-wall PVC pipe surge tanks and did have them upstream of a regulator in the past, so they can take the pressure.

Yah, I do already have a regulator, but I'm planning to setup both arms in separate systems and will want a 2nd one. I prefer to have the regulator near enough to the system where I can see it and adjust if needed. So I'll use the contacts you sent to get the 2nd one.

On the pump being ugly, I wasn't joking... it had seen some use, see here: http://www.ebay.com/itm/330896465118?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649 .

I found the maintenance manual and opened it up... all of the sound-deadening foam is crumbling, need to find replacement. And the pump may not be fully secured on its mounts... will look at it closer this weekend and start some R&R on it.

I not only have 2 ET, but started with an ET-I back in the day! When I got that, I knew I had the arm I'd die with!

Greg in Mississippi

Hi Greg
here is the info on the Schrader Bellows part I referenced earlier in case you decide to pursue it. I called a random dealer to see if the part was available, in case a dealer was not available near you. Cheers.

Chris,

For the Schrader bellow part, 3381101, I found a part, 003381101, which is a ¼” needle valve. The price is $28.20 each and has a 10 day lead time. If this is not the correct part or you have any other questions feel free to email me back.

Thanks,

Stephen Kretz
Ohio Belting & Transmission Co. | Customer Service

(419) 535-5665 x 119 Business

An ET2 base model from France.

Mais Oui!

aucune affiliation à l'annonce

(no affiliation to the ad)

Greg in Mississippi - welcome to the thread and Audiogon !

Another Multi ET2'er .......

the timeter ugly ?

Well I guess...but I prefer the word industrial looking :^)

so now I need to find adapters for the air outlets

I am using a Schrader Bellows Adapter on top of the TImeter.

http://cgim.audiogon.com/i/vs/i/f/1390344387.jpg

Looking at the pic on the right.
Turning the knob allows me to control humidity and psi levels at the pump itself.

Where to buy.

http://www.parker.com

Click on where to buy.
Select Locate by Brand Name.
Select Schrader Bellows.
Follow remaining prompts for your zip code.
It should come up with the places closest to you.

or

If you google "Mississippi Hydraulics Pneumatics" it should provide a list of places near you also for similar regulators.
I recommend bringing the whole pump into the store for three reasons.

- So you can watch their faces when you open up the back panel and they see what kind of compressor/pump it is.
- So you can watch their faces again when you tell them what you are going to use it for (priceless)
- With pump in the store they should be able to match up adapters that will work and connect them for you so you are sure. Let their expertise guide you as long as they know how you will take some air from it.

If any questions you can contact me at bcpguy (at) bell (dot) net

Cheers Chris

Ok, you guys are a bad influence... I just bought a used, ugly ebay Timeter Aridyne 3000. It seems to make air ok, so now I need to find adapters for the air outlets... where to get?

Should work better than my little hobby airbrushing pump. Probably quieter too.

BTW, I found 19 psi to be the sweet spot for my 2.5 too!

TIA!

Greg in Mississippi <- has 2 ET's, a II and a 2.5, both with high-pressure manifolds. Phono's been down for years, excited to be doing something to get it going again.

http://www.ebay.com/itm/Eminent-Technology-ET-2-Tonearm-New-Never-Mounted-/181296809289?ssPageName=ADME:B:SS:CA:3160

from the Jan 7 post. we now have three offers on this base ET2 already.

anyone here.......... 8^)

Hi Cabiendi

In this field
some processes are very delicate and require dry air at a very specific pressure.

An interesting comment. thanks for sharing. The quality (dryness and cleanliness) of the air is very important to the tonearm since the pores that allow the air through to elevate the air bearing spindle, can start accumulating water mineral deposits, other particles .. carried by moisture; thereby reducing the effectivness of the tonearm and the pump. The arm is also designed for very easy cleaning. Anyone buying a used ET2.0, or ET 2.5 or having run one for many years should be performing this procedures documented in manual. Being successful (meaning getting the best sonics) with an ET2, ET 2.5 entails becoming familiar with its parts, and the way it works. this is my opinion after 10 years.

I am not sure your in room regulator is diaphragmatic. They look flatter and I never saw one of them with water separator and filter.

My in room regulator normally doesn't come with a water container and filter.
I purchased the filter/bulb separately with the appropriate threading to attach to it. I am in the business of business contingency planning / business continuity. The processes involved have made me somewhat anal in regards to backup systems . :^) Its ingrained in me that you just can't have enough of them.

http://www.xmc-pneumatic.com/products/HAW-Series-Air-Filter-regulator-1082135.html

Model aw2000
I could get a smaller regulator one that would put the 19 psi into the middle range for the regulator, but this one has been working well and the smaller one had to be special ordered. I am told by the shop that uses and sells it, I verified yesterday that it contains a spring and diaphragm.

The other thing we need to remember with both the ET2 and ET 2.5. Both use only a percentage of the incoming air to work as designed; the rest gets bleeded out around the edges of the manifold. The air has to go somewhere. As has been discussed here they are a captured air bearing meaning air circulates the air bearing spindle 360 degrees.
So when we discuss a bleeding effect in the air supply - the tonearms themselves are also designed to release air as part of their design. Bruce has confirmed this to me in previous discussions.

Placing of a draft detector near the tonearm parts should allow one to see how the air is released and if there are any leaks near the bolts themselves.

Cabiendi - your perspective from an ophthalmic industry view is very interesting.
thank you for your insight and I look forward to more input from you.

Cheers Chris

Hello Chris,
For some reason, my first answer was not shown.

Thanks for your detailed answer.
I have always been in the ophthalmic industry. In this field
some processes are very delicate and require dry air at a very specific pressure. For such applications we always used
diapragmatic air pressure regulators. They indeed expel air through small nozzles to regulate at a very fine level. Standing close to them you can listen the air bleeding out of the nozzles. They are not noisy but I'm not in the condition to say they can be installed inside the listenig room.
Reading the post of Frogman (Dec 12) I imagined that his relief valve could be acting as a bleeding nozzle giving a finer level of regulation, but I do not know.
Chris, I am not sure your in room regulator is diaphragmatic. They look flatter and I never saw one of them with water separator and filter.

Anyway, if I understood well you have a loop system taking 19psi out of the 50psi mains and the overpressure go back to the compressor..?? This is an smart design.

I never had an ET tonearm but I have the highest respect for this design. To me, it can compete against any tonearm. Until I found this thread I sincerely never imagined the air pressure could be so important.

Regards,

Hello Chris,

Thanks for your detailed answer.
I have always been in the ophthalmic industry. In this field some processes are very delicate and require dry air at a very specific pressure.
For such applications we always used diapragmatic air perssure regulators. They indeed expel air through small nozzles to regulate at a very fine level. Standing close to them you can listen the air bleeding out of the nozzles. They are not noisy but I'm not in the condition to say they can be installed inside the listenig room.
Reading the post of Frogman (Dec 12) I imagined that his relief valve could be acting as a bleeding nozzle giving a finer level of regulation, but I do not know.
Chris, I am not sure your in room regulator is diaphragmatic. They look flatter and I never saw one of them with water separator and filter.

Anyway, if I understood well you have a loop system taking 19psi out of the 50psi mains and the overpressure go back to the compressor..?? This is an smart design.

I never had an ET tonearm but I have the highest respect for this design. To me, it can compete against any tonearm. Until I found this thread I sincerely never imagined the air pressure could be so important.

Regards,

A "new - never - mounted ET2". the ad says.

http://www.ebay.com/itm/Eminent-Technology-ET-2-Tonearm-New-Never-Mounted-/181296809289?ssPageName=ADME:B:SS:CA:3160

Not affiliated with the ad.

Hoping everyone has a healthy, prosperous 2014.

Cheers

Hi Cabbiendi

I would like to ask, what kind of air pressure regulators are you using for the arm ?

I hope others chime in as well.
I use three regulators. The first two are inside the Timeter compressor pump.

http://mercurymed.com/catalogs/RDR_Compressors_Accessories.pdf?phpMyAdmin=8bad005e4170814880e9a1aebf2262f1

The main regulator in there, can be seen in the manual link below on page 5 - part no. 13. Part 21 is the tube that drains moisture like a cars ac system.

http://www.alliedhpi.com/images/zs168-263-002.pdf

It is a 50 psi patient respirator and has been a top turnkey air system for me for many years.

this compressor/pump runs all the time. I take 19 psi from it down the line 100 feet of tubing and the rest of the psi escapes into the air at the pump through a regulated T valve. The separate in room regulator is located next to the ET 2.5.

http://cgim.audiogon.com/i/vs/i/f/1301961480.jpg

This one I know is a diaphramatic regulator / air filter and water container.
I can say because of the quality of the timeter - I never see a drop of water in this regulators bulb.

I have a choice to use this in room regulator, as an actual "regulator", or to open it (top knob) so it just acts as an air filter / water trap.

Ultra fine air regulation (specially at low pressures) is better done with diaphragmatic regulators.

But there are passive ones with same performance.

Cummins Hydraulics - where I bought my in room regulator told me the industry considers anything up to 125 psi as low pressure.

Are you in the hydraulics/pump business? Can you provide more info or insight ?

Welcome to the thread.

Cheers Chris

Hello gentlemen,
Very interesting thread.
I would like to ask, what kind of air pressure regulators are you using for the arm ?
Ultra fine air regulation (specially at low pressures) is better done with diaphragmatic regulators. They do have incorporated bleeding system. This is a nice one:
http://www.ebay.com/itm/SMC-ITV1050-311L4-X26-PNEUMATIC-ELECTRO-REGULATOR-/140916413771

But there are passive ones with same performance.

Dlcockrum: Thank you for the posting of the MA article.

On a different note... My system is sounding absolutely awesome! I hope this is a sign for things to come in this new year.

Dover: lack of response by yourself was not noted.
Further, whispers suggest all here join with you, and hope that any further neurosurgery you have is successful.

Received my ET package from Bruce yesterday.
Will post up pictures over the weekend of my air set up along with the ET-2.5 on my system page.

Hi Rugyboogie
your Christmas present hath come early..no?
You must have been really good this year
But aren't you supposed to wait until the 25th to open the box ? :^)
They say its better to give than to receive; if so BT must be feeling pretty good this year.
Congrats and looking forward to your impressions.
Cheers

Richardkrebs, yes, safety relief valve, I have always incorrectly referred to it as a check valve. Interesting proposition. My DIY PVC tank can handle the full output of my Medo compressor which although rated at 22psi can actually output close to 30psi. Dave has the same compressor and it outputs 32 psi. Prior to installing the relief valve I tried higher pressures (without controlled air bleed) but I did not like the sound which would take on an overly lean and rather tense quality. I settled on 18-19 psi for best sound. I don't think that the relief valve can be adjusted, but it would be interesting to hear what higher pressure with controlled air needing sounds like.

Frogman.

I suspect that the check valve you refer to is actually a safety relief valve. And yes it could be the same thing that I am hearing.
It may have an adjustment so you could, entirely at your own risk :-) increase its setting to see if the bleed flow could be stopped but still maintain the same pressure out of the regulator and on to the arm.
Obviously I don't know what your surge tank can take in terms of max pressure, so be careful should you decide to do this.

I read the TAS review and this could be a review of the changes I hear in my system. It is a significant jump in performance and ultra easy to do.
The dimensions given for Motronix unit would imply that any surge tank, if included, would be very small indeed. So maybe it is simply two high quality regulators with a central bleed?

It shows how sensitive the arm is to smooth air delivery. As per my earlier post, the compressor had cycled off, so the air supply was coming only from the reserve in the tank. The "noise" in the air stream could only be coming from the regulators and the associated hosing to the arm.

Richard, interesting comments. Eventhough I settled on 18.5 -19 psi (at the arm) based on what my ears tell me sounds best in my system and not simply what my HP manifold was designed for, that pressure is (coincidentally?) about .5 psi above the pressure at which the check valve on my surge tank starts to release some air without fully opening. As the pressure is increased further the released air increases until the spring loaded valve opens fully (at about 20.5 psi or so AT THE SURGE TANK). Makes me wonder if the reason the arm sounds best at that pressure is not only that it is the ideal pressure for my arm, but also that the released air has a similar effect as what the Motronix accomplishes. Thoughts?

Richardkrebs and readers of this thread,

My apologies to all for not having responded earlier, neurosurgery has precedence.

Richardkrebs has been advocating changes to the ET2 that include adding mass and removing the patented decoupled counterweight. These suggested changes take the ET2 outside of its designed operating parameters.

In February Richardkrebs promulgated a theory that adding 30g+ of lead to the ET2.
He also advocated removing the decoupled counterweight and changing it to a fixed counterweight assembly. He claimed that this was a big improvement on the performance of the ET2 with low compliance cartridges. Richardkrebs claimed to be the only authority on adding lead mass to the ET2. Richardkrebs claimed that adding lead mass and removing the decoupling gave a flat frequency response in his listening room.

To recap…

Richardkrebs on adding mass:

02-15-13: Richardkrebs
I have added a lead slug inside the bearing spindle 25 mm long with its OD equalling the ID of the tube…
This combined with the fixed counterweight means that the arm is HEAVY in the horizontal plane. I have tried magnetic dampening and oil troughs but prefer the pure mass approach. I run at around 12 psi, lower pressures may be problematic when adding so much mass.

03-03-13: Richardkrebs
For those of you who may be interested in adding mass. I would bring your attention to Morch's latest arm which uses massive weights to increase horizontal mass.....Extra weight like this would dwarf the 30 or so grams I have added to my ET.

NOTE : This post demonstrates a lack of understanding. Removing the decoupling of the counterweight also increases that horizontal mass that the cartridge sees and therefore the total increase in mass would exceed the 30g claimed.

03-04-13: Richardkrebs
I have tried both light and heavy ETs. As far as I can tell, I am the only one who has done that. If so, I am the only person here who can speak with any authority on the subject.

Richardkrebs now claims that he has NOT added 30g off mass after all, and that his arm is close to the standard weight.

12-09-13: Richardkrebs
My ET spring a leak, actually one of the o'rings failed. This necessitated disassembly. I took the opportunity to give it a spring clean and weigh it. Total weight excluding cartridge was 86 grams (95 grams with cartridge). I have on loan a standard I beam, counter weight assembly (thank you Grant) this weighs in at 47 grams, excluding the spindle clamp. This would put the total weight of a standard ET2 up to 77 grams with an aluminium wand and 85 grams with a magnesium wand. It is my intention to revisit the use of a sprung counterweight.

12-10-13: Richardkrebs
The 30 gm adder was a guess based on 16 year old memory. Clearly my guess was well overstated. I will be removing this when I do the swing arm counterweight test to bring the arm as close to stock as possible. The 95 gm total, arm and cart weight, is accurate. This depending upon c/weights and cart used by others, being more or less the same as a standard ET2 using a mag wand.

It would appear that the sonic benefits Richardkrebs proclaimed, accompanied by much mathematical conjecture over the past 10 months, are not attributable to adding lead mass as Richardkrebs claimed, and that the benefits of adding lead mass, if any, exist only in his head, in theory, as they have not in fact been trialed.

With regard to the Morch analogy, this is speculation and assumptive on his part by his own admission. Rotational inertia is quite different to linear inertia and I’m not sure how one could possibly use a pivoted arm model to explain the forces involved in a linear tracking tonearm.

For what its worth, I too have experimented with lead mass. I made a lead slug, 25mm long and fitting the ID of the ET2 as per Richardkrebs suggestion. Excluding the string and glue, the mass varied from 26gm to 34gm depending on how tight the slug was wound. Richardkrebs now claims that his arm is only 7gm heavier than standard. I cannot replicate his new claim of a mass differential of 7g with the size of lead slug he advocated.

05-15-13: Richardkrebs
My calculation of weight delta was based on how much weight the air bearing has to carry

Clearly Richardkrebs calculations were incorrect since he has not added anywhere near the amount of lead mass that he believed he had.

Richardkrebs on removing the patented decoupling system on the counterweight:

03-25-13: Richardkrebs
I know that BT designed the arm to have the two spring systems, Cart and Counterweight. I just don't think that it is a good idea….

02-17-13: Richardkrebs
I did my initial tests on extra horozontal mass by disabelling the leaf springs on the counterweight beam

03-20-13: Richardkrebs
The thought that there may be more going on with the decoupled counterweight was triggered by your post where you quoted BT where he said that the ibeam had a natural frequency of 2-5 hz.
This is close to the resonant frequency of the arm itself. This could have performance implications.

03-21-13: Richardkrebs
If fixed, the counterweight beam must be very strong…. Three springs don't cut it.
It is no accident that other arm manufacturers have a rigid joint there....it simply sounds better.

03-25-13: Richardkrebs
Has anyone thought about why the CW spring(s) and their damping are so fussy to set up?
My prime reason for fixing the counterweight is to restore the full bass drive….

04-16-13: Richardkrebs
When I fixed the CW and added further mass and used a low compliance cart, there was an unexplained positive side effect. Focus and sharpness improved. Transients were better. It was some years ago when I made this change and while liking the improvement, I didn't put too much thought into 'why'.

I will not be degrading my arm by converting it back to standard form.

From Richardkrebs posts it would appear that he removed the decoupling spring, but did not understand the implications. Bruce’s testing on the Eminent Technology website demonstrates a rise in low frequency resonances if the decoupling is removed.

Despite this Richardkrebs clearly states that he disagrees with Bruces ET2 design goals of maintaining a low horizontal mass and using a bifurcated spring to split the resonant frequencies to minimize resonant peaks in the low frequencies.

Here is an extract from Bruce’s patent on the ET2.

The damped leaf spring 39 is oriented so as to allow horizontal motion but prevent vertical motion, i.e., decoupling, of the counterweight arm 37 and counterweights 38. Decoupling is necessary to reduce the effective mass seen by the cartridge 36 in the horizontal plane which allows the use of high compliance cartridges 36. The stiffness of the damped leaf spring 39 can be increased to allow higher horizontal mass to match low compliance cartridges 36. The damper material for the leaf spring 39 can be an elastomer. Damping provides the desirable quality of little or no rise in amplitude at resonance horizontally. Also separate horizontal and vertical resonant frequencies can be achieved by decoupling only in one plane of motion.

Removal of the spring decoupling will increase the resonant peak – Bruce measures 6db plus. If you go though the Shure white papers on low frequency resonance, they confirm this – they measure resonant peaks of 6-20db that increase motion 2 to 10 times.

From the Shure white papers -

what happens at the resonance frequency? One important characteristic of resonance is that motions are magnified considerably, in this case, typically from 2 to 10 times.

In both situations, the output from resonance frequency signals in the groove will be increased from 6 to 20 dB. These numbers are just the dB equivalent of the magnification numbers previously mentioned. By itself, this may not be all bad, since this resonance peak determines the low-frequency response "limit" of the pickup and system, and a bit of boost here may not be unpleasant. This was certainly true fifteen years ago, when arm resonance frequencies of 30 to 50 Hz were common. However, with modern pickups and arms, these resonance frequencies are usually subsonic (below 20 Hz), so that reproduction by the loudspeakers may cause distortion. Additionally, preamp overload is most likely to occur at boosted low frequencies since the preamp clipping level is lowest here. Consequently, the arm resonance has lost whatever usefulness it once had and must now be regarded as a liability.

The most pernicious effect of the resonance is shown in Figures 1 and 2 by the "scrubbing" notion developed by the stylus in the groove. This causes program material to warble in pitch, just as if the turntable speed were fluctuating. In fact, the groove speed is changing (relative to the tip), because a fraction of the velocity of arm vibration is added to the groove velocity. (See Appendix I.) The effect is that about 1/3 of the arm vibration velocity is alternately added to and subtracted from the groove speed. For example, at arm resonance, total amplitudes of 1/32" are easily observed by eye. If the frequency is 8 Hz (typical for high compliance pickups and average arms), the resonance velocity will be about 2 cm/sec (see Appendix II). This velocity will produce a "scrubbing" velocity of 0.6 cm/sec along the groove axis. The groove speed at a 4.5 inch radius is about 40 cm/sec; so the frequency modulation will be about 0.6/40 = 1.5% and easily audible.

Another less obvious consequence of the arm resonance is that the stylus force is "used up" when the arm is vibrating. In the previous example, if the compliance of the pickup is assumed to be 20 x 10-6 cm/dyne, 2.0 grams of stylus force will be required to accommodate the arm vibration alone. This is larger than the usual stylus force, so mistracking is quite certain at the extremes of the vibration.

Clearly the removal of the decoupling has negative impacts on both tracking and increased distortion in amplifiers and speakers from the infrasonic distortion generated by the cartridge/arm resonance.

Use of Fluid Damping

Again there are more contradictions in Richardkrebs posts -

02-18-13: Richardkrebs
I do not like the effect of the oil trough.

05-05-13: Richardkrebs
Twenty years ago I made a oil damping trough for the then standard ET2, mounted on a Goldmund Studio.
installed it on the current arm. Nice changes to the blackness of the background. The system is even quieter. As a result, it doesn't seem to extend dynamics upwards but downwards further into the low level detail. A very agreeable effect. Also greater presence and focus. It will be staying. .

Richardkrebs on Stiffness of the Air Bearing

04-21-13: Richardkrebs
....the air bearing employed on these arms is effectively rigid at audio frequencies. So they should look elsewhere when looking for the cause of compromised note leading edge performance. .

This is a very good example of conflating physics and mathematics.
Frogman, Ct0517, DGarretson, Slaw, myself and many others hear significant differences in performance when adjusting the air pressure on the ET2.

Having studied structural, mechanical and materials engineering and physics at university, my view is that altering the air pressure will alter the performance of the arm – either altering the rigidity and/or altering the resonances within the air bearing.

I quote Ralph Karsten of Atmasphere producer of valve amplifiers, and who has considerable experience producing and cutting records.

01-17-12: Atmasphere
If LPs were perfectly concentric like they are supposed to be, I can imagine that having a high lateral tracking mass would have its advantages. But in real life, concentricity is something that we hope for and often come very close to getting, but its not perfect. IOW the arm does need to negotiate such imperfections in the LP. I imagine some of the issues can be tuned out with the leaf-spring device mentioned earlier- so does that mean that you have a different setting depending on the LP?

One other issue of air bearings I forgot to mention is the coupling that needs to occur from the platter surface to the arm tube of the arm. The idea is that the arm and the platter move together as a single unit. That is to say that if there is air-borne vibration, it affects the platter in the same amplitude and phase as it does the base of the tone arm. If there are differences between the two, this will be heard as some sort of artifact, IOW it becomes something that the cartridge can react to. This is why the plinth can have such an affect on the sound of the 'table.

When you have an air bearing, this coupling is not as profound as it should be. One of the demonstrations that this is a very real phenomena is the fact that as you increase air pressure in the bearing (increasing coupling to the base) the arm sounds better.

When I questioned the stiffness of the bearing in relation to the added mass Richardkrebs advocates, he responded -

03-19-13: Richardkrebs
Re quality factor, Q. ... under, critically or overdamped systems, as they relate to the ET2. My running the arm at 12 psi is no accident. I addressed the Q factor of my arm years ago. And the bearing has no issues at all carrying the extra weight, even at this pressure.

And yet now he says he is running 18psi.

11-05-13: Richardkrebs
The output is fed thru two regulators in series, bringing the pressure down to 18 psi for the arm. .

In summary then, despite having owned the ET2 for over 25 years, it would appear that since February this year -

Richardkrebs has advocated adding lots of lead mass, and claimed many benefits, but now claims that his ET2 arm mass is close to standard.

Richardkrebs has proclaimed that Bruce’s decoupled counterweight is not a good idea, and stated in April that putting the arm back to standard will degrade the sound. Now, in December, Richardkrebs is not sure and is going to retrial the decoupled counterweight.

For 25 years, Richardkrebs eschewed fluid damping, but now believes it is of benefit.

Richardkrebs claims the ET2 air bearing is rigid at audio frequencies and 12psi was the optimum air pressure for his set up, having carefully calculated Q. Now he has moved up to 18psi without an explanation.

These contradictions outlined above, demonstrate a lack of scientific rigour in testing and set up. It is not an approach that one would recommend.

It would appear that Richardkrebs has much work to do to determine the optimum set up for his ET2. My suggestion would be for him to put his arm back to standard and set it up as per Bruce Thigpens’ ET2 manual, assuming he now has some understanding of how it works.

For your reference here are links to the Manuals and Patent
http://www.patexia.com/us-patents/04628500
http://www.eminent-tech.com/main.html

Seasons greetings to all..

Dover

Received my ET package from Bruce yesterday.
Will post up pictures over the weekend of my air set up along with the ET-2.5 on my system page.

I found a rare reprint or Myles Astor's TAS review of the Motronix Acuflow Air Regulator:

http://www.whatsbestforum.com/showthread.php?5653-Linear-tracking-Turntables!/page3&highlight=motronix

Apparently, two of the people involved with designing and reviewing this unit are still involved in audio. Miles Astor, PhD is Senior Assistant Editor at Positive-Feedback Online and Marlen Mogilever, PhD, who is mentioned in the TAS article as being "of Motronix" is now the principal designer at Blueberry Hill Audio:

http://blueberryhillaudio.com/index.html

After reading the TAS article, I realize that this unit was more involved than what most of us are now using, i.e. two spring/diaphragm regulators with a surge tank in between. I wonder if we contacted one or both of them that they could/would give us enough detail to be able to reverse-engineer the Motronix unit or, at least, to mod our existing setups to duplicate the Motronix unit's functionality?

Dave

Frogman and Slaw.
You planted a seed when talking about the Montronix regulator and controlled air bleed.
I have just teed off a 1/4" needle valve in between the compressor regulator and the second in line regulator.
The tee is configured such that the compressor output is fed straight to the needle valve and the second regulator is connected at right angles. Such that the air going to the arm has to turn 90 degrees.
The needle valve is just cracked open, bleeding only a tiny amount or air to atmosphere. This does not alter the pressure at the arm since there is a significant delta P between the two regulators.

If your regulators are of similar stability as mine you can expect greater solidity and dynamics and just plain better sound.
This test was done when the compressor was off so the air supply was ex the high pressure storage tank only.

Theory is that the regulator must be dithering about its setting. The needle valve, being non compensated clips the peaks of this pressure perturbation.

Slaw, I remember Gordon's article well; that's how long I have had my ET. I was always intrigued by the Motronix and a couple of years after the article appeared I searched for one without luck. What I remember the article did not make clear, other than the claimed benefits, was what exactly the Motronix did other than provide presumably more accurate control over xthe air pressure? I seem to recall some reference to it releasing some air in a controlled fashion with the supposed benefit of a smoother air supply to the arm. Can you shed some light on this? Thanks.

Frogman: Your point is well taken and one that I failed to address: the possible differences in manufacturing processes of the wide variety of pressure guages. I do listen in a small room/nearfield which is conducive to my hypersensitivity on a wide range of issues. By the way, do you or does anyone remember the ET upgrades offered and reviewed in 1995 by Roger S.Gordon? He reviewed a (Montronix Acuflo Air Regulator). This is what I have, only the DIY version. It is way overdone for 'our' needs but the Montronix sold for I believe $400.00 then, I got the DIY for $150. In his review were the following:
Build-it-yourself-air pressure regulator
ET II Large diameter high pressure manifold
ET II Magnesium Tonearm
Damper trough
Bright Star Padded Cell

His conclusion for most Bang-for-the-Buck was the BIYS air pressure regulator. FWIW.

Ct0517: I ordered my 2.5 so many years ago and without the benifit of this forum that I couldn't tell you what mine is specifically built for. I actually emailed Bruce about this a couple of years ago and his only answer was that it is probably built for the way I'm currently using it. I guess this means no detailed maufacturer/sales info on file record. Anyway, all I know is what I hear and that's good enough for me.

Thanks again for your input on my compressor issue. By the way, as we exceed over 1000 hits here, I want the thank you for your vision and your extraordinary follow-through regarding this thread. It's easy for one's efforts to be overlooked. You are to be commended Sir!

I took my Sony radio cassette player and placed it in front of the single mono speaker of the school record player.

excitement and thrill of hearing this music and being able to play it whenever I wanted.

thanks for sharing this Richard.
it reminded me of something I wanted to share also.
as a kid my first music reproducer was a small hitachi am fm cassette player with a built in microphone. I discovered I could tape good songs from the radio onto cassette and play them back when I liked. Like you said - what power over the music. I was in control.

So I filled a cassette tape and all I did for two weeks was play that tape.

One day I decided to listen to the radio again. the same songs, when they came on the radio all of a sudden sounded..... not as good .... not like my cassette. they sounded slower and lethargic on the radio.

I couldn't understand why. I would figure it out later when I was a teenager playing with turntables. Although the tape cassette player was speed stable and sounded good - it was running a little fast. so the music sounded more up beat. groovy, livelier than the slower radio version. the cassette tape was speed stable but not speed accurate.

this is how I learned the difference between the two.

Hi Harold - high school in 1977...me thinks you may be my lost twin ?

Slaw

What is it you or others prefer going to 19 psi?

My ET 2.5 was a custom build by Bruce designed for 19 psi.
It will still work at 18 but below that it starts having problems.
With no air on the spindle it is very tight in the manifold.
I am using it as designed by Bruce.

Now for why I had Bruce set it up for 19 psi
this is another story and it is documented on the first couple pages here. It involved putting my portable regulator in my lap and raising/lowering the pressure with it while my
older ET2 HP was playing music and listening.

Here is something to consider especially for new owners.
Lets say I just bought an ET2 on ebay or audiogon (or maybe five of them like Manitunc !)

This is what I would do if the previous owner and yourself don't know what psi it was set up for.
First the reference points we know about.
From Bruce' website.
**********************************************************
3.6 PSI - 0riginal Takatsuki and ET-2 or 2.5

5.0- 7 PSI - WISA 300 air pump and ET-2 or 2.5 with high pressure manifolds

>10 PSI - users with shop compressors and ET-2 or 2.5 high pressure manifolds

NOTE; if the pressure readings are higher than those listed above, the manifold could be clogged, if the pressure readings are lower, this suggest that the pump may not be performing correctly.
***********************************************************
That last sentence between the asterisks is very important and could be affecting your PSI.

So unless you have an arm that is a custom build (meaning you told Bruce what PSI you wanted it set up for)
then your LP & HP ET2 or ET 2.5 falls under one of those categories.

I would select the best category that applies and do exactly what Dave did here if you read back.

Lower the pressure to what your specific ET 2 or ET 2.5 will work properly at first - go up maybe one psi.
Use this as a reference point in your system. Get to know its sound.
Then start bumping up the pressure - if you like it great as this is all personal, room/gear dependent.

Imagine Manitunc trying to figure this out with 5 ET2's.
how's the leaf spring listening going Mani ?

Cheers

Speaking for myself and the pressure gauge that I use, I doubt very much that it is accurate to within .5 lbs. So, it is entirely possible (and probable) that my arm is seeing anywhere between 18.5 and 20 lbs. I say that based on the less-than-sota quality of the gauge and the fact that the check-valve in my surge tank (20 lbs max rating), on any given day, will inexplicably open or be audibly on the verge of doing so with the dial on the gauge set to 19, and will be fine on another day. I don't know if its possible for voltage fluctuations to affect the pumps output or perhaps humidity levels? Having said all that, I would say that the somewhat broad range of 17-20 lbs is what gives me the best sound IN MY SYSTEM and TO MY EARS. I am impressed that you can reliably hear a difference of .5 lbs.

12-13-13: Richardkrebs
I persuaded her to let me record the album, so I took my Sony radio cassette player and placed it in front of the single mono speaker of the school record player.

So nothings changed then !

Harold
My music awakening happened when our school music teacher played us side one of Aqualung. She refused to play side two because it criticized the Church of England and had a bad word "balls"
I remember being stunned upon first hearing this record.

I persuaded her to let me record the album, so I took my Sony radio cassette player and placed it in front of the single mono speaker of the school record player.

Typing this takes me right back in time to the feeling of excitement and thrill of hearing this music and being able to play it whenever I wanted.

The emotional power of music.