Eminent Technology ET-2 Tonearm Owners

Dover.

....Sigh.....

My comment re "All or nothing" was designed to open useful dialog on the subject. I was trying to be subtle.

So now, not so subtle..
Do you really think that it is a good idea to have a spring driven mass, ( cartridge and arm ) attached to a spring suspended mass ( ibeam and counterweight). Both with resonant frequencies in the same neighbourhood?
If you refer to the math and resonance graph I posted, it shows that this can be problematic. The two resonances need to be far away from each other to avoid any interaction. At best a good compromise can be achieved with adjustment of the parameters. I don't like compromises. Better to eliminate one of the compliant joints in the system completely.

As I have said earlier. If fixed, the counterweight beam must be very strong. I note that Kuzma also know this as the counterweight beam is substantial indeed. Three springs don't cut it.

It is no accident that other arm manufacturers have a rigid joint there....it simply sounds better.

I don't understand why you are so set on trying to stop people experimenting on this area of the arm. It will do no harm and at the very least add to our collective pool of knowledge. A big hand will not come out of the sky and squash anyone who deviates from the original design parameters, it will be a bit of fun and it may just bring the owner closer to the absolute joy of listening to music, which is what this hobby is all about.

Put on your knitwear cardy so don't catch a cold, your thick lensed glasses so you don't fall, then pop out and replenish your Prozac.

Chris (such a lovely guy):

"You come across as a real hard ass .."

Acronym: PITA

BTW did Richardkrebs pick on you at preschool?

Well I am not sure what to say now. I gotta admit that the folks from down under and specifically NZ, are not a subtle group by any means. You all seem to be in close proximity to one another? Can you by chance hear each others stereos when you turn them up ?

BTW – Does Canadian Shania Twain still live in NZ ? I always had a crush on her.

Richardkrebs
Do you really think that it is a good idea to have a spring driven mass, ( cartridge and arm ) attached to a spring suspended mass ( ibeam and counterweight). Both with resonant frequencies in the same neighbourhood?

Chris,

You always want the horizontal natural frequency of the counterweight to be less than the cartridge/arm resonance, this is the case 98% of the time.
The natural frequency of the I-beam/leaf spring depends on the thickness of the spring, the amount of weight, and where the weight is on the beam. The natural frequency goes down as the weight moves further out on the beam which is where we want it to be.

brucet

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Page 49 of the ET2 manual.

LOW FREQUENCY RESONANCE MEASUREMENTS

The curve below shows the typical response for the vertical resonance of the the tonearm. This was done with a medium-high compliance cartridge (30 x 10-6 cm/dyne) with a mass of 7 grams and two counterweights 15g + 15g. This counterweight combination gives a vertical effective mass for the tonearm of about 12 grams, which results in a resonant frequency of 6 hz (measured).

Horizontally the resonant frequency will be much lower because of the tonearms higher mass (30grams). The horizontal resonant frequency is damped by the decoupling spring and is very well controlled.

************************************************************

Actual measurements and graphs for the above are also shown on page 49.

Thoughts on the above ?

At this rate we will probably have the whole ET2 manual on the thread by Christmas?

My personal take on this as an amateur hobbyist.

Bruce makes a lot of sense and has done the analysis and measurements to back it up. The ultimate test is "hearing is believing". My reference point for sound in my room is 15 IPS master tape dub. Both the MM 420str and MC Benc Micro that I discussed earlier play beautifully on my ET 2.5 with the CF armtube. I have the MM 420str on the ET 2.0 right now with aluminum armtube / other room and it sounds great there too.

Each of us have different gear and rooms. We need to experiment with the different leaf springs to see what sounds best to us. But it is very obvious and clear to me that we should be trying to get

*** AS FAR OUT ON THE I BEAM AS POSSIBLE - THIS IMPLIES THE LEAST AMOUNT OF WEIGHT *******

I haven’t tried a rigid counterweight with damping. If anyone would like to volunteer up a DL103 or similar low compliance cartridge I can give it a longer term try on the ET 2.0. If a good cheap DL103 pops up on the classified I can try to snap it up. I don't have a problem experimenting.
Time permitting.

Cheers

As a New Zealander I would like to apologies for the behavior of Dover. It is a narrow country and this breeds narrow mindedness.

When I look at the pictures of RK's arm I do not see an ET2. It is something specifically crafted and tuned to his system. It is not a universal tonearm. A little bit like the highly modified ET1 that Lloyd Walker uses actually.

Nor for that matter is the ET2 a universal tonearm, as I can attest to from my experience of its truly poor performance in my system. Quite frankly it was clearly out performed by my humble G707 and has remained in the closet ever since.

Now that I am in the process of moving on from my LP12, I will give the ET2 a second chance. In doing this I will be applying a great deal of good advice from Dover, but when Richard gets off his backside and makes a decent new tonearm, you can bet I will be dumpster diving out the back of his place to score the discarded bits from his current arm.

What Bruce has created is a truly outstanding achievement, but here is the rub, in everything I have done with hifi, at no stage have measurements, be it mechanical, electrical, or acoustic, ever done anything but get me in the ballpark. Was is Saul Marantz who has been quoted as saying: "If it measures good and sounds bad, it is bad and if it measures bad and sounds good, you are measuring the wrong thing."

To get back on topic I will just say this. Neither of these guys have a clue. One uses a 'Japanese DD' turntable and one uses a Heath Robinson 'belt drive'. If they used a real turntable there would be much less of this idler bickering.

Ouch, just bit my tongue. Might have to move to Oz now to avoid getting lynched.

Best Regards

Grantn

The discussions (arguments?) between Dover and Richard have been extremely thought-provoking; and very interesting to say the least. I think that the well-intended participants who look for complete harmony, agreement, and absence of confrontation run the risk of they, themselves, doing more to derail what has been one of the best threads on Agon than either of those two gentlemen. Personally, I don't feel Richard is owed an apology at all; certainly, not one instigated by someone on the periphery of these discussions. We all have different styles of communication, and when the issue is something that one feels passionate about, we throw the gloves off (well, we at least loosen the laces) and expect everyone to be a big boy. I have seen no profanity used; no personal attacks, certainly nothing that, at the very least, could not be up for interpretation.

I have found value in both participants' contributions, even if I don't agree (yet?) with all the pecifics about each of their respective stances re set-up of this arm. For instance, I am not yet convinced entirely that IN MY SYSTEM, going for the lightest weight/mass possible is the way to go. Yet, and speaking of loosening the laces, I decoupled (loosened) the I-beam yesterday, and lo-and-behold, on Donald Fagen's new release "Sunken Condos", what had previously been little more than amorphous low frequency energy suddenly became notes that I could discern the pitch of; completely the opposite of what I expected given my experience (extensive) experimenting with springs of different compliances (single, double, etc.), and the reason I had not tried it yet. Point is, let's all be big boys, try things and have a little more confidence in what we hear as being the right way to go. Dover and Richard please continue contributing to this thread.

Regards.