Eminent Technology ET-2 Tonearm Owners

Richardkrebs
With a pivoted arm the horizontal effective mass in multiplied by the head shell offset. Only a percentage of the cantilevers lateral movement is resisted by the arms horizontal mass in trying to rotate the arm the rest of this movement is resisted by the cantilevers efforts trying to bend the arm tube itself. Linear arms do not impose the second characteristic on the cantilever. This I believe is one reason that the pivoted arm guys complain about a lack of gestalt from linear arms. We largely fix that with oil troughs or magnets. Pure mass is another option

Hi Richard – Have you actually measured these forces? I find it very interesting that what you say is supported by information I have from BT on actual testing that he has done with pivot and linear arms. His measurements found that this phenomena (horizontal effective mass, multiplied by the head shell offset and the resulting bending of the cantilever) produced a +6 to 12dB bump between 10-15 Hz versus flat response down to 5Hz (the ET-2).

He also went on to say that “over the years these parameters have been mathematically analyzed and are well understood. There is an easy measurement to prove all of the above, it is called is wow and flutter. If you take the same turntable, put a straight line tonearm arm on it and a pivoted tonearm, both with the same cartridge, the straight line arm will exhibit about half the measured wow and flutter.”

I have his summary findings on this if anyone is interested. Alot of his findings again are in his ET2 manual available publicly.

Some of it was posted here already
here already.

Richard, Dover others ...... any comments on this very basic wow and flutter test ?

Hi Chris - yes I agree with Thigpens comments, but I think Richardkrebs high mass approach throws away the advantage of the ET2 over other tangential arms, that is the light horizontal mass. The ET2 is less than 25gm compared to the 80g of the Terminator. The effective horizontal mass of the ET2 is even lower with a decoupled counterweight. The other problem with adding mass to the ET2 is that not all low compliance cartridges are created equal, as the compliance in the horizontal plane cannot be assumed to be the same. For example the Denon 103 is far more rigid in the horizontal mode than the Koetsu even though they are similar compliance vertically.

Chris.

No I have not measured these forces and would be very interested to read Bruce's comments on same. I assume it is a big file, so can I ask you to email it to me at the contact address on my web page, if not too much trouble. Or if appropriate post it here.

As per my earlier post, both an oil trough and a magnet impose a resistance to lateral movement as seen by the cantilever. They behave much like weight in the lateral plane. I have simply used weight alone.

I did my initial tests on extra horozontal mass by disabelling the leaf springs on the counterweight beam and winding equal lengths of solder around the goose neck and counterweight assembly. This way I kept the lateral balance of the arm static. It didn't look pretty but was informative. I also tried this configuration with and without magnets.

I currently adjust for different cartridge compliances by using a range of counterweights.

Dover, I seem to remember from this thread or another that you no longer use an ET2. If so, we would be intereted in what you are currently using and any reasons for the change. As we all, I think, agree, the ET2 is pretty darn hard to beat.

Hi Richard – email sent.

Where are my manners ? Do you want to try the 420str cartridge?

Your table and arm would need to be set up for the higher compliance.

I was all ready to send it to NZ anyway.

When you are done you can maybe pass it to Dover? I think Dover misplaced his ET2 - and I think it may have something to do with a drink called Slivovitz from Serbia. Maybe Nandric (Nikola) can provide more details on this.

Hopefully Dover gets it back soon
Glad you guys on the other end of the world have a sense of humor.

Cheers Chris

Chris.
Thanks for the offer but I must respectifully decline. I am just dialing in my Shelter and newly renovated enlarged room. More distractions, while delightful, are unfortunately just too much for now.
re my building a new arm. The design would allow for bolting to a flat surface with three screws. Simalar to the ET. It has fully adjustable horizontal mass independant of the counterweight. I am struggling with the wand design at present, which is a little radical. While I can visualise it, I'm not sure I can build it. The whole project may founder on this. If I am to build a new arm, I want to be pretty sure it will be a step up from the present version.

Dover, what did you do, loose your ET2 in a drunken poker game or something?