Eminent Technology ET-2 Tonearm Owners

05-19-13: Ha_ha_he_man
Hi,
I was wondering when someone will add something useful to this thread that is more in line with modifications with results as opposed to a subjective debate?

Regards
Alx
Ha_ha_he_man

Alx – Much is covered at the beginning of the thread.

Based on my 10 years now with the ET2 and ET2.5.

The recently discussed aluminum gooseneck is very nice but it is unique and costs a lot to make (labor wise). A few hundred dollars. I received only a few emails of interest so far. I am willing to pursue reproductions if more interest is shown.

The biggest mods in my 10 years with the ET2 and ET2.5 has been the quality pump, wiring loom and the leaf spring mod.

For those reading who do not own this tonearm.

The ET2 is like a race car.
It can be tuned for our rooms/gear which represent the different tracks.
For a plug and play audiophile this can represent disaster. A bad nightmare.
If you are plug and play and your dealer sets up your cartridge for you or a friend does it – stay away.
It must be obvious by now to anyone reading here that if your are using an ET2 or Et2.5;

you need to be thinking about what you are doing.

If not mistakes will happen; the poor cartridge is always the victim; even though we feel bad ourselves about it.
So many adjustments can be made.

RichardKrebs
This is very hard to reproduce and I do not hear this effect with light linear arms when carrying low compliance cartridges.

Richard your arm started life as an ET 2.0. We have already discussed here how for a really low compliance cartridges the ET 2.5 works best with the double or triple leaf spring.

05-16-13: Dover
Spock15
I currently own an ET2, Naim Aro & Hadcock unipivot and have just sold off my Bluenote Borromeo ( Titanium tubed unipivot ).

Congratulations Dover on reacquiring an ET2.

Frogman introduced the leaf spring mod to us early on in this thread.

One is able tune this tonearm with different leaf springs (single, double, triple) corresponding to the stiffness of the cantilever being used, and the reactions of the resonances in each of our rooms; and to stay within BT’s decoupled design.

Based on my direct experience I encourage both Richard and Dover to order some loose leaf springs and a Two I Beams from Bruce to make up a double and triple I-Beam setup.

I look forward to impressions of a low compliance cartridge with the double and triple leaf spring.

I have already mentioned here I base my vinyl tuning on what I hear with master tape dubs at 15 IPS.
I start the LP then 10 seconds later the tape. I toggle between the two.

I don’t have any issues with my XV1 when I use the double and triple spring in my room.

I believe you can have your cake and eat it too with the double and triple leaf springs and to stay within Bruce’ genius design.

Chris,

The thicker spring results in a higher resonance frequency. Thanks

brucet

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

Cheers

Welcome to the thread Ha_ha_he_man.

Not a bad moniker :^)

CT0517
Based on my direct experience I encourage both Richard and Dover to order some loose leaf springs and a Two I Beams from Bruce to make up a double and triple I-Beam setup.

I look forward to impressions of a low compliance cartridge with the double and triple leaf spring.

I modify my recommendation. It applies to Dover only.

RK you have come down too far a path with your Krebs arm. You are truly enjoying it. I would never ask you to do something unless you are curious yourself. If you did pursue it you would need to implement a wiring scheme similar to Frogmans - to be the least intrusive on the ET2 based on your plinth design.

Dover is about to reacquaint himself with an ET2 and a sound that is very .. well I really like the word that Spock15 used alot ....persuasive.

I am sure his system must have changed in the years that have passed.

Cheers

Richard/John47 thanks for making me curious about the damping trough again.

Arrived the in mail one kit from Bruce.

This kit reminds me of my flu shot ?

I don’t like needles and syringes.

But it went on real smooth

I think Frogman still has his paddle lifted not touching ?

I think SLAW is however still liquified ?

Added 1 CC per Bruce’ instructions – paddle just touching.
Its been over 8 years for me in using one. Will report back later ... so far pretty good !

Cheers

Thekong –

The answer to your question regarding frequencies impacted by horizontal Fr from Richardkrebs are mostly wrong. It is important that they are addressed.
Impact of Fundamental Resonance:

05-20-13: Richardkrebs
Thekong.
The answer to your question regarding frequencies impacted by horizontal Fr is shown in the attached graph. From memory your Horiziontal Fr was around 5hz with the A-90. So substitute 5 for 1 on the x axis and scale up from there. At 15 Hz (3) the rise in response is almost zero. This is what BT was talking about when he mentions 3xFr.

This statement is not correct. I quote from Richardkrebs earlier post

05-15-13: Richardkrebs
In Bruce's paper on the oil trough he talks about the effect of Fr being apparent at 3x its frequency. Targeting say the 12 hz you mentioned would mean that it is causing phase and amplitude problems at 36 hz. This is not good. .

As you can see Richardkrebs appears to be confused. On the 15/3 he cites Bruce Thigpen as saying that there are phase and amplitude problems at 3 times Fundamental Resonance, then on 20/5 he cites Bruce Thigpen as saying the rise in response is almost zero.
Neither of these statements are correct.
What Bruce Thigpen actually says on his website is that on an undamped standard ET with decoupled counterweight there is a resonant peak at 3 times the fundamental resonant frequency, and that this is reduced with fluid damping on a standard ET with decoupled counterweight.

The other mistake that Richardkrebs continues to make is to use as a reference a graph for a single harmonic oscillator that plucked from Wikipedia.

Wikipedia - http://en.wikipedia.org/wiki/Harmonic_oscillator
Richardkrebs - http://s1173.photobucket.com/user/CT-993/media/ResonanceGraph_zpsdd78e0f4.png.html?sort=2&o=7

This graph does not represent the forces on the cantilever because the cantilever and cartridge is not a single harmonic oscillator. A cartridge tracking a record groove has a fulcrum point at both ends – the stylus in the groove, about which the cantilever pivots, and the cartridge end of the cantilever which has a suspension. Forces are exerted on BOTH ends of the cantilever. The graph represents a pendulum with only one fulcrum point at one end only. The mathematics that Richardkrebs uses does not apply.

05-20-13: Richardkrebs
Now look at frequencies below Fr. At say 0.25 Fr we get transmissibility of 1. What this means is that, with the compliance of the cartridge used, the whole arm moves sideways. The cantilever does not deflect. This is important for eccentric record issues. .

This assertion is wrong on several fronts. The cantilever deflects.

Firstly – the record grooves are cut at 45 degrees. The cantilever deflects. For a moving coil cartridge the cantilever deflection moves the moving coils within a magnetic field. That is how sound is reproduced from a record player. This video shows how RCA Living Stereo stereo playback is achieved.
http://www.youtube.com/watch?v=Jq2sjGFvNnM
If there is no deflection of the cantilever then Richardkrebs system cannot be producing any sound that resembles music.

Secondly, the statement defies physics. I quote Bruce Thigpen directly:

Bruce Thigpen
“the cartridge will "see" .55Hz mounted in any tonearm, more so in one with higher horizontal inertia. I don't think Kuzma means the stylus does not deflect at all at .55Hz, that would defy physics.”

Furthermore, Richardkrebs assumption with regard to Bruce Thigpens views on eccentric records are not supported by what Bruce Thigpen actually says in the ET2 manual.

05-20-13: Richardkrebs
BT uses at 30cu cartridge in his manual to calculate horizontal Fr. The arm weight he uses is 30gm plus 7gm for the cartridge. We have to assume that he is ok with this combination and that he is not worried about cantilever deflection on eccentric records.

This assumption again is just plain wrong. I quote from Bruce Thigpen’s ET website:

ET2 Manual page 47 :
“if you like to play severely eccentric records, ones with run out greater than 1/8th of an inch, then we suggest you use a low mass pivoted arm.”

In summary, Bruce Thigpen is very much of the view that the horizontal effective mass should be kept as low as possible, and the decoupling employed to minimsie fundamental resonant peaks at FR and 3xFR.

He has also expressed his view that increasing mass increases distortion, and I quote Bruce Thigpen -

Bruce Thigpen:
If the weight is coupled the system resonant frequency would be extremely low, a resonant frequency at 3Hz with a significant rise in response (6-12dB) results, which would affect tracking slightly because of the asymmetric position of the cantilever, we opt for splitting the horizontal resonance frequency into two points and lowering the "Q" which improves tracking.

More important than tracking, the intent was to reduce the modulation effects of low frequency energy (FM and AM) that increase distortion in the cartridge,

Thekong , I trust this clarifies the queries you raised.