Eminent Technology ET-2 Tonearm Owners

Hi Richard,

I will be using the ET2.5 in my test. My ET started out as a 2, which I later added the 2.5 bearing from Bruce.

I was asking whether replacing the lead counterweight with something else (brass/bronze ?), while still using the decoupled I-beam / leaf springs, would cause a big difference in the sound.

Thekong
Thanks for that

The advantage of lead is of course its high specific gravity, it is dense and self damps quite well.
Don't know the effect of other materials there.

This could be a new line of exploration. I look forward to your findings.
Thanks

Richardkrebs/John47

Quote from ET2 Manual – Bruce Thigpen

P29

It is desirable in most cases ( low to medium compliance cartridges 5x10 dynes/cm – 20x10 dynes/cm ) to use the minimum number of weights, far out on the cantilever stem. This decreases the horizontal inertia of the tonearm while increasing its vertical inertia.

This is the exact opposite of what Richardkrebs continues to advocate. Richardkrebs is advocating increasing the horizontal inertia for low compliance cartridges – the opposite of what Thigpen recommends.

Re the comments on the Kuzma

There is a lack of comprehension of what is claimed with the Kuzma.
Frank Kuzma is quoted as follows

Horizontal disturbances of an eccentrically spinning record occur only at 0.55Hz or 0.75Hz (33rpm or 45rpm). This is well out of the Air Line tonearm's resonance in the horizontal plane, which is between 2 and 5Hz and does not cause problems tracking virtually all LPs.

That is all he is saying.
Kuzma does NOT say the cartridge does not see this resonance, it simply means that it does not cause problems tracking. This is because if the resonance of 0.55hz were within the tonearm resonance range the two resonances could at worst sum and “double up” which could cause tracking problems.

I quote 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

Note that Thigpen says that the 0.55hz is seen “more so” with higher horizontal inertia. I would suggest this is one of the contributing reasons for Thigpen recommending a lower horizontal mass for low compliance cartridges.

You continue to ignore Bruce Thigpens' recommendations based on the laws of physics and his extensive testing, because it would appear you do not grasp the physics and engineering principles involved. Unless you understand those principles then you are unable to understand what underpins Thigpens' and Kuzmas' comments and designs, and are speculating at best.

"..... do not appear to grasp the physics and engineering principles involved."

MF wasn't speculating when he heard 1 of the best 2 arms in the world - I guess you'll never be able to look out the door and see blue sky and appreciate that (the Kuzma is just about the best arm on the globe, dispite it contravening your design principles ..... uuuuuuuuuuuum how many arms have designed and manufactured?

I hope Franc Kuzma casts an eye over your 'advice' to correct his fauly design.

Thekong, Richard, I sometimes use brass weights (supplied by Thigpen) instead of, or in combination with, the usual lead weights. IMO, the concern is not so much the possibly inherently-different sound of something like brass as compared to lead, but the fact that using a material with a different density may necessitate placing it on a different spot along the I-beam, since as Dover points out:

****It is desirable in most cases ( low to medium compliance cartridges 5x10 dynes/cm – 20x10 dynes/cm ) to use the minimum number of weights, far out on the cantilever stem. This decreases the horizontal inertia of the tonearm while increasing its vertical inertia.****

In my case, the use of the supplied brass weights usually results in having to place the weights further in along the I-beam. In my set-up, this is usually not ideal, with inferior overall bass performance. I suppose that it would be possible to have the exact size of brass weight machined to match the weight, and hence placement, of the lead. But, that is not the case with the weights that Bruce sent me.