A few thoughts regarding longer i-beam and leverage:
- While the captive air-bearing has advantages in stiffness, the ET design with stationary bearing has only one point with centered forces within the bearing along the arm travel. This "allows" some maximal leverage at the beginning and end of the travel.
- Having a short i-beam compensated with more weight on the i-beam side increases (lateral) leverage.
Eliminating the leverage on the air bearing by using a moving air bearing has some advantages, but a drawback too:
Either one needs an additional flexible air-tube, which increases vibration coupling between arm and tt chassis, and also vibrations within the air feed.
Or one needs an open bearing with less bearing stiffness, like the (very good) Adanalog MG 1 arm, or the many Ladegaard variations incl. the Trans-fi arm. (see below)
- It is desirable to keep varying leverage at a minimum, a) on the air bearing as well as b) on a sprung subchassis. The latter will lead to varying lateral desiquilibrium, visible as increased "slipping" from a balanced middle position to outwards gliding at the start and end positions of arm travel.
- So a longer i-beam reduces the leverage on the bearing, and on sprung subchassis. It improves balance of the center of gravity along the bearing travel. And it increases vertical mass, which often improves the sound too.
- Regarding "optimal" vertical resonance I did put up the idea, that (maybe) there is not much useful out of phase bass information below 100Hz - this might not be the case... as increasing the (out of phase) bass bandwith below eg. 15Hz, by lowering vertical resonance seemingly still is audible.
- However, there is an end to that, probably below 10Hz because of subsonic vertical garbage information with a maxiumum around 5Hz. This contrary to lateral resonance where the main problem frequency (correctable) is not higher than 0.75Hz.
- Trans-fi arm:
I trust several keen and independent ears, that this is a superb design, technically by design and subjectively by constant tweaking and improvimg.
- the stability/stiffness of it's "open" bearing is still very good by it's v-shape which forces centering of the air bearing by help of gravity.
- the vertical knife edge bearing is a very good and elegant design with no bearing chatter, and with selfcentering by gravity too.
- "optimal geometric design practice" followed by ET keeps the vertical bearing axis on the same height as the tracing / platter level, This reduces FM wow induced by vinyl warp,
- However, this is not without a price: Lifting this tracing level has it's advantages too, leading to improved bass: Trans-fi and RS labs ar examples. This is, because putting the vertical axis in line with the cartridge cantilever ((ca. 20-30 vertical degrees)) eliminates vertical pull on the cantilever bearing, reducing vertical resonance of the arm activated by dynamic friction changes by tracking vinyl, and by variable friction...
No free lunch therefore for ET... and the above mechanism is rarely looked at.
- While the captive air-bearing has advantages in stiffness, the ET design with stationary bearing has only one point with centered forces within the bearing along the arm travel. This "allows" some maximal leverage at the beginning and end of the travel.
- Having a short i-beam compensated with more weight on the i-beam side increases (lateral) leverage.
Eliminating the leverage on the air bearing by using a moving air bearing has some advantages, but a drawback too:
Either one needs an additional flexible air-tube, which increases vibration coupling between arm and tt chassis, and also vibrations within the air feed.
Or one needs an open bearing with less bearing stiffness, like the (very good) Adanalog MG 1 arm, or the many Ladegaard variations incl. the Trans-fi arm. (see below)
- It is desirable to keep varying leverage at a minimum, a) on the air bearing as well as b) on a sprung subchassis. The latter will lead to varying lateral desiquilibrium, visible as increased "slipping" from a balanced middle position to outwards gliding at the start and end positions of arm travel.
- So a longer i-beam reduces the leverage on the bearing, and on sprung subchassis. It improves balance of the center of gravity along the bearing travel. And it increases vertical mass, which often improves the sound too.
- Regarding "optimal" vertical resonance I did put up the idea, that (maybe) there is not much useful out of phase bass information below 100Hz - this might not be the case... as increasing the (out of phase) bass bandwith below eg. 15Hz, by lowering vertical resonance seemingly still is audible.
- However, there is an end to that, probably below 10Hz because of subsonic vertical garbage information with a maxiumum around 5Hz. This contrary to lateral resonance where the main problem frequency (correctable) is not higher than 0.75Hz.
- Trans-fi arm:
I trust several keen and independent ears, that this is a superb design, technically by design and subjectively by constant tweaking and improvimg.
- the stability/stiffness of it's "open" bearing is still very good by it's v-shape which forces centering of the air bearing by help of gravity.
- the vertical knife edge bearing is a very good and elegant design with no bearing chatter, and with selfcentering by gravity too.
- "optimal geometric design practice" followed by ET keeps the vertical bearing axis on the same height as the tracing / platter level, This reduces FM wow induced by vinyl warp,
- However, this is not without a price: Lifting this tracing level has it's advantages too, leading to improved bass: Trans-fi and RS labs ar examples. This is, because putting the vertical axis in line with the cartridge cantilever ((ca. 20-30 vertical degrees)) eliminates vertical pull on the cantilever bearing, reducing vertical resonance of the arm activated by dynamic friction changes by tracking vinyl, and by variable friction...
No free lunch therefore for ET... and the above mechanism is rarely looked at.