Here is Bruce's opinion on using ET2 manifold shims
Richard, Dover, others ?
When Bruce says:
“science of resonance in a phonograph tonearm would first involve a measurement to prove something exists.”
Curious if magnetic and mass damping, and any of its effects can be measured other than just by listening ? Have you done it?
On 3/5/2013 10:05 AM,
Hi Bruce
We would like your opinion on the small space between the ends of the manifold and the rubber rings.
You can slide the edge of a piece of paper in there.
Is it by design for resonance control - to achieve a certain frequency ?
If shims are inserted in there - does this not in theory make the setup more rigid - desirable?
Would this affect the general frequency resonances of the ET2?
We look forward to your opinion on this. thanks. Chris
Chris,
The o-ring is used as a seal, when the manifold is inserted, the ring is flattened and the gap is taken up, that is the design intent.
The science of resonance in a phonograph tonearm would first involve a measurement to prove something exists. This is very easy, Take another ET2 tonearm and use its cartridge to play the tonearm under test. Compare the levels of record playback to the measured level of vibration on the tonearm under test using a spectrum analyzer. If the vibration levels measured are greater than -50dB below playback levels then there may be something significant and you might call it a resonance.
Odds are good that the manifold has no significant vibration levels from a stylus forcing function while playing a record. I hope this helps.
brucet
Richard, Dover, others ?
When Bruce says:
“science of resonance in a phonograph tonearm would first involve a measurement to prove something exists.”
Curious if magnetic and mass damping, and any of its effects can be measured other than just by listening ? Have you done it?