Eminent Technology ET-2 Tonearm Owners

The most extremely test of this sort that I have seen was that, while following your initial settings, instead of jumping around the TT, you kick on its stand!

This is not a test for Structure-Borne Feedback.
It merely places a Dynamic (hitting) sound source into a structure.
I have never seen a scientic correlation between 'Impact' sound sources and Air or Structure Borne sound sources?
It is like the ubiquitous "Boink Test" that some audio reviewers used to do........tapping on the plinths of their turntables to see how 'immune' the turntable is feedback?
Chris' test of jumping on the floor around the turntable is a little more viable as it transfers the impact-induced source into Structure-Borne feedback within the floor........ however the form of that feedback is quite different to that which our systems are normally subjected.
Any suspended floor system (timber or steel-framed or reinforced concrete) will be subjected to Structure-Borne Feedback because of the stresses and deflections caused by the structural spans.....as well as the materials used in the floor construction.
These stresses result in subsonic low-frequency Structure-Borne feedback which passes easily into equipment racks, support stands and into the turntable plinths sitting upon these racks/stands.
That's why a wall-mounted turntable shelf is the best way to minimise this.

These stresses result in subsonic low-frequency Structure-Borne feedback which passes easily into equipment racks, support stands and into the turntable plinths sitting upon these racks/stands.

Hi Halcro,

Thanks for the information! So, any idea what is the frequency range of these structure-borne feedback?

Thanks!

Hi Thekong,
In a suspended reinforced concrete slab......there can be frequencies from 5-10Hz and higher.
In a suspended timber-framed floor they could get up to 10-16 Hz but would not normally get as low as the concrete.
Of course....the 'creaking' we can often hear in suspended floor structures as they 'move' whilst we are in bed at nights......are of a far higher frequency.
It's really the very low frequencies doing the damage as Structure-Borne Feedback as they are indicative of 'movement' within the floor structure.

Hi Halcro,

Thanks for the information again! As I can’t use wall mount in my room, I have never experience its effectiveness!

My room has suspended concrete floor. According to the specification, the pneumatic table could isolate up to 85-90% of the vibration at 5Hz, and 97% at 10 Hz, it has worked out very well for me! I certainly could hear the improvement in background blackness with its use!

Thanks!

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