what is the point of the Minus K isolation being incorporated into the turntable? The Minus K isolation platforms supposedly isolate down to 1.5Hz horizontal natural frequency and our signature 0.5 Hz vertical natural frequency.
seems crazy that you can walk over to the table and the arm skips.
Good luck in getting it fixed.
Hi XV-1 This is a complex interaction with a number of variables. If the MinusK suspension natural frequency (Fz) is sitting at 1.5Hz and a wooden floor with sufficient "give" where the rack is situated is stimulated with a "bouncing displacement" this will create an interaction between the floor and the rack top shelf (which is usually about 700 to 1000mm from the floor surface). if the floor bounce is stimulated to 1.5hz.
As a user walks over to the rack on this wooden floor with lots of "bounce" the subsequent movement in the vertical will "dip" one side or oblique of the rack stand at the base which then is amplified over the distance from the floor to the top of the rack. The horizontal amplitude of this movement will overwhelm most systems when the movement Hz and the DUT (Device Under Test) Fz closely coincide. This includes non suspended tables as well as the tonearm mechanism can form its own resonant "suspension" (due to the fine free moving bearings and linkages).
It will create a large displacement which the suspension system (even if active or air based) will try to settle once the disturbance stops. So the MinusK is actually working during the oscilation and will continue damping once the disturbing force is stopped.
In some tonearm designs the counterweight is connected low on the rear of the arm then if you draw a line from the counterweight into the connecting link to the tonearm wand you can trace a "Z" like shape. So any horizontal movement there will be a displacement which travels through this link and causes an upward motion at the stylus tip. As the armwand keeps moving upward the counterweight travels in an arc downward and forward thus reducing the tracking force even further. In some instances this can accelerate the downforce at the stylus quickly and the arm rises and skips. With super heavy arms this inertia can overwhelm the VTF at the stylus.
In arms like the SupaTrac the physics have been carefully managed and the pivot point and counterweight system resists these forces and keeps the stylus tracking superbly. In other tonearms this energy can be excited even on a rock solid table with no suspension by something as simple as a record warp.
Personally I have installed a good number of the Kuzma Safir arms with positive listening experiences including houses with wooden floors. In some cases the floor joists underneath are spanning extra large (over 7 meters) and are made from natural non-laminated timbers such as Oregon or Pine and have wide joist spacings.
You can feel the floor give underfoot and literally bounce the floors. In these instances there may be opportunities to move the equipment rack closer to the walls where displacement is lower.
In other instances additional stiffening underfloor is possible using underslung trusses or added laminated beams to help support the wider span. One solution for super compliant flooring is to create a tie from the top shelf of the rack to a wall anchor point which prevents the max displacement and sudden forward movement from floorwalkers.
We strive to proivide quality advice and support to all our community and are confident the MinusK technology still delivers the massive cleanup in the bass region under music signals punching in to these softer floors via subwoofers and heavy bass articulation from speakers. The nomograms published by MinusK show 0.5hz in both vertical and horizontal in our Helix One and 0.5hz vertical and 1.5hz horizontal in the Helix Two model which uses a smaller more compact model form MinusK.
Getting comparative nomograms from other suspension isolation systems (Active and Air etc) will show the MinusK technology has the lowest Fz commercially available on the market. This is why the solution is still favoured by the scientific and engineering community for their most difficult vibration isolation problems. In domestic environments sometimes there are additional challenges which must be addressed as they arise. A good dealer backed by quality distributor in close consultation with the manufacturer that understands the issues, means a lot of the technical challenges can be resolved.
We hope this helps shed some light on the discussion in this thread. We also are keen to provide timely responses to any customer enquiries via our email
mark@dohmannaudio.com and
george@dohmannaudio.com which being in Australia are UTC+10.
