Discuss The Viv Lab Rigid Arm

Exactly, and that has been my point in this thread. To make real progress, we need to correlate measurements with what we hear.

@cleeds Its been my experience that's what you do to sort out what's going on.

That is what led me to increasing rigidity in the plinth of our turntable; increasing coupling between arm and platter surface and overall making it dead as possible- damped platter, damped plinth. As I did these things the impervious nature of the system began to emerge; when I started the system was sensitive to volume pressures of 90dB; after I was done even at 105dB it was measurably and audibly superior. 

My technique was to place the stylus on the platter pad and measure the phono preamp output while playing a 100Hz tone thru the line stage of the preamp, amps and speakers. 'Success' was in reducing the output. I found that the better the coupling, the more dead the system, the lower the output at any frequency accompanied by a perceived improvement in bass, mids and highs- the system sounded less congested.

Damping the platter was easy but the plinth got tricky since it had to be machined out of solid aluminum.

I've been trying to correlate amplifier distortion vs how the amplifier 'sounds' for a very long time. My experience with that is both the measurement guys and those that prefer to only trust their ears hate what I've been finding. I think this is because the work messes with their world view. Its not surprising to find some pushback on this thread on the same account.

Lew and Dave: The Viv armtube can slide back and forth in the direction of its length through the housing by about 1mm. It can rotate around the axis of the tube a few degrees and it can be lifted a couple of mm to the top of the housing, tho here it takes some lifting to oppose the magnetic force of the fluid--not likely to happen during play.

@maxson 

Thanks for confirming.  I suspect it is this additional ability for movement that plays a big part in the arms response to and recovery from movements that cause mistracking. 

dave

Maxson, First, thanks for your response. To your direct observation, does azimuth remain stable over the course of traversing an LP during play? The top surface of the headshell on a Well Tempered Reference tonearm, for example, visibly rolls over toward the spindle as it moves from outer to inner grooves.

@lewm I've never seen the arm roll as you describe. It takes a bit of twisting on my part to get it to leave its upright position.