Herzan/Table Stable "Active" Isolation table.

rockitman

Member Sponsor
Sep 20, 2011
6,868
1
38
Northern NY
Any resonant suspension would be a potential problem due to a possibility of beat oscillations if the natural frequencies are too close. However with pneumatics one can control the natural frequencies by the air pressure so it may be possible to find such a combination of pressures in the AF1 suspension and the underlying pneumatic platform that the two suspensions cooperate rather than excite each other. Experimentation is needed.

Cheers,
That's interesting and makes sense for those willing to experiment.
 
May 30, 2010
13,916
7
38
Portugal
(...)

Active isolation
Active vibration isolation systems contain, along with the spring, a feedback circuit which consists of a sensor (for example a piezoelectric accelerometer or a geophone), a controller, and an actuator. The acceleration (vibration) signal is processed by a control circuit and amplifier. Then it feeds the electromagnetic actuator, which amplifies the signal. As a result of such a feedback system, a considerably stronger suppression of vibrations is achieved compared to ordinary damping. (...)
IMHO it is the Achilles knee of such systems from an audiophile perspective. It is a feedback system, and errors are electronically corrected to very low values, leaving an history behind the correction. I can easily imagine that people who object to feedback in turntable motors will not feel happy having feedback in the platform ... :D .

BTW, I know that my Studer A80 capstan motor - by far my best analog audio source - has a feedback system. As a consequence I can not be against feedback and trying an active table in my system is written somewhere in my wish list, but only after I stabilize my system. :eek:
 

ddk

Industry Expert
May 19, 2013
3,439
3
38
Utah
Hi Taiko,

Hi David,

Well its achieving a certain level of isolation through damping, amongst others :)
Just following instructions :)!

Isolation is of course not equivalent to damping. You would call the tablestable and isolating device, but it isn't, it is dissipating vibrational energy by producing a counter force.
david
 
Oct 22, 2011
616
0
16
The video is saying it is blocked for copyright content.
 

Mike Lavigne

Member Sponsor & WBF Founding Member
Apr 25, 2010
7,072
3
38
I don't see that. Hmmmm
if music is playing, it reads that sound as protected content; and won't allow open distribution. same way phone apps can figure out which CD it is.
 
Oct 22, 2011
616
0
16
well I am having a little lesson in youtube today, Hendrix astro man is copyrighted...
Do you have a Grateful Dead bootleg album? That shouldn't be detected! :)
 
Feb 10, 2017
185
0
16
Hi Taiko,



Just following instructions :)!



david
Ah yes I see where that went wrong! It should read this:
"Isolation is of course not equivalent to damping. You would call the tablestable a damping device, but it isn't, it is dissipating vibrational energy by producing a counter force."

Now this is in fact out of context as a single statement, as the isolation the tablestable provides is by means of A) destructive interference that cancels-out incoming vibrations for lower frequencies, the active isolation, but it also provides passive isolation by means of (spring) damping. If you disable the active isolation it would be a strictly passive isolating device by a mass/spring damping principle.

The corrected sentence above strictly applies to the active isolation mechanism of the tablestable.
 

ddk

Industry Expert
May 19, 2013
3,439
3
38
Utah
Ah yes I see where that went wrong! It should read this:
"Isolation is of course not equivalent to damping. You would call the tablestable a damping device, but it isn't, it is dissipating vibrational energy by producing a counter force."

Now this is in fact out of context as a single statement, as the isolation the tablestable provides is by means of A) destructive interference that cancels-out incoming vibrations for lower frequencies, the active isolation, but it also provides passive isolation by means of (spring) damping. If you disable the active isolation it would be a strictly passive isolating device by a mass/spring damping principle.

The corrected sentence above strictly applies to the active isolation mechanism of the tablestable.
Ok :). So the active part is reacting to vibrations it senses from the top plate?

david
 
May 30, 2010
13,916
7
38
Portugal
(...) Now this is in fact out of context as a single statement, as the isolation the tablestable provides is by means of A) destructive interference that cancels-out incoming vibrations for lower frequencies, the active isolation, but it also provides passive isolation by means of (spring) damping. If you disable the active isolation it would be a strictly passive isolating device by a mass/spring damping principle.

The corrected sentence above strictly applies to the active isolation mechanism of the tablestable.
Although this mechanism can be used in some noise cancelling devices - they have a sensor outside the isolated volume and drive this volume with an out of phase signal created from the signal generated by this sensor, I am not sure that a similar technique is used in laboratory active tables - I had got the idea that the system is much more sophisticated than just destructive interference, particularly because the fixed part of the table is not an inertial reference. Do you know if there are any sensors in the upper part of the table?

The best AFM (atomic force microscope) tables combine passive pneumatic and active piezoelectric - but surely at a much higher price!
 
Feb 10, 2017
185
0
16
Although this mechanism can be used in some noise cancelling devices - they have a sensor outside the isolated volume and drive this volume with an out of phase signal created from the signal generated by this sensor, I am not sure that a similar technique is used in laboratory active tables - I had got the idea that the system is much more sophisticated than just destructive interference, particularly because the fixed part of the table is not an inertial reference. Do you know if there are any sensors in the upper part of the table?

The best AFM (atomic force microscope) tables combine passive pneumatic and active piezoelectric - but surely at a much higher price!
Ok, I'll admit to having disassembled a TS-150 in a very early stage, out of curiosity, which is something nobody should do as I ended up having to return it to the factory for recalibration :eek: Without specifically focusing on this particular subject, I was more interested in the motor assemblies at that time, I did count at least 12 sensors, it's quite possible there are more, they are located on both the top plate and bottom structure. Which sensor serves which function I do not know and did not investigate.