Active isolation; what can it do for music reproduction?


i was involved in a thread about stylus drag on turntables where my use of active isolation came up. it was asked for me to discuss my views and use of this approach for system optimization. i mentioned it likely needed it's own thread to do justice to the topic. here it is.

excuse me if i get too basic here to begin with. i've not seen this subject discussed in depth on Audiogon before.

active isolation devices use piezoelectric sensors in 6 axis to sense resonance and piezoelectric actuators in 6 axis to compensate for that resonance. in essence it's a feedback loop of read and compensate. 

http://en.wikipedia.org/wiki/Piezoelectric_sensor

passive devices are more or less springs to one degree or another. springs float, settle and overshoot. active devices are relatively stiff; 500 times stiffer than passive since they can STOP and START. passive can't stop and start. you do see passive devices with automatic leveling, but otherwise they can only act passively as a spring. 

an example of an active device; the Herzan TS Series;

http://www.herzan.com/products/active-vibration-control/ts-series.html

the limitations of active devices are mainly as follows; 

---they are only really effective under 200hz.
---in stock form they typically have signal path corrupting switch mode power supplies.
---to be effective they need a solid base. which means a solid rack grounded to a solid concrete floor. suspended wood floors, or non-solid racks are going to compromise the performance.
---the gear being isolated cannot have it's own self resonance that might excite the active sensors. and not every piece of gear will benefit from active isolation. so active is very system context dependent. you can't just use it anywhere and expect a particular result.

there are very very good passive devices that approach what an active device can do; the Minus K, Stacore platforms, and Vibraplance are three popular examples. i'd recommend investigating these before considering any active devices. those examples do need the same solid floor and rack as active to be effective.

and another consideration is a passive isolation rack; the best example i can give is the Artesania decoupling rack systems. likely the best passive rack. again; a solid floor is going to allow the Artesania to perform at it's best.

finally; there is a website tutorial which can really get granular with deeper levels of information on active devices for those interested. 

http://www.herzan.com/resources/tutorials.html

lastly i will say that active devices are something you consider when you've mostly done everything else you can do and want to take things further. cross otherwise impossible thresholds of performance. you have a system that is where you want it to be. active is the bleeding edge. it will allow the music to escape the confines of resonance in a way nothing else can do. it's just physics.
mikelavigne
A point that should be made is isolation is the long-term path to higher ultimate sound quality, "tuning" limited to short-term gains, but ultimately a ceiling, or dead end.
@mijosyyn -- re the effect it is "slap you in the face" obvious, not at all subtle. And this in the context of my TT that has a pretty effective inbuilt suspension, and was mounted on a very high end wall shelf. @bdp24 will provide an unbiased perspective ... so yes these things do have an effect. As to whether this is worth it for you I cannot answer but vibration control is in any sufficiently resolving system the prime route to continuing (increasing not diminishing returns btw) and my system employs a plethora of passive approaches as well as the one active stand described above.
@mijosyyn said "You could argue that capacitors might be affected. Is there any evidence for this. Not that I can find. If anybody can find something on this please post a link. Can vibration affect the travel of electrons through anything else?

Take a look at the photo of the damper ring on the cap

https://www.whatsbestforum.com/threads/taiko-audio-sgm-extreme-the-cr%C3%A8me-de-la-cr%C3%A8me.27433/#post-555910

Taiko Audio does not CNC machine this Panzerholz damper to fit around the cap for fun, there is a reason for it

Dueland uses cast copper in their caps for a reason too

All caps are microphonic to a degree and managing those vibrations and microphonics is the key to their sonic performance in High End audio applications




Speaking of capacitors, I encourage people to use Marigo VTS Dots or cork to dampen vibration of Capacitors, in fact I’ll go as far as to suggest isolating the entire printed circuit board PCB in components from vibration, especially vibration of the large Transformer, which is direct coupled to the chassis. This is important even if you have isolated the component on an iso stand.

The way to isolate the PCB form the transformer is to remove or at least loosen the screws holding the PCB to the chassis. Also loosen all bolts holding the Transformer to the chassis. Use thin natural cork squares or slices as shims between the PCB and the chassis. Use a thin cork sheet or viscoelastic sheet underneath the Transformer. Cork can be gently wedged between capacitors in capacitors banks. If anyone needs some natural cork, I’d be happy to send some free of charge for these porpoises. 🐬 PM address.
I did not say vibration control was not important. For turntables in particular it is very important for rather obvious reasons. My point is that there are ways to do it that are just as effective and seriously less expensive. It seems to me this is analogous to driving a finish nail with a sledge hammer. 
Folkfreak, whenever someone uses hyperbole in reference to sound my BS antenna goes up. Describe what it is you think you are hearing.
Mike, unfortunately few people will give their real opinion in such circumstances, not to hurt your feelings. I only have one close friend who will let me have it when I screw up. Not that there is no improvement but I would suspect It is primarily to isolating the turntable. Get it out of the room an it will be even better. I am very skeptical of isolation platforms improving the performance of purely electronic devices. I would only believe a well run double blinded study on that issue. I would not even believe myself. I love experimenting and it be loads of fun having your resources to play with.

Mike