Vibration isolation

I suspect you’ll find isolation devices like springs and roller bearings under speakers prevent mechanical feedback to other components, via the floor. It doesn’t make sense that springs or roller bearings (primarily) prevent seismic vibration from getting into the speaker since the speaker itself is producing vibration. That induced vibration is still there in the speaker crossover, cabinet, etc. Obviously seismic vibration is attenuated for the case of speakers, too, but so what?

It is not the speaker’s vibration that roller bearings are dealing with, it is the vibrations traveling across the floor upon they are sitting. The bearings prevent those vibrations from being transferred into the speaker cabinet or planar frame. At least, that’s my understanding. I’m looking at using the Townshend Pods or Geoff's springs (much cheaper than the Pods!) on my speakers though, not roller bearings. Isolation in ALL planes!

Super stiff springs like Townshend’s and your humble scribe’s are extremely stiff in the lateral direction, which is actually how you can support very heavy objects with springs in the first place. If I diasagree with Townshend so be it.

I didn’t say roller bearings wouldn’t work under racks. But most roller bearing assemblies would be quite unstable against accidentally knocking into the rack. Especially in set of three. That’s why the preferred location for most roller bearings in under components not the rack.

You don’t put roller bearings under a rack, silly

@geoffkait - Not always silly -- Grand Prix Audio Apex footers are roller bearings and they work perfectly under all my racks.

I also think you are incorrect in regard to speakers -- the whole point of the Townshend video and explanation is to discuss how small displacements front/back in the speaker can affect the sound, their spring based solutions have some lateral flex so can move in both vertical and horizontal planes

You don’t put roller bearings under a rack, silly, you put them under the components on the rack. For speakers you don’t actually have the same situation as seismic type vibration as almost all the speaker vibration is vertical, i.e., toward the floor. So roller bearings would bring nothing to the table. Springs would be sufficient.

Ha, good point Kenny! I'm not comfortable with the idea of putting roller bearings under my 5' tall planar speakers for the same reason, though recording engineer and roller bearing proponent Barry Diament has his 6' tall Magneplanar MG3.7's sitting on them. 

That's a great point about using the Seismic Corners to handle the entire rack. I would have to first get comfortable about having my rack wobble around like my subs when nudged, however. Honestly, I'm not sure if I'm ready for that one yet...But, in theory!
Kenny

Kenny, the Townshend Seismic Pods are also available as a model name the Seismic Corner---two Pods on a metal plate that is placed under each corner of a rack. With them in place, anything sitting in the rack is isolated from vibrations coming up into a rack from below. Individual Pods under each component may be the most effective, but that can get expensive!

hifiman5,

Thanks. My subs have never been spiked. Like my main speakers, the subs started out sitting directly on top of Symposium Super Plus platforms. While these platforms noticeably improved the bass of my main speakers in my old house, the platforms under the subs did not take care of the feedback oscillation.

The current setup that cured the oscillation was adding the Townshend Isolation Bars under the Symposium platforms. I'm going to try the subs directly on top of the Isolation Bars without the Symposium platforms for checking feedback and SQ.

My system, is in my new home in an unfamiliar room in terms of sound. It's like starting over. Producing the feedback and curing it was an education. Despite my heavy rack of maple and brass with Mapleshade Heavy Feet, my problem revealed that my rack is quite "active" and does not have a good defense against mechanical vibrations. I can take two approaches. One, is to put the Townshend Isolation Bars under my rack, or second, to do my components separately with Isolation Pods. I've also read here that Isoacoustics makes similar products with good results, but when I discover something that really works, I tend to stick with it.
Kenny

@kennythekey   Good post.  If you still have the subs and they are spiked, have you considered decoupling the subs from the suspended wood floor.  This should significantly reduce the subs. sonic vibration getting through to your equipment.

I have my two subs sitting on a carpeted concrete slab and decoupling  made a great difference.  The great side benefit is that the deep bass is not transferred through the rest of the house making my dog think it's thundering and driving him crazy!

Herbie's Audio Lab has a nice assortment of devices to accomplish decoupling that you can implement for little $.

All the best!

My problem was mechanical feedback causing my turntable to oscillate from the addition of subs sitting on a wood suspended floor also shared by my rack. I first tried dealing with the turntable by upgrading the feet to Raven Black Night that have a built-in spring system. This rig is also sitting on top of a Silent Running Audio platform. While there was a slight decrease in the oscillation, I could still reproduce it at higher volume levels.

I wound up adding Townshend Seismic Isolation Bars to the bottoms of my subs and that completely cured the oscillation. I've decided to now try their isolation pods under the rest of my gear starting with my mono blocks. The Townshend products use a spring system as well, but whatever they're doing they seem to do it well.
Kenny

You might consider the Golden Cone DH Cones.
http://www.soundstage.com/revequip/todd13.htm

This might also be of some interest to you: https://forum.audiogon.com/discussions/isolation-feet-cones-for-ps-audio-nuwave-dsd-dac

Thanks Ted,
Very happy former AQ customer here.  Love your cables.  I have Level 4 SC on order with David Weinhart as well as Black box and UEF Panels.  MIG 2.0's are performing great under my PowerCell12....I'll get with David on the MiG's.  Thanks for the heads up!

Patrick if the MiG 2.0‘s aren’t quite clicking in your system why not have your dealer send you a set or two of the original MiG’s which can sound warmer and more organic in some systems.

Your’s in music,
Ted Denney Lead Designer Synergistic Research

I've not tried the roller bearings yet, but have had great luck using compression springs I buy from Grainger. They usually list the load of the spring, so the math is simple: weight of component/number of springs you want to use = spring load.
The fewer the springs, the better. I also put cork on the bottom of each spring so they don't scratch my rack when I'm moving them around to level the component.

Thanks hifiman! I'm just shocked that the simple, reasonably priced Herbies seem to deliver a soundstage with more body, warmth and musicality than the roller bearing designs.  Wondering if perhaps they extract too much detail from an already detailed system??  Does our search for greater detail inevitably bring us to a point where we lose the music?  Interesting hobby!!!

@ptrck887 As far as I can tell you are right on track. I use a combination of Herbie’s Tenderfeet and Firm Tenderfeet under all of my components. Just as you stated earlier, they reveal the best overall sound. Detail with good soundstaging without overdoing it. What I have found is that if the regular tenderfeet render a bit too warm of a sound I switch in a pair of the firmer tenderfeet to compensate.

Years ago, I was on the Black Diamond Racing Cone bandwagon only to discover that as my component and speaker system quality improved, the sound took on an upper midrange/lower treble hardness that I found unmusical.

Example of tweaking with the Tenderfeet. I upgraded the tubes in my SACD player and power supply. As they ran-in the sound took on a slightly warmer quality. I began mixing tenderfeet with firm tenderfeet to tune the player to the most accurate/musical sound I could get. I find the sonic response of the Tenderfeet to be very predictable which helps to facilitate tuning your system.

Stay the course. Your compass is true.

If you are experiencing brightness from using Symposium products, I would try to track down the brightness in your system that you don't like.  I have not experienced brightness from Rollerblocks, only what you described above as positives.  In my system the Rollerblocks on top of the Ultra shelves, my phono preamp, and mono blocks sound sublime.  Have a look at my system and you will see I use Symposium under all my gear, speakers included.  I have Rollerblock 2+ double-stacked under my speakers, what a big upgrade.

Good luck.

Thanks, one product at a time under one component at a time....I originally had Herbies under everything....first components I worked to upgrade were the monoblocks using Iso Pods....they did an incredible job, especially bringing out some bass that just wasn't there before as well as better level of detail all around....no overly bright results so they remain there.  With that success I bought a couple of more sets and tried them under the pre first....wasn't overly impressed, nicely focused imaging but very bright.  A friend brought over a couple of pairs of Rollerblocks so we tried a set of those under the pre....it really locked in the sonic image, which we liked but again so bright as to be fatiguing quickly....we both decided, of all things, the Herbies feet were slightly less detailed but more engaging...we continued the same protocol with the Lumin next....same kind of result.  By that time a set of MiG 2.0 demos showed up....placed them under the Lumin first....Ambient direction....both of us agreed, at least under the Lumin....it did a better job....more detail without getting crazy bright.  Experimented with all the above under the the power supply with similar results.  At this point, with good but surprising results, Iso Pods remain under the monoblocks, Herbies under everything else but the Lumin streamer which sits on the MIG2.0's.  Just a FYI, all my frontend gear including a Synergistic PowellCell 12 line conditioner sit on a side wall.  5M Atmosphere Level 4 connects monos on speaker wall.  I was just wondering if anyone had similar results....not at all what I expected!

try some ball bearings set on miniature dollhouse ceramic tea cups

It sounds like you are using various different products at the same time?

VooDoo Iso Pods
MIG 2.0
Herbies soft feet
Rollerblocks

Or are you swapping out these products under 1 component?  If so which component are you using these devices?