Sorbothane: who has experience with them?

audiojerry · « **on:** 23 Oct 2003, 04:01 pm »

Who has used this product, and what were your results?

I recently discovered it myself by browsing the AC, and it inspired me to gave it a try in the form of Pandafeet under my P1a/P3a dac. I think it was the best $20 tweak I ever tried. My impressions were posted as a review in Critics Circle: http://www.audiocircle.com/index.php?topic=5401

Is it a relatively new application for audio isolation and damping?

JoshK · « **Reply #1 on:** 23 Oct 2003, 04:03 pm »

no, actually I think it has been around a long time in many shapes and forms. I had some AQ sorbothane feet that I used with my MMF5 but those results weren't very great so I gave them away. I could have been misusing them or that had deterious affects on my TT. Who knows?

audiojerry · « **Reply #2 on:** 23 Oct 2003, 04:09 pm »

ya, I guess that the density and shape have a direct affect on performance. If the object is too heavy, or the sorbothane is to soft, the results aren't ideal and vise versa. The footers I used were were intended for use within a narrow component weight range, and depending on weight it affects the resonant frequency. My footers are so soft they feel like breast implants - not that I'm an expert on how breast implants feel

byteme · « **Reply #3 on:** 23 Oct 2003, 05:22 pm »

Interestingly, I'm pretty sure the AQ sorthobane feet LOOKED like breast implants!

I'm hoping to have some time this weekend to do some listening using some pandathumbs under either my Transport or preamp.

gary · « **Reply #4 on:** 23 Oct 2003, 07:09 pm »

Quote from: JoshK

no, actually I think it has been around a long time in many shapes and forms. I had some AQ sorbothane feet that I used with my MMF5 but those results weren't very great so I gave them away. I could have been misusing them or that had deterious affects on my TT. Who knows?

sorbothane has a mixed reputation in audio, mostly because it's so often used badly. one downside of the material is that since it works most efficiently when at strain levels of 10-20%, supports need to be designed properly to work right for given loading situations. this means it's not well suited to a one-size-fits-all kind of approach.

and that's exactly what the hemispheres are. think of the hemisphere as a series of thin disks, decreasing in diameter from the top to the bottom. the ones on top will be too wide, so strain will be low and this part of the material will be ineffective. the ones on the bottom will be too skinny, they'll be compressed to rigidity and that will make them ineffective as well. here's the upside: somewhere in the middle, a portion of the hemisphere will be at the proper strain level and will work to damp vibrations. so you gain a wider window of acceptable load with this approach, but really sacrifice performance to do so. not to mention the fact that resonant frequency will vary significantly through the hemisphere from top to bottom (high on top, decreasing to a minimum where the strain hits about 20%, and then increasing once again toward the bottom). very unpleasant stuff.

(hoping that didn't sound like a sales pitch)
-gary

KevinW · « **Reply #5 on:** 23 Oct 2003, 07:36 pm »

Since I am ex-glaciologist/geologist with lots of experience dealing with stress and strain in visco-elastic materials, I can say that Gary is right on with his explanation of the downfalls of the hemispherical sorbothane products. His solution using the constant-diameter column of sorbothane is the best way to do it. This gives the most absorbtion of vibrations. The only drawback is that the user has to engage their brain to determine which stiffness is correct for their application. This is not a problem for most of us...

Hantra · « **Reply #6 on:** 23 Oct 2003, 07:57 pm »

Well if Kevin likes them, I'm gonna have to give them a try. You're right though, I think that past applications have been laughable at best. The AQ Big Feet I had were the worst tweak I have ever tried, and I was so glad I got them FREE from a friend of mine who also hated them. . .

So how do you go about calculating the proper application?

B

audiojerry · « **Reply #7 on:** 23 Oct 2003, 08:15 pm »

Quote

...determine which stiffness is correct for their application.

Kevin, don't you think we should get a woman's viewpoint on this

Quote

So how do you go about calculating the proper application?

I'll do the sales pitch for Gary. Go to his website, which has an application chart or ask for his recommendations.

gary · « **Reply #8 on:** 23 Oct 2003, 08:17 pm »

Quote from: Hantra

Well if Kevin likes them, I'm gonna have to give them a try. You're right though, I think that past applications have been laughable at best. The AQ Big Feet I had were the worst tweak I have ever tried, and I was so glad I got them FREE from a friend of mine who also hated them. . .

So how do you go about calculating the proper application?

B

when you say 'Big Feet', are those the ones that were cylindrical, very large in diameter and thin? or are those the hemispheres? the cylinders are just too thin with too large a diameter to be effective. that is, unless you've got about a 100lb load to put on them. also, sorbothane needs to get up near 1" in thickness before resonant frequencies will drop below 20Hz (damping begins at 1.3x the resonant frequency, according to sorbothane). i'd have to measure one and do the math, but those things are more like 200Hz. and that's not going to help with a whole lot.

my offer to send out evaluation pieces ended, but i'd be willing to extend it to you as the last person. the best place to start would most likely be under your dacs (very informative writeup on those, by the way), and for that you'd need a set of the soft ones that audiojerry was talking about. they're very soft & squishy, and yes, they feel something like breast implants. just pm me with your address if you're interested and i'll mail some out. all i'd be looking for is honest feedback, and a contribution to Response Audio's benefit fund if you actually like them and want to keep them.

-gary

[edited to add: i was thinking of the write-up on the amps, not the dacs]

KevinW · « **Reply #9 on:** 23 Oct 2003, 08:37 pm »

Quote from: Hantra

So how do you go about calculating the proper application?

B

Would be that be with or without using your brain?

Here's how I do it. I'll let the masses decide on which category that places me...

Step #1: figure out how much your piece of gear weighs.
Step #2: divide by four
Step #3: buy four panda thumbs that are individually rated for the weight calculated in step #2.

I actually put one stiffie thumb under the power transformer of my amp, and three not-so-stiffies under the other three corners. This achieved the proper 20% strain ratio on all four footers. The sonic benefits were very nice. Having even one footer outside the proper strain region did not work as well.

Tonto Yoder · « **Reply #10 on:** 23 Oct 2003, 09:35 pm »

Quote from: audiojerry

ya, I guess that the density and shape have a direct affect on performance. If the object is too heavy, or the sorbothane is to soft, the results aren't ideal and vise versa. .....

I have a set of Sims Navcom silencers that are 3/4" tall discs of Sorbothane (or some similar material) and maybe 2 1/2 in diameter. They have a metal band around them that keeps them from squishing down too much, but one favorite tweak at that time was to cut the band for more squishiness.

_scotty_ · « **Reply #11 on:** 23 Oct 2003, 10:54 pm »

Here is more information on Sorbothane http://www.sorbothane.com/
Dealer for Sorbothane inc. products
search on sorbothane at http://www.mcmaster.com/

gary · « **Reply #12 on:** 23 Oct 2003, 11:36 pm »

Quote from: Tonto Yoder

I have a set of Sims Navcom silencers that are 3/4" tall discs of Sorbothane (or some similar material) and maybe 2 1/2 in diameter. They have a metal band around them that keeps them from squishing down too much, but one favorite tweak at that time was to cut the band for more squishiness.

kudos to the people who figured out they needed to cut the straps off.

the "bulging" as sorbothane calls it is key (because, it means the material is in a state of strain). as a further to _scotty_'s post above, i'd suggest that anyone who's interested read through their "Industrial Standard Product Guide". a quick read, but very informative.

-gary

Hantra · « **Reply #13 on:** 24 Oct 2003, 12:09 am »

Quote

when you say 'Big Feet', are those the ones that were cylindrical, very large in diameter and thin? or are those the hemispheres?

These were hemispheres. They made all my vocalists sound drunk and slurred. Slowed down the music terribly, and just made a mess of things IMO.

So you think the DAC would be better to try them under than my transport? I'll take you up on your offer since I was mean to you earlier.

I'll give a fair evaluation, and let everyone know the results as compared to my current Ayre myrtle blocks.

Like I said, I think if Kevin likes them, then I lend more credibility b/c his listening preferences are very close to my own. . .

L8r,

B

lkosova · « **Reply #14 on:** 24 Oct 2003, 02:27 am »

I have used sorbathane but alittle differently. I am a Podiatrist and have used Sorbathane to cover orthotics with. They have one of the best shock absortion properties for this application. The maker in Ohio is out of business but I think you can by this in sheets. So....why not just cut a sheet for the shelf you have the equipment on?????

Larry

gary · « **Reply #15 on:** 24 Oct 2003, 02:43 am »

Quote from: lkosova

...So....why not just cut a sheet for the shelf you have the equipment on?????

Larry

unless the sorbothane is in the target strain region (meaning it's being compressed so that it's "bulging") it will not work to anywhere near its full potential to damp vibrations. a big flat sheet will compress very little, and will have a high resonant frequency with poor damping (and no damping at all below that resonant frequency).

in the case of this material, there is definitely a "right" amount and not only is more not better, in fact it's worse.

also, keep in mind that shock absorption is not the same as vibration isolation or damping. very different requirements apply*... when you're talking about shock absorption basically you want as much the material as you can get in a low strain state, so that it's ready to absorb as much energy as possible when subjected to an impulse. in this case, more is better and you don't want it to be bulging so that it can upon impact.

hopefully that made some sense.

-Gary

* well, that's my s.w.a.g. at it anyway

lkosova · « **Reply #16 on:** 24 Oct 2003, 02:45 am »

Gary,

Excellent Response.

Larry

gary · « **Reply #17 on:** 24 Oct 2003, 03:34 am »

Quote from: lkosova

Gary,

Excellent Response.

Larry

thanks!
-gary

MaxCast · « **Reply #18 on:** 24 Oct 2003, 12:53 pm »

Gary, how do we know if we need to drain or isolate?

bubba966 · « **Reply #19 on:** 27 Oct 2003, 01:21 am »

So what are the dimensions of these things? I checked Gary's site, and could find no mention of dimensions anywhere.