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Dont use sorbothane directly underneath the speakers, it will absorb the bass and make it sound muddy and less detailed.
You can use the sorbothane under the granite, then try the speakers using their feet or spike them...see which gives you the clearest bass response. This way the speakers and granite bass will be decoupled from the floor.
And I agree, Herbie makes excellent isolation products. Try what you have on hand first.
That was my original plan, .25"-.5" sorbothane discs under the granite tile and the KEFs directly on top, maybe add the spikes to the KEFs feet. Where I lived before I had a solid, cement underneath carpet, floor and used the spikes to couple directly to the floor and it sounded good.
I've read good things about the Herbies stuff before and will look into it further.
Based on what I’ve read, if the floor is cement or tile, covered with carpet or not, it’s best to couple the speakers with the hard floor using spikes, direct or through the carpet. If the floor is suspended and is covered with hardwood, e.g., basement underneath, second floor, etc., it’s best to decouple using a semi hard material, e.g., sorbathane, etc. I can only attest to the second scenario and am using Herbies brass gliders with a layer of their Fat Dots together under the speaker spike. Happy with the results. YMMV.
Within the budget you mention, I think you should consider @geoffkait's suggestion. He does understand the mechanics of springs. I am personally familiar with the Townshend speaker podiums which perhaps are above your budget. The Townshends are superb at the kind of isolation Geoff is talking about. But I expect Geoff's solution will get you much of the way to the Townshends' level. Springs in my experience are better than other devices for isolation. I have a bunch of springs (Geoff's actually) under my other components though not my speakers.
Whatever form of isolation you chose (sorbothane or springs) will need to be compliant/soft enough to get as low as possible (<10Hz).
That will make the speakers very wobbly so will you need to use some form of wedges underneath the speakers or the platform with a minimum clearance of say 1-2mm to prevent accidents.
The benefits of isolating speakers have been well documented. Spikes induce resonance in the baffle hundreds of times greater than that of even soft rubber when the speaker is in use.
The problem with isolation is that it’s cheap to implement and the sonic gains are huge (bass starts to play notes) but apart from a few companies like Townshend or Herbie’s there is little profit in it. Whereas with spikes the opposite is true.
It would probably be easier and you'd get better results if you used a Herbies product rather than an unbalanced granite platform.
I use Decoupling Gliders on my hardwood floor. Heavy brass tip-toes on my speakers sit in the decoupler and there is no resonance introduced into the floor or back into the speaker (as far as I can tell).
Or you could try the threaded stud glider. Seems like many are getting good results with Herbies.
I know you said Gaia and Townshend are out of budget, but if they ever come into budget please do trial them. I found both upgraded my speaker in the bass department to an unexpected and astounding level. In Munich Isoacoustics were demoing their Gaia in the noisy main hall on an open stand. Two sets of speakers were running next to each other, one on Gaia one not. Even in this noisy place the differences were so apparent, as they switched between them A/B fashion.
I have tried thick foam in the past, under each corner, folded over so that the speakers gently rock on the four wedges. That did something and is nearly cost-free. Worth a try.
In the meantime, definitely try the spikes if you have a set as they will probably help a little.
@kalali, yes finding springs with the optimum compliance can be a problem especially if large heavy drivers render your speakers front heavy.
Like with most things in audio, it can be a fools mission to pursue perfection, but springs are probably the way to go if you insist. Otherwise rest easy in the knowledge that even bits of soft rubber can offer huge improvement in isolating the baffle from unnecessary resonance.
Since Sorbothane is measured in shore durometers it shouldn't be too difficult to mix and match to get decent isolation. For anyone with kids, don't forget to spoil their fun by preventing any unnecessary wobbling by placing some wedges underneath!
I find Sorbothane to suck the life out of the sound. There are materials that look just like Sorbothane I have used in the past that really do work, especially in viscoelastic damping situations. I have also used some other similar materials that didn’t work. So I guess you never really can tell just by looking at the stuff.
Thanks for the input geoffkait,
I was wondering about Sorbothane, Vibrapods and the various Herbie’s offerings and what materials are being used? I have some 2.5" diameter x .25" high 70 duro sorbothane discs and I also have a bunch of various Vibrapods that I could use under my KEFs feet (which are about 1.75" diameter). Now I’m thinking use the sorbothane discs under the granite tile slabs (which are .4"ish thick) and then the KEFs with spikes installed in the brass feet on top of the granite. Again, it’s a tile holllowish floor underneath. My KEFs sounded really good at my last place with just the spikes through carpet on a solid cement floor.
At any rate I have a bunch of stuff to try and I’m also not against tossing some coin Herbie’s way. One thing about his cone/spike decoupling gliders, and lets face it, aesthetics matter, is that they aren’t too visually appealing for where I’ll be putting them. Also, they may look a little strange as the diameter is much less then the KEFs feet.
Thanks again for the input everyone. :)
Anyone (geoffkait?) think the IsoAcoustics Modular Aluminum Series stands will translate the same Performance as their smaller stands and footer devices???
Im thinking of trying them under Harbeth 40.2 (that I want lower than traditional stands for this speaker). The 40’s like the bottom to ‘resonate’ just like the rest of the cabinet and are getting good reports gently resting on top of the extended tenons on the TonTrager stands, so I’m wondering if the ‘rubber cups’ on the IsoAcoustics will kill some of the resonance that is making these speakers sing a bit more. I know, Tough specific question here without trying... and no trial with the Modular Aluminum Series. Drat.
I’m high on mass-on-spring isolation devices which have become ubiquitous. In the beginning there was Bright Star, Vibraplane, Townsend and yours truly. It’s like walking a tightrope or a razor blade trying to balance all the variables - internal damping, spring rate, number of directions of isolation and load capacity and of course cost. I eschew getting rubber but I suppose a little bit can’t hurt much, and too much slows things down too much. For myself I forego all rubber and almost all internal damping, preferring very hard cones, high carbon springs, high mass and extremely stiff boards.
@jriggy Whilst you may see improvement by trying out different stands with the Hatbeths don't forget that they are probably the most advanced speakers ever built when it comes to controlling resonances.
Everything from driver material, driver mounting, and panel resonances has been meticulously considered by the designer. In fact the designer, Alan Shaw once said that you could place them on a stack of telephone directories if you so wished and they would still sound good.
I'm sure he's right. I just wish all speakers were designed and built with such care.
@cd318, thanks for the reminder. While choosing my stand solution and height, I have the speakers up on wood frame w/ granite platform amp stands. There were sorbothane ‘half-ball’ pads Gibbon under the granite—bad!
So I replaced with hardwood blocks—much better!
Then one step farther, was raising the speakers off the amp stand surface with 1 & 1/2 inch wood blocks at corners only—even better! Letting the bottom of the M40’s breath freely, like the TonTrager stands achieve, does seem to benefit... so with this finding, your reminders, and geoffkait’s comments on rubber (which is where my concern was), I think I’ll forego the IsoAcoustics Modular stands for these particular speakers.
@jriggy Yes, you shouldn’t need fancy stands but it definitely a good idea to let all the speaker panels breathe freely. All Harbeths are constructed that way to allow the resonances to fall below the threshold of hearing in terms of frequency range.
The M40s have always been fantastic speakers and are the sum of one man’s attempt at getting as close to neutrality in the midband as possible with the fewest compromises. Does any speaker do voices better?
My best advice to the OP, keeping it cost effective and simple, is not to overwhelm yourself by trying to many things, in to many combinations. Using what you have, first try the individual items you have - by themselves. Listen and compare and if none of the products, by themselves - spikes, sorbothane, granite slabs, etc - brings the sound back to what it was when coupled to the cement with spikes, then try what you have in simple combinations. Usually the simplest solution ends up being the best solution....Jim
I haven’t compared to those but I have some IsoAcoustics Apertas under my KEF LS50 Wireless in my man cave setup. Excellent stands that helped clean things up a bit.
jhills, excellent advice that I’m taking. I have so much stuff already to play around with and if I do spend more, I’ll at least have an idea of what might work best based on materials, application, etc. from experimenting.