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Turntable Isolation Journey

Nearing the end of my journey to solve footfall & feedback issues in my small-room "home office" system with very bouncy floor and flexible walls. Turntable is the only source here -- and it’s a Clearaudio Innovation Compact with no suspension or special isolation feet. This system always sounded good, but was rendered nearly unusable at higher volumes due to turntable isolation that was inadequate relative to this room’s challenges. The worst artifact was when structure-borne feedback from the speakers would cause amp clipping on bass-heavy tracks. This clipping would manifest as an extremely loud singular POP sound, especially hitting the tweeters. It only occurred during the loudest parts of track with bass-heavy elements, and was so loud it was still significantly above the level of the music -- much louder than a POP you would hear from vinyl surface defects. The POP sound was startling, and clearly very bad for tweeters (fortunately my Tannoys seem to have survived several of these incidents). For a time I thought these POPs were from static electricity discharge, but they were NOT. In my quest I tried many solutions and tweaks over a few months, and I’d like to share a rundown of what worked versus what didn’t.

What Helped (MVP products & tweaks):

  1. Townshend Seismic Isolation platform -- Single biggest difference maker, for combating both footfalls and structure-borne feedback from speakers. Amazingly-well designed and built. Leveling was a snap. Well worth the price! If you spend money on isolation, spend it here. Highly Recommended. I’m now considering more Townshend products for under my speakers and in the big loft rig.
  2. Rack Bracing -- Pushed rack right up against the wall (stud / drywall) with a 2’x2’x2" Auralex foam panel tightly wedged in between the top half of rack & wall. This SIGNIFICANTLY cleaned up rack oscillation from footfalls. I see a LOT of folks with nice turntables atop tower-style audio racks, and they could benefit greatly from this "hack". It is cheap & free; the only downside is you may need to reposition your rack. I learned about this "hack" by a couple comments buried in "turntable isolation" threads searched via google. This really CANNOT be overstated.
  3. HOCKEY PUCKS -- Placed under rack spikes in place of the stock aluminum cups or Herbie’s Giant Gliders. Just let the spikes sink right in! This actually cleaned up the very last bit of energy from footfalls; foot stomps with needle-in-groove are now DEAD QUIET. super cheap and effective! Far superior to most audiophile footer devices. Might also help in rack bracing by tightly constraining the rack between wall & floor (Herbie’s Gliders were too slippery).
  4. Rack positioning -- Get your turntable & rack away from the speakers. If you can move the rack far enough behind your speakers, that might be OK, but most rooms cannot accommodate enough depth for this. Placing the rack several feet down a sidewall worked best in this room. Choosing a structural wall also aids in rack bracing. Make sure you don’t place the rack in a room "node" where bass is amplified. Walk around while music is playing to find a nice quiet-ish spot. I kept my amps by the speakers and ran 5 meter XLR cables from the preamp / rack.

What Underperformed:

  • Critical Mass Sotto Voce rack -- the rack is gorgeous and nicely rigid, but doesn’t have nearly enough mass to combat the bouncy floor in this room. Once braced against a wall, the rigidity of this rack was allowed to shine. However, before the bracing, its performance was poor. I will say I have Critical Mass’s Maxxum rack in my (main) loft system on a more solid floor, and the immense mass & rigidity of that rack was game-changer for that system. I do like CMS products, but they are dearly expensive.
  • Critical Mass Black Platinum filter -- Top shelf of the rack. This actually has a significant positive effect, but is limited to the midrange and treble frequencies. It cannot combat footfalls or low frequency feedback. I still like and use this platform, but at more than twice the cost of a Townshend platform it belongs in this category.
  • SOTA Nova V Turntable -- I thought this table’s suspension would render it impervious to room issues, but it’s not. It helped with footfalls but some structure-borne feedback was still getting through. I suspect the suspension needs a tune-up. Quite frankly I think the OLD suspension (it started life as a 1990s Star III) was better tuned and more stable before it came back as a fully rebuilt Nova V, circa 2018. The new vacuum platter was a huge improvement but the new suspension has been disappointing. The Clearaudio deck also sounds a bit better, so now with the Townshend platform it’s an easy choice. Note that the Townshend also uses springs as its isolation mechanism, but I noticed that the Townshend’s oscillation is far better controlled and damped versus the SOTA. You can SEE and HEAR its performance advantage.
  • ISOAcoustics Gaia III speaker feet -- these seemed to have some small positive benefit, but honestly not a lot. Not worth the money.
  • Lovan Sovereign modular rack (three 10" modules high) -- these are very similar to the VTI racks I see everywhere (which I’m also familiar with). These racks lack rigidity and stability. I would not recommend placing a nice turntable on one of these racks. However, if you do, please brace it against a wall (Auralex foam works great). They’re relatively cheap and look good, so I at least understand their popularity. If you have this rack, at least try hockey pucks under its spikes :)

What Was Worthless (Don’t waste your money like I did):
I’m not going to bother expanding upon these; suffice to say they had no discernible positive effect.

  • ISOAcoustics Orea Indigo feet (under maple board & turntable).
  • Symposium Segue ISO turntable platform
  • Herbie’s Lab Giant Gliders (steel) - Placed under Sotto Voce rack spikes
  • Speaker spikes -- at least they look cool :)

128x128mulveling
karl_desch's avatar
karl_desch
442 posts
 

Thanks for this @mulveling ! 

My main system is in my living room on a suspended wooden floor. My new Stabi R is on the top shelf of a SolidSteel 3 level rack.  It sits on a Symposium Svelte platform which covers a Vibraplane. I bet the Symposium svelte shelf would work nicely on top of the Townshend Seismic Isolation platform, not for footfalls but for higher frequency vibrations. This is the advantage of the pricey HRS platforms. Their footers absorb down to very low frequencies and their constrained layer damping platforms absorb higher frequencies generated by the component.  I use HRS shelves throughout my system. If I could only afford their racks as well...

I use the Townshend Seismic Platforms under my Vandersteen Quatro Woods. A vast improvement over Herbies gliders. 

I am wondering if you could expand on rack bracing and use of the Aurelex foam.  Not sure I understand what the foam is doing here and how the rack is braced. 

knittersspouse's avatar
knittersspouse
28 posts
 

Pindac - 

The bottom line is Does It Work for YOU? Ingenuity and experience are often able to trump pure marketing hype and money when carefully accommodating the realities of the space you have to work with. 

When I picked up my Nakamichi Dragon a few years back, the seller was listening to it using equipment that cost much more than I would ever dream of investing, and the sound was very good - even though it was in the middle of an active clothing warehouse.  He had a small  table, a couple of desk chairs, some wine, and very nice jazz to listen to.   His point was that he can only demonstrate that the unit works well, but how it sounds to ME in My Home, is up to me - the system components and environment I choose to set up will make more difference than any one part, although each will affect the whole. 

I, and I believe you, will never stop being curious if this or that little (or big) tweak will make the difference we are looking for, but in truth, all we have is the enjoyment of the journey.  The road to Nirvana has no end except our own and it appears you have found a few things you can enjoy and be satisfied with (at least for now) along the way.    I look forward to discussing many aspects of aural enjoyment in the future with many "Gon" devotees, each with different ears, experiences and resultant recommendations.  My aging ears have not been golden in decades, but like you, I know what makes my listening area an enjoyable space.

mulveling's avatar
mulveling OP
1,941 posts
 

@karl_desch

I am wondering if you could expand on rack bracing and use of the Aurelex foam.  Not sure I understand what the foam is doing here and how the rack is braced. 

It’s very simply just a shim of flat material that you wedge tightly between the rack and the wall behind it. Just push the rack against the panel to hold it tightly in place - press & friction fit. For the shim I’d previously used a semi-rigid panel (the red backing in my 1st turntable pic above), but now I’ve ended up using a single 2" thick Auralex foam tile. I like the foam because its compliance facilitates good contact area for both the wall and rack frame, plus it helps reject vibrational energy in the wall itself.

The idea is that nearby footfalls (on bouncy floors) cause a ripple shockwave which sends your rack into oscillation, because it lacks infinite rigidity & mass. The maximum displacement from oscillation is observed at the TOP of the rack (normally back & forth, but could also be side to side), which is unfortunately right where our turntables reside. Such displacement can easily excite the arm + cartridge resonant frequency (even if in the "ideal" 8 - 12 Hz zone), which causes us so much angst. The idea with the wedged material is to damp & reduce this oscillation, by bracing the rack against the wall exactly where it’s needed. This significantly reduces both duration of oscillation and its maximum displacement. It works kind of like a constrained layer sandwich that "changes direction": floor > rack feet > rack frame > shim > wall. It allows your rack to leverage the strengths of both floor and wall.

Before this "hack", what I noticed was a sort of tradeoff with my Sotto Voce rack frame which was rigid but low mass: the rigidity somewhat reduced maximum displacement, but then this rigidity happily transferred more of the shockwave energy to the turntable. Meanwhile the Lovan lacked rigidity which resulted in a HUGE max displacement, but the frame itself was kind of lossy on overall energy transfer. The result was that both racks were roughly equally bad with footfalls, but the more visible displacement from the Lovan was quite disconcerting to see. The wedge / shim trick works well with both racks :)

I was looking at SolidSteel racks a while ago and almost went that direction. Quite honestly they look like a solid back-for-buck on a nicely rigid rack. I think if you can get enough contact area on the frame to brace them against a wall, the result should be quite excellent. And yes, HRS racks look amazing too but like CMS they are quite expensive and I’m still not sure they’re a complete solution on their own to combat these really bouncy floors.

prof
3,479 posts
 

@mulveling

 

Also forgot to mention, I’ve had these 1" thick granite slabs since forever. They ring like crazy. Tried them under my speakers (with Herbie’s Giant Fat Dots under each corner) and they just sounded BAD. Really bad. I realize this was not a good setup -- granite with proper damping (e.g. sandwich with sheets of some kind of isolation material) could possibly be great. But my lazy granite application was just awful. It made the sound bright, dry, brittle.

Interesting. My 1 1/4" thick granite slab did not produce a brittle sound at all. However, it is also sitting on a 1 1/2" thick layer of wood (Cedar I think) between it and the floor, which seems to further absorb vibrations. If I just hold up the granite and hit it with my knuckles it rings. But sitting on the wood bass the rap test yields a very dead "thunk."

Nonetheless I was actually talking with a contractor today about his building me an alternate version using a constrained layer damping approach. Two 3/4" slabs of granite, in between a sheet of metal (bronze because I like the color) with wall damping on both sides of the metal.

This formation worked remarkably well when I made an MDF sandwich shelf with the steel/wall damping in between. The difference in the knuckle rap test with just the MDF vs with the steel/damping included was pretty profound.

 

noromance's avatar
noromance
9,892 posts
 

Concur on the sound of granite. I tried a 24x24" x 1" slab under a turntable and it was awful. Dry and scratchy. Admittedly, it was not damped.

they just sounded BAD. Really bad.

 

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