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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

Showing 3 responses by whart

whart's avatar
whart
2,967 posts
 

The Kuzma, like the Herzan, are active units and based on my discussions with Franc Kuzma and Mike Lavigne, respectively, neither product is designed to deal with footfalls, which the Minus K is capable of absorbing. Instead, those active units maintain a sort of constant balance through a feedback loop (my description may be crude but I understand similar tech is used to keep centrifuge floors level).

I’m running 245 lbs worth of TT, including HRS plinth it sits on- the Minus K has a metal top so you want something between that and the table/plinth unless the latter is already able to deal w/ a metal interface.

I use the largest bench top model- they are spec’d to load and you want to load them close to max to get the most out of them. Since I’m in an old Victorian wooden house with wood floors, the Minus K wasn’t an extravagance but a necessity. If you pursue the active isolation tables, make sure you have a stable base already because given my understanding above, they aren’t meant to deal with wallowing floors and the sort of resonance created by footfalls. I’d say the engineered slab is the start.

whart's avatar
whart
2,967 posts
 

I certainly don’t advocate getting all spendy on a Minus K if you can solve a footfall problem less expensively. I couldn’t for a couple reasons- one, the structure of the house- it is an 1880s landmark that was painstakingly rebuilt from the original wood (longleaf pine and shiplap) but the floors are springy and the walls could not support the weight of the table (245 lbs) even with a steel frame installed. I had a structural engineer come in to advise. Note that the room where the hi-fi is located has been modernized- downstairs is all original wainscoting, shutters, transom windows above the interior and exterior doors, elaborate door frames and pocket doors, etc.

What I did was install a subfloor beneath the front end area- made of two layers of marine ply with a barn mat on top-- thing is dead level.

The MinusK does allow you to adjust for an uneven floor but it adds another variable and to top that off, my linear tracking arm needs to see a slight tip up in the front right corner--it’s a very fine adjustment that is made by playing with the arm and watching its travel-- something a level or other measuring device would not enable me to zero in. The net result is that I can play this table without issue. Here’s what it looks like using the MinusK stand (which is also adjustable). There is an HRS platform between the Minus K and the table.

whart's avatar
whart
2,967 posts
 

Duck, if the image is already on the web (in my case the above from a web site I control), you simply capture the image address and use the tool that looks like a panorama, open and paste in the image address.

I don’t know if A-gon supports images directly. If it doesn’t you can use a free photo library-- I use Flicker-- upload the image there, then you need to paste the BB code or whatever it is called from the image hosting service into your post.

I’m sure there is a "help" function here somewhere, but that’s pretty much how I do it.

A lot of sites don’t want to support the bandwidth required for direct posting of photos, thus the indirect methods mentioned above.

This seems to be consistent with the approach I take: https://forum.audiogon.com/discussions/how-to-upload-photos-in-a-post#:~:text=Select%20any%20picture%2C%20right%20click,Easy%20Peasy. 

 

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