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Help! Tweaking My Lovan Rack for new Big A**ed Transrotor Turntable!

Folks, some input would be mighty appreciated.

I’ve been using a hand-me-down (though very nice!) Micro Seiki dd-40 turntable for a number of years and finally got the upgrade itch (it helps the upgrade itch when your cartridge is going on 30 years old, and sounding like it!).

I went down the rabbit hole and picked up a Transrotor Fat Bob S turntable, with an Acoustic Solid 12" arm and a Benz Micro Ebony cartridge. All with only about 30 hours of use at a great price. Yay!

Though I have considered getting rid of my old Lovan Classic rack for a new custom jobby, I’m pretty much spent out and I think I’ll have to make do for now, working with the Lovan.

The Fat Bob turntable is 55 lbs of solid aluminum and built like Thor’s hammer.

I figure this will finally get me to fill my Lovan stands for a bit more rigidity - probably with rice. The stand is the old 3 legged triangular shaped bass, which means the thin MDF shelves can feel like they sit sort of precariously on top. But the stand itself feels quite solid.

I want to incorporate a wood platform base, as many do, because I really love the look of a nice wood slab.

At first I thought maybe I’d have 3 spikes drilled in to the bottom corners of the wood base to directly couple it to the rest of the Lovan frame, vs resting it on the top mdf shelf. But I’m not sure that’s really necessary. And I’d like to incorporate some isolation as well, I think. So I’m thinking of just laying it on the top shelf, with something in between.

My first thought is to place a Symposium Segue shelf between the top of the Lovan shelf and the wood base.

Other than that...I’m flummoxed as to all the other choices...roller blocks? Symposium Fat Padz? Vibrapods? Herbie’s Tendersoft footers? Voo-Doo Isopods?  What should I put between the wood platform base and my Lovan shelf?

Any comments of suggestions on the direction I’m going?

Thanks!

(BTW, I’m an resolutely NOT a DIY/Handy-man type, so I’m not trying to go to heroic efforts, wishing this to be as painless as possible).
prof

Showing 11 responses by geoffkait

geoffkait's avatar
geoffkait
23,365 posts
 
Hey, that reminds me. Another good use for Cones is node Dampers on the walls, where max vibration occurs. It also occurs to me I sell Blue Meanies for room walls, one per wall, but as they have nothing to do with vibration or acoustic waves I probably shouldn’t talk about them. 
geoffkait's avatar
geoffkait
23,365 posts
 
You are the creator! It’s an art as much as a science. The shelf or top plate should be damped but not overly so. Oft times a thing that seems like a no brainer hurts the sound. Audio can be defined as an endless parade of trial and error. 😛
geoffkait's avatar
geoffkait
23,365 posts
 
I always use points down cones under the component and under the stand. It minimizes the contact area considerably, by what, a million to one?
geoffkait's avatar
geoffkait
23,365 posts
 
Generally speaking, springs should be loaded according to their springs rate (stiffness). The more mass the lower the resonant frequency of the isolating system thus the better the isoalation, all things being equal. In the case of speakers it’s not really critical how you load them since speaker feedback via the floor to components cannot be less than what, 30 Hz or so anyway, whereas for electronics the seismic vibration goes down to 0 Hz. So for very low frequencies you definitely want to minimize spring rate and maximize mass. Thus, whilst stiff springs like mine or Townshend’s under speakers do prevent vibration from the floor being transmitted to the speakers, that’s a true statement, the real issue is mechanical feedback to the electronics.

The rule of thumb is to load springs until they are 2/3 of their uncompressed height. But it depends since springs have different numbers of coils, different heights, etc. But obviously you don’t want any coils to touch each other. Due to center of gravity issues for heavy objects like speakers, lateral support must often be increased by using the outrigger idea which I think Townshend does. The speakers/springs are way too unstable (top heavy) if you try to place springs directly underneath them.🏋🏻‍♀️
geoffkait's avatar
geoffkait
23,365 posts
 
slaw
Well knocking on a material, does give one a very good reference as to how it will react in audio applications when that person is an observant "knocker".

Holiday Hint: Don’t knock on the stand whilst music is playing. If your stand is on springs or air bladders the top plate is isolated anyway, so in the case of real seismic isolation the actual material of the top plate becames almost, uh, immaterial. It could be rabbits if you could catch em. 🐇 🐇 🐇 As I’ve observed previously stiffness of the top plate is a high priority. Furthermore, ANY residual resonance of the top plate can be controlled by damping.
geoffkait's avatar
geoffkait
23,365 posts
 
I submit that rapping or knocking the stand or the iPad seismic app is actually ineffective for determining whether a particular stand design is effective or whether seismic vibration is getting into the component, especially a turntable.

First, as far as I could tell, the seismic apps are insensitive to the very lowest frequencies - the ones that are the biggest problem. These are the ones in the range of 0 to 20 Hz. Second, rapping or tapping a surface doesn’t generate the seismic vibrations of concern 0-20 Hz, only higher ones, ones that the turntable is relatively immune to, including acoustic waves. For turntables, the resonant frequencies of the tonearm, cartridge and platter are usually around 10-14 Hz, so the isolation stand resonant frequency should be much lower than 10 Hz to be able to significantly attenuate those frequencies 10-14 Hz, assuming a mass-on-spring device, since it’s a low pass mechanical filter. For example, if your isolation stand has a resonant frequency of around 4 Hz, attenuation at 10-14 Hz will be only around 50%. But if you can get the resonant frequency of the stand down to 2 Hz the attenuation will be up around 80%.

Of course the analysis is more complicated, since there are six count em directions of motion that should ideally be isolated. Holiday Hint: The effectiveness of isolation in a particular direction is proportional to how easily the component is able to move in that direction. This is why one should be wary of overdamping. Thus, undamped springs can be more effective than rubbery type materials or rubber air bladders or air springs.
geoffkait's avatar
geoffkait
23,365 posts
 
Actually the word plane is correct since isolation occurs for ALL DIRECTIONS in the horizontal plane. Whereas the vertical direction is not a plane. Nor are twist, rock, roll. They are directions. Lets twist again like we did last summer!
geoffkait's avatar
geoffkait
23,365 posts
 
@bdp24 I’m pretty sure you meant roller bearings work in all directional except the *vertical* direction. That’s why they work well with springs, a la Barry Diament and yours truly, since springs are relatively poor in the lateral plane. Thus they don’t interfere with each other.
geoffkait's avatar
geoffkait
23,365 posts
 
Nice reaction, Professor! 😃 Welcome to the big leagues! ⚾️
geoffkait's avatar
geoffkait
23,365 posts
 
@prof The vibrations that the turntable is most susceptible to ARE the low frequency seismic ones since the natural frequencies of the platter, cartridge, and tone arm are very low, around 10-14Hz. That is by design. The turntable is thus more affected by very low frequency seismic vibration (that includes frequencies 10-14Hz) than by other forms of vibration such as acoustic vibration - since it’s relatively immune to those higher frequencies, by design. Since most speakers cannot produce any significant energy in the 10-14Hz range the turntable is relatively immune to acoustic waves in the room.

geoff kait
machina dynamica
geoffkait's avatar
geoffkait
23,365 posts
 
People often comment that some rack or marble plate or granite slab rings when struck with a small hammer or other implement and therefore the thing would ring under normal circumstances. Allow me to disabuse you of that idea. Don't strike the rack or granite slab during play and it won't ring. Case solved! There is much more of any issue with low frequency seismic vibration getting up through the rack than any ringing.
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