Butcher block or Granite!

[MrAcoustat]

I am struggling to see how granite resonance properties enter into turntable isolation when used as a platform for a TT with its own suspension system but as previously noted my ears of clay probably cannot hear such things anymore. I tend to focus on optimizing the overall suspension/isolation properties of the system, which is pretty complicated when multiple spring systems are involved.

Corian is a great idea IMO.

MrAcoustat, the Krell amp stands look awesome, but this thread is about turntable isolation...

Agree but those can also be made for turntables.

 

[BobM]

Just an FYI. Here's a pic of my DIY turntable with a 1" Corian plinth, sitting on a butcher block, suspended by squash balls, on another butcher block in a sand box (seismic sink). Easily passes the rap test (rapping on the stand when the needle is in the groove and the platter is stationary) - very little if anything coming through the speaker.



and the seismic sink racks

 

[DaveC]

Granite slabs will be resonant for sure... if I were to try using them a constrained layer damping (CLD) assembly might be well worth trying. I'd probably use a thin sheet of damping material (like Herbie's grungebuster sheets) glued in between 2 layers of granite. Or simply some caulk that does not harden. Undamped granite will probably not work so well but in a CLD layer it could work very well. Maple is a classic material and can sound good, I'd also check out Plyboo stranded bamboo plywood. Aluminum also works well for a CLD material. Vibrational properties of materials add their own sonic signature so results can be very subjective.

 

[DonH50]

Don,

As far as I understand it, the thread is not about turntable isolation, it is a general thread about platforms that make a turntable sound good.

Now for the technicalities. Although we have many types of granite, in general if you tap a thin granite slab it will resonate - unfortunately my current kitchen countertops and tables are all made from Corian, much more silent that the previous one in black granite - otherwise I could measure it. Considering that most turntable suspensions are not optimized in these frequencies, and also that many turntables must drain energy in the platform, we can easily understand why the platform material can be of great importance. Do you remember the Goldmund mechanical diode theories? Sometimes a material must dissipate the incoming energy in itself, not reflect it back in a delayed way.

I had a great experience with Corian some decades ago. Although I already referred it in WBF I will repeat it. In the 90's a good friend became Dynaudio distributor and imported the great Dynaudio kits. Using the factory supplied plans we built two Gemmini's (D'Appolito" configuration) pairs of monitors - one in MDF, the other in Corian, as the Wilson speakers of that period. They sounded very different. But there was no clear preference between listeners - although the Corian one was cleaner and had better definition, some found the Corian excessively alive and bright sounding. Only many years later, reading about the Wilson Audio Watt speakers I learned that Dave Wilson damped the Corian of his speakers with lead to eliminate the Corian intrinsic resonances. Do you remember the Dukas The sorcerer's apprentice? Fortunately in audio, apprentices are not spanked ...

The first line of the original post is: "The Frugal Audiophile can't really entertain the idea of turntable platforms from Symposium and other manufacturers, so he has to improvise to keep costs real." Bold added by me. That is why I (perhaps mistakenly) focused on turntables.

I agree with the rest, with the caveat that any isolation system design needs to include an understanding of which frequencies are of importance becuase they are being injected into the system or because system resonances at those frequencies lead to other problems. I have very little experience with these things, mostly for laser/lidar test beds, IC probe stations, and of course IC fabrication. The other experience I have is not really relevant (keeping an oscillator running in spec at G forces and such that turn normal dampening materials into goo and rip packages through their boards).

If granite "rings" at high frequency (relative to the suspension), does that matter? Is there a path that lets that get into the sound? Or does the mass of granite (lead, whatever) outweigh any such transmission path (if significant)? Wood is pretty "dead" but has much lower density so you need a lot more of it if your goal is to add enough mass to a particular spring to bring down the resonance. Then there's spring force to consider, how much force it takes to compress the spring, what is the resultant frequency response, etc. etc. etc.

A turntable usually has its own isolation (suspension) system and providing additional isolation to handle broadband vibrations both mechanical and airborne as found in a typical audio system can be a daunting task. Adding a fancy isolation system only to find it solved one problem (resonance) while creating and/or emphasizing another is vexing. Been there, done that, and probably will again...

Many years my Linn (located on the upper floor of an old house) would skip whenever Grandmother walked into the room. After a lot of trial and error I built a tall box with a number of mattress springs. The number I selected such that when I jumped up and down on the floor the cartridge did not skip. That empirical approach was way easier than all the math...

 

[JackD201]

Exactly.

I try to design around the interface of external materials because I never know what the end user might try. Still, influences to some degree are unavoidable at times. I do know, like another poster mentioned, that granite reflects back. I avoid it. Bamboo works pretty well, so does maple. A little maple goes a long way, however. It can suck the life out of things when overdone. I have found that slate works well, as does Delrin and Paperstone. Concrete and various kinds of plywood can also be nice, depending on the content. My opinion is that the whole affair can get pretty subjective.

^
What he said, except Win said it better than I ever could. Never tried slate or paperstone though I've tried delrin.

 

[JackD201]

The first line of the original post is: "The Frugal Audiophile can't really entertain the idea of turntable platforms from Symposium and other manufacturers, so he has to improvise to keep costs real." Bold added by me. That is why I (perhaps mistakenly) focused on turntables.

I agree with the rest, with the caveat that any isolation system design needs to include an understanding of which frequencies are of importance becuase they are being injected into the system or because system resonances at those frequencies lead to other problems. I have very little experience with these things, mostly for laser/lidar test beds, IC probe stations, and of course IC fabrication. The other experience I have is not really relevant (keeping an oscillator running in spec at G forces and such that turn normal dampening materials into goo and rip packages through their boards).

If granite "rings" at high frequency (relative to the suspension), does that matter? Is there a path that lets that get into the sound? Or does the mass of granite (lead, whatever) outweigh any such transmission path (if significant)? Wood is pretty "dead" but has much lower density so you need a lot more of it if your goal is to add enough mass to a particular spring to bring down the resonance. Then there's spring force to consider, how much force it takes to compress the spring, what is the resultant frequency response, etc. etc. etc.

A turntable usually has its own isolation (suspension) system and providing additional isolation to handle broadband vibrations both mechanical and airborne as found in a typical audio system can be a daunting task. Adding a fancy isolation system only to find it solved one problem (resonance) while creating and/or emphasizing another is vexing. Been there, done that, and probably will again...

Many years my Linn (located on the upper floor of an old house) would skip whenever Grandmother walked into the room. After a lot of trial and error I built a tall box with a number of mattress springs. The number I selected such that when I jumped up and down on the floor the cartridge did not skip. That empirical approach was way easier than all the math...

In my experience there is a very apparent correlation with single material platform's mohs scale figures. The harder the more tipped up, the softer the more rolled off, the more loose the sound of the bass. In the end I ended up with passive CLD filter platforms. Tonal balance is most similar to the amps being literally carried during playback. Too chicken to carry the turntable! LOL.

I've noticed the same thing with cartridge bodies. No surprise then that really non-resonant carts like the A90 are so devoid of characters of their own. Some might say that's boring, I'm not one of them.

 

[Lobster]

I use 2" maple butcher block under my amps

Hello Steve. Are your butcher blocks placed directly on the floor, or on any type of footers, spikes, discs, etc.?