Turntable Resonance Fix


I've been investigating different materials of turntable mats in hopes that I can find one that will help tame a -30dB rumble centered around the 20 Hz region that I fear is affecting the rest of the audio spectrum to some degree. I'm guessing that either platter bearing noise is to blame, or possibly vibrations from the motor creeping into the tonearm. Ultimately I would like to take steps to eliminate the source of the rumble, but I fear that will involve several thousands of dollars (a different turntable). With the vast amount of experience and knowledge out there, can any of you share an example where a particular mat helped with this sort of issue? Baring that, do any of you have advice for altering or upgrading the Pro-ject turntable to eliminate this problem? 

For reference, the setup is as follows:

- Pro-ject 2Xperience turntable (stock)
- Soundsmith Aida cartridge
- PS Audio NuWave phono preamp (digital measurements were taken from the USB output of this unit)

The well-isolated and -damped audio rack sits 25 feet from the speakers. But regardless of that, measurements were taken with the speaker output at a whisper. 

I have taken screen shots of the analyzer that I will post to my profile page. 
sixfour3
sixfour3:
Thanks again to @millercarbon for his advice. This has to be simultaneously the cheapest and most effective fix for an audio problem that I’ve yet come across. 


You're welcome. Happy to have helped. You have a really good handle on the situation, too. The vast majority of vibration control problems are generated within the component itself. A lot of guys miss this so congratulations are in order for figuring it out all by yourself. 

What is always happening, not just with turntables but with everything, the component generates its own vibrations. They travel down the feet into the shelf or rack or floor or whatever. What exactly it is really does not matter. Some find magical properties in concrete. Sorry, no. Carbon fiber is way better but even that has been demonstrated nowhere near as effective as isolation- and springs are the best isolation. 

All these different things, none of them eliminate vibrations. Every time we try and do that all we wind up doing is having a different set of vibration characteristics. We shift the energy around the spectrum. Ultimately it remains and colors the sound until finally it dissipates.   

What you have just measured then is this: In the beginning you had a tiny little bearing rumble that would have been inaudible, but for the sad fact it was at just the right frequency to excite sympathetic resonant vibrations in the shelf and rack and everything else around the turntable. All of it, and you could knock yourself out trying one thing after another in search of the culprit. If even it was just one thing. Probably not. Now the bearing is making just as much vibration, but being on springs this stays within the turntable which has been designed (we hope!) specifically to dissipate and attenuate exactly this sort of noise. 

This same principle applies to every single component. Every single one. Tube amp, DAC, speaker- speaker cables and power cords, even! Think about it. Think about the tremendous improvement you can see and hear just from this one thing. Now imagine doing your whole entire system. That is what I have done. Now I bet you can understand why.
I should probably add, the general term for this is ringing. One thing excites another until the whole mess is ringing. The best demonstration of this I know is this one by Max Townshend. https://youtu.be/BOPXJDdwtk4?t=5 The demo is a speaker but the same applies to everything else as well. The main difference between his Pods and Podiums and your Nobsound springs is damping. Nobsound has none and so allows resonance, and this colors the sound. Townshend eliminates this with an ingenious air damping valve. It is hard to notice the resonance you are hearing now with Nobsound. I know because I had them, everywhere. Moving to Pods however, when it is gone the improvement in authentic tone and timbre is impressive.
I started looking at the Townshend Pods, too.  Problem is cost, not much less than a good used Minus K shelf, for a Pod suitable in size and weight bearing capacity to suit one of my heavy turntables (typically 60 lbs and up).
"Which reminds me, in 1978 I lived in an apartment building in down town Miami on the top floor. The Mechanicals were on the roof"

The Mechanicals played a rooftop show in 1978 Miami? How did I miss that one...Darn!