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

Showing 3 responses by mijostyn

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 and I could hear all of it on a Micro Seiki turntable I had for a short period. I realized it was not the turntable because the noise would change and sometimes disappear. Finally the light turned on. I pulled the carpet away at its edge and listened to the floor with a stethoscope. Sure enough the noise was coming from the building and the special feet on the bottom of the turntable were doing not much of anything. I had an LP 12 several months later which solved that problem. 
Then the noise is extrinsic to the turntable and a correctly isolated turntable will get rid of it completely.
sixfour3, Not that oil! Too thin and too many additives. Single weight non detergent oil only. Compressor oil is perfect for this use. This may be your problem or part of it. No amount of damping or isolation is going to cure a rumble problem. 20 Hz is also quite high for rumble. You sure this is not feedback? Can you hear it at all volumes?
For turntable isolation these pods are next to worthless. MinusK makes the best isolation platform. Townsend makes a platform but I have no idea how well it works. None of these will address any intrinsic turntable noise only extrinsic environmental noise.
If the turntable is rumbling this bad it is more than likely time for a new one or a new bearing or motor. Don't buy crutches for a bad turntable, buy a better turntable instead. The Thorens 1600 is a great table for the money and completely isolated. Following this would be Sota turntables like the Sapphire, the Avid Acutus then Basis and SME models. If you have the bucks the Dohmann Helix is the last word. All of these tables are completely isolated and will not pass on any environmental noise of vibration over 3 Hz.