The article states:
Quote:What I've found is that all of our components are being substantially inhibited from delivering their best because they are subject to external vibrations. By far, the most sonically and visually degrading are those vibrations in the ground that enter the component via its feet.These seismic vibrations (the ones very low in frequency and amplitude, so tiny we don't even normally feel them) are creating spurious signals within the sensitive circuitry of your components. These spurious signals mix with the real music and video signals to distort them, hardening the treble, thinning the bass, muddying the soundstage and annihilating dynamics. Seismic vibrations add grain to video pictures, ruin color purity and contrast and soften focus.
I have not found what I highlighted in green to be the case... at least with tube gear. In fact the vibration of the transformer is much higher unless you live by busy train tracks or something similarly extreme. I also found that the low frequencies have proportionately less effect on the sound as the frequency drops below 40Hz.
I can confirm that the vibrations from the ground are so tiny they are difficult to even detect let alone measure in the average home. For example, I repeated the measurements from last night but with the component turned off. Just trying to see what airborne and seismic vibration is there without the transformer turned on. I found that the average high number between the three peaks was 50dB. If 50dB is all we can measure from the air and vibration from the ground during the day, and 67dB is what we can measure from the transformer through the chassis, clearly it is the transformer that is the bigger issue.
Airborne noise I would say would be far more damaging because it would typically be both low and high frequencies as opposed to predominately low frequencies from the ground and of course airborne energy collects in the structures that surround it.
Another issue with airborne noise(sound) is a high gain circuit, like a phono stage, where the first stage of gain is going to be a hundred times more sensitive to noise and vibration than the last tube in the stage. This first stage tube then becomes critical in some circuits and if the tube is microphonic it's a big problem. The sound is coming in mostly through the amplifier chassis as sound in the air hits it, the rack it's on, and etc, sound coming through the glass of the tube itself is probably unmeasurable in comparison. Nevertheless, if you put enough gain on a tube that is microphonic it can pick up everything you say clear across the room, just like a microphone.
Microphonic's is almost never an issue with low gain devices such as line-stages and amplifiers. High gain devices like microphone preamps, and MC phono stages are where it becomes a factor. Still, low frequencies below 40Hz are hard to hear in a microphonic tube, whereas voices can be easily heard.
When microphonics are bad, AND the volume of the speakers is raised to a certain point you will even have feedback that squeals at that frequency rendering your stereo useless at that point.
On a different angle, sound in the air induced vibrations in the 40-320Hz band can find nooks, or alcoves, or closest, or boxes, or cabinets, or racks with 5 sides that have their own resonate frequency. You can be sure that if you have one in your room, the resonance inside that space will likely be 12dB higher than the sound that excited it. That's 400% louder. Set an amplifier in that cavity and any issues with sound vibration are now multiple by 4.
So it's looking to me like vibration from the power supply is number one, vibration from the air when music is loud is usually number two, and seismic vibration from the ground is number 3.
Steve
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