Vibration Isolation (in room distortion reduction)
My main HiFi is in our lounge (11ft by 18 ft) which has a suspended floor with a significant air volume beneath. The laminate floor and the air volume beneath vibrates and has added noise / distortion to the music being played to a greater or lesser extent over the past 25 years. During this timeframe I have tried various things to reduce the 60-70 Hz resonance in the room (main room mode):
1. Increased mass of speakers and Mana sound stages resulted in a tighter bass, but it did not change the main resonant modes that still left records like the Prodigy being played with excessive bass.
2. Increased the height of the Mana stack under the speakers. This reduced the energy getting into the suspended floor. I could feel the vibration reducing down the Mana stack (7 soundstages), level by level, but the sound still had too much bass distortion.
3. Introduced tuned Helmholtz resonators to take out the main room modes. This was done 20 years ago and made all tracks playable with reduced bass distortion. The measured graphs showed a very messy RT60 beforehand (multiple spikes at up to 4 seconds in the main modes) and a very smooth 1 (correction from 2 sec (thanks ToToMan) but will measure to confirm) sec RT60 after the Helmholtz resonators were installed.
4. Changed loudspeakers to Wilson Sophias and removed the Mana speaker stacks under the speakers. This tightened up the bass and reduced the energy input into the floor further, but I could still feel it anywhere in the room by putting my hand on the floor.
I then started to experiment with vibration isolation again.
Having used Mana for a long time I was aware that it added its own distortion (the Mana effect), which I like, as well as providing some isolation (but it is not its focus).
So I did a lot of research and came across Barry Diament’s roller bearing approach, Stacore (heavily developed bearing plus air bladder plus constrained layer damping, plus heavy mass), Symposium USA (bearings plus other solutions, Townshend Audio (tuned vertical springs and constrained layer damping metal sheets), Running Silent Audio (very expensive military tech) and Sonority (roller bearings, laminate boards and cone+bearing equipment interfaces). From a physics perspective the bearing and cups approach is the equivalent of a horizontal spring and hence provide a measure of horizontal isolation. The air bladder or vertical springs provide vertical isolation. The constrained layer damping generally provides higher frequency isolation through conversion of vibration energy to heat.
Sonority and I had discussed F1 a few times and then the conversation then moved onto HiFi isolation as Sonority makes some isolation shelves and I was looking to experiment in that area. Steve then very kindly gave me some boards to experiment with the bearing cups that I had had machined (+ a range of bearings purchased for experimentation). He also gave me a complete Sonority board and bearing system to use as a reference. In parallel we discussed noise reduction in HiFi systems and adding tuned vertical springs to his speaker stands. Results of my experiments with roller bearings and Sonority boards:
1. Just putting the bearing and bearing cups under my Audio Synthesis DAX Decade (second system) or my nCore nc400 power amps (main system) showed a reduction in noise (cleaner notes, easier to hear bass lines) but with the bigger effect occurring with the Audio Synthesis.
2. I then added one Sonority roller shelf under the Auralic Altair G1 (HDD player, steamer, digital preamp) in the main system. This further reduced the noise and was a bigger step than all others made so far.
3. I then added Sonority boards (with aluminium sheet for bearing runners on the top boards) and more machined aluminium roller cups and bearings under the nc400 power amps and the Dynavector phono stage and Norton Air power supply for the LP12. This resulted in a similar effect for the analogue chain (LP12 still in a Mana Soundclamp, Mana Soundframes and on a Mana Wall Shelf) with noise much reduced and all instruments and voices much clearer and a clearer soundstage.
4. Steve then visited my house and we (+occasional PFM poster, Paul Ogle) installed the Sonority speaker roller shelves with springs under the Wilson’s. It was immediately obvious to all 3 of us that it was a much cleaner sound, with very clear bass lines and a much clearer stereo image. With no observable vibrational energy getting from the loudspeaker into the suspended floor.
All vibration isolation experiments measured with my hand on equipment and with the iPad accelerometer and Seismograph software. Both with tapping the equipment or the floor and observing the reaction or with music playing.
In summary installing the Sonority noise reduction system has been the biggest improvement to my HiFi since installing the Wilson Sophias. My experiments were successful in that I got rid of the floor resonance and in parallel got a large reduction in noise / distortion and a large improvement in sound quality and enjoyment.
My main HiFi is in our lounge (11ft by 18 ft) which has a suspended floor with a significant air volume beneath. The laminate floor and the air volume beneath vibrates and has added noise / distortion to the music being played to a greater or lesser extent over the past 25 years. During this timeframe I have tried various things to reduce the 60-70 Hz resonance in the room (main room mode):
1. Increased mass of speakers and Mana sound stages resulted in a tighter bass, but it did not change the main resonant modes that still left records like the Prodigy being played with excessive bass.
2. Increased the height of the Mana stack under the speakers. This reduced the energy getting into the suspended floor. I could feel the vibration reducing down the Mana stack (7 soundstages), level by level, but the sound still had too much bass distortion.
3. Introduced tuned Helmholtz resonators to take out the main room modes. This was done 20 years ago and made all tracks playable with reduced bass distortion. The measured graphs showed a very messy RT60 beforehand (multiple spikes at up to 4 seconds in the main modes) and a very smooth 1 (correction from 2 sec (thanks ToToMan) but will measure to confirm) sec RT60 after the Helmholtz resonators were installed.
4. Changed loudspeakers to Wilson Sophias and removed the Mana speaker stacks under the speakers. This tightened up the bass and reduced the energy input into the floor further, but I could still feel it anywhere in the room by putting my hand on the floor.
I then started to experiment with vibration isolation again.
Having used Mana for a long time I was aware that it added its own distortion (the Mana effect), which I like, as well as providing some isolation (but it is not its focus).
So I did a lot of research and came across Barry Diament’s roller bearing approach, Stacore (heavily developed bearing plus air bladder plus constrained layer damping, plus heavy mass), Symposium USA (bearings plus other solutions, Townshend Audio (tuned vertical springs and constrained layer damping metal sheets), Running Silent Audio (very expensive military tech) and Sonority (roller bearings, laminate boards and cone+bearing equipment interfaces). From a physics perspective the bearing and cups approach is the equivalent of a horizontal spring and hence provide a measure of horizontal isolation. The air bladder or vertical springs provide vertical isolation. The constrained layer damping generally provides higher frequency isolation through conversion of vibration energy to heat.
Sonority and I had discussed F1 a few times and then the conversation then moved onto HiFi isolation as Sonority makes some isolation shelves and I was looking to experiment in that area. Steve then very kindly gave me some boards to experiment with the bearing cups that I had had machined (+ a range of bearings purchased for experimentation). He also gave me a complete Sonority board and bearing system to use as a reference. In parallel we discussed noise reduction in HiFi systems and adding tuned vertical springs to his speaker stands. Results of my experiments with roller bearings and Sonority boards:
1. Just putting the bearing and bearing cups under my Audio Synthesis DAX Decade (second system) or my nCore nc400 power amps (main system) showed a reduction in noise (cleaner notes, easier to hear bass lines) but with the bigger effect occurring with the Audio Synthesis.
2. I then added one Sonority roller shelf under the Auralic Altair G1 (HDD player, steamer, digital preamp) in the main system. This further reduced the noise and was a bigger step than all others made so far.
3. I then added Sonority boards (with aluminium sheet for bearing runners on the top boards) and more machined aluminium roller cups and bearings under the nc400 power amps and the Dynavector phono stage and Norton Air power supply for the LP12. This resulted in a similar effect for the analogue chain (LP12 still in a Mana Soundclamp, Mana Soundframes and on a Mana Wall Shelf) with noise much reduced and all instruments and voices much clearer and a clearer soundstage.
4. Steve then visited my house and we (+occasional PFM poster, Paul Ogle) installed the Sonority speaker roller shelves with springs under the Wilson’s. It was immediately obvious to all 3 of us that it was a much cleaner sound, with very clear bass lines and a much clearer stereo image. With no observable vibrational energy getting from the loudspeaker into the suspended floor.
All vibration isolation experiments measured with my hand on equipment and with the iPad accelerometer and Seismograph software. Both with tapping the equipment or the floor and observing the reaction or with music playing.
In summary installing the Sonority noise reduction system has been the biggest improvement to my HiFi since installing the Wilson Sophias. My experiments were successful in that I got rid of the floor resonance and in parallel got a large reduction in noise / distortion and a large improvement in sound quality and enjoyment.
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