While my wife is busy sewing up masks using layers of cotton, scavenged HEPA material from vacuum cleaner bags, and other filter media, I decided to investigate the spikes vs isolation question. I have no expertise here, just curiosity.
My speakers are BG Radia 520s (planar magnetic), running off of a Marantz SR7012. I'm using REW for measurements. I set up a measurement rig with the miniDSP mic, positioned at the center listening position. The speakers are very precisely positioned, with exact same distance to the mike, and toed the same amount using a laser alignment tool.
I evaluated the following materials
1) Spikes with the floor disc:
3) Spikes-->disc-->Vibrasystems EVA-BFR antivibration pad (labeled "Wagner" in the graphs). (No floor disc is shown here, but it was there for measurements) See https://vibrasystems.com/foam-rubber-pad.html. This is a 1" thick pad, sort of a constrained layer approach with a softer foam center and harder rubber outer layers.
2) Spikes-->disc-->50 Shore, 1/4" thick closed cell foam ("Blue pad"). See the blue pad in the next photo.
3) Spikes-->disc-->70 Shore, 1/4" thick rubber disc. See the next photo. I did measure this configuration but did not include it the graphs. So just imagine each material by itself.
5) Spikes-->disc-->Isonode 1" Sorbothane half dome.
I set the system up for "large" speakers, no subs, and Audyssey turned off. I measured only the left channel for simplicity since I only had enough materials for 4 footers. For each configuration, I took three measurements (sweep 20-15k) and averaged them (wash out the variance in background noise, etc.). Also, after changing the materials I checked and adjusted the speaker position. Here are the results, first 20-300Hz:
and 300 to 15000
Observations:
1) There is more variance in performance at higher frequencies than at lower frequencies, contrary to my expectations. Some materials damped response (relative to the spikes), whereas others boosted it.
2) At low frequencies the variance in performance is concentrated around some peaks (80-100, 210-250), while other regions (120-200) are essentially identical. Overall, below 300, the various materials did tend to damp response, except between 230 and 240 where all of them boosted response.
3) The Sorbothane domes (expensive) did not show significantly better damping at low frequencies than the cheaper materials. Indeed at higher frequencies, the domes appeared to damp the response more than the other materials.
4) The thick Vibrasystems anti-vibration pad performed about the same as the 1/4" "Blue pad". Notice how the blue and purple lines more or less track together.
5) At low frequencies, the hard rubber disc seemed to provide the most "even" damping, but at higher frequencies, tended to accentuate the peaks between 2k-4k, returning more energy to the room.
I'm curious to hear from those of you with real expertise to further interpret and explain the results. The original REW file available here https://drive.google.com/open?id=1_cZaJaRQtTdRFw1cHVG_F4OFmxM0tV3a.
Bob
My speakers are BG Radia 520s (planar magnetic), running off of a Marantz SR7012. I'm using REW for measurements. I set up a measurement rig with the miniDSP mic, positioned at the center listening position. The speakers are very precisely positioned, with exact same distance to the mike, and toed the same amount using a laser alignment tool.
I evaluated the following materials
1) Spikes with the floor disc:
3) Spikes-->disc-->Vibrasystems EVA-BFR antivibration pad (labeled "Wagner" in the graphs). (No floor disc is shown here, but it was there for measurements) See https://vibrasystems.com/foam-rubber-pad.html. This is a 1" thick pad, sort of a constrained layer approach with a softer foam center and harder rubber outer layers.
2) Spikes-->disc-->50 Shore, 1/4" thick closed cell foam ("Blue pad"). See the blue pad in the next photo.
3) Spikes-->disc-->70 Shore, 1/4" thick rubber disc. See the next photo. I did measure this configuration but did not include it the graphs. So just imagine each material by itself.
5) Spikes-->disc-->Isonode 1" Sorbothane half dome.
I set the system up for "large" speakers, no subs, and Audyssey turned off. I measured only the left channel for simplicity since I only had enough materials for 4 footers. For each configuration, I took three measurements (sweep 20-15k) and averaged them (wash out the variance in background noise, etc.). Also, after changing the materials I checked and adjusted the speaker position. Here are the results, first 20-300Hz:
and 300 to 15000
Observations:
1) There is more variance in performance at higher frequencies than at lower frequencies, contrary to my expectations. Some materials damped response (relative to the spikes), whereas others boosted it.
2) At low frequencies the variance in performance is concentrated around some peaks (80-100, 210-250), while other regions (120-200) are essentially identical. Overall, below 300, the various materials did tend to damp response, except between 230 and 240 where all of them boosted response.
3) The Sorbothane domes (expensive) did not show significantly better damping at low frequencies than the cheaper materials. Indeed at higher frequencies, the domes appeared to damp the response more than the other materials.
4) The thick Vibrasystems anti-vibration pad performed about the same as the 1/4" "Blue pad". Notice how the blue and purple lines more or less track together.
5) At low frequencies, the hard rubber disc seemed to provide the most "even" damping, but at higher frequencies, tended to accentuate the peaks between 2k-4k, returning more energy to the room.
I'm curious to hear from those of you with real expertise to further interpret and explain the results. The original REW file available here https://drive.google.com/open?id=1_cZaJaRQtTdRFw1cHVG_F4OFmxM0tV3a.
Bob