cabinet dampening part II

[sunnysal]

Just got in some dampening sheets from speakercity.com, the "black hole pad" and "black hole 5" these will be mounted on the big panels of my k-horn bass module to dampen upper-mid and high frequency vibration of those panels...these sheets in addition to a couple of threaded steel dowels pressuring wooden blocks set against those same panels...between stiffening and dampening I hope to "purify" the bass somewhat...these pads are neat in that they are constrained layer dampening all-in-one with9out the fuss of making it up yourself...an excerpt form the catalog description: "Layer 1 - High loss vibration damping material (same as the Black Hole Pad), deadens resonance from the cabinet. It is very strongly bonded to the wall with PSA film for optimum performance.

Layer 2 - Polyester urethane flexible open cell foam ¼ in. thick. Thanks to its special vibration-isolation characteristics, it de-couples the vibrating structure (the cabinet wall) from the rest of the damping system, thus optimizing its performance.

Layer 3 - Barrier septum 1/8 in. thick. Made of limp flexible vinyl copolymer loaded with non-lead inorganic fillers, it acts literally as a dead wall, thus isolating the vibrations in the walls of your cabinet and the vibrations created inside the enclosure from each other.

Layer 4 - Polyester urethane foam 1 in. thick, structurally optimized for acoustical dampening, (specific permeability, density, stiffness, pore size and shape). It is highly effective at "soaking-up" maximum sound energy with minimum thickness.

Layer 5 - Thin diamond pattern embossing, densified with polyurethane film surface. This unique surface layer improves dramatically the performance of the whole acoustical system, especially the lower mid-bass frequencies, (very sensitive range where simple acoustical foam becomes mostly ineffective)." sounds cool, huh?

let you know how the project turns out...regards, tony

[sunnysal]

well its in...I started with one side only and think I heard some interesting changes...since I have that really screwed-up "floating" speaker problem on one side I cannot be sure of any scientific analysis but...here it goes...post installation I think I can detect some change, especially in the mid-bass region...vocals, acoustic guitar, sax, pianos seem to have a slightly "faster" mid-bass sound...I think I also have achieved a little more tonal variety from the bass...this could easily mental, since I was hoping for some of these results but...I feel less "one-note" bass from the k-horns...how much comes from the stiffening of the panels and how much from dampening vibration I do not know...I am happy with the mod...regards, tony

[Randy Bey]

Tony,

can you explain what you did in more detail? It sounds like you just stuck the panelling up against the inside of the speaker with some dowels to compress it between the panelling and the wall?

[sunnysal]

I´ll try to post some pic some (have to borrow thge digital camera again) but you are basically right...I took dowels (threaded steel dowels) and they psuh against oak blocks on both ends which are pressing against the constrained layer dampening sheets...the sheets were cut into pieces roughly 8" X 24" and glued to the side walls with contact cement...they really do seem to have lowered the coloration effects I thought were caused by cabinet vibration...I may even glue some sheet to the upper sheet of wood on the squawker cabinet...it dampens like I assume the caulking works on the horns...only you need to put some pressure against the wood sheets to help them stabilize...I tried putting just the dampening material on the wood but I could still feel vibrations until I added the pressured blocks...pictures to come...regards from sunny el salvador!, tony