Every design is a set of choices and hopefully intelligent compromises that make sense for the room and how we prefer to listen. Audio reproduction will never be a one size fits all. On the other hand, some of us like more than one room to enjoy excellent music with friends, home theater, or very personal desk top near field listening. In all of them if a cabinet is involved you want the music not the panel resonances. Why do we do it? as Siegfried said Truth and Beauty.
That's odd, usually OB's image well over a large area, what's the polar response like?
Below is a chart from Martin Collom's "High Performance Loudspeakers" book:
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COLORATION
Boomy, 50 - 80 HZ
Chesty, plummy, 100 - 150 Hz
Boxy, hollow 150 - 300 Hz
Tube like, tunnelly 400 - 600 Hz
Cup like, honky, 700 - 1.2 kHz
Nasal, hard, 1.8 - 2.5 kHz
Presence, upper hardness, wiry 2.5 - 5.0 kHz
Sharp, metallic, sibilant 5.0 - 8.0 kHz
Fizzy, gritty, 10 -15 kHz
Hi Gedlee,
What ratio of polyurethane to micro-balloons would you suggest? Do you recall a brand of 2k soft polyurethane?
I've been testing Sika Self Leveling Polyurethane with some 3M Micro Bubbles in a 1:1 mix by volume. It's a bit worse than the Polyurethane by itself, but I wonder if I should try a different ratio.
Hugh
Gedlee,
Thanks for that. I'm glad to hear I'm not way off base with the ratio,
Admittedly, it could be the test methods or the materials I'm using to evaluate the damping that make the mixture look poor. The Polyurethane on it's own seems to be a little better at the higher frequencies. I'm being thrifty and using 2 pieces of 3" x 6" as well as 6"x6" ceramic tile only because it's a challenging material. I'll test a little more with other materials later on (now that I know a 1:1 ratio is reasonable).
The Sika Self Leveling Polyurethane is nice because it stays very pliable when it sets. It's available from Home Depot. Intended for sealing small gaps in concrete on flat surfaces.
Thanks,
Hugh
Thanks for that. I'm glad to hear I'm not way off base with the ratio,
Admittedly, it could be the test methods or the materials I'm using to evaluate the damping that make the mixture look poor. The Polyurethane on it's own seems to be a little better at the higher frequencies. I'm being thrifty and using 2 pieces of 3" x 6" as well as 6"x6" ceramic tile only because it's a challenging material. I'll test a little more with other materials later on (now that I know a 1:1 ratio is reasonable).
The Sika Self Leveling Polyurethane is nice because it stays very pliable when it sets. It's available from Home Depot. Intended for sealing small gaps in concrete on flat surfaces.
Thanks,
Hugh
I should have asked earlier...
Is the 2K Soft Polyurethane that you mix with Microballons a foam or more like a caulking?
I Googled "innovative polymers soft poly" and got a web site for RAMPF Group, Inc. based in Wixom, MI. Does that sound like the right company? Do you recall which product? They seem to make many.
Thanks,
Hugh
Is the 2K Soft Polyurethane that you mix with Microballons a foam or more like a caulking?
I Googled "innovative polymers soft poly" and got a web site for RAMPF Group, Inc. based in Wixom, MI. Does that sound like the right company? Do you recall which product? They seem to make many.
Thanks,
Hugh
Could this be the one?
https://polyurethanesupplies.com/collections/flexible/products/099-014
They have a selection of hobby Polyurethanes. This is the softest one at 35 Shore A.
https://polyurethanesupplies.com/collections/flexible/products/099-014
They have a selection of hobby Polyurethanes. This is the softest one at 35 Shore A.
Great! The web site indicates they ship to Canada too.
By coincidence, the Sika Self Leveling Sealant is 40 Shore A after a curing for a few weeks. I do see that it contains a small amount of ethylbenzene from the safety Data sheet. That's not so appealing for indoor use. I see that DAP and Quickcrete also make Self Leveling sealants, so I'll try one of them too.
Thanks again.
By coincidence, the Sika Self Leveling Sealant is 40 Shore A after a curing for a few weeks. I do see that it contains a small amount of ethylbenzene from the safety Data sheet. That's not so appealing for indoor use. I see that DAP and Quickcrete also make Self Leveling sealants, so I'll try one of them too.
Thanks again.