Soundman2020 wrote:Source of the post
There's some differences, but as you say, not all that significant. But you say you can definitely hear the difference, subjectively, and it is very noticeable? That implies two things: 1) the original tests might not have been valid, or done with the mic ans speaker in different locations. 2) There is still significant "bleed" through other paths, different from the floor. Probably airborne transmission. The floor isolation from the riser would mainly affect structure-borne isolation: the riser won't accomplish much for air-borne.
Apologies, I think my graph labels could have been clearer - that particular measurement pertains only to the room across from the room with the amp in it. I don't hear any significant difference in airborne sound from that test either, and didn't expect any - just did the test for thoroughness
I did the on and off riser tests in the same session with good measurements so have confidence in the test method. Edit: Although I controlled for position of the amp in terms of length and width in the room, it was ~10cm higher when on the riser than when on the floor. It might account for some small difference.
There was some worthwhile attenuation from the amp to the room below though, see post 33 and this graph;
There is a huge & hilarious difference in impact sound when on and off the riser to rooms both below and across though. Only ear tests done for that at the moment, alas, as the difference is obvious, and more importantly, sufficient. I really should figure out some Heath Robinson type device to test this objectively and repeatably though
Edit for further clarity as I have several threads going at the same time: I have noted significant differences in airborne transmission to rooms across from and below the main studio room, room 1, but these are from the improvements made in my other thread. Putty pads on electrical outlets, caulking around perimeters and so on. There are independent tests measuring these improvements over there.