Quote:
Originally Posted by
Northward
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You have to calculate that geometry (ray tracing, & behaviour @ LF.) vs speaker dispersion etc.
1:1:1 is unlikely to be it.
No angle is better yes
You will never load these properly following this diagram (Old Genelec Drawing IIRC). Sadly your speakers wouldn't load even one sufficiently.
Even if you dummy load the system, then these will remain very soft and the whole speakers will move/shake. Which is not good.
Think out of the box
I Wouldn't base decoupling scheme on these old drawings. I think they are technically misleading: there is no way this is going to work well. They describe pretty much one of the worst possible way to do it. :(
Northward / Thomas: Could you please explain a bit more about what you wrote? Right or wrong, I presume you mean the vibration damper in the link is much too stiff with its max load of 20 kg/pcs versus a light full range speaker. A too light speaker on top will give a too high natural resonance in the vibration damper so lower frequencies will not be isolated to the surrounding / shelve where it is positioned. (Also, I feel that kind of vibration damper (a “rubber ball” type) is not the best with a down angled speaker, there is a risk it might topple over.)
I have installed the very same kind of vibration damper on my speakers and I feel they work well in my case. As a free standing speaker, it certainly wobbles back and forth if I give it a push. But playing at 95 dB / 1 m, only a
very, very slight vibration can be felt with fingertips on the baffle. On the surrounding “baffle wall” the vibration is
extremely small, hardly noticeable and I cannot say if these minimal vibrations come from connection through the vibrations dampers or from airborn noice.
(As side note: I use a version for max load 9 kg/pcs versus 44,5 kg speaker weight, so 5 pcs are used which should give a natural resonance of about 14 Hz according to manufacturers diagrams. Mounting is horizontal as in the picture and the room is a basement concrete bunker, partly below ground, with surrounding noice levels at around 15-20 dB. The room is meant only for entertainment / listening room. The dog house / “baffle wall” is not solid concrete / brick but still fairly stiff and heavy. The grey / black wood around the speaker sides are 132 mm / 5,2” thick solid particle board, behind and to the side inside concrete as well as the floor. The speakers are only meant to play down to about 110 Hz where separate subs will take over. So there should be good margin between the vibration dampers resonance of about 14 Hz and the frequency range the speaker shall play. Gaps to the sides are 5 mm, gap at the top about 15 mm. Ratio of speaker weight versus cone weight is quite high, 890:1, so the speaker should not move much back and forth with cone movement / acceleration. Still I will insert some pieces of viton rubber hose of suitable diameter at the top to stop any rocking motion.)