just because I'm an idiot and act impulsively as per usual…my italianism kicking in I guess
Hey there Mr. Impulsive Italian! Slow down a bit, and wait for answers to your posts!
I sort of understand the "Italian" thing, though: not because I'm Italian, but because I live in Latin America, and the Italian blood runs strong in many people here too...
OK, so you don't run into the need for a wrecking bar again... How about if you put your front panels on temporarily at first, so that they can be removed easily a few times, just in case you need to make more changes, and only fix them in place permanently when you are satisfied that everything is working fine? For example, put just a few screws in each panel for the early tests, just enough to hold them tight, without any glue, finishing "plugs", decoration, or anything. Then you can take out the screws again if you need to get the panel off, without breaking it!
Same with the speaker boxes: Don't glue or nail anything, just use screws, so you can disassemble the box again if you need to.
You could even do some initial sine sweep tests without the baffles in place, just the speaker, to see if any vibrations is being transmitted to the frame.
I have to admit I could definitely feel the kick drum while touching the baffle!
That might not be the resonance I was talking about, but rather just the front panel of the soffit vibrating naturally at some resonant frequency. How thick are your baffles (soffit front panels)? Also, is all of that framing very firmly braced? (I mean the framing that the front panel screws to.) Like John said, the soffit itself has to be very rigid, so nothing can vibrate naturally, so maybe running a couple more cross pieces behind your front panel would help with that, and also perhaps using thicker wood, or more dense wood for the front panel.
On the actual mounting of the speaker / box, there are two different approaches: I call them the "John Sayers" approach, and the "Barefoot" approach. There's a discussion on the forum somewhere that they had about this a while back, but I can't find it right now. John's approach is to hold the speaker and box extremely rigidly to the rest of the soffit, and keep
everything very heavy, massive and rigid so it cannot vibrate. Barefoot's approach is to decouple the speaker and/or box from the front baffle, so it floats, allowing the speaker a little room to vibrate freely, but heavily damped with rubber, and not allowing it to contact the front baffle at all. But he still uses John's approach for the rest of the soffit: Rigid, solid, heavy. It looks like you were trying to do the Barefoot system, and that can work too, but only if the speaker/box really is floating. I've also see Barefoot do his system two different ways: one is to put the front baffle on one rigid frame with the speaker on a separate rigid frame, and the other is the way you are doing it, with a single rigid frame and rubber to decouple just the speaker. I haven't seen Barefoot on the forum in a long time, and I wish he were here to clarify his methods, as I might not be explaining it correctly, but that's what I've seen in his posts.
So, with what you have there in your room, at this point you can either go 100% with John's method (all rigid), or 100% with Barefoot's second method (the way you were doing it) but getting the rubber deflection right so the speaker really does "float". So that's the decision you should make first.
Now, as Ro mentioned, if you do use rubber in their to decouple the speaker, it has to be done correctly, to get the correct deflection so that the speaker really does "float", and that is generally in the range 10% to 20% deflection, depending on the type of rubber. I agree with Ro that your Sorbathane is probably not deflecting enough, since you have a very large surface area there but not all that much weight. So you might need to just use a few strips of Sorbathane cut to the correct width, rather than an entire large pad. Do the experiment that Ro outlined, to make sure you are getting at least 10% deflection in your rubber, and probably more like 15% to 20%. Check the specifications for the exact type of rubber you have (call the manufacturer for that), and keep within whatever range is correct. The specs should tell you what load you need to get optimum deflection (kg/m2), so if you weight your speaker assembly you can then figure out how many square cm of rubber you need, and cut it accordingly.
I'd guess that your 6mm rubber should probably be compressing down to about 5mm, in order to float correctly.
it's just that removing the rubber underneath the box would have been impossible as it was sandwiched between two layers of ply screwed together
Ummmm.... if you screwed those together THROUGH THE SORBATHANE, then there is no decoupling at all! The screws are transmitting the vibration directly from plywood plate to the other, and the sorbathane is just sitting in the middle, as a spacer.... It wont float at all like that...
!! right, back to square one - wish me luck… and patience
Patience more than luck! And put down that wrecking bar....
- Stuart -
and come back with more calm tomorrow.
, and let's hope for a better day tomorrow.
and re-frame tight around it.
