So I'm back after a somewhat complicated birth, and needless to say I haven't progressed much! But I have a healthy baby boy which is super cool
Congratulations, Tim! Wow! A new addition to the family AND a new studio! Lots of "news"...
So I'm returning to my soffits and a bit perplexed - I haven't started to install anything since the last set of photos and now I'm somewhat confused about progressing. We went through the soffit design somewhat, atnd yes I will be beefing it up with plenty of beams and mass. But what I'm curious about is that this soffit design seems to do the opposite of this one: . . . . . So I assume these are somehow different approaches.
Correct. "There's more than one way of skinning a cat", as the saying goes (a rather strange saying, actually!). There's more than one way of building a soffit.
I also saw another approach where the speaker is on a shelf just more or less in the middle of a superchunk.
That's not a soffit! It's just a speaker stuffed into a superchunk. Whoever would call that a "soffit mount" would have to be pretty ignorant of both soffits and bass traps!
The concept of a proper flush mount ("soffit mount") is very simple: remove the speaker from the room, in order to eliminate the artifacts caused by having the speaker inside the room. To do that, you mount the soffit in the wall. Except that you angle that part of the wall a bit, in order to get the right angle for the speaker. The surface of the wall acts as an "infinite baffle": it replaces the tiny front "baffle" (front panel) of the speaker cabinet itself, with a much larger one. The larger it is, the more it acts like an "infinite" one. There are multiple benefits to doing that.
In order to do that well, the speaker must be held very firmly in position, by a very tough, solid, rigid frame, such that it cannot transmit any of its vibrations into the frame or the baffle.... or alternatively, it can be "floated", for the same purpose. "Floated" in the sense of being fully suspended on resilient mounts, such that it cannot transmit any of its vibrations into the frame or the baffle. In both cases, the baffle itself must be very massive: very heavy.
So you are looking at two different ways of accomplishing the same thing. You can chose whichever you prefer.
Here's a link to a room I did recently, where the speakers are floated on a suspension system:
http://www.johnlsayers.com/phpBB2/viewt ... =2&t=20471 . The only problem with this approach is that you have to "tune" the suspension system such that the resonant frequency is at least an octave below the lowest frequency that the speaker will be producing, and preferably two octaves. In this room, the mount is designed to have a resonant frequency of 14 Hz., so it isolates above 28 Hz (one octave). The speakers can theoretically go down to about 34 Hz, but they are paired with a couple of subs in that room, and are crossed over at 86 Hz., which is nearly 3 octaves higher than the resonance. So there's no issue there with the speaker causing the soffit itself to vibrate, as you can see from the acoustic measurement graphs.
Now for the sake of clarity (and not having measured the room yet - I will do so at some point soon I hope), which of these approaches is the most useful here? And easiest perhaps
"Easiest" is to use John's method: Mount the speaker very solidly and rigidly, with very tough framing and a rigid box around it. That works very well, as you can see from John's rooms. I prefer to do the "floated suspension" approach when I can (which isn't always possible).
Remember the room is quite small, approx 300*260cm... I'm slightly concerned as I have seen it mentioned that soffit is often not the way to go for small rooms...
Actually, a soffit can benefit a small room just as much as a big room, if not more. The only problem is that it takes up space. As long as there's enough space to do that and still have a usable room, then soffits mount is the way to go.
And what about speaker upgrading - ie I might at some point exchange my Tannoy Reveal 6D for Adam F7... so I would like to leave the speaker cavity a bit larger to allow for this. Should I do so and just pack the gap with wood sheets or rockwool etc?
In the link I gave above, I originally designed the soffits for exactly that situation: the studio owner expected he would need to upgrade his speakers at some point. It happened sooner than he expected, when one of his old speakers started making strange noises. The way I had designed it, there's a removable "tray" that actaully carries the speaker, and it is large. It is solidly bolted into the soffit, so by removing the bolts you can slide it out, and slide in a new "tray" that has the new speaker already mounted in it. So that's what the owner did: Build the new "trays" while the studio was still in use, mount the new speakers inside the rays at the correct height and angle, then one day in a a few hours of down time he popped out the old trays, popped in the new trays, and carried on running. (We later spent a lot of time re-tuning the room for the new speakers, as you can see in the graphs).
- Stuart -
More soon!
)
Thanks for the kind words!
Can you still hear OK? Did you cook your speakers? Probably not, as the A7X should be able to handle that OK, but WOW! Why did you set your level 100 times higher than standard? Calibration level is 85 dBC, not 106...