My 5.1 Combined Studio / Control Room, Lake Tahoe, USA

[Soundman2020]

Again, we're in an earthquake zone,

Check my location: we have something in common! I'm very, very aware of seismic issues! We had an 8.8 a couple of years back... The entire country moved over a couple of meters, so some GPS maps are no longer accurate: what used to be the location of the middle of the street is now the sidewalk! So I'm big-time aware of how much things can shake, rattle and roll in a biggie, and it's scary: Fortunately, everything I designed and built myself stayed together, with no structural damage, because I do tend to over-design and over-build them. So I hear what you are saying, and I "get it" for sure!

I'm a little worried things will shift from tremors and eventually create flanking paths when the bolts touch the framing plates.

You might want to consider adding isolation sway braces to your wall tops, and perhaps even seismic snubbers to the base plates, if you are really concerned and you really do get major stuff going on where you live. How big do they get? Take a look at the Mason Industries web site for some products that you might need to consider. They make a lot of isolation mounts, for all types of situations, and some of them are meant specifically for seismic stabilization.

have even survived my first framing inspection.

Congratulations! That's a nice milestone.

I'll loosen things up, pinpoint the problem and post my results.

Looking forward to it! But don't forget one thing: "Pics, or it didn't happen!".


- Stuart -

[Dave_D]

Well, there's no flanking paths and loosening the screws didn't help.

Here's the situation: Conveniently for my purposes, an attic fan produces a reliable hum from above this room. [The fan will be addressed later, but for now, it's a useful noise source.] Having replaced the ill-conceived isolation materials from the inner walls with proper Iso-Sill material and joist isolators, one would expect the attic fan's noise to be reduced, if anything. However, when I put my ear to an inner-wall framing member, the noise is significantly louder than that from an existing, outer-wall framing member at the same location. [?!] Not what I expected.

I've done lots of tests now (even removed the screws!) and can only conclude that the existing, outer walls transmit less of the attic fan's vibrational energy than my new, isolated inner walls (the open framing, anyways). Perhaps it's because the outer wall is comparatively rigid - the framing members are bound together with sheeting, etc. And they've got insulation between the stud. The inner walls don't have drywall or insulation yet - they're pretty loose, and being suspended in rubber doesn't help their rigidity any.

On the bright side, if I put my ear to the inner wall and hit the outer wall with a hammer, there is very, very little noise transmission. And vice-versa. So, maybe my new framing members are sympathetic to the attic fan's vibrational energy?

Should I just move on and complete my inner walls then?

[Soundman2020]

I'm wondering if you are maybe seeing this from the wrong perspective?: If the entire wall is now vibrating in sympathy with a nearby noisy fan, then that means it is NOT coupled to the floor! It was before (which is why it didn't vibrate so much, as it was being damped by the floor: it was transferring most of that energy to the floor), but now that it is properly isolated, it can vibrate freely, like it is supposed to do, since it is NOT connected to the floor any more...

and can only conclude that the existing, outer walls transmit less of the attic fan's vibrational energy than my new, isolated inner walls (the open framing, anyways).

Right! ... Sort of... Because your outer-leaf walls are still fully coupled to the outer-leaf floor, those walls vibrate less, apparently, but that's because they are transmitting MORE energy to the floor, not less.

That might be one explanation, assuming that the issue is airborne sound from your fan, not structure borne. However....

The inner walls don't have drywall or insulation yet

Ahh! Then they most likely are not floating properly yet. The Isosill stuff is designed to work under the compressive load of the entire wall weight. Right now, you only have a bit of framing on there, not the full load of the finished wall. Once the wall is completed, the full load will be compressing the rubber to the optimum point, and the wall will float at its best.

On the bright side, if I put my ear to the inner wall and hit the outer wall with a hammer, there is very, very little noise transmission.

Bingo! That shows it is decoupled. Maybe not as fully as it will be when the full load is on it, but even so it is decoupled.

So, maybe my new framing members are sympathetic to the attic fan's vibrational energy?

That would be my guess.

Should I just move on and complete my inner walls then?

Yup! I'm betting that as soon as you get the first layer of drywall on there, even just a few sheets, that resonance should go away, or at least drop in intensity. Right now you are trying to measure the effect of an incomplete system, but MSM only works when all the parts are in place. It's like you were trying to test how your car's suspension is working, but you only have the bare chassis, no engine, no shock absorbers in the suspension (only springs), and the tires are only half inflated! You won't be able to discern anything at all about how well the car will ride once all the parts are in place.

So I would say don't sweat it too much: just go ahead and build!

- Stuart -

[Dave_D]

That's a huge relief. Thank you, Stuart!

[Dave_D]

Status update: Thanks in part to Tahoe's ridiculously dry winter, I'm making some good progress. Here's some pics.

I've gotten the analog and digital (including MIDI) tie lines run, patch bays soldered together, and studio panels roughed in (figs 1, 2, & 4). The six Genelec digital speakers passed their first tests (fig 3) just before my digital audio workstation crashed, forcing me to move the Lynx card into another machine and re-install REW (fig 6). Insulation has been installed in the inner shell (fig 5) and both drywall and cement board have been installed on the front walls (fig 7), ready for stone veneer (per Lawrence Newell studio design strategy).

For the record, I built the XLR patch panels with quad-core cable. I don't know that there's any benefit to this (but certainly more soldering effort) - I had already run star quad for all the tie lines and figured it made sense to keep it all the same. I've got plenty left over for crafting patch cables when it comes to that. Also, the Penn Elcom strain relief bars are really nice but don't quite fit a 16-port wide Neutrik XLR rack panel. I had to grind out quite a bit of material to make them work - but they do work. Now that all three are installed (one digital, two analog), I'm pretty happy with the results.

Also, I'm starting to see some positive trends in REW. While I don't know how to interpret the output exactly yet - need some education here - the spectrogram is smoothing out a bit. In particular, the room's primary resonance at 18 Hz has dropped by more than 200 ms. I'm pretty sure that's good.

[Soundman2020]

Damn! The place is starting to look a lot like a studio! And a pretty darn nice one, too... can't wait to see the stone in place.

Also, I'm starting to see some positive trends in REW. While I don't know how to interpret the output exactly yet - need some education here - the spectrogram is smoothing out a bit.

Post the MDAT file here on the forum, or if it is too big then upload it someplace and post the link. Then we can download it and analyze it for you.

In particular, the room's primary resonance at 18 Hz has dropped by more than 200 ms. I'm pretty sure that's good.

- Stuart -

[Dave_D]

Thank you so much! That's a very kind offer. My computer is wrapped up in plastic right now while I do drywall, but I will absolutely share those MDAT files when it's accessible again - probably a week or so. Thanks again!!!

[Dave_D]

Here are some progress photos taken since I last posted. Necessarily, I've stayed true to the construction permit drawings and - surprise, surprise - passed my final inspection!

That said, I ended up going with a hanging cloud rather than the hanging baffles typical of a Hidley/Newell non-environment studio. Part of this decision came from the limited ceiling space and was perhaps inevitable. Part of it came from my failure to fully draw my plans in Sketchup before launching construction. Had I done so, I would've realized the value of ceiling joists in my inner shell! Instead, I had already addressed the ceiling with Green Glue and hat channel, making it very difficult to attach ceiling clouds and especially hanging baffles (whose suspension lines might not be exactly vertical). In the end, I drilled through the ceiling drywall, suspended my cloud from decoupled hangers (which do hang vertically, thank you very much) attached to the pre-existing ceiling joists, and then filled the holes with acoustic caulk. Live and learn. But it's done now and appears to be working well enough.

Now, all that's left for me to do is apply cosmetic fabric to the ceiling cloud and build a nice production desk around my rather huge Kurzweil MIDIBoard. [You can have my poly-aftertouch MIDI controller when you pry it from my cold, dead hands. ]

[Soundman2020]

This place is starting to come together nicely! I can't wait to see it finished, and get the REW results!

- Stuart -

[thismanysounds]

Looking really good Dave. Glad to see it come together and definitely looking forward to measurements.

I have a few questions, if you don't mind:
- How deep is the sidewall and ceiling absorption?
- How was the Wallmate to work with (it looks very tidy)?
- What made you choose the Phillips system? Have you had any noise/RFI issues?


Colm

[Dave_D]

Hi, Colm.

The side walls are covered in 8" of Roxul RHT 40. The ceiling cloud varies from 4" to 12". [See attached drawing.] To be clear, these decisions were made somewhat arbitrarily - as much by aesthetics as by acoustics (I'm embarrassed to say) and by examining the designs of many, many other studios. To clarify, the non-environment strategy calls for wideband absorber arrays on those surfaces as well, but these became logistically impossible. So, these design choices were a result of available space, the door and window, and the existing construction of my inner shell. By going as thick as possible with the insulation (floor registers were already installed at 10" from the inner shell, so any thicker wasn't possible), I was trying to stay as true to the non-environment strategy as possible with lots of absorption. And by extending the ceiling cloud across the entire ceiling, rather than focusing on spectral reflection points, it not only facilitated my lighting design but offered more low-frequency absorption in the corners. After much consternation, I finally plowed forward with the confidence that I had a safety net - if the result is disproportionately absorptive on the high end, I can insert reflective slats of appropriate widths behind the fabric and seal 'er back up. Again, this departs from the non-environment strategy, but ya gotta do what ya gotta do.

Wallmate is TEDIOUS to install!!! And expensive. But I'm very happy with the results. [And, for the record, it's not so tedious that I didn't choose, after the fact, to do the ceiling cloud with it too.] And I like that it's somewhat serviceable, so if I spill something or put a guitar through 'er, it won't be a major construction project to pop the tracks and replace the fabric.

I spoke with my electrician about dimmers, colored lighting and automation, and he recommended traditional incandescent fixtures as the safest way to avoid introducing any unwanted EMI/RFI. I liked that it was the easiest and least expensive to install too, and it strikes me as the most future-proof. Consequently, the Philips Hue LED bulbs were ideal because they work with regular sockets, run cool, can be dimmed without requiring a dimmer switch (EMI/RFI noise generator?), and offer all the automation features. And, at the end of the day, if they didn't work, I could always revert to traditional incandescent bulbs. By comparison, Lutron, etc., are a commitment that aren't easily swapped out. I have twelve Hue bulbs and three Hue light strips installed in the studio and haven't detected an ounce of noise. When I'm back online, I can maybe do some concerted tests and share the results - see if I can't generate some detectable hum through the tie lines, for example.

I hope this is helpful!