Move My Studio Out of the Upstairs Bedroom

[profwacko]

This is a view of the rear chamber behind the speaker shelf.

I have drawn panels of 7 1/2" thick Roxul attached behind the front walls.

Will this be sufficient or should this area also be totally filled with Roxul?

ADVthanksANCE

-Jack (room demo almost done in central Texas)

[profwacko]

Anyone??

[Soundman2020]

Will this be sufficient or should this area also be totally filled with Roxul?

That's probably fine, but "more is better". You can fill the entire cavity if you want: I normally suggest using it to dump all your insulation off-cuts from the entire studio. Each time you have a left over piece of any type of insulation while you are building the walls and ceiling, hangers, bass traps, or anything else, then save it in a big bag until you have the soffits done. Then pour the contents of the bag into the cavity...

- Stuart -

[profwacko]

While I really like the idea of putting the scraps to work, I recently saw the sample shown below.

Would putting full height hangers here be better use of the space for bass trapping?

I also need to post some pics of my more recent Sketchups of the room.

ADVthanksANCE

-Jack (still drawing Sketchups in Bastrop, Tx)

[Soundman2020]

Would putting full height hangers here be better use of the space for bass trapping?

You can certainly do that below the speaker shelf, which is exactly what John usually does with his soffits (take a close look at his sample), but it's not much use doing it above the shelf, as the hangers would be behind the infinite baffle, sealed off from the room (except for the tiny speaker ventilation slots).

- Stuart -

[profwacko]

And finally, some progress. Ain't it funny how life gets in the way sometimes...

The drywall is all done (walls and ceiling have additional 5/8" with Green Glue, 26 sheets, 24 tubes) and so is the flooring (additional 3/4 OSB subfloor with subfloor adhesive and laminate flooring with thin foam underlayment).

I had a choice of either filling in an existing hole in the front wall where an huge exhaust fan was mounted or putting in a window so I can look out at my many backyard trees, so I opted for the window. See photo below.

I also ran the initial measurements with REW. See links below.

Right side only https://dl.dropboxusercontent.com/u/447 ... Right.mdat
Left side only https://dl.dropboxusercontent.com/u/447 ... 0Left.mdat
Both together https://dl.dropboxusercontent.com/u/447 ... Right.mdat

Please checkout the images from my most-recent Sketchup design.

Since I have no idea how to read much of the data in the mdat files, I am asking for any assistance The Illuminati can provide.

ADVthankANCE

-Jack

[profwacko]

Anyone??

[Soundman2020]

Jack, with REW you can save multiple test results inside one single MDAT file: you don't need to create separate files for each test, like you did here.

There are also some issues with the way you did the tests: You are starting the seeps from 0 Hz, which isn't necessary and just clutters the files with unusable data. Start the sweeps at about 20 Hz. You are also ending the sweeps at about 15 kHz, but you really should run the all the way up to 20 kHz. In addition, then test for both your left and right speakers only goes to 4 kHz!, so you are missing the entire top two and a half octaves of the audio spectrum. Run all tests from 20 Hz to 20 kHz.

You also seem to be running them at a level that is too low. Assuming you calibrated your setup correctly, right now you are running them at around 70 Hz, but you should really be doing them at around 80 Hz, to increase the SNR and also make sure you are testing the room at the typical level used for critical listening.

That said, there are still some pretty clear points visible your REW graphs. First, the modal response is really obvious, and quite scary, so I'm guessing the room was absolutely empty when you did those tests, right? That's actually good, because the room response is pretty clear. Several modes are behaving exactly as expected, especially the first few axials. The frequencies are all a bit higher than predicted (based on your original dimensions that you mentioned in your first post), so I'm guessing that the room ended up a bit smaller than you expected, or that you did the angled side walls and ceiling? Got any photo's of the room as it is now? Also, please post the final inner dimensions of the room.

One other thing I noticed; there's a fairly large difference between your left and right speakers: are you sure you had them set up perfectly sympathetically? Is there anything in the room that is not symmetric? Are the speakers themselves identical? There's probably a reason for the lack of symmetry, and you should try to figure it out.

OK, about your treatment design: you seem to be planning to do slot walls on the angled front sections, between the speaker soffits and the side walls. Personally, I wouldn't do that, as you'd be changing the frequency response of the reflected sound, due to absorbing some energy at specific frequencies, or in a range of frequencies (depending on how the slats are tuned). In general, it's better to have either a simple reflective panel there, or absorption.

The rest looks OK. but I wouldn't do those three side panels on each side until after you get the basic treatment in place. That make make the room too dead. I would put the initial treatment in, then test the room again to see how it is doing, and decide on what to do next.

The window up front is fine, by the way. No problem with that.


- Stuart -

[profwacko]

Stuart, thanks for your in-depth reply. I truly look forward to your replies.

There are also some issues with the way you did the tests

I will adjust my settings accordingly for the next round of testing.

First, the modal response is really obvious, and quite scary, so I'm guessing the room was absolutely empty when you did those tests, right?

Yes, absolutely empty, the worst case scenario.

Got any photo's of the room as it is now?

Check the picture below of how the room looked during the initial test.

Also, please post the final inner dimensions of the room.

The room was originally 160" wide, 189" long, and 98" high on average. I say on average because the ceiling is higher in the center by 10". Also, the raised ceiling panel is asymmetric in the room and unavoidably so. Perhaps this accounts for some of the differences between the left and right measurements.

There has been an additional sheet of 5/8 drywall added on all wall and ceiling surfaces, and an additional 3/4" subfloor with the 3/8" laminate flooring. This brings my "final" dimensions to 158 3/4" W, 187 3/4" L and 96 1/4" H.

Are the speakers themselves identical?

I believe so. I just had the crossovers re-capped and they seem to be improved.

There's probably a reason for the lack of symmetry, and you should try to figure it out.

Probably due to the asymmetric ceiling panels and also due to having a table near the center of the right side wall holding the computer and the small LCD monitor.

you seem to be planning to do slot walls on the angled front sections, between the speaker soffits and the side walls

The slot walls aft of the speaker soffits mimic a John Sayers design I have been basing this room upon (picture below). The end of the slat walls is just behind the seated listening position. I have planned to have these be the primary mode busters in the room, as the spacing between the slats comprises about 17% of the total panel area. Would it be better to increase this percentage to say 35%, in order to make the slat walls act as broadband absorbers rather than tuned ones?

I wouldn't do those three side panels on each side until after you get the basic treatment in place. That make make the room too dead.

Those three panels are there to eliminate flutter echoes between the otherwise parallel side walls behind the listing position. I am planning to put plastic film behind the burlap outer covers on at least half of them (if not all of them) to retain some of the highs in the room. Is this not a suitable solution to the expected flutter between those two walls?

Also, as I am continuing with the construction, at what point(s) should I run additional measurements?

Thanks very much for your input on all of this madness.

-Jack (still crazy in Central Texas after all these years)

[profwacko]

Anyone?

[Kevstar]

Hey Jack, just begun following your thread with eager eyes, ad I'm mid-design on a very similar project.

From what I've learned, slat/slot walls in such a (relatively) small space can potentially cause more problems than solve anticipated ones. If I'm reading your model right, those slats are in the position of your first reflection points of the opposite speakers when sat at your theoretical listening position. That just needs too be good broadband absorption.

Regards frequency of your REW tests, along the diagnostic principle of only change one thing at a time, then keep it simple, methodical, and often as your instincs dictate. If in doubt, just do it.

As everyone says, bass trapping is (going to be) your biggest problem. Solve that first, then perhaps refit your gear/seating, etc., then shoot REW again.

Just my penneth worth until the cavalry (Stuart) arrives. Nice work so far though, It's gonna be great!

Kevin (UK)