New Studio Design/Build in Highland Park, L.A., CA

[mattsal]

Awesome.. How's the project coming along?

[lavenders]

Sorry for the mega delay in posts. The end of the build got pretty intense - so many little things to consider! Seals, doors, electrical, decor, STAINING, HVAC... I took my first weekend off in a long time yesterday and am excited to report we're pretty much wrapped on construction! I had my first session last Thursday and things went well. There are a few elements we'll continue to work on that I'll detail below. I may need to do this in a few posts too with the photo limit...

The window installation went surprisingly smooth! I was expecting this to be a major hassle, but with Rod's excellent step-by-step on this forum and our carpenter's knowledge the process was relatively simple.

Window Framing stuffed with fluff:

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Rather than using some sort of neoprene plug here or something as Rod described, I just ended up taping the gap in the framing. I figured this wouldn't couple the walls to any damaging degree, and would seal it off from having fluff or dust enter the window cavity:

IMG_0621.jpg

I ended up doing one pane of 1/2" tempered glass (tracking side) and then 1 pane of the "55 Glass" brand soundproof glass. If you're in the L.A. area, I highly suggest using this stuff. They sell to a lot of recording studios apparently, and they were a breeze to deal with.

Rather than buy some window suction cups to install the panes (only the 2nd piece, the first can obviously be cleaned of fingerprints on both sides) I went to the local glass shop and asked if I could "rent" some. The guy was super nice about it, and ended up being 1/4 the price of buying pro cups for such heavy glass:

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Windows in:

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I stuffed the new jamb gap with rigid foam (same as with door pictured below), then opted for the ceiling tile wrapped in black duck cloth pushed between the jambs to cover it. Naturally, I got the hang of this on the last piece I made. Because the ceiling tiles we had were only 4' wide, and the window 6' wide, I had to splice 2 "slices" of the tiles together for the top and bottom gap. I really don't recommend doing that. I've noticed (something probably no one else ever will) that one half of the tile on the top has started to sag a bit, and I'm now dreading the day that it hangs down - stuck in between two giant pieces of glass. Fingers crossed that never happens! haha Luckily it's only noticeable from one angle, which is now inaccessible with the console in place.

Detail:

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Casing being nailed in:

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The door jambs, in my opinion, were the gnarliest part of construction. It took WAY longer than anticipated, and since we were dealing with pre-exsting construction (read: not plumb) it was a true challenge to get these in place, and ready to hold a massive door or two. Come to think of it, I think one of the hardest parts was finding the appropriate wood! 5/4 stock is just not as popular as it apparently once was, so I settled on true-1-inch plywood that we ripped down. I went with one piece of 1-inch birch for the super door, and regular 3/4 pine for the double door. This actually ended up being pretty cost-effective, and if you have a table saw, I highly suggest going this route instead of hunting down weird dimensions and getting all those confused looks from lumber yards.

We jambin:

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^^^Complete with Edge-Banding (for the ply edges)

Framing gap stuffed with 703:

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Shimmed, Nailed and Caulked:

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I'll move onto Door Install and more in the next post!

[Soundman2020]

I'm just wondering why you tilted your glass in your windows, leaving a much narrower gap at the bottom? You DO realize that doing that greatly reduces your isolation between rooms, and is not necessary for any acoustical reason?

I'm pretty sure that Rod even mentions that in his book, which you mention that you read. So I'm curious as to the reason for doing that...

You lost a lot of isolation by doing that, especially in the low frequencies.

- Stuart -

[lavenders]

Totally valid question! Because I like the way it looks I've always loved the lines in traditional studios, and tilted glass brings to mind "studio" - which IMO helps people feel comfortable creatively. I've also gotten a lot of compliments about the way it looks, which is always good for business if people feel like they're in a cool-looking space.

I had a chance to work in the Capitol A Room a few weeks ago, and the entire control room front is tilted glass. It's a huge element of the beauty of that room, and "there's just something about it".

There's definitely no noticeable sound coming through the window... any bleed is definitely coming through the floor since the control and tracking room are built on the same 2nd floor wooden deck. There's a level of isolation we just can't expect with some of the choices we made. I'll detail the rest of that in my next post...

[lavenders]

This post will cover Door Construction through to Move-In Day! Unfortunately, with the stress and rushing to finish I didn't photograph quite as thoroughly as I did in previous steps. I did take pictures when I thought something we were doing was complicated, so we could retrace our steps and to show others with questions...

Finished Double-Doors:

IMG_0898.jpg

Close-up of the stop seals:

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I went with the "K"/"L"/'55 Malibu Trunk Rubber Rod recommends. I also went with Pemko Automatic Door Bottoms and Acoustic Sealing Thresholds for all 3 doors. I can't say enough good things about the Pemko seals - all very solid construction, and do a great job of sealing. I opted out of getting the magnetic weather stripping. I think you can get away with it on double doors, but I do think it would've made a much better seal for our super door.

Just to put it in another place on this forum, you can buy the trunk rubber at perfectfit.com, Item No. AV04731

The Pemko models I bought were:

AUTOMATIC DOOR BOTTOM: 4131_RL
ACOUSTIC SEALING THRESHOLD: 2006STC

I much prefer double doors to the super door. It's a bit more expensive... double doors/seals/thresholds, etc. But, I found all that stuff easy compared to making a super (heavy) door that doesn't latch closed. I think there's something psychosomatic about walking through two doors as opposed to one. Really feeling the effect of that second seal closing is important to creating that atmosphere I think. Obviously having an airlock (like most pro studios) really does the trick, but IMO the double-door is a great solution when going DIY.

That being said, the super door was our only option for the live room because of the hallway adjacent to it, and it did a pretty great job of sealing out the sound from the hall. Here's a shot of the hung door with the lead rubber-cemented and nailed on:

IMG_0870.jpg

Sheet lead was hard to find in-town, Bobco had it but was pretty pricey. I ended up ordering on Amazon with free Prime shipping (!) from a company called Roto Metals. Lots of different thicknesses and widths to choose from. I opted for the 1' roll of 1/16th and cemented 3 strips. I found that having a hard roller, like for ironing out bubbles from vinyl stickers, was key in getting the lead to flatten out on the door... otherwise it would've been difficult to mount the ply on top.

Here's the completed super door, complete with pulls on each side, 5 inch backset deadbolt (with stainless grommet to cover the lock's recession) and door closer:

IMG_0961.JPG

After doors was Electrical, which we ended up doing entirely ourselves. It was nice to actually improve the existing electrical as we went, and bring it up to code in the spots where it was a little funky. No pictures here, as most of it was installed in the attic, then fished down through conduit into the studio. We ended up only making 6x 1/2" penetrations total, and 2 are behind our hemholtz diffusors so are pretty well sealed off.

For lighting, I went with a combo of recessed lights in a ceiling cloud + track lighting. Big thanks to simo for the inspiration here, his ceiling cloud build gave me the confidence to do this myself! Here's a picture of the cloud getting wired up by our contractor:

IMG_0926.jpg

And a pic of the aforementioned hemholtz slot diffusers ('tuned' to 153hz) being built:

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And here's the finished product (panoramic shots, I swear the walls aren't crooked):

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And one with me for good measure

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I've still got some work to do... have to build some absorbers/diffusors to finish treating the room (after some more testing), install a thermostat, build a lot of cables, etc. The tracking room is currently being used for storage, but each day I'm doing a little bit to organize things in there.

I've started building the signal pass-through between the rooms. I was able to modify an inexpensive punched rack panel to work perfectly for our needs... I think they came out pretty good for this novice woodworker:

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And that's pretty much a wrap on construction! I'm so stoked to start working on SOUND again! This was by far the hardest endeavor I've ever undertaken, and the results are massively gratifying. Looking around and knowing I've touched (and probably stressed over) each component in the room is a great feeling.

In terms of the effectiveness of isolation, I haven't had time to test SPL and compare the results yet, but it's a night/day difference from before we started. At normal monitoring levels, there is NOTHING outside in the hallway. Pin drop status. With the speakers and sub cranked all the way up, there's some low end that can be felt in the hall/office, but is drowned out by typical office noise.

The floor is the obvious weak-point. We didn't touch it because of concerns of weight/cost/awkwardness, and there are a couple of creaky floor boards we're trying to fix that make noise in the room when people walk through the hall. None of this was unanticipated, and I suppose is a reality of building a studio on the 2nd floor of an old building. We're figuring out a "red light" system in the meantime to keep people out of the sensitive spots while recording is happening. Old School! haha

We're in sort of a soft opening phase right now, with friends using the room alongside some of my own projects. We've gotten some great feedback so far, and are hoping to have the branding, gear and full acoustic treatment ironed out by the new year. At that point we'll start advertising and try to get some new business pumping in.

Let me know what you think! Would love to hear any constructive criticism or suggestions... Can't thank you all enough (as well as those who've posts I've scoured) for contributing to this community. I definitely couldn't have imagined myself doing all this a few months ago, but knowing so many have had success doing it on their own was a major confidence boost and saved us some serious dough.

I'll try to update the thread once we make more changes and post the completed live room once that's done.

[Soundman2020]

It's looking really nice I must say! Good workmanship.

How about if you run a REW test in there, to see how well it is doing acoustically? If you post the MDAT file, I'd be happy to take a look at it, and analyze it for you.

By the way, one comment you made caught my attention:

And a pic of the aforementioned hemholtz slot diffusers ('tuned' to 153hz) being built:

Why did you pick 153 Hz? Is that a specific modal problem that you are concerned about? I looked at the dimensions for your room and did a modal analysis, but I didn't notice any issues at all at such a high frequency: your modal issues are all much lower for that room, all of them are down below 89 Hz. So I'm curious as to why you chose 153 Hz as the tuned frequency for your Helmholtz resonators?

Also, to me it looks like you built those slot resonators (not diffusers) diagonally across the front corners. Did you build some type of fixed-depth sealed box behind those, that isn't visible in the pictures? If not, then they are not tuned to 153 Hz. Since the depth of the cavity varies (very shallow at the edges, very deep in the middle), then it isn't not tuned sharply to a specific frequency with a high Q and high efficiency. Rather, it is tuned as a broadband absorber that covers a very wide range of frequencies, is not sharply tuned, and has a rather low Q and low efficiency.

To confirm:
What thickness are the slats, what size are the gaps, and how big are those slats (height and length of the planks)? If you give me those numbers, I'll let you know what they are actually tuned for.

Also, how about a photo towards the back of the room, showing the rear wall treatment?

But most interesting of all would be the REW test.


- Stuart -

[lavenders]

Hi All,

Sorry for not updating sooner... it's been a long few months! Been sorting gear, having sessions... but the quest to perfection continues

To answer Stuart's question about the Slat Resonators... those were to built to spec from Rod's book, including size and angles. Frame built behind, 4" of insulation, felt, then the wood slats. If by airtight you mean caulked with the frame going all the way around, I suppose it's airtight. The (actual) wood dimensions were 0.625 in. x 7.125 in. x ~54.75 in. We spaced them 9/16".

I used 153Hz because I noticed a large spike there in testing before building. I was testing in a hurry to begin work, but it seemed like just about everywhere I put the mic (especially mix position) there was a big 153 buildup.

I've finally gotten the room to a semi-permanent point, with nice speakers. And some general treatment. I'd love if anyone would take a look at my most recent Fuzz test.

Testing was done through an Aurora Converter with Pacifica Preamp and AKG 414... I know these probably aren't the most accurate testing apparatus, but figured it'd be in the ballpark.

These are linked in the title to show a larger version:

Mix Position:

mix_position_sm.png

Client Position (couch):

client_position_sm.png

In general I'm noticing a few things about the sound in the room...

1. There's a big null in low frequency near where the rug ends toward the back of the room... about 3/4 back from the front. Especially noticeable when standing. The ceiling in this area is untreated.
2. There's a big bass buildup on the client couch. Not the worst thing since we're hip-hop focused... but would love to tame it a bit to give a more accurate representation of the mix.
3. There was a big buildup of 105hz at the mix position, but has been significantly tamed since adding a 4" trap under the window in the front of the room. Not sure if that means anything special.
4. Most of the ceiling (save for the mix position), and the wall with window are untreated.

I think a big issue right now is my speaker placement. I have this dumb desk I'm working on until we buy a console (soon hopefully) and it keeps me from having the speakers pushed a little further back. Otherwise the computer screen would block the center of the image (I'm assuming)...

Here are new photos of the room, front AND back (excuse the mess...)

Front:

IMG_1161.JPG

Back:

IMG_1162.JPG

The tracking room is still being used for storage... hoping to have that up and running in a couple of weeks.

Things seem fairly flat to me, though I'm sure there's room for improvement. Would greatly appreciate any advice!

[Soundman2020]

If by airtight you mean caulked with the frame going all the way around, I suppose it's airtight.

No, what I mean is that there must be a completely airtight enclosure behind the slats: a "box". It must have a top, bottom, two sides, and a back, and all of those must be sealed to each other, to make it completely air-tight, except for the front, where the slats are. It must be impossible for air to get in and out of the cavity behind, except through the slots between the slats.

If you did not seal the cavity behind, them that is not a slot wall: it is not working as a series of Helmholtz resonators: It's just an attractive decoration. It might also be doing a bit of diffusion, and maybe some low frequency absorption, but it is not a tuned resonator. Helmholtz resonators need an enclosed volume of air in order to work. Without that, there is no resonance.

The (actual) wood dimensions were 0.625 in. x 7.125 in. x ~54.75 in. We spaced them 9/16".

How deep is the cavity? Did you put insulation in the cavity, but not touching the slats?

And since the cavity varies greatly in depth, that thing is NOT tuned to 153 Hz. It is tuned to a very broad range of frequencies, which I can calculate for you if you tell me the dimensions of the triangular cavity behind them. Of course, that only applies if the cavity is sealed: if there is even a tiny crack where air can leak in and out, then it isn't tuned to any frequency: it's just a bunch of wood on a frame.

I've finally gotten the room to a semi-permanent point, with nice speakers. And some general treatment. I'd love if anyone would take a look at my most recent Fuzz test.

Your graphs aren't a lot of use: I would need the actual data. Please export an impulse response file for each measurement that you took, upload those to a file-sharing service (such as DropBox), and post the link here so I can download them..

Testing was done through an Aurora Converter with Pacifica Preamp and AKG 414...

Did you set your 414 to omni pattern for those tests? If not, then the tests are not valid. Acoustic tests must always be done with an omni mic...

I know these probably aren't the most accurate testing apparatus, but figured it'd be in the ballpark.

If you did not use an omni mic, set up correctly, and calibrated correctly, then probably not.

These are linked in the title to show a larger version:

You are using way too much smoothing on your graphs. 1/6 octave is hiding all of the details that are critical to seeing what is actually going in. Room modes are very narrow band, just a few Hz wide: if you smooth the data to 1/6 octave, you won't see them at all, or at best you'll see them as a slight, smooth bump, instead of the sharp, high Q event that they actually are. I rarely use anything more than 1/48 octave smoothing.

1. There's a big null in low frequency near where the rug ends toward the back of the room...

Rug? Why is there a rug in the room??? Carpets do terrible things to room acoustics. Take a look at photos of world-class studios in magazines: How many of them do you see with rugs on the floor? There's a reason for that...

about 3/4 back from the front.

... which would be at the quarter wavelength position for all X.0.0 axial modes... Indicating that you do not have enough bass trapping on the front and back walls.

2. There's a big bass buildup on the client couch.

Once again, indicates a lack of sufficient bass trapping, and probably the couch is in the wrong position too.

In fact, looking at the photos, I do not see any bass trapping at all!

And I also see that the client couch is right up against the rear wall, in the pressure peak for all modes, and right under a Schroeder diffuser that is not necessary, and does not look to be tuned to a useful frequency range. What are the upper and lower cut-off frequencies for that diffuser? Why is it there? Are you aware that you should never have a critical listening position within ten feet of a tuned diffuser, due to the lobing patterns it creates?

I think a big issue right now is my speaker placement.

I agree. There clearly are issues with the setup there. That needs to be fixed.

What speakers are those, and which are your mains? Why do you want three sets? Why are they all at different heights?

Otherwise the computer screen would block the center of the image (I'm assuming)...

The screens do need to go much lower down, yes. In general, it's not good to have anything between the speakers and your ears, but as long as they don't block the direct path for the tweeters it might be acceptable. Check the dimensions of the monitors vs. the wavelengths produced by the mid-range driver to be sure. As long as the wavelength is significantly larger than then largest dimension of the monitor, you should be OK.

But I would get rid of that desk with the large boxy reflective, resonant thingies all over it, and get a simple flat desk that is very solidly built for your console. Set up your screens as low as you can get them, on articulated arms, beyond the console, and adjust them so that they interfere as little as possible with the sound path from speaker to ear, and also do not cause unwanted reflections that get to your ears within the Haas time.

though I'm sure there's room for improvement.

Me too! There is undoubtedly a LOT of room for improvement in there: I can tell you, just from looking at the photos, and without even seeing the actual impulse response data from your tests, that you have serious modal issues, SBIR issues, large peaks and dips in the bass, frequency response variations greater than +/- 10 dB, variations in decay times that exceed the specs for control rooms, flutter echo, stereo imaging problems, early reflection problems, and several other less important issues. I'd say there's a lot of room for improvement! You are not seeing that in your graphs, because you have smoothed all of that out of view, and not set useful parameters for viewing the data: It LOOKS good like that, but all you have succeeded in doing is masking the issues, so you can't see them. But they are still there. Even at the scale you are showing, there are some pretty major issues visible, and I'm betting that unsmoothed and shown at the proper scale, they are actually a bit scary...

So please send me the impulse response data from all of your tests, and I'll take a look at it, and show you where your issues are, then we can decide what to do about them.



- Stuart -

[lavenders]

Hey Stuart,

Can't thank you enough for your thorough responses. Answers below:

Helmholtz resonators need an enclosed volume of air in order to work. Without that, there is no resonance.

I see. We did not build boxes. Just framed around the wall, following the instructions in Build It Like the Pros for a "Helmholtz Corner Slot Resonator". Here's the plan we used, save for the dimensions I mentioned in the last post:

corner_hem.jpg

We used 4" Rockwool Batt Insulation with netting behind it to prevent it from falling back into the cavity.

Please export an impulse response file for each measurement that you took, upload those to a file-sharing service (such as DropBox), and post the link here so I can download them..

Here are brand-new tests done this am... sorry for the incomplete data before. Happy to re-run these or export any additional info you may need. I'm using FuzzMeasure for Mac:
https://dl.dropboxusercontent.com/u/724 ... c_data.zip

Rug? Why is there a rug in the room??? Carpets do terrible things to room acoustics. Take a look at photos of world-class studios in magazines: How many of them do you see with rugs on the floor? There's a reason for that...

It's just kinda thrown in there, can take it out if you think there will be an improvement. I've definitely seen carpet & rugs in lots of top studios (capitol, westlake, paramount) so is there something inherently bad about this placement? Perhaps a rug is better suited in the back of the room?

What are the upper and lower cut-off frequencies for that diffuser? Why is it there?

It's there to help with echos I was hearing in the back of the room, and that's where I usually see them in studios... Manufacturer says effective from 325Hz-3kHz

What speakers are those, and which are your mains? Why do you want three sets? Why are they all at different heights?

The mains are Focal Trios. I've been tweaking all this constantly, so no logic here other than trying to use this desk as effectively as possible, and going by my ears. The tweeters of the Focals are about 4.5' from the front wall currently. We had a couple of other pairs setup just for listening. Planning to adjust all this and move things toward the front of the room once we get the console situation sorted. I'm hoping all this data is still relevant even though we're planning to move things around in the next month.

Me too! There is undoubtedly a LOT of room for improvement in there

Sorry! Wasn't trying to come off as arrogant... poor word choice on my part. There will always be TONS of improvements to be made to this humble room - and I can't thank you enough for taking interest!

[lavenders]

I just realized it may be better to do these tests without our subwoofer on... I've re-performed the tests with it muted:

https://dl.dropboxusercontent.com/u/724 ... NO_SUB.zip

We're usually monitoring with the sub, but I turn it off frequently when mixing.

[Soundman2020]

Ok, got some analysis results for you, and it ain't so pretty.... take a deep breath, and take a seat...

First, here's the true frequency response, smoothed to 1/48 octave, at the mix position:

Lavenders-Initial-FR-Full-range--Mix-Pos-01.jpg

As I expected, there are some pretty wild swings in there, +/-10 dB. Mostly in the lows, but also in the low mids, as well as a steep roll-off in the highs, above 12kHz. Perhaps that's the rug, or it might just be speaker-related.

Here's the graph at the client position:

Lavenders-Initial-FR-Full-range--Client-Pos-01.jpg

Even WILDER swings! +/-20 dB! Not an accurate place to be sitting at all: And the bass build-up is clearly evident.

Now a comparison of both, for the low-end of the spectrum (which is the most critical):

Lavenders-Initial-FR-Comparison-Client-vs-Mix-01.jpg

Blue is mix position, red is client position. Comment: Ummmmmm.....

There's a major difference in the low mids. And I mean MAJOR! The client is not hearing the mix anything like youa re hearing it. For him, there's a hole in the vocals and low end of guitars, the snare sucks,, and the bass is booming... as compared to what you are hearing, which is also not accurate....

OK, those are just a tiny part of the situation, since they are only frequency response. Now for the important stuff...

Waterfall plot of the low end, at the mix position:

Lavenders-Initial-WF-Mix-Pos-01.jpg

Hot damn! That's pretty poor, and indicative of a major lack of bass trapping.

You have clear modal issues at 51 Hz, 56 Hz, 102 Hz, among other possibles, and they are strrreeeettttchhhiiinnnngggg out way far in time. (I've got the cut-off set to 300 ms for that view). Lot's of not-so-nice stuff going on in the low end. There are also signs of flutter echo in the low end, and a heap of other stuff.

And no the same waterfall plot, but for the client position:

Lavenders-Initial-WF-Client-Pos-01.jpg

To be honest, I would hate to b sitting in that location, trying to make critical decisions about the mix.... The room is lying to your client: he is not hearing anything at all like what is coming out of the speakers.

The spectrogram presents the same time-domain data in a different format, that is also very interesting:

Lavenders-Initial-SP-Mix-Pos-01.jpg

You can clearly see the large amount of unevenness in the low end, with major differences in decay times, all across the board.

Also, your sub is in the wrong place.... It either needs to be moved, or your mains need a time delay on them.


Now for the overall RT60 graph:

Lavenders-Initial-RT-Mix-Pos-01.jpg

Not so smooth, too bright overall for that room, and with a large rise in the decay times in the low end.

And finally, the actual impulse response itself:

Lavenders-Initial-IR--Mix-01.jpg

Ouch! There's no ITDG at all, and some very prominent early reflections throughout the Haas time, even up to about 40 ms! That's screwing up your stereo imaging, sound-stage, and sweet spot.

For the client position, the IR is even worse:

Lavenders-Initial-IR--Client-02.jpg

That's scary. To me, it looks like the client position is totally outside the direct field, with numerous reflections in the Haas time, and something that you don't see too often: reflections that are more powerful than the direct sound. Here's a close up of the first 12 milliseconds, which show it very clearly:

Lavenders-Initial-IR-Detail-12ms-percent-Mix-Pos-01.jpg

At about 2.7ms, there is a very strong reflection that exceeds the direct sound level by several dB, plus several other reflections. There's no way that your client is getting an accurate stereo image.


So overall, that room needs some major treatment and re-arranging to make it usable. It is more or less what I expected, and nothing like your graphs show, because you over-smoothed them and used scales that don't mean much. These graphs show the acoustic reality of your room, and clearly it needs fixing.

And it turns out there's nothing at all unusual happening at 153 Hz.... !!! The closest issue is what appears to be some modal ringing at 143 Hz, but that's a long way from 153.... It's two notes down the scale.

I just realized it may be better to do these tests without our subwoofer on... I've re-performed the tests with it muted:

There's no impulse response files in there, so I could not look at it, but in fact the tests do nned to be done with the sub on.

Also, you are doing your tests at a level that is too low: it needs to be done at around 85 dB for each individual speaker, but yours were done much lower than that (assuming you calibrated your system correctly before doing the tests). 85 dB is typical mixing level, and doing the tests at a lower level might not have triggered all the modes.

Also, if you repeat your tests, please do one with just the left speaker, one with just the right, one with just the sub, and one with all three of them. That reveals a lot more detailed info about the room, such as problems with symmetry, or problems with cross-overs, interference between sub and mains, etc.

I've definitely seen carpet & rugs in lots of top studios (capitol, westlake, paramount)

Right, but those are added at the end of the room tuning process, as a final tweak, and they are done for specific purposes.

so is there something inherently bad about this placement? Perhaps a rug is better suited in the back of the room?

Carpets do the exact opposite of what most rooms need. Carpets are pretty good at sucking up the high end, mess up the mid-range randomly, and do nothing at all for the lows. Whereas what rooms need is major absorption in the lows, some controlled treatment in the mids, and practically nothing at all in the highs. A carpet in your room will skew the acoustics towards the low end, so that it sounds "muddy", "boomy", "lifeless", and similar terms.

[ diffuser ] It's there to help with echos I was hearing in the back of the room, and that's where I usually see them in studios..

... and they are frequently mis-used in many studios. Read the book by Cox and D'Antonio, the guys who did all the initial research on how diffusers work, how to tuned them, how to use them, etc., and wrote many papers on them. Numeric-sequenc diffusers produce a pattern of lobing around them, in both the frequency and time domains (implying phase domain as well), with levels varying greatly between lobes. They are the ones who came up with the rule that your ears should never be within ten feet of a numeric-sequence diffuser if you are doing critical listening, since the lobing artifacts totally mess up your brain's ability to determine directional and tone. Just moving your head a few inches one way or the other will put your ears in very different lobes, and you will have vary different perception, for the exact same sound. Their research revealed that at about ten feet the lobes are fairly well merged, so the effect is no longer important. However, in addition they discovered that if your head is within three wavelengths of a particular tone, then you would be suffering from the same issues, so they also suggested that you should be at least 3 full waves distant, for the lowest tuned frequency of the diffuser. Later the changed that to 7 full waves, as they discovered that scattering can still happen for an entire octave below the cut-off frequency. You say that the cut-off for yours is 325 Hz, which is a wavelength of 3.5 feet. Therefore, you should not have a listening position with 10.5 feet of that, based on their old rule, or 24.5 feet based on their 7-wave rule...

Yes, you do see many studios with diffusers right behind the listening position, but you also see many studios with speakers on the meter bridge, and others with egg-crates on the ceiling, but that does not make any of that right! Not everything you see in studios is acoustically sound. Many studios just do things because they saw it done in another studio, but don't have a true understanding of why it was done, or how it was done. Acoustic treatment is not transferable: You can't just take something you see in one room that sounds good, and assume it will work in another room: all rooms are different, and each needs it's own specific treatment. The only time you'd be justified in copying treatment used in someone else's room to your room, is if your room is identical to theirs: exactly the same dimensions, same building materials, same speakers, same everything. If your room is a different shape or size, or is build differently, or has different speakers, or different furniture, then very likely you would not be able to "cut and paste" something from another room.

The mains are Focal Trios.

Nice! I would definitely use those as your mains, but set them up correctly for that room, then treat the room accordingly, then tweak.

I've been tweaking all this constantly, so no logic here other than trying to use this desk as effectively as possible,

The desk is part of the problem: I would replace that with a low, flat desk. All that stuff sticking out on top is messing with your clarity.

and going by my ears.

Ears are great... but nowhere near as precise as a proper acoustic analysis: Plus, a big part of the reason why you have not been able to find good locations for your speakers, is because the room response is preventing you from doing that! You will never be able to set up your speakers correctly by ear in a room that lies to you. No matter where you put them, there will be some problem. And no matter where you put your head, there will be other problems. Until the room is treated to get the acoustics under control, you will not be able to get your speakers in a position that is accurate.

It's sort of like asking an artist to paint a picture while he is wearing glasses with one lens colored pink, the other colored blue, and while you are shinning multi-color lights on different parts of the canvas, which is itself stained with coffee, dirt, blood, mustard, and ketchup! No matter how hard he tries, or how good he is an artist, he will never be able to paint a picture like that. It might look great to him, under those conditions, but when he takes off the glasses and takes his painting outside into sunlight, he'll see just how terrible it is.

The tweeters of the Focals are about 4.5' from the front wall currently.

That would explain some of the comb filtering seen in your frequency response, ans well as the SBIR issues.

Planning to adjust all this and move things toward the front of the room once we get the console situation sorted. I'm hoping all this data is still relevant even though we're planning to move things around in the next month.

Absolutely it is relevant! Everything matters. When I'm designing a room, I very often need to re-do the whole thing because the client told me was going to switch out his speakers, or desk, or console, or furniture, or whatever for something different. Anything that changes in a room could potentially affect the acoustics. The bigger the change, the greater the effect. Just getting all of the junk out of your room and cleaning it up is going to make a difference... but probably for the worse....

I'm not sure what your goals are here, but if you want your room to be as accurate as possible, with world-class acoustics, I would suggest that it needs a major re-design, in terms of layout, geometry, and treatment. First you should decide on what equipment and furniture you want in there, then on the best places to put it (both acoustically and also ergonomically, as well as aesthetically), and based on that do the actual basic layout design. With that in place, then you can look at the geometry of the relationship between the speakers, the listening position, and the room: Based on that you can predict what basic treatment will be needed, so you can design that and put it in place. They you can test and analyze the room (as I did above) to see what still needs to be done, design new treatment for that, install it, test, rinse, repeat....

That would be my suggestion.

Have you considered soffit-mounting your mains? That would work VERY well in that room...

Sorry! Wasn't trying to come off as arrogant...

Don't worry! I didn't take it that way at all. My answer was part joking, and part serious. It's hard to express emotions over the internet...

and I can't thank you enough for taking interest!

I love a good challenge, and your room clearly has some challenges. It's a nice size, and you have decent equipment, so it can be made to sound pretty darn good, if you want it to.


- Stuart -

[lavenders]

Thanks so much Stuart! I'll start making some changes...

Seems like these would be first good steps?

1. Move speakers/console position closer to front wall.
2. More Basstraps on front/back walls (especially corners)
3. Basstraps on ceiling in back of room (ceiling is completely untreated)
4. Remove Rug

In the short-term, I was able to swap out some of the 2" traps for 4" in the front/back sides of the room. I quickly ran the two tests again (all speakers, was hurrying before a client came in). The new impulse responses are included, as well as difference graphs between the old and new tests. Seems like the changes smoothed things out a bit, but don't seem major.

https://www.dropbox.com/sh/bw8ksep5viht ... _MYea?dl=0

Will report back once I've made more changes! Thanks again.