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PostPosted: Tue Sep 11, 2018 4:00 am 
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Location: Chicago, IL
I'm about to start the process of revamping the acoustics in my control room and would like to get some insight into ways I can improve the treatment of the room. I have my REW measurements linked to dropbox below and some additional details not shown in the measurements or the photos. I recently built a 'B' Room based off of John's small studio design and it sounds so good I need to get my older control room up to that level. I'm flexible with my budget, we'll be doing the work ourselves and I'm willing to put up to $2,000-3,000 into this if needed (I do however have several 2x4 sheets of 703 left over from my last build, so that will cut down on a decent amount of cost). We don't have any room to modify dimensions of the room as it stands.

All the current corner traps & treatments are R13 (I was on a tight budget when I built this initially, I'll definitely be upgrading to 703 for all treatments)
Above the mix position I have two clouds which measure 24x84, filled with R13
The room is 15-1/2' deep, 10' wide behind the speakers and 12' wide in the rear of the room.
My ceiling height is 9'4" and is parallel to the floor unfortunately.
The absorbers on the left and right walls near the console are both 36" x 36" x 3"
Mix position is roughly 72" from the wall behind the speakers.


REW mdat files:
L_Baseline- https://www.dropbox.com/s/1qyd83csgnsqx ... .mdat?dl=0
R_Baseline- https://www.dropbox.com/s/0q6b6hku3rq3u ... .mdat?dl=0
L+R- https://www.dropbox.com/s/74uzqqhwu6fm8 ... .mdat?dl=0

Any insight or guidance is greatly appreciated, thanks!

Pete


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http://www.bricktoprecording.com


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PostPosted: Tue Sep 11, 2018 5:53 am 
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Location: Santiago, Chile
Hi Pete, and Welcome! :)

Quote:
...would like to get some insight into ways I can improve the treatment of the room. I have my REW measurements linked ...
Unfortuantely you caught me at a bad time, so I can't take a look at that right now, but from what I can see, your room does have potential. It needs a lot of work, yes, but there's a good chance that it can be made quite decent.

Quote:
The room is 15-1/2' deep, 10' wide behind the speakers and 12' wide in the rear of the room.
So around 180 ft2, give or take? That's decent.

Quote:
My ceiling height is 9'4" and is parallel to the floor unfortunately.
Height is very good! Parallel to the floor is not a problem. That's a myth...

Quote:
Any insight or guidance is greatly appreciated, thanks!
Stay tuned! With a bit if luck I'll get back to you late tonight...


- Stuart -

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PostPosted: Tue Sep 11, 2018 2:47 pm 
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Location: Santiago, Chile
Quote:
I have my REW measurements
It's much easier if you save each set of measurements in one single file, instead of three separate files...

Anyway, I took at look at your data, and I'm having a hard time understanding the room. It is a bit too dead for that size, but it is also rather unbalanced, and the phase is all over the place! Not surprised that it doesn't sound good. But I can't quite put my finger on the underlying problem. Your decay time is around 190 ms, and should be more like 220 ms. Not a huge difference, and it wouldn't fully explain why the room sounds poor.

I would need to know a lot more about the treatment in that room to understand what's going on there. Maybe you could add more detailed accurate, information to your diagram, showing what the surfaces of the room are, and what treatment materials you have where.

By the way, you have a grounding problem of some type: there's constant 120 Hz. "hum" in your system: If you can't hear it in your speakers, then it is probably a faulty mic, or faulty mic cable, or bad connector. Or it might be an actual electrical issue. Whatever it is, you will need to figure it out and resolve it.

Another "by the way": the angle of your measurement mic in the photo is not correct: It needs to be angled up far steeper than that: about 60°. You seem to have it at maybe 45°, or even less. For future measurements, please angle it up more.

Anyway, to get the room sounding decent, first you will need to get rid of all the clutter: in the photo, there's a lot of "stuff" that just shouldn't be there: that bookshelf thing on the left and everything on it, for example, and the huge desk on the right with that big "thing" sitting on it: those will have to go. Acousti symmetry is very important for the front half of the room, and you don't have it at all! Here's what your speaker balance looks like:

Attachment:
LeftHandPete--FR-20-20k--L.vs.R-speaer-compare-1..48-c.png

That's unsmoothed (1/48 octave), and you can see the really wild swings there. That graph compares the level of your left channel vs. your right channel across the entire spectrum, for every single frequency. Wherever the graph curve is above the 0 dB line, your left speaker is louder, and wherever it is below the line your right speaker is louder. There's a range of over 30 dB there! :shock: That's a huge, major, room-wrecking imbalance.

OK, your ear's don't really have the resolution to hear 1/48 octave difference, but they sure do have the ability to hear at 1/12 octave, so here's what it looks like when smoothed to 1/12:

Attachment:
LeftHandPete--FR-20-20k--L.vs.R-speaer-compare-1..12.png

The swings are still really wild even at that level of smoothing, an there's still more than 20 dB variation between the speakers, but now you can see another disturbing issue: the entire graph is skew! For low frequencies, your right speaker is louder, but for high frequencies your left speaker is louder. Your entire sound stage is skewed. This is even more obvious at 1/6 octave smoothing:

Attachment:
LeftHandPete--FR-20-20k--L.vs.R-speaer-compare-1..6-c.png

You can clearly see how the curve slopes upwards to the right: it should be flat and level.

Specifications for critical listening rooms call for that line to be dead flat: no more than 1 dB difference. Here's what the 1/12 octave curve should look like:
Attachment:
Frank-REW-FR-20-20k-speaker-compare-Baffles-on-1..12.png


That's from the room linked above, which isn't finished yet, but we are already beating the specs on that point. The speakers are nearly perfectly balanced. Yours are not... In your case, part of that is the clutter, part is probably the signal chain or speaker setup, and part is the room itself. That needs to be fixed.

Quote:
Above the mix position I have two clouds which measure 24x84, filled with R13
Details please! How were they built? Materials, angles, thicknesses, etc.

The rear wall pic shows some type of triangular protrusion that isn't shown on the diagram: What is that, and how was it built?

Quote:
Any insight or guidance is greatly appreciated, thanks!
If you really want your room to be as good as it can be, I'd suggest that instead of trying to fix it the way it is, you start over from zero by gutting it: take everything out: all of the treatment, all of the clutter, all of the everything, and start again. Start with a REW test in the empty room. Then flush-mount ("soffit mount") your two best speakers, in a properly designed soffit (see the thread for details....), set up your desk and chair at the correct location (determined acoustically), build major bass trapping for the rear wall, and re-do the treatment on the side walls, as well as the cloud. Do REW tests at each point in the process to check that things are working correctly, and adapt your treatment plan as necessary to deal with each result. If you follow the thread all the way through, you should get a good idea of how the room-tuning process goes. That room is nearly done: just a couple more weeks and he'll be able to hang out his shingle and start making music!

There's decent possibilities for your room, since you have the high ceiling, and that's a big plus. But my basic suggestion would be to take out everything and start again. I don't think it is worth trying to figure out what is wrong and fix it: much better to start with an empty slate. I'm not sure if you can do that on the budget you mentioned, though: it will probably cost more than 3k, if you go the full RFZ style room with soffit-mounted speakers. You might be able to do it for 3 k, but it would be tight.


- Stuart -


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PostPosted: Tue Sep 11, 2018 3:50 pm 
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Hi Pete.... Save your materials if you gut the room. Looks like you've got a lot of insulation and fabric there, maybe even the lumber....You probably already thought of that, but I thought it worth a mention. I've definitely gotten thrifty with all of my materials over time....


Good luck!


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PostPosted: Wed Sep 12, 2018 3:22 am 
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Awesome, thanks so much. I'll take a close look at that thread and see what I can pick up from there before I begin anything else.

Quote:
If you really want your room to be as good as it can be, I'd suggest that instead of trying to fix it the way it is, you start over from zero by gutting it: take everything out: all of the treatment, all of the clutter, all of the everything, and start again. Start with a REW test in the empty room. Then flush-mount ("soffit mount") your two best speakers, in a properly designed soffit, set up your desk and chair at the correct location (determined acoustically), build major bass trapping for the rear wall, and re-do the treatment on the side walls, as well as the cloud. Do REW tests at each point in the process to check that things are working correctly, and adapt your treatment plan as necessary to deal with each result. If you follow the thread all the way through, you should get a good idea of how the room-tuning process goes. That room is nearly done: just a couple more weeks and he'll be able to hang out his shingle and start making music!

There's decent possibilities for your room, since you have the high ceiling, and that's a big plus. But my basic suggestion would be to take out everything and start again. I don't think it is worth trying to figure out what is wrong and fix it: much better to start with an empty slate. I'm not sure if you can do that on the budget you mentioned, though: it will probably cost more than 3k, if you go the full RFZ style room with soffit-mounted speakers. You might be able to do it for 3 k, but it would be tight.


I was bracing myself for the possibility of completely re-doing the treatments but I wanted to measure the room in its current state to see how bad it was and if a complete overhaul was necessary; which it seems to be the case!

I'll have to do the 'empty room' measurements very strategically as we have sessions going on in here at least 4 days out of the week and that's pretty much the case till December (hopefully we can get this room renovated in Dec during some of our holiday downtime);
I'll do some measuring and reorienting of the speakers first to try and get those better honed in. In order to measure the room without the treatments but have everything put back in time for the next sessions, I will have to keep the framing for the corner traps and clouds in tact; strip them of insulation and fabric, get the extraneous stuff out of the room, do the test and have everything back in within a day or so. I know it wouldn't be perfect since the room wouldn't technically be empty but do you think we would reap enough of the benefit?

Thanks
Pete

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Bricktop Recording
Chicago, IL USA
http://www.bricktoprecording.com


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PostPosted: Wed Sep 12, 2018 4:53 am 
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Location: Santiago, Chile
Quote:
(hopefully we can get this room renovated in Dec during some of our holiday downtime);
Sounds like a plan! But do allow several weeks if you are going to do the work yourself single-handed. There's lots to do! If have several experienced carpenters working at once then it can go faster, of course, but still allow enough time, as there will probably need to be some modifications to re-tune things that didn't work out properly. And planning to build in December gives you three months to plan and fully design all of your treatment. Note the key words there: "fully design"! Very important to have your complete design in place BEFORE you start! Even if things will be modified along the way, you do still need to have the complete design before you start.

Quote:
I'll do some measuring and reorienting of the speakers first to try and get those better honed in.
For the initial "baseline" test, take out all the other speakers an only use your best ones, set to flat response (not cuts or boosts applied), at identical levels (volume/gain controls set to the exact same), and set them up in the theoretical best location, tight up against the front wall of the room, an NOT angled down as you have them at present (!). The acoustic axis of the speakers must be 48" above the floor, or a little higher (maybe 49 or 50, if needed), the speakers must be exactly equidistant from the side walls (measured very accurately to the acoustic axis of the speakers, not the sides of the speaker cabinet), the mix position must be in the theoretical best location, and the speakers must be toed-in to aim at the same exact spot about 16" or so behind your head. That's roughly the right layout. Not that everything is relative to the acoustic axis of the speaker: check with your manufacturer. From the photos, I can't quite figure out if those are Eve Audio speakers, or Adam speakers? I'm guessing Adam, but not sure what model. As far as I know, Adam doesn't publish the acoustic axis location, but if you tell me the model then I can help you estimate it. Eve Audio does publish that, and in fact it is marked on the speaker itself in most cases, if you know where to look... :)

Quote:
In order to measure the room without the treatments but have everything put back in time for the next sessions, I will have to keep the framing for the corner traps and clouds in tact;
No problem. It won't make a big difference at all. Not an issue.

Quote:
I know it wouldn't be perfect since the room wouldn't technically be empty but do you think we would reap enough of the benefit?
That's fine. Just get as much stuff out as you possibly can (the desk has to say, I guess?). The baseline test is mostly about room modes, SBIR, and low end response, so leaving small items in, such as thin framing, is not going to affect that much, but get all the large stuff out, especially the clutter. The desk can stay if it has to, but do make sure it is centered (side to side), and in the location where it will be once they room is complete. That "location" is the correct spot where you can operate it comfortably while seated at the correct mix position, with your head in the center of he RFZ sweet spot...

- Stuart -

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PostPosted: Tue Oct 02, 2018 2:16 am 
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I had some time open up this past weekend and was able to clear out the room to make some room measurements with out any of the R13 insulation or clutter in the room. The only things present in the room was the console and the couch in the rear which isn't going anywhere, all the other speakers, amps and things were taken out. I took out all the other speakers as well, set the Adam A77x's to flat and got them backed up right up to the corner trap framing and spent a lot of time getting them positioned the best I could.

Here are the findings:
https://www.dropbox.com/s/pnv7ydv2puv9n ... .mdat?dl=0


Thanks
Pete

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Bricktop Recording
Chicago, IL USA
http://www.bricktoprecording.com


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