Seeking feedback on acoustic treatment and design

[Krakadon]

I don't think the first set of measurements were very good (I think I messed the calibration up and I also left the ceiling fan on, doh!) so I don't think the comparison is very meaningful unfortunately. I do plan to take some baseline measurements of the room but a) I want to upgrade my radio shack SPL meter and Behringer ECM8000 first and b) it will take a long time to take everything out (and since I don't have anywhere to store it, but it back in) so I don't know how soon I can do that. Yes it would have been infinitely easier when I moved in before I moved my stuff in (doh! again). I did take measurements with the doors closed and open but the difference observed was far smaller than I expected to see. Leaving the front door open isn't really an option anyway do to the weather, insects, road noise and my neighbors who let their dogs bark non-stop all day and night.

Regarding super chunks, are there some designs you can point to?

 

[Krakadon]

Update 171102

UPDATE 171102

Completed:
• Removed ceiling fan blades.
• Removed polysorbers from sidewall/ceiling corners flanking sweet spot.
• Reworked front corner bass traps. Removed diffusion grates, limp mass membranes and 6” of 8 lb./ft^3 and replaced with 8” of OC703. Once I complete the Superchunk bass traps, I’ll relocated all six of the reworked 8” bass traps to the ceiling/wall corners. Also, since I have a ton of 8 lb. Roxul and some OC703 scraps, I shredded them into fluff (<2 lb./ft^2) and mixed them 1:1 then put them into small garbage bag “cells” which I tacked behind the front corner traps. Putting them into cells prevents them from settling to the bottom which increases density and unbalances the trap. Depending on the feedback I get, I plan to put them behind the 8” traps when I put them up on the wall/ceiling corners.
• Took new REW measurements and uploaded to Google Drive (link below). These measurements I think are of decent quality. Also, I took all seven measurements (-L,-R,-LR,-S,-SL,-SR,-SLR).
• The results are a definite improvement but there is still are nulls at 100Hz, 3-6kHz and 13kHz.
• Regarding the high frequency nulls, I tried to move things around and put up some hard board and plywood here and there just to see if I could improve them but I didn’t really so I’m not sure what do to there.
• Regarding the sub, no matter where I placed it or set the crossover the results weren’t very good. It increased the reach towards 20Hz but exaggerated the null at 100Hz and also cut out a huge chunk all the way down to 60Hz. It seems there is no point using it until I add more trapping except to check the kick on EDM or whatever.

Galaxy 51 Acoustic Treatment – Google Drive

Planned:
• Remove limp mass membranes from rear traps and add additional OC703 to fit gap.
• Build floor to ceiling Superchunk traps in front corners. Someone suggested putting peg board on the front as a possibility. I’m thinking of taking some hardboard and drilling out holes in some type of pattern and putting in on the front of the Superchunks in the front corners.
• Move 6 reworked old bass traps to ceiling/wall corners.
• Build 2 additional framed 8” OC703 traps for back corner behind door where I can’t fit Superchunks.
• Upgrade RadioShack SPL meter and Behringer ECM8000 calibration mic.
• Retest room.
• Remove everything from room and do baseline characterization (this will take several days and take my studio off-line so I don’t know when I can get to this. All of the other stuff I can do in the margins so to speak).
• Solicit input for revisions.

 

[miroslav]

The one thing that puzzles me, and I've mentioned it before, is that it appears every time you do measurements, you seem to change your reference level...?
Doing that would make comparisons invalid, as different levels will generate different amounts of null/peak.
80-82 dB SPL would be the recommended/monitor calibrated level using the pink noise generator...one speaker at a time.

I also asked if you ARE measuring one speaker at a time...or both together...?

 

[Krakadon]

The one thing that puzzles me, and I've mentioned it before, is that it appears every time you do measurements, you seem to change your reference level...?
Doing that would make comparisons invalid, as different levels will generate different amounts of null/peak.
80-82 dB SPL would be the recommended/monitor calibrated level using the pink noise generator...one speaker at a time.

I also asked if you ARE measuring one speaker at a time...or both together...?

I think (hope) I"m getting better at it. I follow Soundman2020's procedure from the Recording Studio Design Forum. I set the level of each speaker independantly to 80dB while REW plays -12dBFS. He recommends you also calibrate with the REW SPL meter (I think you use only one speaker for this step and I think I messed up and used two at least once). I'm not sure how that affects the final level. I need to remember to set the mic input gain to the same level each time. With my ECM8000 and Apollo I have to set the input gain quite high to get the input level to -20dBFS. This makes me uncomfortable that it might hiss, but the Apollo is pretty good to go to this level I guess. I was setting it at 45dB of gain. This time I used 50dB of gain. I put a mark on the floor and use a permanent plumb bob I made for this purpose to try to get the capsule in exactly the same spot every time (i.e. 58" from the front wall on the centerline at 50" height with a 60 degree angle on the mic). Regarding the subwoofer measurements, I wasn't sure how to calibrate the sub. I set the crossover to the highest frequency (90Hz I think), selected "use subwoofer test signal" in REW and also set the level to 80dB.

 

[miroslav]

In REW you have the SPL meter, and a way to calibrate it.
You choose the level you want to use, hit the calibrate option and you get Pink Noise, through one speaker, while monitoring your RS SPL meter placed at the proper measuring point/distance.
You then adjust your monitor level until your RS SPL meter is registering 80 dB SPL...and at that point you hit the Set/OK button on the REW SPL meter, so now it knows that your room level is the same as what the REW SPL meter is showing.

After that...don't touch the mic gain, or monitor levels...that's it.

I just keep seeing substantially different levels in your measurements...so making comparisons is pointless.
Plus...if you monitor at 80 db SPL...but you use 70 db SPL level to measure, or 90 dB SPL...then your monitoring at 80 dB SPL is not going to deliver the same frequency response in the room as what your measurements showed.

Why don't you just use the RS meter mic and avoid having to mess with mic gain...then take a feed from the meter output to your interface.
Also use the RS meter calibration offset that comes with REW. There are a couple specific to the RS meters, just pick the one that matches your RS meter model.
OK...it's not the best mic reference mic...but at least REW has the calibration for it to make it usable and consistent.

 

[Krakadon]

Wow thanks for the reply. I need to think this through and try it. Let me get back to you.

 

[Krakadon]

Update 171114

Completed:
• Reworked all six old bass traps. They are now 2’x4’x8” OC703 and have been relocated to wall/ceiling corners. Behind each trap is two plastic bags of <2 lb./ft^3 of 1:1 Roxul/OC703 fluff.
• Built and installed floor to ceiling Superchunk bass traps in front corners (24”x24”x36”). Put a lattice of vertical slats in front of traps (1.5”, equidistant, 70% coverage). I did this with cheap furring strip, but I like the way it looks and would love to upgrade to a premium finish appearance board, such as select pine from Home Depot, assuming it doesn’t get shredded by the acousticians of course.
• Built and installed a large columnar bass trap in left rear corner where a Superchunk can’t fit. It is 2’ wide, 8’9” tall and has 12 inches of OC703. Also has lattice in front like Superchunks.
• Built and installed 46”x52”x3” Roxul 8 lb./ft^3 broadband absorber trap to cover the brick fireplace. Finished with vertical slats (1.5”, equidistant, 70% coverage).
• Relocated 2’x’4’2” OC703 broadband absorber that was in front of fireplace to hang in front of rear wall broadband absorber increasing the depth to 6” in the area behind the sweet spot.
• Took new REW measurement.
• Updated slides.

Galaxy 51 Acoustic Treatment – Google Drive

Planned:
• Upgrade RadioShack SPL meter and Behringer ECM8000 calibration mic.
• Remove everything from room and do baseline characterization (this will take several days and take my studio off-line so I don’t know when I can get to this. All of the other stuff I can do in the margins so to speak, maybe over holidays).
• ??? – Not sure where to go from here. It is disappointing to see how little $450 of additional OC703 impacts the room response. There are a couple of spots where I can add some panels (~2’ superchunks in wall ceiling corner above door and fireplace, 2’x4’x6” panel across floor wall corner on left side of room). Other than that, I can add a ton more treatment on the back wall and maybe add more treatment to the ceiling.
• Solicit input – OK I’M OFFICIALLY SOLICITING INPUT. WHERE DO I GO FROM HERE?

 

[Krakadon]

Update 171118

Here is the latest update. I don't know how much further I will go until I replace the KRK 10S subwoofer (planning to add Adam 10S) and new SPL meter and measurement mic. It depends on the feedback I get from people.

UPDATE 171118

Completed:
• Repositioned subwoofer (after testing many positions) to optimize low end response
• Repositioned sidewall broadband absorbers to get into reflection zone
• Added equidistant 1.5” vertical slats (70% coverage) set 1.25” from face of rear broadband absorber on each side which is not in reflection zone
• Added 2’x4’x3/16” wood panels (horizontal orientation) with equidistant 2.5”d circles (70% coverage) to the face of the top corner treatments on the side walls and rear wall
• Added 2’x4’x3/16” wood panel (vertical orientation) with equidistant 2.5”d circles (70% coverage) to the face of the top corner treatments on front wall (they curve up over the top of the ceiling cloud)
• Took new REW measurement.
• Updated slides.

Galaxy 51 Acoustic Treatment – Google Drive

Planned:
• Upgrade RadioShack SPL meter and Behringer ECM8000 calibration mic
• Replace KRK 10S sub with Adam Sub10
• Remove everything from room and do baseline characterization (this will take several days and take my studio off-line so I don’t know when I can get to this. All of the other stuff I can do in the margins so to speak, maybe over holidays).
• Solicit input

 

[Krakadon]

I can't get the pics to upload for some reason but you can see them and the REW mdat file on Google Drive (see link above). Here are some REW results.

 

[rainton]

Wow great info on here!

I also went down the same road.
If I can add something - it might be of value to you, but you can decide for yourself

My last setup was ADAM P11 nearfields + an ADAM Sub 10 MK2

And I invested a lot of time measuring and treating my room. And even though when adding the Sub 10Mk2 to my P11 it made Stereo definition much better,
since it seemed to take some stress off the P11s.

But in general I found working with a subwoofer was extremely tricky in terms of where to place it.
I always ended up with some kind of phase issues.

At some point I had the chance to get a pair of ADAM S3X-H for relatively little money - like 2.5K for the pair - and they replace both P11s + the sub.

And the difference was night and day!!

The bass response seemed so much more under control and all phase issues were completely gone

I know 2.5k is still a lot of money, and I'm sure it doesn't have to be S3X-Hs, I just read you're thinking about getting an ADAM Sub10, so I thought I'd share my experience

 

[Krakadon]

At some point I had the chance to get a pair of ADAM S3X-H for relatively little money - like 2.5K for the pair - and they replace both P11s + the sub.

Thanks for sharing. A pair of ADAM S3X-H is $8k new. $2.5k is an astonishingly low price for those speakers...like "where they stolen?" low, so great deal for you It might be possible to get a pair of used Focal Twin6 Be at that price. Anyway, I don't have it. I would get less than $1k for my A7X and I'm only planning to spend $1k for a used Sub10. There might be other deals I can find at that price point. I'll look into it before I pull the trigger, but I also don't want to obsess on speakers that would be a marginal improvement. The A7X sound pretty good. I'm also a little paranoid about buying expensive studio monitors (and expensive microphones) used.