Erie Sound Studio (Sandledfoot Returns)

#16

Hi All,

I'm starting to get a bit nervous on my measurements. It seems i'm either getting some significant modes or comb filtering looking at my waterfall plots. The significant caviot is that i still don't have the door installed, but I will remedy that this week. (the doors have arrived and are mostly done, I just need to install the door bottom. I will re-test after the door.

I feel like i'm getting the decay down, but there is something going on.

I posted the MDAT on my sharedrive (https://drive.google.com/file/d/1a6LR2zo0ObCiGBnH76wSt5qm73nxuNFX/view?usp=sharing).

Any input would be helpful.
Cheers,
Kevin

#17

Hi Erie,

May you post yout .mdat file here in the forum? I wasn't able to find your last measurements in this thread. I just found the ones from the empty room.

Cheers,

Eric

#18

Eric, All,

I didn't realize the share link was file specific, not to the folder. (I also edited the post above to include the link above)
https://drive.google.com/file/d/1a6LR2zo0ObCiGBnH76wSt5qm73nxuNFX/view?usp=sharing

The first photo shows both clouds, and the 'temporary' absorption panel on the side. I added these to see if I was getting artifacts from the side wing walls. You will see them in the mdat files as "ESS_LR_2xcld_side_Pr". They do not have much impact (as i was suspecting).

I also need to note that I committed a cardinal sin, and changed mics through testing! I had previously been using an old behringer :oops:

measurement mic, but I ordered a new presonus PRM1. You will see the first couple measurements with the behringer, then re-ran the tests with the PRM1. The baseline tests were only done with the behringer mic, I didn't get the PRM1 in time for those. When comparing the two, they line up fairly well, so I don't believe that will impact the comparison of testing, I think mic placement is more sensitive at this point than the difference between the two mics. (Again, you can see the tests for both mics in the MDAT file.)

I was reviewing the soffit build, and noted that I still have a gap between the front wall and front edge of the baffle. I plan on filling this with wood and caulk to seal, but was waiting to see if I needed a hard or soft surface between the baffles (black wall area). I mention this, because I am now wondering if this is a source for some of my comb filtering? It seems odd, since I would expect that to only effect lower frequencies, but... I don't know. It seems odd that this would cause the problem, when I am also going to cut a speaker vent into the top of the baffle. I will try to get them properly sealed, as well as the door installed today and tomorrow and re-test.

Cheers,
Kevin

#19

MDAT:https://drive.google.com/file/d/19Cn97K2Jlqg68ZDYRvX66CPMXkAtSlDK/view?usp=sharing

So here are some additional readings after the door has been installed,

and the front baffle edges have been sealed.

I also played with changing the angle of the front cloud by two chain links.

I am looking for ways to even out the frequency response of my mix position. I'm not sure what types of treatments I should be looking at at this point.

I also see there is some extended resonance at 65hz and 95hz. I feel i'm running out of room for bass trapping, but looking for ways to tame that as well.

#20

Hi Kevin,

How is your back wall treatment?

Maybe you could make some measurements in all available locations for basstrap, in order to see where maximum pressure for these resonances is, and put in there some tuned traps.

#21

Currently back wall is two corner traps, both about 4ft across the front, the right rear trap (by the door) is about 8" deep, angled to 4" deep. The Left Rear trap is 2ft deep angled to 4". Between the traps, there is about from the floor to 30" of 4" thick rockwool batts. The corner traps are superchunks. I plan on using a few more absorption panels in the black wall area, but they will be 'moveable', not permanent. I will also use the same 'moveable' panels on the side walls. I wasn't sure adding more panels would help the comb filtering, and i didn't want to over-deaden the room.

#22

Hi Kevin,

IMHO, you already have plenty of room for treatment. Front wall between soffits, back wall at mid point, and side walls behind listening position are bare walls yet.

What I would do, but I didn't do ever, so I don't know if it would be the best way, is to take some measurements against those bare walls, in order to see where are max pressure zones for those annoying resonances at 65 and 95 hz, and if is it there any other resonances that could be interfering into the listening position, beside we couldn't see them in measurements you already took.

Then, maybe, you could try to make some tuned devices for those particular problems, and to not end up without room for being into the studio.

Let me know if there are some missing points or if it's a good idea.

Cheers,

Eric

#23

Hey Eric, all,

So i built another absorber on the rear wall. It is 3'x6'7" of 2"703 mounted 1.5" off the wall. (so a 1.5" air gap). See picture.

I took more measurements and did not really see that much of a result. I will build side wall absorbers, but I'm beginning to think I need professional assistance in treating a few of the trouble areas, and trying to get a smoother response. I posted the new MDAT to the share drive: https://drive.google.com/file/d/1JkQXALLSyv8ue9lPQLneqvA57kfGlqBa/view?usp=sharing

Speaking of which, when we look at the total SPL and waterfall plots, should we be using smoothing (it seems like it would be helpful to catch trends, but counterproductive to treat specific frequency problems.

Any feedback would be great.

cheers,
kevin

#24

sandledfoot wrote:Source of the post I took more measurements and did not really see that much of a result. I

I think it's because 2" 703 mounted 1.5" off the wall has almost nothing to do with low frequency issues. You would need either so much thicker porous treatment, or tuned devices.

Best regards,

Eric

#25

Eric,

Yes, the rear 703 I added was to improve absorption along the back wall. I knew I didn't have enough, and was going back and forth on having 'mobile' panels just hung on the wall, but I built the large absorber permanently to maximize the surface area of absorption. It did a good job cutting down some long decay overall, and I will still add additional 'mobile' panels on the side walls and that will probably also drop those 3-5k down further.

But I am not sure how to effectively even out what appears to me again trying to even out the upper freq bands. I am also not sure why I have so much falloff after 6k, or if thats normal. seems not...

There are settings on the A8X for both a High and Low shelf. before installing, I trimmed the low shelf by about 1.5db (or 3 clicks), it was a guess, based on the expected increased bass boost from soffit mounting... Those soffits are NOT easy to take off, and the speakers are not easy to pull out of their boxes, so I wanted to try to hedge a bit. If I have clear direction that I need to adjust them, I will, but wanted to get as close to dialed in as possible before resorting to removing the baffle. (Which, with the adams, you have to, since the little angle at the top keeps the speaker in).

I'm not sure what to do about the 64.6 and 97 hz... the helmhoz trap to target that may be too large for my room, and I already have every verticle corner of the room taken. The right wall/ceiling corner is a duct chase, the rear has hvac unit, so that only leaves the left corner wall-ceiling. Not sure how to approach those.

Baseline waterfall

Before rear absorber

With rear 703 absorber. cleaned up some of the long decay

i'm still trying to understand how to read this...

Can see minimal differences.

Cheers,
Kevin

#26

Hi Kevin,

sandledfoot wrote:Source of the post I am also not sure why I have so much falloff after 6k, or if thats normal. seems not...

My bet is that 6k issue is due to different distances from L and R to de mic. If you zoom in your lasts LR measurements impulse responses, you could see that there are two spikes, almost an inch apart one from the other.

But when you look at individuals L and R measurements, that issue isn't there.

sandledfoot wrote:Source of the post If I have clear direction that I need to adjust them, I will, but wanted to get as close to dialed in as possible before resorting to removing the baffle. (Which, with the adams, you have to, since the little angle at the top keeps the speaker in).

In regard to this, I think you could already adjust low shelving a bit lower. Now it looks like there is so much low frequency energy in that area. Anyway, the only way to know which is the right set is making measurements after every adjustment. By guessing, you will be wondering for ever.

sandledfoot wrote:Source of the post I'm not sure what to do about the 64.6 and 97 hz... the helmhoz trap to target that may be too large for my room, and I already have every verticle corner of the room taken. The right wall/ceiling corner is a duct chase, the rear has hvac unit, so that only leaves the left corner wall-ceiling. Not sure how to approach those.

As I mentioned early in this topic, you could take some more measurements right against the naked surfaces, where you could then make and put there some tuned devices. They could be helmholtz or membrane absorbers, but first I think the most important thing is to find out where these resonances build up and have more pressure, and also why they are there, between which surfaces they build up. As these devices are hard to tune, you should know that once they're finished, you may have to retune them if they don't seem to work at first attempt.

Cheers,

Eric

#27

OK,

so after much adjustment of the speakers here's what i ended up with (green was final).
grey (ESS LR Baseline) -- Low -1.5db, High +0db tweeter +0
orange (ESS LR Shelf) - -Low -4db, High +1.5db tweeter +0
blue (ESS LR Shelf 2) Low -6db, High +1.5db tweeter +75%
purple (ESS LR Shelf 3) Low -6db, High +6db tweeter +75%
green (ESS LR Shelf 4) Low -6db, High +6db tweeter +0%

added the front cloud and desks...

just wondering how much i should be chasing down, and when I might consider further tweaks with a miniDSP eq?
i'm really surprised how much variation I am still seeing in the mids thru the highs...

cheers,
kevin

PS - i've contacted ADAM about the hi/low shelf eqs for more information, (the manual is confusing) they have responded, but I am hoping for further clarification before I post any details.

#28

Greetings Kevin,

Beautiful! Really looks nice with the desks added.

All the best,

Paul

#29

I'm playing catch-up on really old threads, now that I'm getting back into the swing of things after a longish absence! This seems to be the oldest thread, so I'm starting here. And hopefully, the comments are still useful!
As Eric mentioned, there's some pretty good improvements in the response, and I'm sure it sounds a lot better, but it seems to me there is still room for further improvement. Specifically, the 60 Hz "hump", and the 300 Hz, "hump" look problematic. Perhaps one or more of the following would help:

1) Limp membrane traps at the key pressure points for the problematic frequencies (limp membrane traps are pressure-based, not velocity based, so they do well against walls and in corners....)
2) Add one (or better: two!) subs, and tune them in both position, timing, phase, and level, along with the mains, to create a plan-wave bass array. That can do magical things, when done right to cancel out modes and other stuff. It does need careful analysis and careful tuning, though. Usually only works for one (maybe two) locations in the room, but that's fine because the key location is the mix position.
3) Digital tuning. Sometimes incorrectly called "room correction". Don't get me started on that huge misnomer! it is impossible to "correct" the "room" with software, but you sure can correct for some types of acoustic issues. Also needs careful analysis and tuning, but can achieve good results, when done correctly. Also generally only works well for one (maybe two) locations.

I suspect you could get some significant additional improvements with these options.

- Stuart -

#30

Stuart,

Thanks for the response. I have been thinking of adding subs for that purpose (the Adams A8Xs have fantastic low end response), but I don't think I have the physical space for additional traps... I have verticle corner traps in the rear corners, the right hand ceiling/wall is a duct chase, and the front wall is soffit. I did pick up a MiniDSP SHD (Dirac) digital EQ and was going to start that process this weekend to see how far I can get. I chose that particular EQ due to the input/output options, and after looking at the Dirac software, seems pretty good... so I'm hoping it works for my purposes. Not sure I'll use or be able to take advantage of the 'streaming' device side, but we'll see...
I've also thought about building a custom couch/bass trap along the back wall, which would give me a rear center corner absorber... (it would be in front of the black fabric on the back wall... part of the reason that wall is not yet trimmed out and completed yet, still trying to figure out what to do about the low end room modes.

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