How to bring highs back into a room thats "too dead"?

[Jens Eklund]

Sticky with links?

4m x 5m x 2.5m room - modal resonance problem

Room Measurement After Consulting Gearslutz

1D diffusor - vertical or horizontal?

[DanDan]

Usually a lot of absorption creates a MF and HF reflection free zone around the source and mic. While this will obvious not sound lively to the ear it usually doesn't actually sound dull. Do you find conversational tone dull outdoors?
The much dumber mono mic makes this blatantly obvious. Dead vocal booths deliver sparkling clear vocals due to the lack of reflections. Problems can occur if your LF treatment is inadequate at the bottom end of the vocal range. e.g. A square room resonating at 80Hz needs extensive LF treatment. However do note that such modes have locations. e.g. A cubic room resonating at 80Hz will have little or no 80Hz at half height, room centre.
The lack of reflections can be disconcerting. However, unlike acoustic guitar, fiddle, drums, the vocal chords are not significantly affected by room return.
Thus you can easily establish exactly whatever you need to perform using decent headphones and a good reverb.

DD

[Maverick87]

Well for a little while I just had the four superchunks in all the corners and 9 denser panels around the room, and just speaking in the room sounding nice and crisp and clear. I like a little distance from the condensor microphone Im using(cant stand muddy, boomy, proximity effect), and I noticed when I would solo vocal tracks in my DAW, it sounded too open, like I could hear too much of the room.

After that I decided to add the three movable gobo panels that I put to the two sides of my mixing and tracking position, and behind me(the wall that the monitors are FACING, back wall??) The one behind me is actually doubled up, two side by side 3" thick panels of Safe n Sound, and two more on the back. All three are wrapped in pretty breathable burlap.

Originally I was going to bring them close to me since the problem I was having was the vocals sounding too 'open', but now it made things sound boomy. I mean it sounds unnatural. Before when you talked in the room it had a very nice clean tone and there was already broadband absorbption going on. Now it sounds just dead.

Maybe this is what some people prefer, but I actually think its affecting how my mixes translate. I like the fact that its dead enough where I can accurately measure when I'm adding reverbs and things like that.

But it seems like when mixing, I overcompensate what appears to be dead sounding vocals(plus hearing them in the same dead sounding room) by adding more mid highs and high. When I check my mixes elsewhere for reference in playback systems that I'm very familiar with, the vocals sound weak, lacking low end(usually a result of too much high pass filtering out this boomy effect).

Its like I wish I could maintain having the most fiberglass for the low end absorbption, but want that old crispness that my room had before. Thats where I started thinking, maybe I can just cover the gobos with something that will bring some highs back in the room, then Ill get a little bit of that natural clarity back.

For me, since Ive experienced the "too open" and now the "too dead", its crucial for me that I find that perfect in-between and how to effectively get there. With all the bass trapping(broadband trapping really, since it's all just fiberglass and fabric), I cant imagine that I somehow added boominess and muddiness with adding the gobo panels. It makes sense to me that so many highs are being eaten up, that the room APPEARS boomy and woofy. If this sounds like Im way off please steer me in the right direction.

Something I just thought of as Im typing this... Im looking at the three gobos as the cause of the overkill of trapping, so these are the ones I was looking to add either the wood slats or plastic or whatever(this is where Im VERY interested in learning about)to. BUT... considering these three gobos are placed where early reflections from the mixing/tracking position occur, would I be making a crucial mistake by treating them like that? After all people make it a point to if anywhere, deaden those refleciton points dont they? Im just so lost on where to go from here, and am trying hard to figure out how to not take any steps backwards.

[Maverick87]

I remember stepping into an isolation booth at a friends basement studio some years ago, and it had nothing but foam in it. I remember that when I closed the door there was almost like a vaccum-like effect, where you could even hear yourself breathing. I never understood it since foam is supposed to eat up mids n highs and leave you with muddiness. Before the gobos, my room(while an average sized room, is still way larger than that booth I was in) lacked the vaccum like effect, but the clarity in speech and when I was tracking was very similar.

DanDan, what you describe is what Im trying to acheive, that dead that has the clarity. I feel like I had the clarity but needed less open-ness, now I have too much dead and not enough clarity and natural room sound.

What I was REALLY hoping too accomplish, was something I could put on the gobos that would give me highs back at least while tracking. This way if the slats/plastic/whatever had a negative effect when it came to mixing, it would be something I can easily add and remove for when I transition from tracking to mixing.

[Adhoc]

You could place slats in a binary sequence on a frame and hang the frame in front of the insulation when needed. An alternative could be plywood sheets with or without a milled or drilled hole pattern. I did both in my room with the latter according to RPGs BAD panel sequence for the holes (Ø10 mm instead of RPGs Ø ½”). Result was about 0,1 second improvement (longer) for midrange and high frequencies. (Low frequencies should have been improved as well = shorter ringing, as the BAD-panel versions were built as Helmholtz boxes). Treated area which was previously only absorbtive area: About 12 m² (129 ft²), => 9,5 m² (102 ft²) got 50% covering with binary slats and 2,5 m² (27 ft²) got BADs.

Diagrams (provided by Jens Eklund) show simulations of 190 mm absorbtion+cloth only vs the BADs with 260 mm + plywood (blue curve with low density glassfiber, 7 kPa, and red curve with higher density glassfiber, 33 kPa)





Before:



After:







As you see, this is a listening room only for pleasure, no music production or mixing but from the diagrams you should get an idea what some hard treatment on top of absorbtive surfaces can accomplish.

[Maverick87]

Which is more effective for what I'm trying to accomplish? Slats cut into strips? Or the plywood with drilled holes? Both seem pretty easy to make.

I read another thread that confirmed my suspicion that making the gobos more reflective is both counter productive and plain silly(since they are placed at early reflection points). Is that correct? Sort of an inconvenience since IMO they're the direct cause of the dead sound I'm dealing with.

If it is then I don't see any way around getting rid of at least one or two of the gobos and seeing how it sounds. Having the three gave me a more symmetrical design of absorbption so this is a last resort.

[DanDan]

I am confused Maverick. There is something amiss here.
The close gobos should deliver crisp reflection free transmission from mouth to mic or speaker to ear. Something must be causing the boom when you move the gobos around the mic. This should not be happening. Perhap your gobos are somewhat reflective. Have you tried measuring with and without gobos?
ETC can be broken into frequency bands to show the reflection (i.e. inverse absorption) spectrum.

Even a recorded example would be useful. I could probably tell early reflection combing from the later room tone, if any.



DD

[Adhoc]

The slats (as they are usually presented on GS) give a 50% perforation open to the underlaying resistive absorber material. Such a high perforation means “no help” for low frequency absorbtion while giving reflection( and some diffusion due to edge diffraction) for higher frequencies => some more “liveness” to the room. RPGs BAD with hole diameter of ½” has less than half that perforation, about 22%, and will of course reflect more of higher frequencies, diffusion is improved due to the hole pattern compared to slats (still not phase delayed diffusion as the panels are flat). If the panel is fixed to an air tight box with insulation inside, you also get a helmholtz device and low frequency absorbtion will be improved, besides the added liveness. Choosing smaller holes => less perforation => increased reflection / liveness + increased low frequency absorbtion.

[Youn]

I always wondered how effective placing paper or cardboard around the room would be to bring back some HF liveliness... would be cheaper/easier to try then wood slats... anyone ever done this? Maybe hang some posters/pictures on an as-needed basis, also depending on the vibe you are going for... just an idea