help optimizing acoustics in control room

[takman]

also, in wondering about something else.

i asked in another post about this, but didnt get a reply.

since REW puts the arrival time at 0. Do we need to offset the graph by the time it would take for the direct sound to arrive?

for example if the distance from mic to speaker is 5 ft. 5 x 1.13 = 5.65 ms

so i would click controls then use the t=0 offset(ms) and set it to 5.65ms?

[rez]

good morning everybody...

can anyone comment on the uploaded rew measurements?

and might anyone say something regarding the bass traps on the door and in the back corner? what design would be most efficient for these locations when depth is an issue (about 20-30cm only)?

personally i believe that the big construction at the rear wall / roof would give the best results, but the studio owner likes to get around building that if we get the room to sound good without it.

we also think about changing the monitors to active ones (probably some adam a77x with dual woofer) and get rid of the old subwoofer for mixing.

peace, rez

[takman]

rez, focusing on the ETC, because its really important...and it integrates with your rear will QRD...

you might want to look at this thread...


LEDE room with Haas trigger

i will try to help you, since no one else has replied specifically about your graphs...but keep in mind i am not a professional, and i am learning myself....

lets compare lupos ETC to yours (second one)







looks alot different doesnt it?

compare it to what a text book ETC should look like.



after the initial direct sound, within the first 0-20ms ( more or less depending on the size of the room) you want the reflections down to at least -20db. This creates your RFZ. In lupos RFZ, he has his down to -25db, which is really good.

The length/time of the RFZ is called the ISD ( initial Signal delay) at the end of the ISD...or after the RFZ has ended, you want to re-introduce the reflections of the original sound as diffuse field. But when you re-introduce the reflections of the original sound, you want them as hot a possible....no lower than -12db....then a nice diffuse decay of that. see that spike in lupos second graph that hits -16? That matches up with the text book ETC.


The reflection panels knock down the level of the early reflections, then the QRD sends the back wall reflections back to the listening position as a diffuse field. this is the LEDE concept.

And it creates this loop, where the diffuse rear wall reflections blend in the incoming reflection free direct sound.

[takman]

rez, forgive my sloppy paint skills.

I pointed out with arrows some reflections. particularly the first one as its the hottest.....a reflection from the desk possibly? after zooming in, the first is happening quite early, less than a 1ms. maybe they should be disregarded, im not sure. although looking at lupos ETC, i dont see anything at all after the direct sound.

the second looks to be almost 2.5ms.

[johndykstra]

Originally Posted by ciro

I´d focus on the "shy" low end, you have the ~75 peak and a roll of, almost nothing below 60hz. Move your mix position and monitors to see if helps. Sub woofer between monitors is not an easy thing to deal (there´s some great posts about it here).

Ciro

As important as ETC is (and sorry for all the "off topic" discussion), I think this is (Ciro's quote above) really where you should be beginning. Adjust the speaker and/or listening position, while taking waterfall graphs of every movement and find the best possible position for the lowend. Ideally, you would have the mixer out of the room for this bit... it's presence it sure to create an acoustical anomoly, but not one we are trying to fix during positioning.

No point in focusing on early specular reflections if you aren't sure you're in the right spot yet.

[takman]

Originally Posted by johndykstra

As important as ETC is (and sorry for all the "off topic" discussion), I think this is (Ciro's quote above) really where you should be beginning. Adjust the speaker and/or listening position, while taking waterfall graphs of every movement and find the best possible position for the lowend. Ideally, you would have the mixer out of the room for this bit... it's presence it sure to create an acoustical anomoly, but not one we are trying to fix during positioning.

No point in focusing on early specular reflections if you aren't sure you're in the right spot yet.

yes you correct. I am jumping the gun with the ETC.

[rez]

thank you for the answers...

yes, experimenting with speaker placement and mix position is what i will do first. then we will add broadband bass trapping to the front corners and the front wall and see how far we get.

the four reflection areas on the console, the cloud and the side walls are identified and will be treated next.

when i have done that i will be back with some more specific questions.

when we start building the absorbers should i post the pictures in this thread or should i start a new one in the bass traps or in the pictures of studio constructions subforums?

peace, rez

[Paul Spencer]

Nice work on the rendering.

With your waterfalls, did you set the window as 300 ms? I find it can also be useful to look at the 2D decay plots. It can show some things more clearly.

One challenge I can see is that all those angles make it difficult to put in bass traps, hence the depth will be limited. How about the ceiling/wall junction?

I can see some angled panels there - are they actually bass traps? If not, could you perhaps consider using them? Let's say you have a perforated membrane on the face? This is something that I'm planning to try, using a binary arrangement like RPG BAD panels.

It looks to me like you have some pretty hairy modal ringing in there.

[rez]

hello paul,

if you look at my sketchup renders you can see big corner chunks in the front corners with a vertical extension at the front wall / ceiling corners.
these cornerchunks will be build a llittle more into the depth of the room so they actually end at the big window to the recording room and will be filled with glasswool. the two small rectangular traps at the reflection points of the side walls will not be built, because the corner chunks will reach over that area. also there is a smaller rectangular trap on the front wall between the windows. all the yellow parts in the renders and the diffusor is what i have planned to build, so the existing room is actually the outer shell in my renderings. the room was purpose built and has double drywall all around. even if soundproofing to the outside world is not important here the separation between the control room and the recording room is quite good.

the cloud is a massive woden frame with two perforated drywall plates in it. the perforation is many holes from diameter 0,5cm to 2cm. we plan to lay one layer of glasswool onto the cloud and see if it makes a difference.

at the back wall there will be a big diffusor, like 1x2m, and the rectangular bass traps in the back corner and on the door. the whole angeled area above the diffusor is another super chunk that i like to fill completely with glasswool. this big chunk is the last thing we have planned to build when all other improvement is not enough.

if this deadens the room to much i will place perforate panels or something like that over the rear traps to gain some reflections again.

on the 2d decay plot you can see the ringing at 75hz and the holes like in the waterfall, but to me it looks like i have also serious flutter echo or comb filtering problems. this can be due to the bad angles of the console and cloud or due to room reflections, because there is nearly all hard surfaces in this room now. if you like to look at the measurements yourself i have linked the rew file on the previous page of this thread.

@takman: good looking out on the "lede room with haas trigger" thread, very informative! thank you for your effort.
even if i make music for over 35 years now, and was into production and live events i´m also fairly new at accoustics. formerly i used to use good rooms so i think have a feel for what i should look for in building a room myself. on the other profession i come from a technical side so i know how to deal with technical terms and data. and i´m an crazy googler to find all the data i need for any particular problem.
with your help and the forum we can bring this room to a good accoustic and technical level (nevermind the budget, as there is none...).

peace, rez