Odd shaped control Room

[betserd]

Hey All,

I'm in the process of setting up a control room that is not an exact rectangle (height is 300cm);


I have some questions about this room;

1) What would be the best wall to set up the speakers, A or B or C
Personally I thought that using A might cause some troubles with the door on the east wall, since that makes it hard to control early reflections from the east. Secondly I thought that position B might screw up the stereo image with the different length of rear walls and some strange reflections coming from it. These are all not well fundated so please give me some advise on this.

2) How will the roommodes behave in this room. My thinking was that it's a combination of two rooms one which is 451x308x300 and one that is 451x348x300. Is that a correct assumption? Below are the roommodes in graphic from ethan's ModeCalc;






The 348 width has a much more even spacing of the modes, is this telling me that sitting in position A will be better (that's where your ears are) or position B (the sound will travel backwards so better to have it trapped in a space with more even modes and put basstrapping there).

Lots of questions thanks for looking into this!

Bastiaan

[johndykstra]

definately not b, you want to fire the longest dimension of the room.

i would favor c over a, because there's no wall jutting out to reflect back at you from behind.

as far as the room modes go, I believe you use an average of the two, but come to think of it, I had learned that about a consistantly slanted surface, so in your case, I have no clue.

[Ethan Winer]

I agree with C.

How will the roommodes behave in this room.

It almost doesn't matter because you need as much bass trapping as you can manage regardless.

--Ethan

[betserd]

dijkstra & ethan thanks for your thoughts. I have used the recommended place and started drawing everything in place. I'm quite pleased with the result, but maybe some akoustic feedback can improve the whole thing.

The desk etc are not the ones to be used, this is just for the mockup.

Please let me know what you guys think!

[Weasel9992]

Looks great except for one thing: the very last thing in the world you need on that back wall is diffusion. A.) the room is two small, and B.) you'll need that back wall for bass trapping. If you put diffusion there you're going to solve a tiny problem and create a huge one...some of the biggest peaks and lowest valleys will come off an untreated back wall. Bass trapping, bass trapping, bass trapping...6" traps with at least 4" of air space if you can manage it.

Frank

[betserd]

Ok I changed the diffusor with three more basstraps on stands (there's a window so they cannot be attached to the wall). They are 10cm thick and 30 cm away from the wall.




I calculated the RT60 time and the following graph is the result.




It looks ok to me although I really hate rooms that sound too dull. The High frequencies are suffering quite a bit under all the basstrapping. Am I just taking this graph too serious or should I change some of the basstraps in the back to paneltraps or helmholtz resonators to improve the sound?

Any suggestions are more then welcome.

[Glenn Kuras]

I am not going to disagree with Frank because he is RIGHT, but add that if you do want to use diffusion there is no reason you can not divide up the back wall and have both. Right behind you I would put the absorption, but there is no reason that you could not put diffusion (polys, skylines, QRDs) around that. Also you can put the diffusion on the back side walls.

Glenn

[betserd]

thanks for all the advise. I did some measurements today with room EQ in the room and it was quite flat except for two dips, which were not that bad.
So it looks like a very good startingpoint and it will only get much better. I'll try to post some pictures of the installation and a pre and post measurement if that is interesting?

[DanDan]

Nice sketches. I think you will find the apparent HF roll off is very welcome.
That calculated stuff looks great, don't be disappointed when real world measurements don't come out so good. Or don't measure! (see my primer)
I will offer a couple of tweaks.
More Bass Trapping is always welcome. I would change those stand mounted ones to another Superchunk or TriTraps mounted across the back in the Ceiling Wall corner junction. If you chose to do this you will need some HF treatment to stop a flutter echo between your behind window and front wall. A single MicroTrap worked for me. There will be strong flutter echo between those parallel walls behind you. There will also be flutter between that wooden floor and gyp ceiling behind you. Those flutters will be bad and will need HF treatment. A cloud or a rug. A wall hanging perhaps with 703 behind, or of course commercial panels.
Best Regards, DD
Sound Sound - Homepage

[betserd]

Originally Posted by DanDan

There will be strong flutter echo between those parallel walls behind you. There will also be flutter between that wooden floor and gyp ceiling behind you. Those flutters will be bad and will need HF treatment. A cloud or a rug. A wall hanging perhaps with 703 behind, or of course commercial panels.

If I go with HF absorbtion there to avoid the flutter echoes, where is the best place to hang it and how much? This is always something I have found hard to get, there seems to be no calculation on how much % of the wall should be covered and where exactly to hang it (bottom, middle, top)..

[Weasel9992]

Originally Posted by betserd

If I go with HF absorbtion there to avoid the flutter echoes, where is the best place to hang it and how much? This is always something I have found hard to get, there seems to be no calculation on how much % of the wall should be covered and where exactly to hang it (bottom, middle, top)..

That's because there is no such calculation, and the few papers that have been written disagree. Every room is different, so each has to be treated on its own merit.

Frank

[DanDan]

You will need- Yourself , a friend, and a Sheet of 703 or a MicroTrap or such.
Go into the suspected problem area. Clap your hands. Move around, you will easily find the best triggering spot. Visually you will probably see two parallel surfaces opposite each other. Have the friend hold the panel over one of the surfaces. Clap and tweak. You will find the spot that kills the flutter very accurately.
I have used a MicroTrap but some here use 4 inch. Either will kill the flutter. The 4 inch will remove some honk. Go with what is practical.
If you chose a wall hanging, make sure it is thick and absorbent, not an oil painting. Ethic wool rugs can be nice. Leave a gap behind.

DD

[Glenn Kuras]

Originally Posted by DanDan

You will need- Yourself , a friend, and a Sheet of 703 or a MicroTrap or such.
Go into the suspected problem area. Clap your hands. Move around, you will easily find the best triggering spot. Visually you will probably see two parallel surfaces opposite each other. Have the friend hold the panel over one of the surfaces. Clap and tweak. You will find the spot that kills the flutter very accurately.
I have used a MicroTrap but some here use 4 inch. Either will kill the flutter. The 4 inch will remove some honk. Go with what is practical.
If you chose a wall hanging, make sure it is thick and absorbent, not an oil painting. Ethic wool rugs can be nice. Leave a gap behind.

DD

Actually Dan a cool trick is to play a clap through your monitors and see what flutter you here from the mix spot.

[DanDan]

Glenn, what does it take to get them to do that?
My monitors never clap for me!
Very good idea.
DD

[betserd]

Originally Posted by Glenn Kuras

Actually Dan a cool trick is to play a clap through your monitors and see what flutter you here from the mix spot.

No need for a friend anymore..

But that does raise a question, since how important is flutter echo in the rear of the room if me and my monitors are in the front? When walking around any given room most of the times you can hear only flutter echo when you're producing the clap in that spot as well and not when somebody else claps in a different location.
So although you might hear the flutter when you are at the back of the room and clap there but not when playing something back at the monitors (the clap) it could be left untreated?

Please read this as ignorance instaed of stubbornness

[johndykstra]

well, you still need the friend to move the panel around. the use of the monitors is to measure exactly the effect you are talking about in the second half of your post. what effect does the flutter have on the material coming out of your monitors, not a clap generated from an arbitray location

[Glenn Kuras]

Originally Posted by betserd

No need for a friend anymore..

But that does raise a question, since how important is flutter echo in the rear of the room if me and my monitors are in the front? When walking around any given room most of the times you can hear only flutter echo when you're producing the clap in that spot as well and not when somebody else claps in a different location.
So how likely is that flutter will be produced and in the rear section and then influence the listeners position?

Please read this as ignorance instaed of stubbornness

What matters is what can be heard from the mix spot and yes you may here it from the back of the room when sitting in the mix spot.

[Glenn Kuras]

Originally Posted by DanDan

Glenn, what does it take to get them to do that?
My monitors never clap for me!
Very good idea.
DD

Well I guess you could record a clap or kick one out from the drum moecheen!

[johndykstra]

Originally Posted by Glenn Kuras

Well I guess you could record a clap or kick one out from the drum moecheen!

making sure you record a flutterless clap of course

[betserd]

Originally Posted by dykstraster@gmai

well, you still need the friend to move the panel around. the use of the monitors is to measure exactly the effect you are talking about in the second half of your post. what effect does the flutter have on the material coming out of your monitors, not a clap generated from an arbitray location

Originally Posted by Glenn Kuras

What matters is what can be heard from the mix spot and yes you may here it from the back of the room when sitting in the mix spot.

Great, luckily things remain understandable. Then I leave the rear of the room as is, until all is setup and then some tests must provide a clue on how to treat it.

I was thinking about milling a couple of those flutter free strips, so that could be a nice test as well to see how they affect the situation.

[DanDan]

Glenn's version is more pragmatic, addressing specifically what you hear it at the mix position. Clearly he also has no friends :-)
Mine is a seek and destroy approach. Flutter is quite position sensitive. Your monitors may not provoke it as much as a clap in exactly the right spot. My version may be overkill, but what about listeners sitting back there, or you may want to record a vocal or such there?
You will find Flutter becomes very audible when your other treament is done.

DD

[Glenn Kuras]

Glenn's version is more pragmatic, addressing specifically what you hear it at the mix position. Clearly he also has no friends :-)

PROVE IT!!!!!!!

Mine is a seek and destroy approach. Flutter is quite position sensitive. Your monitors may not provoke it as much as a clap in exactly the right spot. My version may be overkill, but what about listeners sitting back there, or you may want to record a vocal or such there?

good point. thumbsup

You will find Flutter becomes very audible when your other treament is done.

sad but true, but proves how bad other problems really where.

[betserd]

Originally Posted by Glenn Kuras

Ethan Winer This message has been deleted by Ethan Winer. Reason: Just kidding around with my main man Glenn

Yesterday, 09:27 PM Glenn Kuras This message has been deleted by Glenn Kuras. Reason:

Yesterday, 09:32 PM dykstraster@gmai This message has been deleted by dykstraster@gmai. Reason: well that wasn't any fun was it?

Yesterday, 09:36 PM Glenn Kuras This message has been deleted by Glenn Kuras. Reason:

Wow, what was that all about?????

[johndykstra]

those two were going through with drawl symptoms of the shenanigans over on the cathedral ceiling thread.

save it for the ring guys!

[betserd]

Originally Posted by DanDan

Glenn's version is more pragmatic, addressing specifically what you hear it at the mix position. Clearly he also has no friends :-)
Mine is a seek and destroy approach. Flutter is quite position sensitive. Your monitors may not provoke it as much as a clap in exactly the right spot. My version may be overkill, but what about listeners sitting back there, or you may want to record a vocal or such there?
You will find Flutter becomes very audible when your other treament is done.

DD

Yeah that's absolutely true, the room must be flexible enough to record some things like vocals. Sometimes you see a checkerboard pattern to reduce flutter echoes, is this comparable to one big sheet of absorbtion in the exact right spot (if there is such a thing like that), or will this outperform the single sheet?

[DanDan]

A chequerboard pattern should work nicely keeping a bit of life in it,
I would rather see that than a complete cover on one side and nothing on the other. However if you intend doing serious vocals back there you will need a full RFZ environment. Definitely a cloud. Vocal booths are most often totally dead, it gives a great clarity. This will sound awful on snare or fiddle or sax however, you can't have it all. Perhaps do the chequerboard, and have stand mounted traps, (MicroTraps work great) or a portable vocal booth, for the vocal occasions. I find it difficult to believe in those small Reflexion things, but that's just a gut instinct. Remember the cloud though.
I have a 2x4 panel of light rigid fibre, wrapped in Polyester. It is very easy to hold up in situ, if you, unlike Glenn, have a friend that is ;-)
Even if you have no friends, like Glenn, you can suspend it on a mic stand. A combination of this and visual clues (parallel bare hard areas) will pinpoint the worst spots easily. Why don't you just start doing it, and keep adding until you are happy. When it comes to HF trapping, that's exactly how I would do it. Do the sure things first, then add seasoning to taste.

DD

[Glenn Kuras]

Even if you have no friends, like Glenn,

would you be my friend??

[Glenn Kuras]

Perhaps do the chequerboard, and have stand mounted traps, (MicroTraps work great) or a portable vocal booth, for the vocal occasions. I find it difficult to believe in those small Reflexion things, but that's just a gut instinct. Remember the cloud though.

Actually next week we are coming out with a new panel that is 2 panels hinged together. Each panel is 17" x 6 FEET and 4" thick. The thought is a person can use it in the back corners (or front) for bass trapping (free standing) but when needed pull it out to use as a "booth" kind of thing. The nice part is you can hing as many together as you like to be used for different things. Nothing new as other people have done this, but maybe the OP might think about building something like that.

Glenn

[DanDan]

Oh all right so, one friend....
Great idea Glenn. Similar things have been done, but your R and D is repeatedly spot on. I had Tri Traps in my mind and then suddenly there they were. Speaking of which. I am not sure about the UK, but in Ireland many ceilings are 8ft. or 2.45m. Carpet and variations mean it is impossible to install two TriTraps or RealTraps. I know you do custom but perhaps it is not too late to consider EU versions over this side of the pond, rounding down in the process. 1.2 2.4 and so on.
DD

[Glenn Kuras]

Originally Posted by DanDan

Speaking of which. I am not sure about the UK, but in Ireland many ceilings are 8ft. or 2.45m. Carpet and variations mean it is impossible to install two TriTraps or RealTraps. I know you do custom but perhaps it is not too late to consider EU versions over this side of the pond, rounding down in the process. 1.2 2.4 and so on.
DD

Damn good point and will note it. The Tri Trap will be the next product to be made in the UK.

BTW thanks for being my only friend. Can I loan some money from you and crash on your couch? Oh please make sure the frig is stocked with plenty of beer and food.