Null 116Hz in my Studio need advice!

[AudioPostChris]

Hi,


My room is aprox 14W x 20L x 9H feet... 5.1 Mix room for Post Audio... I have deep a null @ 116hz.

My Room is well treated with multiple Realtraps and diffusers, corners, ceiling, side walls, front wall and rear wall diffusers. 52 + 4 diffusers..


I tried moving the speakers around didn't change much in the null, tried redirecting all the bottom to the sub (up to 140)... still a null.

My mix position is at 38 percent from the front wall

The null is present everywhere in the room at sitting position, if I stand or lay down on the floor it's better but that's not an option for mix position.


The null has to do with the hight and width.

I can adjust the hight of the monitor somewhat but it doesn't seem change to much (a few inches doesn't seem to be enough for a null @ 116Hz).

Bellow is frequency graph of my room mix position ( with both speakers on with Sub with Bass Management set at 85 cross over.


The null is deeper on the right side of the room, that is the foundation side of the building, the other wall are very thick drywall, steel stud with isolation.

I've used ARC software to mix in this room but I prefer not to use it ( I have hard time
getting use to the way it sounds ) and it's not surround.


Good translation is my main goal.


Anyone any advice,tips,tricks,comments?


The Studio Pix is before treatment was done to front wall ( 4 Realtraps )

[AudioPostChris]

Freq Graph and Studio Pic

[PaulP]

Originally Posted by AudioPostChris

The null is present everywhere in the room at sitting position, if I stand or lay down on the floor it's better but that's not an option for mix position.

It sure sounds like the floor-to-ceiling mode which for a 9' ceiling is 125 hz.

[Edit : oops, make that 62.5 hz. Anyway, see below...]

What's the exact height of the ceiling ?

Can you give more detail on what you've got on the floor and ceiling ?

Paul P

[AudioPostChris]

Hey PaulP,



I have a Realtrap drop ceiling not sure of hight but the real ceiling above that is sheet rock with probably cement above that the front of the room is 9'7" and the back is 8'10".


I attached a file with exact measurements.( it's the large room on the right )

[AudioPostChris]

exact room dimensions ( room to the right)

[Arksun]

This may sound obvious but, you mentioned moving the speakers to different positions but, have you tried shifting the actual seating position itself?. I realise it means also moving all the desk etc and possibly speakers again too, but it might make the difference you're after.

[AudioPostChris]

Hi Arksun,


Yes I did measurements 2-3 feet closer to the front wall and also in 4- 6 feet behind the actual mix position.


Chris

[PaulP]

Originally Posted by AudioPostChris

the front of the room is 9'7" and the back is 8'10".

Interesting.

Here's some simple math :

speed of sound / ceiling height = frequency

1125 ft/s divided by 9.58 ft = 117.4 hz

You're vertically about in the middle of the room so you're right in the center
of a 117 hz wave which is null.

The room's resonant frequency (mode), vertically, is half that at about 59 hz.

I think you'll have to do something either on the ceiling or on the floor.

Paul P

[AudioPostChris]

The ceiling is completely covered in bass trapping not sure I can make it much thicker, I could treat the floor? Build sub floor and fill it or Lay down bass traps bellow the monitors, desk and perimeter of the floor?

[PaulP]

Your room is the one in Ethan's ad for the ceiling ? I'd talk to Ethan.

Paul P

[AudioPostChris]

I had not noticed they put up the pix I sent them..... cool.....

I've been consulting regularly with James from Realtraps about the room since construction and this is the last most elusive issue to deal with.... ( Realtraps have been great to work with and consulted me on many aspects of my studio from treatment to monitor position to mix position to measurement software, )

So I'm trying to get advice and different view points from other studio builders....

[Jeffrey Hedback]

very interesting...

First, I have had to trap assymetrically to offset different building types between sidewalls...BUT I don't think that is the main issue.

I suspect the telling statement is that your test graph is with both speakers, sub and bass management. I would like to see graph with only left speaker. Then one with only right speaker. While you're at it, a sub only would be helpful. We would then know what is room and what is speaker system a lot better.

There are no glaring red flags in realm of room modes, treatments & speaker/listener position.

It could be that the calibration/bass management system is in need of tweaking???

From that point you may need to beef of thickness of right wall panels.

This type of ceiling treatment does a really good job of damping major modal peaks in uniform manner.

Hope this helps.

[Jeffrey Hedback]

actually...before new tests, where is the sub located? Exact position.

I utilize a predictive program that inputs speaker/ear location in room. Just stereo speakers...can't expose any issues at 117Hz that should be problematic at all with your treatments/room.

But, I can put a single subwoofer in area that causes major dip.

So I think it's likely in this area that the main concern lies.

[AudioPostChris]

Hi Jeffrey,


Thanks for the reply.


The sub is left corner of room facing the corner ( theirs Tri-Traps in the corners ) I tried flipping the phase not much change in the Null area but it eliminated lower nod ( bump ).

I played with LP filter on the sub I set it too low in makes null wider ( my bass Management is done by Blue Sky BMC at 85Hz )


Im away from my studio for the week-end so Im going give you my description of readings I did by memory ( Im going to try get someone at the studio to e-mail them to me )


I did measurements sub only roll off at about 150Hz and I do get the same null

Tried different speakers manufacturer "Null"

I put the sub in the mix position played 117 tone thru walk around the room found around the left speaker the sound almost dissapeared....

I did many reading probably 50, move the speakers in many directions the null was consistently there, also the measured in the back of the room and the front the middle same-thing

The one thing I did that made difference was the monitor on the floor behind my desk it lowered the Null ( around 85, if remember right )

I did Left and Right with Bass Management in Left the null dip is about minus -14 and the Right side - 24

I did reading with bass Management Off (bypass) I did have the nulls both sides

I did reading no sub null is still present

Also tried using waves surround controller and experimented with different crossover types and points...

[Arksun]

Perhaps the problem lies in a piece of equipment, a part of the audio chain thats been overlooked? either an amp, mixer, soundcard, cabling, something, anything that could be causing this issue. Just to rule that out before deciding its definitely the room, even with all that treatment.

[Jeffrey Hedback]

Just to be specific, is null present with just one of stereo pair in sweep?

If so, then it does point back to room...but I'm still not convinced its not still in speaker chain.

Frustrating though.

Where are you located?

[AudioPostChris]

Hi Jeffrey,


Thanks for the reply.


The sub is left corner of room facing the corner ( theirs Tri-Traps in the corners ) I tried flipping the phase not much change in the Null area but it eliminated lower nod ( bump ).

I played with LP filter on the sub I set it too low in makes null wider ( my bass Management is done by Blue Sky BMC at 85Hz )


Im away from my studio for the week-end so Im going give you my description of readings I did by memory ( Im going to try get someone at the studio to e-mail them to me )


I did measurements sub only roll off at about 150Hz and I do get the same null

Tried different speakers manufacturer "Null"

I put the sub in the mix position played 117 tone thru walk around the room found around the left speaker the sound almost dissapeared....

I did many reading probably 50, move the speakers in many directions the null was consistently there, also the measured in the back of the room and the front the middle same-thing

The one thing I did that made difference was the monitor on the floor behind my desk it lowered the Null ( around 85, if remember right )

I did Left and Right with Bass Management in Left the null dip is about minus -14 and the Right side - 24

I did reading with bass Management Off (bypass) I did have the nulls both sides

I did reading no sub null is still present

Also tried using waves surround controller and experimented with different crossover types and points...

[jdg]

you could try one of these.
Untitled Document

not ideal, but i've only read great things about em

edit: their dumb site uses frames.

goto: Bag End Loudspeakers 847 382 4550
then products, then professional acoustics

[AudioPostChris]

Originally Posted by Jeffrey Hedback

Just to be specific, is null present with just one of stereo pair in sweep?

If so, then it does point back to room...but I'm still not convinced its not still in speaker chain.

Frustrating though.

Where are you located?

The null is present Sub/Left/Right speakers individually and together.. the worst being the right

Im located Atlantic Coast Of Canada


Monitors chain is the following; Digi 96 I/O out to Blue Sky BMC to Speakers all Balanced


Thanks for you interest!

[AudioPostChris]

Originally Posted by jdg

you could try one of these.
Untitled Document

not ideal, but i've only read great things about em

edit: their dumb site uses frames.

goto: Bag End Loudspeakers 847 382 4550
then products, then professional acoustics

I was looking at the E-trap interesting.... but it's for 20Hz to 60Hz not sure if it would work for my problem.

[Jeffrey Hedback]

The E-Trap is solid technology and can in fact be used to fill in null (not just attack peaks below 100 Hz). So in theory it could help. There is a great case study by Bob Hodas with just such an application (google to find if curious).

Shouldn't have to go there in this room with your factors...It's just (in theory) not that problematic, expecially at 116 Hz.

Have you called BlueSky? They're very supportive and might be helpful.

I would try elevating the sub 3' above floor which would excite more modes a lesser degree...might lose some punch but find smoother response. If so, then finding an optimal speaker set-up may be approachable.

[AudioPostChris]

Originally Posted by Arksun

Perhaps the problem lies in a piece of equipment, a part of the audio chain thats been overlooked? either an amp, mixer, soundcard, cabling, something, anything that could be causing this issue. Just to rule that out before deciding its definitely the room, even with all that treatment.

I had this problem before my Blue Sky BMC, so the only thing left is my Digi 96 I/O and the cabling but it's not likely it would be the same across 3 channels...

[AudioPostChris]

Originally Posted by Jeffrey Hedback

The E-Trap is solid technology and can in fact be used to fill in null (not just attack peaks below 100 Hz). So in theory it could help. There is a great case study by Bob Hodas with just such an application (google to find if curious).

Shouldn't have to go there in this room with your factors...It's just (in theory) not that problematic, expecially at 116 Hz.

Have you called BlueSky? They're very supportive and might be helpful.

I would try elevating the sub 3' above floor which would excite more modes a lesser degree...might lose some punch but find smoother response. If so, then finding an optimal speaker set-up may be approachable.

I'll try elevating the sub I had not thought of that.....


just to clear things up I use Adam P11a and with Adam Sub 12 and use Blue Sky BMC for Bass management and volume control fed from direct from Digi 96 I/O