How to treat nulls

[Adhoc]

Originally Posted by boggy

... snip
"Totaly open" characteristic of HH absorber depends of overall design (volume of box and length of neck too), so it may not be the case with "no significant" influence. Fully closed neck opening, on contrary, is extreme case where HH absorber has no significant influence in room acoustics.

snip

In this particular case the foot print of V4 and V6 is 438x438 mm and 600x600, external height 1120 mm for both. If 16 mm wall thickness, internal volume would be around 180 and 345 L. If my memory serves me OK, neck length is about 150 mm in both case and maximum open width about 150 mm in both cases => Going on some theoretical formulas, one ends up at roughly 100 to 130 Hz tuning if fully open, more than 1 octave above the mode in the 40:ies.

[diffusor.com]

In my opinion its not possible to do meaningsfull labtest under 100 Hz on tunable HH . BTN room is a perfect example ,V-6 in the backcorners made little different in frequence respons moving them to opposite corners the dip evens out
Testing Level 1-3 basstrapps is even more meaningless becouse I use big custom built trapps for the first axielle mode witch are tuned by me or one of SMT trained Roomtuner One of many tricky part is to adapt the big trapp(diffusors are included ) to the rooms own Q-value

A pro Roomtuner have much similarity with a Piano tuner, either you do it by ears or with some kind of instrument In my case I have learnd a lot from mans best friend



Lassie = Large Array of Sound Sensors Indicating Exitation.

Seagrave Instruments LASSIE Room Analysis System - YouTube

It take some time to set up Lassie but its a very usefull and a cool tool to show the client

Lassie in action during tuning from Studio Fenix Fenix studios

I try to load the file asap

Best
Matts Odemalm
SMT AB

[ritelec]

Originally Posted by diffusor.com

In my opinion

with the way the world is going, does it really matter. many hits $$$ have been recorded,mixed and mastered in lesser rooms than are strived for here.


thank you for letting me vent.

[DanDan]

Matts, I see little or no reason why a Lab would be incapable of performing almost any acoustic test. However, I reckon in situ testing is more appropriate in context here. Our rooms generally have one low mode which is stronger and longer than others. A lab will be built to avoid this!
Here we see plenty of spectacular shortening of modes in situ. My Experiment with a Metal Panel Absorber
So I will welcome any more actual tests showing before and after your devices in actual rooms. Plse do include the actual number of units and room size so we can realistically get a sense of how efficient these are.
DD

[boggy]

Originally Posted by DanDan

.....
Here we see plenty of spectacular shortening of modes in situ. My Experiment with a Metal Panel Absorber
......

And I will add........ ....without any tuning, then it is very helpful for amateurs/enthusiasts.

[Mctwins]

Originally Posted by boggy

And I will add........ ....without any tuning, it is very helpful for amateurs/enthusiasts.

You got to be kidding, right. What about thickness, big or small plate and so on...
and not tunable??

It takes time to read all 21 pages and I will try to read all pages with an open mind. But

Feel free to expand/explain it a bit further!!

[boggy]

Originally Posted by Mctwins

......
Feel free to expand/explain it a bit further!!

It is already explained in attached thread

[SörenHjalmarsson]

Originally Posted by ritelec

with the way the world is going, does it really matter. many hits $$$ have been recorded,mixed and mastered in lesser rooms than are strived for here.

Such as: RIGS - Ken Lewis - YouTube

The only obvious treatment i can see is some foam on top of one of the high racks, just saying...

And there's more where that came from...............

[Mctwins]

Originally Posted by diffusor.com

In my opinion its not possible to do meaningsfull labtest under 100 Hz on tunable HH . BTN room is a perfect example ,V-6 in the backcorners made little different in frequence respons moving them to opposite corners the dip evens out
Testing Level 1-3 basstrapps is even more meaningless becouse I use big custom built trapps for the first axielle mode witch are tuned by me or one of SMT trained Roomtuner One of many tricky part is to adapt the big trapp(diffusors are included ) to the rooms own Q-value

A pro Roomtuner have much similarity with a Piano tuner, either you do it by ears or with some kind of instrument In my case I have learnd a lot from mans best friend




Lassie = Large Array of Sound Sensors Indicating Exitation.

Seagrave Instruments LASSIE Room Analysis System - YouTube

It take some time to set up Lassie but its a very usefull and a cool tool to show the client

Lassie in action during tuning from Studio Fenix Fenix studios

I try to load the file asap

Best
Matts Odemalm
SMT AB

So this means that.....when Lassie is used, there schould be an overall flattness of the freq response/pressure thru the entire area/volume in 3D of the room.

If this is the case, then all room schould be measured with Lassie or similar when measurering low freq behavior and not only at the LP.

EDIT: When the flatteness of the freq response/pressure is achived across the room then one dosen't need to bother/concern about the SBIR anymore. Basically, one can put the loudspeaker or LP anywhere in the room whithout altering the freq response IF the rooms Q-value has been properly tuned.

[kasmira]

Originally Posted by Mctwins

So this means that.....when Lassie is used, there schould be an overall flattness of the freq response/pressure thru the entire area/volume in 3D of the room.

If this is the case, then all room schould be measured with Lassie or similar when measurering low freq behavior and not only at the LP.

Yes, precisely Mctwins (by the way, what is your name if you don't mind me asking?)

However, using Lassie you won't get an accurate representation of comb filtering, I would think. Comb filtering at a certain frequency hits at exact spots in the room. Like, within centimeters. In other words, it could very well happen in between the mics/lights/boxes or whatever they are called. ETC measurement will show you the time that certain reflections happen, so you can see where they are coming from, like floor, wall, or desk. This may have an option for viewing ETC, but I didn't see it in the video or on the software. Even if it did, though, ETC is only useful from listening position.

That considered, it looks like a cool ass way to test your room! I bet it is pretty expensive though..

Originally Posted by Mctwins

EDIT: When the flatteness of the freq response/pressure is achived across the room then one dosen't need to bother/concern about the SBIR anymore. Basically, one can put the loudspeaker or LP anywhere in the room whithout altering the freq response IF the rooms Q-value has been properly tuned.

I see how you got the idea from that, but no, that is not correct. Lassie is used when speakers are already in their position. If you change the speaker position, the measurement of the room will change. You always treat for when the speakers are in their position, which is why most people usually suggest setting up the speakers first. The treatment is therefore used to address problems that happen because of: room modes - standing waves - SBIR - comb filtering - flutter echo - RT60, etc. If you treated your room perfectly for Lassie, you would be able to walk around the room and it would sound the same everywhere (of course, this is impossible, but lets just go with it). However, if you move a speaker even a few centimeters, you are changing the air pressure in a different position than when measurement was made, which will yield different results. Sorry if you aren't catching what I'm trying to say, I'm having a hard time explaining it.

Matts, as you don't need to worry about flutter echo and stuff like that with the heavy use of diffusing, I'm sure this is a great tool for you!

[Mctwins]

Originally Posted by kasmira

I see how you got the idea from that, but no, that is not correct. Lassie is used when speakers are already in their position. If you change the speaker position, the measurement of the room will change.

I am correct, as long as the Q-value has been even out and properly tuned in the room. The loudspeakers position and loudspeaker itself is not affected.

If you change the speaker position or LP and the measurement is changing, it doesn't mean that the Q-value of the room is also changing. By this I mean that the Q-value is the same in the room, not changed.

Lassie is only for 20-200Hz and a god complement. Use ARTA or any other for ETC.

[kasmira]

What is q-value?

[kasmira]

Originally Posted by Mctwins

If you change the speaker position or LP and the measurement is changing, it doesn't mean that the Q-value of the room is also changing.

You just said in your other post that frequency response will not change if speakers are moved. That is not true. This is only possible in a true anechoic chamber - a vacuum. This is literally and physically impossible in a room. So, what are you arguing? If the measurement changes, then the measurement changes. Then we have different problems. From SBIR. And different reflection, different comb filtering, etc. Room response is speaker dependant, period, other than room modes and standing waves. And those can be excited by SBIR as well.

Sent from my ADR6425LVW using Gearslutz App

[Mctwins]

Originally Posted by kasmira

You just said in your other post that frequency response will not change if speakers are moved. That is not true. This is only possible in a true anechoic chamber - a vacuum. This is literally and physically impossible in a room. So, what are you arguing? If the measurement changes, then the measurement changes. Then we have different problems. From SBIR. And different reflection, different comb filtering, etc. Room response is speaker dependant, period, other than room modes and standing waves. And those can be excited by SBIR as well.

Sent from my ADR6425LVW using Gearslutz App

Where did I say that?? Please point it out, and if I said it I mean only when the rooms Q-value has even out in the modal region. Please do check out what Q-value is first.

One dosen't need to be in a vacuum or in a chamber, just go outside with your speaker and measure and away from the ground plane. You get the response of the loudspeaker.
Sound can't travel in a vacuum.

You mean otherway around, speaker response is room dependant, right.

[Companda]

EDIT: When the flatteness of the freq response/pressure is achived across the room then one dosen't need to bother/concern about the SBIR anymore. Basically, one can put the loudspeaker or LP anywhere in the room whithout altering the freq response IF the rooms Q-value has been properly tuned

How do you come up with this? SBIR is a product of the speaker relationship to the boundaries and the receiver. If you move the speakers, or boundary if you are strong, then the SBIR will fluctuate. If you are talking about a room's Q-value the way I think you are, that is evening out the modal response (dips and peaks) and practically becoming anechoic to some degree...

I can't go on, there's previous posts you have made that indicate your knowledge of SBIR is limited to none. Mine is far from perfect but I'm pretty sure I'm right in saying that you are wrong but I am happy to be corrected by a 3rd party(ies).

I think you are focused far too much on modes when acoustic treatment and room design are much bigger than just that.

[johndykstra]

Originally Posted by Mctwins

So this means that.....when Lassie is used, there schould be an overall flattness of the freq response/pressure thru the entire area/volume in 3D of the room.

If this is the case, then all room schould be measured with Lassie or similar when measurering low freq behavior and not only at the LP.

EDIT: When the flatteness of the freq response/pressure is achived across the room then one dosen't need to bother/concern about the SBIR anymore. Basically, one can put the loudspeaker or LP anywhere in the room whithout altering the freq response IF the rooms Q-value has been properly tuned.

Right here. You said it right here. This is the post you were asking about where you said those things. It was 7 hours ago.

[kasmira]

As stated, if you treat all the modes in a room, you still have SBIR. You can't just treat modes and then SBIR doesn't exist, that is silly. I tried to read up about q-value but can't find anything pertaining to it except your posts. Can you link me?

Sent from my ADR6425LVW using Gearslutz App

[kasmira]

Originally Posted by Mctwins

One dosen't need to be in a vacuum or in a chamber, just go outside with your speaker and measure and away from the ground plane. You get the response of the loudspeaker.
Sound can't travel in a vacuum.

You mean otherway around, speaker response is room dependant, right.

Ah you are right, sound doesn't travel in a vacuum. If you measure away from the ground, yes, you will have no SBIR. But you cannot get your speakers so far from the ground in a room. You can treat SBIR, but it won't disappear. If you move the speakers, you will have other problems because of SBIR.

Edit: and no I don't mean it the other way around. whatever comes out of the speaker comes out of the speaker. The same frequencies come out of the speaker wherever the speaker is. The room is what changes things.

Sent from my ADR6425LVW using Gearslutz App

[Jens Eklund]

Originally Posted by SörenHjalmarsson

Either way, It's a shame!

+1

[Rod Gervais]

Originally Posted by SörenHjalmarsson

it was at that point quite clear to all of us (including himself i think) that he didn't know whether the term referred to a treatment technique or something you can eat

+2

Personally I like my SBIR medium rare.........

It's fantastic to find out that it can't possibly change in a properly treated room once the Q is right........

Whatever would we do without him?

Rod

[gullfo]

Originally Posted by Rod Gervais

Personally I like my SBIR medium rare.........
It's fantastic to find out that it can't possibly change in a properly treated room once the Q is right........

hey, nobody ever said this stuff was intuitive

[kasmira]

McTwins, perhaps this is an easy way of explaining it:

Room modes are dependant on the room. If a room exists, it has modes. If we change the rooms dimensions, the frequency of the modes change. We all get this and I believe you do too.

Similarly, if a speaker is in a room, SBIR exists. If we change speaker position, the frequency of SBIR changes.

Does that make sense? I feel like that's the easiest way to make sense of it.

Sent from my ADR6425LVW using Gearslutz App

[Mctwins]

Originally Posted by johndykstra

Right here. You said it right here. This is the post you were asking about where you said those things. It was 7 hours ago.

You are wrong. You are missing my big IF.

I never said it like this.......
You just said in your other post that frequency response will not change if speakers are moved
Kasmira wrote this.

[Mctwins]

Originally Posted by kasmira

McTwins, perhaps this is an easy way of explaining it:

Room modes are dependant on the room. If a room exists, it has modes. If we change the rooms dimensions, the frequency of the modes change. We all get this and I believe you do too.

Similarly, if a speaker is in a room, SBIR exists. If we change speaker position, the frequency of SBIR changes.

Does that make sense? I feel like that's the easiest way to make sense of it.

Sent from my ADR6425LVW using Gearslutz App

I agree about room mode and SBIR if it is an empty room, not treated.

But, if you treat a room in the modal region properly, the modes will become more and more even out and the SBIR will diminish and become insignificant.

About Q-value or Q-factor, for me it is the same, it means according to MHOA;

"Quality factor. A measure of losses in a resonsnce system. The sharper the tuning curve, the higher the Q."

[Glenn Kuras]

But, if you treat a room in the modal region properly, the modes will become more and more even out and the SBIR will diminish and become insignificant.

If you treat with broad band bass trapping you might also treat an area of the room that SBIR is a problem, but if treating with something targeted like HH then no (for the most part).

[Rod Gervais]

Originally Posted by Mctwins

I agree about room mode and SBIR if it is an empty room, not treated.

But, if you treat a room in the modal region properly, the modes will become more and more even out and the SBIR will diminish and become insignificant.

A week ago you didn't have a clue what SBIR is (I don't believe you do now either - seeing what I read above).

ROD

[johndykstra]

Originally Posted by Mctwins

You are wrong. You are missing my big IF.

I never said it like this.......
You just said in your other post that frequency response will not change if speakers are moved
Kasmira wrote this.

If there was any uncertainty of this in your initial post, all trepidation seemed to have vanished by they time you made the "[edit]" Read your edit. Tell me where there is a hint of wonder, or if it is in fact a statement that implies you have it all figured out.

[Rod Gervais]

Originally Posted by johndykstra

If there was any uncertainty of this in your initial post, all trepidation seemed to have vanished by they time you made the "[edit]" Read your edit. Tell me where there is a hint of wonder, or if it is in fact a statement that implies you have it all figured out.

John,

I don't believe he could possibly understand less about this if he tried on purpose.........

You could write a couple of books about what he gets wrong - doesn't understand in the least........

And that's when he's having a good day.........

Rod

[Rod Gervais]

McTwins,

Perhaps you would take a moment to explain to us exactly what SBIR is - and how the treatment of modal activity through the use of these products would minimize SBIR to the point that it would then be what one would consider "insignificant"......... what (exactly) is insignificant to your mind in this regard......

I (among others I am sure) would love to be enlightened in this........

Rod

[Mctwins]

Rod...

SBIR(Speaker Boundary Interference Response) is a type of a acoustic distortion. This distortion is affected in the entire freq response but is mostly dominated in the lower freq response. And don't forgett, that this is an addition to modal response.

SBIR is an issue that can give destructive interference from the adjacent walls, typically the wall behind your speakers.

Modal response is when sound waves reflects back and forth between hard walls. This is the inteference that cause resonance due to the geometry of the room.

Modal response and SBIR is two diffrent things.

The difference between SBIR and resonance is that when the resonance is bouncing around the room and when a suitible bass trap has the opportunity to dampening it, multipel times. SBIR must be fight against in the first bounce and it is easier to deal with.

I will take Boggys design, AES E-Library is a great example to have +/-3dB in 1/3oktave is resonable to have in a good treated room.

I would like to hear Boggys comment about SBIR in his room design??

Another thing I like about Boggys design is this;

"We also concluded that diffuse early reflections in control rooms are extremely important for quality, and more precise (hence more objective) assessment of sound image, and thus faster decision making during the production"

That's why i wrote that SBIR is insignificant. The resonances is far more important to deal with.