regarding the photo above with the red wall around the diffusers... the side walls of this room ... what are they made of? it that standard gypsum or is it some sort of constructed trap?

i like (aesthetically) how the floor and the wall meet with no baseboard trim and the divisions between panels on the wall make for a nice look as well.

I believe Nenad will explain details about this. heh

ETCs for first and second room:

That looks like effectively anechoic. No reflections above about -20 to -25 dB and the energy drops below -60 dB before about 75 ms …

I already wrote:
Second studio doesn't have all diffusers mounted... but first one is complete (with all reflecting surfaces)... and ETC for first one is final.
This type of rooms aren't anechoic , they are "ambechoic"... similar to Blackbird Studio C.
They don't sound anechoic to people, but all recordings and therefore all acoustical measurments from this type of rooms, sounds/looks nearly anechoic.

The Ambechoic room done by RPG has a decay time of about 0,3 seconds, not 0,1 or lower:

http://www.rpginc.com/news/seminars/...2007_iRoom.pdf

Decay time always depends on final room volume. Blackbird studio C is much larger than this rooms...

Exactly, and I don’t think you can call a room with a decay time of 0,1 seconds for "Ambechoic". I think a more appropriate term would be "effectively anechoic".

...and the dense diffuse returns are relevant to much much lower frequencies.

does anyone know the criteria for meeting a true Ambechoic room? i am not sure full room (HF only) diffusion would correspond to the claim that it is ambechoic in the same sense as the room that defined the model, but clarification from the designers would be nice.

the true impact of the ambechoic model is the incredibly dense diffuse return.

t_d:
left, right and front walls - sandwich/combination of different densities and thickness of rockwool. So this is red fabric.
On ceiling and rear wall are hangers (different construction like in original MyRoom principle).

Jens Eklund:
Recommended RT60 (AES, EBU, ITU...):
Tm = 0,25 * (V/V0)ˆ1/3
V - final volume
V0 - referent volume (100m3)

So recommended RT60 for this kind of volume is around 0,16sec. with tolerance shown in tabel.

Both rooms have final volume around 27m3 and will have (with all diffusors mounted) RT60 around 0,18sec.

Nenad P.

No it is not appropriate, because this rooms doesn't sound anechoic to people.

This is probably similar phenomenon as George Massenburg wrote about ETC measurements from Blackbird studio C here:
Bolded by me.

I think the Ambechoic model is out of reach for most (due to the reasons stated above like true diffusion for not only the midrange frequencies etc.) and also worth remembering; the model is a solution for surround setups. It does not in other words, necessarily “replace” the normal LEDE/RFZ concept. It’s just a solution for specific needs (if you have the space and budget …!).

effectively anechoic != anechoic. even GML stated this regarding Blackbird C (so many wanted to assume that -30dB was "anechoic").

'effectively anechoic' is the same term used as with regards to the ISD-gap; which means all signals are below human detection threshold. the low-gain signals in ISD are NOT anechoic, but effectively anechoic and thus not processed by ear-brain as distinct signals.

Not only is the decay time a lot longer in the RPG room, but as stated by localhost, the diffusion is not limited to the midrange and up. I don’t think you can call your room "Ambechoic", at least I wouldn’t …

Lowest working frequency of diffusers in MyRoom design principle is limited because minimum allowed distance to listener... So lowest working frequency of diffusers depends on the room dimensions and volume, so if you like to have "true Ambechoic room" in much wider frequency range you need a much bigger room at least.

correct. i was advising caution by labeling such a small room with HF-only diffusion as "Ambechoic".

Reverberation times does not exist in a normal control room.

https://www.gearslutz.com/board/5910172-post3.html

Oh, I didn’t know "semi-ambechoic" existed as a definition. What are the criteria’s for this?

As I already wrote, this room doesn't sound anechoic at all... they sound much more alive than anechoic rooms. Actually, before mounting diffusers we have anechoic room (in MyRoom design) so it is easily to notice difference...

That might be true, but it’s still a long way to "Ambechoic".

To be honest, I don't know. heh
Bolded by me.

heh

i dont believe anyone claimed it was anechoic - just effectively anechoic (by the ETC): https://www.gearslutz.com/board/7563898-post72.html

+1

Ok... I know, Ambechoic is trademarked. heh
I don't know better term for room which have measurements similar to anechoic room but it doesn't sound anechoic to listener, as GM already said. We have similar situation here. "Effectively anechoic" isn't a good term from listener point of view, because it is not "effectively anechoic".... heh

Limboid ?

Zomboid ?

hi Boggy,

Do you think the "air transparent diffusion" concept would work using a "BAD Panel" type designs?

RPG Diffusor Systems

thanks

AA

This is amplitude 2D binary diffusor and yes it will work... also 1D amplitude binary diffusors will work:
MyRoom Acoustics
look 6th (wall&ceiling) and 10th picture (ceiling) & first picture in post https://www.gearslutz.com/board/7554391-post58.html (ceiling/cloud)

Yes, it is similar, but keep in mind that BAD panel is binary type, amplitude grating (only) diffuser without phase grating component, so diffuse field produced by BAD panels is more limited in frequency range and intensity.
I build rooms with similar principle as BAD, but only 1D (one dimension), using MLS (Maximum Length Sequence, a quasi random binary sequence)... with slats, as shown on picture below. This is principle basically similar to MyRoom, with decent results, very usable for not-that-big budget studios, but without strong diffuse field, needed for more detailed overall stereo image.

You're welcome.

Also, BAD panels do not have "spectacular" absorption coefficient below 100Hz.
It is needed something much more appropriate for low frequency room damping than (only) BAD panels.....

http://www.rpginc.com/products/badpa...ion%20Data.pdf