John Sayers' Recording Studio Design Forum

Hi,

I think I need some further improvements:

the sound on the hearing position is not ideal (see other thread the frequency response) but very good. Stereo image is wonderful, frequency response seems to be quite good. The problem is, soon behind my hearing position, some 10 cm behind the sound gets hearable worse. (comp filter)
The reason for this is the ceiling absorber/cloud I didn't installed yet.
But I wonder If some kind of diffusion will improve the overall sound. E.g. above the first reflection absorbers on the side wall or on the side wall right side of the rack.

You see I got a good RT60 except in the range of 120Hz.
What to do?

In all avaiable corners are superchunks. The rearwall is 100mm rockwool and above the door a 800mmx600mm horizontal superchunk on the ceiling-rear wall corner. Even on the side wall-ceiling corners are 1.5m long superchunks.
On the floor on the frontwall lies a 1250x625 thermowall (hemp) packed in fabric.

Thomas

Translations:
Nachhallzeit Regieraum leer = reverberation time control room empty
Nachhallzeit Regieraum fertig = reverberation time control room ready
Empfehlung = recommendation

Not in a room that size, no! It's way too small for diffusion to be of any use.

If it is comb filtering, then it is probably coming off the walls or ceiling. And you also say "the ceiling absorber/cloud I didn't installed yet." so that is almost certainly the problem! I'm betting that once you install that, the situation will improve quite a bit.

Link??? You might know which thread you are referring to, but unless you post the link nobody else is going to know!

What are your room dimensions, and how much bass trapping do you have in there already?


- Stuart -

Ethan Winer says the opposite. Why is diffusion bad? Initial time gap to small.



Sure. But my secondary goal is to have quite good sound in the back of the room to let the musician hear what I hear.


viewtopic.php?f=3&t=14367



Width 3m
Length 4.5m (frontwall is angled by 10°)
Hight 3m

Backwall (except door) is covered with 10cm rockwool.
Superchunk, horizontal 3m width at the backwall-ceiling over the whole room width.
Superchunk, vertical 3m hight (room hight) at the left wall - backwall corner.
2x Superchunk, horizontal 1.5 m at the sidewalls - ceiling - corners.
1x 1250mm x 600mm x 100mm absorber on the frontwall - floor - corner

Ouch.
Width and height share the same size, not good.
You will have some serious mode issues.

Better install that ceiling absorber and see what that does.
Your room is too small for diffusion to work properly.

Have you entered your roomsize into roommode calculator to giove you an idea of what modes will (can) cause issues?
This one for instance:
http://www.bobgolds.com/Mode/RoomModes.htm

Enter your room size and see what happens below 121 hz.

The room sizes are rounded. They are not exatly the same. 2.9m and 2.7m I think.
I know the problem and I did a lot of calculation. But there is no "good ratio" with a room of 3mx5m with acceptable ceiling heights.

So why bother posting them, then? Acoustics is science, and precision is important.

You seem to be going about it backwards: Start with the maximum possible ceiling height you can get, then see what other dimensions you can find for the remaining two, that are close to a good ratio. Tweak all three until you hit one of the best.

In your case, assuming that the height is 2.7m, and you have a 3m x 5m space to work with, then you do have some reasonable options:

H=2.50 m, W=3.00 m, L=3.75 m is exactly Louden's 5th best ratio (1 : 1.2 : 1.5)
H=2.60 m, W=2.97 m, L=3.62 m is exactly Sepmeyer's very best ratio (1 : 1.14 : 1.39)

And there are MANY other good ratios in that general region.

Looks like you didn't do the right calculations!

In any event, you didn't answer the original question with enough accuracy to be useful in helping out with your problem: What are the exact dimensions of your room? (Meaning the dimensions as it is right now, measured between the inner-leaf wall surfaces, not including the existing treatment).

- Stuart -

Because I have to lie when I try it without final measuring.
It's 4.5x2.83x2.9 But the floor height differs by 5-10cm from front to back. And the frontwall are complicated angled because of the flush mounting of the monitors.

Using http://www.bobgolds.com/Mode/RoomModes.htm I got somethink like:
L. W. Sepmeyer: 1965" 1 : 1.14 : 1.39
Derived from C. P. Boner (stylized ratio)" 1 : 1.25 : 1.6
and a "worst case scenarion" but "green"!

Its very likely that the 120Hz peak is actually a room mode.
So the question is now: what can I do? Without changing the room.



There you can see the problem: I loose more than 1m of the room!



I think not. The bad thing I did was perhabs - I don't know actually - to make a wrong compromise.
Indeed I did a lot of calculating, reading and designing by using the actuall circumstances which also includes a comparable very low budget and time! The latter is an issue, because I lost my studio just after signing a label contract. And If you know the conditions of todays label contract there is no advance payment and we are glad not to have to pay! Things are very complicated. And so is the ergonomie of the studio. In the extreme case I (and many musicians) would prefer a studio thats comfortable and has a good sound over an uncomfortable with an impressive sound. Thats fact. Dispite the fact that acousticans (and even I - the engineer in me) would choose the other way round.

Edit: I added some construction sketches.