After First Reflection

[Adam_Weishaupt]

I mounted 3 panels for the first reflections for the rfz.
What do i do with the space between desktop areak an back wall?

"Add four GIK 244’s at the first and second reflection points, two GIK 244’s above the mix position and two 242’s just ahead of the firs reflection point. Moved the listening position back 6” more. I knew that moving back had produced a dramatic reduction in the 70-80Hz problems, so I decided to try moving back a bit more to see if I could reduce it further." <--- i read this on the GIK acoutic page.

What are second reflection points? Why did he put two 242´s ahead the first reflections points?

[Glenn Kuras]

It could have been the person was dealing with SBIR.
Learn what is SBIR (Speaker Boundary Interface Response).

[SAC]

asdasd

[PaulP]

Originally Posted by SAC

Quite frankly, without time domain measurements providing insight into the gain and arrival times of the specular reflections, as we are no longer talking about room modes, and without a valid acoustical room response model to follow, you are running blind.

Something's been nagging me. Where does frequency fit into the impulse and
it's response ? For example, you might be properly absorbing the higher
frequencies of an unwanted reflection but not lower frequencies of the same
reflection. It seems to me that the ETC will tell you that there's a certain
amount of energy at a given time, but not what it's made up of, which would
be useful in deciding how to treat it.

Paul P

[Adam_Weishaupt]

Wow thanx Sac. Well ill do the measurements, so it wasnt a good approache to get "gik tritraps"(basstraps) for each corner(floor to ceiling), 242 Panels for the early Reflections(side walls and ceiling), 244Basstraps for the rear and backall and 2 Dimensional Diffusors at the backwall:

greetings Adam Weishaupt

[Adam_Weishaupt]

Wow thanx Sac. Well ill do the measurements, so it wasnt a good approache to get "gik tritraps"(basstraps) for each corner(floor to ceiling), 242 Panels for the early Reflections(side walls and ceiling), 244Basstraps for the rear and backall and 2 Dimensional Diffusors at the backwall:

greetings Adam Weishaupt

[SAC]

fsd

[Weasel9992]

Originally Posted by SAC

In other words (some of them in English ) EQ cannot be used to correct for anomalies caused by the superposition (combining) of multiple out of absolute phase signals such as those consisting of the direct and reflected signals by the manipulation of only the source direct signal!

Well stated.

Frank

[Adam_Weishaupt]

I got me a behringer ecm omni measuring mic. The mic has to face the ceiling in the height if my ears right? Im using fuzz to get the measures.


Adam

[Weasel9992]

Originally Posted by Adam_Weishaupt

I got me a behringer ecm omni measuring mic. The mic has to face the ceiling in the height if my ears right? Im using fuzz to get the measures.

Right.

Frank

[Adam_Weishaupt]

Ok i hope that helps?


Thanx for the help

[Adam_Weishaupt]

Another pic with no smoothing

[Adam_Weishaupt]

No Help? did i do something wrong?

[SAC]

dsgf

[Adam_Weishaupt]

Dimensions

9.9 X 15.06 height 8.07


well is it possible to inverse Schroeder integration curve on fuzz?
i have a window from the left to the right of the frontwall.

[SAC]

dfsgdf

[Adam_Weishaupt]

i attached the pix.

[DanDan]

Adam, many of us do not treat the front wall, i.e. the one behind the speakers, if that is what you are referring to? If you think there is a reflection, a slap or a flutter, temporarily put a panel up there and see if it vanishes.
I recommend that you read the Room Analysis Primer Sticky. There are some points not covered in it though.
I would point the mic directly at the tweeter, who knows the off axis response of those Behringer Lethal Injection things. :-)
For Frequency Response I would drive one speaker at a time and point the mic at it. If you drive the two you will get horrible comb filtering, which ears do not hear. The head is in the way.
When moving to the other side I generally move the mic a head distance to the other side and repoint the mic at the new tweeter. We have two ears!
For Waterfalls and Modal work I would drive both speakers.
As SAC says, don't bother with EDT and such, only useful for comparisons, and even then the Waterfalls are much more reliable. FYI REW is much better for Decay stuff.

SAC I can't seem to upload the .pdf FM manual for you. email me soundsound@eircom.net and I will send it to you.
Adam is using a Mac so those other programs.....
FM is very competent. It shows the impulse response graph, which is probably your ETC, also a log squared version and an Energy Decay curve. It has all sorts of cropping and scaling and can generate Minimum Phase copies of the responses, whatever that means? It has great averaging functions, even RMS. Version 3 can even average the actual Impulse responses. I am assuming ADAM is on V2 like myself, as V3 has third octave EDT.

Both- I will be watching with fascination to see what info SAC can extract from the Impulse Response window. I have never managed to identify individual reflections and such. Normally I would treat the side reflection and overhead mirror points to create an RFZ. After that if I generally investigate for slaps or flutter using handclaps, moving about the room. Mouth noises too, clicks and grunts. It would be difficult to find a better tone and impulse generator which can move about and actively 'tune in' to problems! If I find an problem area I confirm it by inserting an absorbent panel. If the slap or flutter goes, I was right. The Impulse Response window will confirm these things but it seems like you have to know where to look and magnify it massively. I find the empirical method is hard to beat. In all of the above I am assuming small rooms. That is what the property boom has done to us........

Happy New Year
DD

[SAC]

fgds

[Nordenstam]

Originally Posted by DanDan

Both- I will be watching with fascination to see what info SAC can extract from the Impulse Response window. I have never managed to identify individual reflections and such.

Try the floor reflection! It's usually easy to identify in the ETC of a well treated room (where the other first reflections are damped). Dropping a thick absorber at the floor reflection point should give instantly visible results on the ETC.

[Weasel9992]

Any chance you could post a picture of the room as it is now? I'd like to see what you've got where.

Frank

[SAC]

Pdfg

[Adam_Weishaupt]

ok ill take the picture and the measurements, is see you guys r not so familiar with fuzz, what programm should i use to get proper measurements?

[SAC]

cxvcxgxg

[PaulP]

Originally Posted by SAC

If we can get a 'useful' ETC () there are a number of ways that we should be able to determine just about everything we need to address the problems.

Using the ETC to identify reflections is clear enough. How about when you
want to cut down on the overall time it takes for the room to die down. For
example, my empty room keeps on ringing forever, well several seconds
anyway. At many frequencies. If I go about tracking down every unwanted
reflection (up to what, 20ms ?) will I automatically cut the ringing down to
acceptable levels ?

I'd be interested in hearing your opinion on dealing with modes as well.

Paul P

[SAC]

dfgadfg

[SAC]

sdag

[Adam_Weishaupt]

Ok i got me room eq wizard but i have trouble to get settings right, i loaded the calibration files for the behringer mic.

I dont get an input? I use the fireface 800.



PS HAPPY NEW YEAR TO EVERYONE!!!!!!!!!!!!

[SAC]

dsfdsffgse...

[Adam_Weishaupt]

oh yes sac i got you, ill get measurments with both programs. I just wanna how i assign the input to the room eq wizard. I dont get a input, im using the behringer ecm, with a rme fireface800. Can someone tell me what to do`?