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Need help to tune my control room. (First Measures Included)
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#121
24th December 2012
Old 24th December 2012
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Quote:
Originally Posted by Alejandro Varela View Post
I don't realize what you're talking about...
Now, I' m more confused what to do!!!
All I am saying here is this, it is not so easy as one might think.

Either you need two boxes in corner A, one at 35Hz and one at 55Hz, OR some other tuned freq in queation. The only way to see the result is to build and test and remeasure, build and test and remeasure again and again and so on... untill the resonaces is gone and the peaks and the decaytime is reduced.

Good luck...
#122
24th December 2012
Old 24th December 2012
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Quote:
Originally Posted by Mctwins View Post
What I ment about "leave it as it is" is this. If you don't see any changes in the freq response and waterfallplot despite the treatment you are choosing or installing then it is better to leave it untreated.
He specifically stated they HAVE helped, why would he remove them?

Quote:
Originally Posted by Mctwins View Post
I tell you what I know, it is very difficult to treat the first modal axiell resonaces with porus absorber, broadband absorber, membrene boxes because these are inefficient below 100Hz, period.
How do you know this information so well? Do you believe that Riverbank produces faulty results with tests? Do you believe that tests designed to carry out low frequency experiments (like impedance tube measurements) are incorrect? They have shown (with data, not opinions) that porous absorbers DO in fact work under 100 Hz (and quite well/efficient if thick).

--------------------

Alejandro,

While there is good info in this thread of your own, there is GREAT information in Tim's thread where people have tried these builds and know much more about them and the underlying concepts there. You will get much better results posting in that thread for questions posed to these absorbers. Yes, its a thick thread, but it has the information you want & need in it.

If you want a sure fire way to treat the room, either go for extensively thick porous absorption in the corners for getting 56 Hz or whatever it is taken care of, build your own tuned or enhanced absorber with a lot of research, or purchase tuned traps from companies that have their products tested and guaranteed. You can build VPRs, membrane absorbers, helmholtz resonators as much as you'd like but very precise methods are typically used in construction, so you will need to put effort into creating them in a well controlled manner. This would likely need a lot of reading up on first to ensure you miss the pitfalls that many people overlook when building them.

I'm not trying to deter you from building your own - it is a fun experience and makes for great knowledge to know. But if you're concerned with getting on with your music, I would go with the faster routes.
#123
24th December 2012
Old 24th December 2012
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Quote:
Originally Posted by kasmira View Post
He specifically stated they HAVE helped, why would he remove them?



How do you know this information so well? Do you believe that Riverbank produces faulty results with tests? Do you believe that tests designed to carry out low frequency experiments (like impedance tube measurements) are incorrect? They have shown (with data, not opinions) that porous absorbers DO in fact work under 100 Hz (and quite well/efficient if thick).

--------------------

Alejandro,

While there is good info in this thread of your own, there is GREAT information in Tim's thread where people have tried these builds and know much more about them and the underlying concepts there. You will get much better results posting in that thread for questions posed to these absorbers. Yes, its a thick thread, but it has the information you want & need in it.

If you want a sure fire way to treat the room, either go for extensively thick porous absorption in the corners for getting 56 Hz or whatever it is taken care of, build your own tuned or enhanced absorber with a lot of research, or purchase tuned traps from companies that have their products tested and guaranteed. You can build VPRs, membrane absorbers, helmholtz resonators as much as you'd like but very precise methods are typically used in construction, so you will need to put effort into creating them in a well controlled manner. This would likely need a lot of reading up on first to ensure you miss the pitfalls that many people overlook when building them.

I'm not trying to deter you from building your own - it is a fun experience and makes for great knowledge to know. But if you're concerned with getting on with your music, I would go with the faster routes.
No offense, isn't it better that you tell the OP how to excatly build the proper trapps so he can get the result he is after, namly, reduce the ringing and even out the peaks.

About this
Originally Posted by Mctwins
I tell you what I know, it is very difficult to treat the first modal axiell resonaces with porus absorber, broadband absorber, membrene boxes because these are inefficient below 100Hz, period.


This is my own experiance.
#124
24th December 2012
Old 24th December 2012
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Quote:
Originally Posted by Mctwins View Post
No offense, isn't it better that you tell the OP how to excatly build the proper trapps so he can get the result he is after, namly, reduce the ringing and even out the peaks.
I told the OP exactly where to find the information to build the membrane traps himself. I should not need to re-instate the (literally) hundreds of posts that have already been made before on this board by people who have used these and understand their workings better than I. Obviously, I would not teach him how to build one as I never have built one of Tim's devices myself (but many people in the thread HAVE).

Similarly, there are many posts & threads made about Helmholtz devices, panel traps, VPRs, and the like all over Gearslutz, to which many people who are more qualified in practice than I am to talk about them and the challenges faced with building such devices.

My post had simple advice: Find out more about & ask questions about the absorbers you built in the thread dedicated to them, build different pressure based absorbers and make sure you read up on them so you don't construct them improperly, or build very thick porous absorbers (not just 4" panels straddling a corners).
Alejandro Varela
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#125
24th December 2012
Old 24th December 2012
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Quote:
Originally Posted by kasmira View Post
My post had simple advice: Find out more about & ask questions about the absorbers you built in the thread dedicated to them, build different pressure based absorbers and make sure you read up on them so you don't construct them improperly, or build very thick porous absorbers (not just 4" panels straddling a corners).
I haven't dude about How to build a Mass Limp absorber and how it works, in fact I built 4 boxes (neither works fine). I had read thousands of threads, specially Tim's one, but (as my knowledge in acoustic is null) nobody told me exactly which freq I must Attack. I' m looking graphics at REW and imagine things but that carried me to build my failed boxes. Tim Farrant suggested me an "about 55 HZ and about 90 HZ" I have no problem to modify my boxes in an about 55 HZ box, but this about not guaranteed to work fine. As I read somewhere, boxes have a margin 1/4 octave... Can't someone answer me if a 55 HZ box is the exactly freq to attack in my room?
McTwins suggested me this:
Quote:
Originally Posted by Mctwins View Post
You can do like this, put the speaker and sub at left corner(floor) and measure on the opposite corner(diagonally), inside wardrobe's upper corner. You can only use sub for this operation as well.

Here you will see all the modes this room have.
I don't know what to think. I'm not his lawyer. He's always contributing in my thread and I had read in a hundred of posts you blame him of shilling.
#126
24th December 2012
Old 24th December 2012
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Don't know how much room you have to dedicate to treatment, but this may be of interest:
40Hz, go to hell!
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#127
24th December 2012
Old 24th December 2012
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Quote:
Originally Posted by AwwDeOhh View Post
Don't know how much room you have to dedicate to treatment, but this may be of interest:
40Hz, go to hell!
Thank you m8. I ll take a look.

Meanwhile I got measures Mctwins asked.

Floor to Ceilings corners.zip I measured 2 diagonals, perhaps help! I used only Sub.

Happy X-Mas!
#128
24th December 2012
Old 24th December 2012
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Alejandro,

I was only suggesting that any questions relating to the boxes would be best posted in Tim's thread, as you will get better suggestions there. When I was talking about reading the threads, I was talking about if you wanted to go with other routes for absorption (helmholtz or panel absorbers, for example).

This last test you have provided is very helpful for determining what room modes are prevalent. In those tests, you can see ~45 Hz in one corner and ~47 Hz in another corner. I would build a box centered around 45 Hz if its possible. I haven't really seen limp mass absorbers being that efficient at a frequency so low, but if you could alter your boxes easily, perhaps it would be a good thing to try. For any frequencies under 50 Hz, your best treatment will be tuned absorbers or panel traps from what I've seen (and as McTwins has suggested).

When we say "around 45" Hz, we mean the actual frequency might be 45.23 Hz but the extra isn't necessary. Don't get too hung up on that

The reason these tests are helpful is you can compare them to your listening position measurements. Whichever frequencies are prevalent in the corners are due to modal behavior, while other frequencies (like that 56 Hz bump for example) are not due to your dimensions, but your (or your speaker's) placement in the room. Did you actually place your speaker in the opposite tri-corner for these measurements?
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#129
24th December 2012
Old 24th December 2012
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Quote:
Originally Posted by kasmira View Post
,,,In those tests, you can see ~45 Hz in one corner and ~47 Hz in another corner. I would build a box centered around 45 Hz if its possible...
....Did you actually place your speaker in the opposite tri-corner for these measurements?
Great NEWS!!!
It´s easy, and simple. I just need to cut my boxes around 20 cm from deep. I was asking just that.

Yep. I just placed my sub speaker in A & B three corners and mic on opposite three corners, as McTwins suggested.

Thanx for your help.
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#130
24th December 2012
Old 24th December 2012
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Just 1 more dude...
How you know my freq is around 46 HZ ?
I am watching REW scopes I dont noticed?
Which scope should I look?
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#131
25th December 2012
Old 25th December 2012
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Well, yesterday, before cheers I made a measurement with a box "around" ~45 Hz in The A corner...
Let me know if I'm right or not.
Give me a hope pleaz!
Just 1 corner limp.zip (after & before measurement)

Cheers for everybody!!!
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#132
25th December 2012
Old 25th December 2012
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Could someone check my new files?
I need to know if my absorption looks fine?
#133
26th December 2012
Old 26th December 2012
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Alejandro, this method I have used in many rooms. Calculate the room modes, build the traps at the problem frequencies and it should help immensly. As I mentioned, your room is cubic so you may need quite a few units to make a difference.
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#134
26th December 2012
Old 26th December 2012
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Quote:
Originally Posted by Tim Farrant View Post
Alejandro, this method I have used in many rooms. Calculate the room modes, build the traps at the problem frequencies and it should help immensly. As I mentioned, your room is cubic so you may need quite a few units to make a difference.
I trust in you, but I don't know if I'm doing right. Just made 1 Box and measured. Tomorrow I will be building 7 more boxes and I need to know if I am in the right way!
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#135
26th December 2012
Old 26th December 2012
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Quote:
Originally Posted by Alejandro Varela View Post
Just 1 more dude...
How you know my freq is around 46 HZ ?
I am watching REW scopes I dont noticed?
Which scope should I look?
OK, I began to understand how this tool works!!!
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#136
26th December 2012
Old 26th December 2012
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Damn!!! F*cking S*it!

Those boxes I had made works very fine or am I crazy!!!!????
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#137
26th December 2012
Old 26th December 2012
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How long must be frequencies decay to became acceptable in Waterfall.
#138
26th December 2012
Old 26th December 2012
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Quote:
Originally Posted by Alejandro Varela View Post
How long must be frequencies decay to became acceptable in Waterfall.
Alejandro,

Everyone here may give a unique subjective opinion about this. There do seem to be some general guidelines in various "expert" papers that agree to a range of times. One of the papers is linked here:http://tech.ebu.ch/docs/tech/tech3276.pdf

Also, decay times are generally dictated by the size of the room. A larger volume having a longer decay time and smaller room with a shorter decay time.

Typically, decay times of .25s and .33s are deemed acceptable by most people for small rooms.

But don't take it from me. Perhaps other folks will link to additional published information if that even matters to you.
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#139
26th December 2012
Old 26th December 2012
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Quote:
Originally Posted by John White View Post
Alejandro,

Everyone here may give a unique subjective opinion about this. There do seem to be some general guidelines in various "expert" papers that agree to a range of times. One of the papers is linked here:http://tech.ebu.ch/docs/tech/tech3276.pdf

Also, decay times are generally dictated by the size of the room. A larger volume having a longer decay time and smaller room with a shorter decay time.

Typically, decay times of .25s and .33s are deemed acceptable by most people for small rooms.

But don't take it from me. Perhaps other folks will link to additional published information if that even matters to you.
Thank You John.

Anyone knows how to hang up this boxes?
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#140
27th December 2012
Old 27th December 2012
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Quote:
Originally Posted by John White View Post
...Typically, decay times of .25s and .33s are deemed acceptable by most people for small rooms.
Being this, my room don't look so bad at all, isn't it?
(Although it seems a little dead)

Regards

PS. Still building more boxes. I hope to finish tomorrow.
#141
27th December 2012
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Quote:
Originally Posted by Alejandro Varela View Post
Being this, my room don't look so bad at all, isn't it?
(Although it seems a little dead)
That figure was really just a generality even if it does coincide with the paper's recommendation. I've never actually polled engineers' opinions regarding their preferences. The important thing is that the decay times throughout the frequency spectrum are somewhat consistent.

For instance if you have a .3s decay time at 100Hz and only .1s at 5,000Hz, then the room would certainly seem "dead" without it actually being a dead room. ----- AKA "muddy".
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#142
27th December 2012
Old 27th December 2012
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Quote:
Originally Posted by John White View Post
For instance if you have a .3s decay time at 100Hz and only .1s at 5,000Hz, then the room would certainly seem "dead" without it actually being a dead room. ----- AKA "muddy".
OK, I began to understand (little by little) what you mean. My room is muddy, maybe by that carpet on walls (?)
#143
27th December 2012
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Yes, carpet could surely contribute to a muddy room. In this example the carpet absorbs well at higher frequencies and very, very little at low frequencies.

Since it takes far more absorption to absorb low frequencies than high frequencies, it could possibly take several feet of carpet on every surface in order to make the decay times consistent. Even then I doubt it could work evenly. So, I would use just enough high frequency absorption to make the high decay times consistent with the lows rather than try to match the lows to the highs.
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#144
27th December 2012
Old 27th December 2012
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Quote:
Originally Posted by John White View Post
Yes, carpet could surely contribute to a muddy room. In this example the carpet absorbs well at higher frequencies and very, very little at low frequencies.

Since it takes far more absorption to absorb low frequencies than high frequencies, it could possibly take several feet of carpet on every surface in order to make the decay times consistent. Even then I doubt it could work evenly. So, I would use just enough high frequency absorption to make the high decay times consistent with the lows rather than try to match the lows to the highs.
What do you recommend me?
Maybe adjust the low-end and add reflections treatment to high end?
That's my conclusion, not what it should be...
#145
27th December 2012
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Carpet on the walls ???

Most every acoustician says 'trouble' at the mention of that.
#146
27th December 2012
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Quote:
Originally Posted by Alejandro Varela View Post
Thank you m8. I ll take a look.

Meanwhile I got measures Mctwins asked.

Attachment 322400 I measured 2 diagonals, perhaps help! I used only Sub.

Happy X-Mas!
Hallo...
In your measurement in "A Foor Corner to D Ceiling Corner", did you have the mic inside the wardrobe at tri-corner or outside in front of the door?? Because in this measurement you have flatter freq response and less resonances, which puzzeled me.

In "B Foor Corner to C Ceiling Corner" you have a resonance at 46Hz.

Just want to know how you have the mic positioned, the mic schould be pointed in the tri-corner around 10-15cm.
#147
27th December 2012
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Quote:
Originally Posted by Alejandro Varela View Post
How long must be frequencies decay to became acceptable in Waterfall.
The decay time in waterfallplot schoud have an even decay from 20Hz-20kHz, depending of the room volume around 300ms, give or take. Not to dead and not to bright.

As you know, I don't use any absorbtion in my rooms.
#148
27th December 2012
Old 27th December 2012
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Quote:
Originally Posted by Alejandro Varela View Post
Well, yesterday, before cheers I made a measurement with a box "around" ~45 Hz in The A corner...
Let me know if I'm right or not.
Give me a hope pleaz!
Attachment 322460 (after & before measurement)

Cheers for everybody!!!
Hi..I have lookt at it. Don't get mad at me.

Sorry, there is no difference. I asume it is measured at the LP.
#149
27th December 2012
Old 27th December 2012
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Alejandro....

I am satisfied with the measurement you have provided so far regarding corners ABCD and floor, one opposite corner. Too me, you can only measure at LP with both speaker and sub when comparing boxes/without boxes.

As I said before, and looking at your measurements, you have peaks and resonaces at around 45-55Hz in the corners as well as in LP. This corrensponds well with your room dimension.

Let's hope and see if the result will be better after you have installed more boxes.

EDIT; Sorry, forgot to mention; you have according to measurements at post99, there is resonances at 19Hz and 35Hz as well.

Last edited by Mctwins; 27th December 2012 at 08:54 AM.. Reason: More information, forgot to mention.
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#150
27th December 2012
Old 27th December 2012
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Quote:
Originally Posted by RJHollins View Post
Carpet on the walls ???

Most every acoustician says 'trouble' at the mention of that.
Yep, but I designed this room long time ago for other purpose.
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