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Mctwins
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#91
3rd July 2012
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Are you happy now....

bwo
#92
3rd July 2012
Old 3rd July 2012
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That's better. Your response looks to be within +/-15 dB. Frequency response isn't everything, but you might have a tonal balance that is too bright.

My frequency response with former speakers wasn't that great, but posting them with 1/3 they can look impressive. Left and right separately.
Attached Thumbnails
My room-right-speaker.jpg   My room-left-speaker.jpg  
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3rd July 2012
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Quote:
Originally Posted by bwo View Post
That's better. Your response looks to be within +/-15 dB. Frequency response isn't everything, but you might have a tonal balance that is too bright.

My frequency response with former speakers wasn't that great, but posting them with 1/3 they can look impressive. Left and right separately.
If looking at the median value I have not +/- 15 dB. I have +/- 7,5 dB in 1/24.

If I put 1/3 as overlay then you will understand what I mean.
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3rd July 2012
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I mean like this...Overlay.

red 1/24
green 1/3



I have +/-3 dB below 100Hz. In both plots/curves.
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3rd July 2012
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With 1/24 oct. your overall response is within +/- 15-17 dB.

Edit:
Someone told me one reads from the middle. I wasn't aware of that and learned something new. That's means the response is showing about +/-7-8 dB.
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3rd July 2012
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Quote:
Originally Posted by Mctwins View Post
Are you happy now....

Unless you know how to position the measurement microphone exactly right in-between the L&R speaker, only use one speaker at the time when looking at full range FR-graphs or you´ll see nasty comb filter effects like above due to the slight difference in arrival time between the L & R speaker. Also; why use a 100 dB scale for a graph that only swings +/- 10dB ?
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3rd July 2012
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How much to get in?
#98
4th July 2012
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Quote:
Originally Posted by Mctwins View Post
There was some question about my Impulse response.

Here it is...

People wanted you to upload the impulse response audio file. It should be in WAV or AIFF format. This will help us be able to look at the graphs through the programs we like to use, and through our own eyes.

Thanks McTwins.
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4th July 2012
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Quote:
Originally Posted by Mctwins View Post
I have +/-3 dB below 100Hz. In both plots/curves.
You probably have +/- 3db in a larger range than you actually think. As Jens stated:

Quote:
Originally Posted by Jens Eklund View Post
Unless you know how to position the measurement microphone exactly right in-between the L&R speaker, only use one speaker at the time when looking at full range FR-graphs or you´ll see nasty comb filter effects like above due to the slight difference in arrival time between the L & R speaker. Also; why use a 100 dB scale for a graph that only swings +/- 10dB ?
What you should do is drive both speakers individually for separate tests, and average them (or if you cannot average them, just keep them separate)

You see how your measurement looks almost like a triangle wave form? As Jens stated, that is due to comb filtering.
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4th July 2012
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Quote:
Originally Posted by kasmira View Post
What you should do is drive both speakers individually for separate tests, and average them ...
?

Why average when you can make accurate meassurments for the combined response (if one finds this to be important).
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4th July 2012
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Quote:
Originally Posted by Jens Eklund View Post
?

Why average when you can make accurate meassurments for the combined response (if one finds this to be important).
1. Because it is a clearly laid out simple instruction that is hard to misconstrue, and wouldn't really need any extra instruction or read up on

and (this one, mostly)

2. Because I wasn't aware that there were ways to make accurate measurements for combined response at high frequency, haha
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4th July 2012
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Fine Tuning the Mic Position

Quote:
Originally Posted by kasmira View Post
... I wasn't aware that there were ways to make accurate measurements for combined response at high frequency ...
I use ARTA's FR1-window (1 input channel frequency response) with its "live" FR to manually fine tune the mic-position (+-5mm [~+-1/4"] via rotating the upper part of the mic-stand for dual channel measurements. This gives accurate FR up to 20kHz
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#103
4th July 2012
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Quote:
Originally Posted by Mctwins View Post
There was some question about my Impulse response.

Here it is...

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#104
4th July 2012
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How can it be combfiltering in my room when I have treated all of my walls and ceiling with broadband diffusion and when many small reflections mixes with the rest of all other small reflections in the room, it can not be Combfilter.

If one single strong reflection is sticking out and causes time delay compared to the direct signal, then it is combfiltering.

You don't see the combfiltrering in my ETC curve and I am mesurening in log-scale and not in linear-scale in the FR. If you have Linear FR graph then you can see the combfiltering.

So I ask again, how can it be combfiltering??

The measurement is made with BOTH SPEAKERS and the LP(mic) is 4,5 meters away from the speakers.
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4th July 2012
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McTwins, the comb filtering present in your graphs isn't due to your room, and we aren't suggesting that. The slight difference in time (more than likely tenths or hundredths of milliseconds) between your two speakers is showing comb filtering from your measurement. This isn't an error in your room, but just an error in your mic placement for measurement.

You can actually easily see the comb filtering easily in both your measured FR as well as ETC.

Again, this isn't from your room - I doubt you hear much comb filtering - but because a measurement mic can't differentiate which speaker a signal is coming from, it takes the combined response at a certain point in the room, which will almost always result in a comb filtered signal when driving multiple speakers.

Sent from my ADR6425LVW using Gearslutz App
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6th July 2012
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Quote:
Originally Posted by G. E. View Post
I use ARTA's FR1-window (1 input channel frequency response) with its "live" FR to manually fine tune the mic-position (+-5mm [~+-1/4"] via rotating the upper part of the mic-stand for dual channel measurements. This gives accurate FR up to 20kHz
Thanks for the info Gernot. I actually wasn't aware ARTA was free until today (I was under the impression it came with hardware purchase for some reason)

I downloaded ARTA and will give it a go. I'm planning to make a thread with my results in my room (awaiting my new monitors) so being able to finely adjust my microphone position for testing is a priority for such a thread. Even more excited now that I won't have to take separate measurements for L/R speaker to show the FR in each position. Hopefully I will have time to play with ARTA and get to know it beforehand. I do plan on showing results in the typical REW waterfall view as it is easily understood and changes are easily seen, but I will look into using ARTA for mic positioning.

Anything else I should look into with ARTA specific to testing that can help?

Sent from my ADR6425LVW using Gearslutz App
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6th July 2012
Old 6th July 2012
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Quote:
Originally Posted by kasmira View Post
Thanks for the info Gernot. I actually wasn't aware ARTA was free until today (I was under the impression it came with hardware purchase for some reason)

I downloaded ARTA and will give it a go. I'm planning to make a thread with my results in my room (awaiting my new monitors) so being able to finely adjust my microphone position for testing is a priority for such a thread. Even more excited now that I won't have to take separate measurements for L/R speaker to show the FR in each position. Hopefully I will have time to play with ARTA and get to know it beforehand. I do plan on showing results in the typical REW waterfall view as it is easily understood and changes are easily seen, but I will look into using ARTA for mic positioning.

Anything else I should look into with ARTA specific to testing that can help?

Sent from my ADR6425LVW using Gearslutz App
Please, do start a new thread about ARTA and I will try to help accordingly.
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6th July 2012
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Quote:
Originally Posted by kasmira View Post
McTwins, the comb filtering present in your graphs isn't due to your room, and we aren't suggesting that. The slight difference in time (more than likely tenths or hundredths of milliseconds) between your two speakers is showing comb filtering from your measurement. This isn't an error in your room, but just an error in your mic placement for measurement.

You can actually easily see the comb filtering easily in both your measured FR as well as ETC.

Again, this isn't from your room - I doubt you hear much comb filtering - but because a measurement mic can't differentiate which speaker a signal is coming from, it takes the combined response at a certain point in the room, which will almost always result in a comb filtered signal when driving multiple speakers.

Sent from my ADR6425LVW using Gearslutz App
I will look into seperate L/R speaker measurement if the ripple of FR is the same or not. When time permits of course.
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6th July 2012
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Quote:
Originally Posted by Mctwins View Post
Please, do start a new thread about ARTA and I will try to help accordingly.
Thanks, McTwins. I will probably just add my questions to this thread: Verify my testing procedure
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6th July 2012
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Quote:
Originally Posted by kasmira View Post
Thanks, McTwins. I will probably just add my questions to this thread: Verify my testing procedure
Ok, I will take a look at this thread.
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27th August 2012
Old 27th August 2012
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I've looked at this thread once before but at that time, the images wouldn't load. Holy crap, I'm guessing you can play your system pretty loud in there...
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29th August 2012
Old 29th August 2012
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Thanks,

Yes, you can play very loud in here. Only the eardrums sets the limits.
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4th October 2012
Old 4th October 2012
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Hallo....

I just want to share some measurements from my downstairs livingroom. This room has been renovated with some fresh paint and I have removed the entire perforated gypsium panel with absorption on the ceiling.

Here is the broadband absorption and gypsium of the entire ceiling ready to go for recycling.


And this is the room in question





The layout of the room with the mic(at LP) and speaker position.



Matts from SMT AB help me this summer with some tunings of my HH resonators in my downstair livingroom.

The graphs in question is under the "Helped McTwins this summer with a room under the mancave". shown in this post: Tim's Limp Mass Bass Absorbers.

The diffusion on the left and right side has not been removed during the entire measuremet procedure. The only that has been removed during before and after measurement is the HH resonators. The mic and the speaker position has been in the same place all the time.

This is without any HH resonators in place




This is with tuned HH resonators in place.





The sound is better now compared to before when I had the broadband absorption in the room. The bass is even better now as well, tight and punchy.
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#114
4th April 2013
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Hallo
I have done some changes and removed the two Varitunes from the sides and put them above my TV.



For two days ago I have measured inside and outside on the left side V4 and V6 and only used the right speakers in full range.

ALL of the V4 is tuned at around 55Hz and the two V6 is tuned at around 30Hz.

V4, the red inside the HH and the green outside, around 10cm from the port hole;



V6, the red inside the HH and the green outside, around 10cm from the port hole;



Measured at the same day at Listeningposition;







I am suprized that nobody has guess what freq I have tuned those Varitunes resonators and by using various room mode calculator despite that I have provided the layout and pictures of the room. This only proves that there are lots of experts here in this forum that really lacks the understanding how to treat the first axiall modal resonances below 100Hz and the understanding about Helmholtz resonators and phase shift phenomena. Now you all know

I am waiting for 16pc of wing-diffusors to arrive and I will provide with more measaurements.
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#115
4th April 2013
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wow for 1/3rd smoothing, things are not looking all that great. Can you post the IR file?
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#116
4th April 2013
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Mctwins, why are we looking at 1/3 octave ? For me, that says nothing of relevance at all. Can we have 1/24 please?
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#117
4th April 2013
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Nice if you can post freq. response with 1/24 or 1/48 smoothing before and after. And waterfall before and after wihtout smoothing below 500 Hz. That should tell us something of the effect.

1/3 smoothing with 10 dB resolution makes everything look good. Actually, yours looks a bit uneven having this in mind.

Here something to strive for by the way. 1/12 smoothing in the first and no smoothing in the second.
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My room-12-glatting.jpg   My room-non-smoothing-bass.jpg  
#118
5th April 2013
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Quote:
Originally Posted by bwo View Post
Nice if you can post freq. response with 1/24 or 1/48 smoothing before and after. And waterfall before and after wihtout smoothing below 500 Hz. That should tell us something of the effect.

1/3 smoothing with 10 dB resolution makes everything look good. Actually, yours looks a bit uneven having this in mind.

Here something to strive for by the way. 1/12 smoothing in the first and no smoothing in the second.
The graphs shown dosent say anything if not at the same time there is more info of where and how it is measured. Is it 1 cm from the speakers or 10 meter away? Pictures or layout of the room where the measurements are taken and how many/kind of treatments is involved would be nice.

You guys are missing the whole point regarding Mctwins measurements. It is not if it is smoothed, 1/x or resolution of the graphs that is important here. It is more of how little treatment there is in that big room that has given a result that is more than acceptable good. Everthing can be improved but still it is in an domestic environment.

To me, this rooms measurements looks better compared to many rooms that are fully treated.
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5th April 2013
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Some info of ARTA program. The CSD has the highest smothing and it is 1/12.
Freq response has highest smothed in 1/24. Burst decay shows in periods and is in highest resolution. DFT is the one that is fully unsmothed in the highest octave namely 1/24.

All of this can be read in the manual of ARTA, if intrested.

The normal standard is 1/3 or 1/6 when presenting freq response. We humans dont hear better than 1/6 octave if my memory serves me correct when reading about it. I think it was in MHOA. Have to check that out.
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5th April 2013
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Quote:
Originally Posted by Glenn Kuras View Post
wow for 1/3rd smoothing, things are not looking all that great. Can you post the IR file?
IR file, I dont think you will get it, why should you?
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