# My first graph with REW



## informel (Jun 21, 2011)

I just bought a UMIK-1 and started to experiment, using REW is not difficult, but interpreting result is another story,
I am also using an HDMI cable to connect to my receiver

To begin I am only checking in the 0- 200Hz region

At first I got scared when I saw the result, but I saw that peoples use 1/6 octave smooting and that makes things look beter.

I would like to know what you think about that, I know I have one nasty dip at 173 Hz, but my microphone is not at the listening position right now (I need a longer cable).


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## Phillips (Aug 12, 2011)

Post crossover + waterfall graph (0 - 200hz).


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## informel (Jun 21, 2011)

Phillips said:


> Post crossover + waterfall graph (0 - 200hz).


here is the waterfall


For crossover, I am not sure, my understanding was that if I answer Yes to THX sub it would be crossover at 80Hz, but setup for main and center are set at 40Hz


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## Phillips (Aug 12, 2011)

The decay looks pretty good, certainly something for the receiver to work on.

Just wait for the mic to be in the listening position.

Good to see that you are experimenting with different positions.


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## informel (Jun 21, 2011)

Phillips said:


> The decay looks pretty good, certainly something for the receiver to work on.
> 
> Just wait for the mic to be in the listening position.
> 
> Good to see that you are experimenting with different positions.


Thanks for the reply, I should post result from the listening position today.
What I am also looking is how to interpret those graph myself, so I could also help other in the near futur


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## informel (Jun 21, 2011)

Here I have taken measurement from the listening position.
I had to lower the volume because I was constantly running out of headroom (I had to change the setting from my amp from -14DB to -21DB)


But if the reading are correct, I was constantly over 120DB and I still have this nasty dip at 127Hz


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## Phillips (Aug 12, 2011)

First of all i think you should to look at a better LP and speaker position, worth a try. Sometimes the LP is easier to move. You can use the RTA for this. By doing this it optimizes your Receivers power to EQ.

Is the graphs Full Range with both playing, the drop off at the HF could be timing. Do a measurement with Left only then Right only and post. Actually post the mdat file.

Check and make sure that the SENS FACT is on top of the mic calibration file, is the sweep really loud?
Also check and make sure that your "mic input" settings in your laptop are about 33%.


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## informel (Jun 21, 2011)

Phillips said:


> First of all i think you should to look at a better LP and speaker position, worth a try. Sometimes the LP is easier to move. You can use the RTA for this. By doing this it optimizes your Receivers power to EQ.
> 
> Is the graphs Full Range with both playing, the drop off at the HF could be timing. Do a measurement with Left only then Right only and post. Actually post the mdat file.
> 
> ...


Listening position is kind of limited and I could move main speaker a bit.

Yes Full range is main + sub

As for the mic, I am using a USB mic (UMIK-1)

I am including separate response for main (left and right) without the sub as I was doing some test


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## informel (Jun 21, 2011)

Phillips said:


> Is the graphs Full Range with both playing, the drop off at the HF could be timing. Do a measurement with Left only then Right only and post. Actually post the mdat file.
> 
> .


Sorry I am not home right now and do not have an mdat file, I just posted the full response for the main speaker and I am concern, those speaker are old, but here where specified at 20-30K +- 3DB, since I have similar response from both speakers (measuring where taken aproximatly 1 meter away), it does not look like it is the room that is doing that. It would be the speakers or the combo laptop + USB microphone


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## Phillips (Aug 12, 2011)

informel said:


> Sorry I am not home right now and do not have an mdat file, I just posted the full response for the main speaker and I am concern, those speaker are old, but here where specified at 20-30K +- 3DB, since I have similar response from both speakers (measuring where taken aproximatly 1 meter away), it does not look like it is the room that is doing that. It would be the speakers or the combo laptop + USB microphone


When you get a chance:
Measure approx 6 - 12 inches from tweeter on one speaker.
Measure left only and right only in your LP
Measure both combined in your LP

If you have another or borrow another laptop try this as well, i don't think it is this, but good to eliminate.


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## informel (Jun 21, 2011)

Phillips said:


> When you get a chance:
> Measure approx 6 - 12 inches from tweeter on one speaker.
> Measure left only and right only in your LP
> Measure both combined in your LP
> ...


I just had a bad thought, I remember changing the tweeters couple years ago and since I am not listening to music has loud as before; and I am pretty sure that the tweeter is not as strong as the previous ones.

But when I purchase my sub, everything change, I really drove those old speakers hard (I wan't satify with the sound for the past couple of months, but I though that at age of 58 lddude:, my earing was simply not what it was.

I tested one of the tweeter, but they are soldered and the crossover prevented me from checking the DC resistance, I will take my soldering iron out tomorrow and check them


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## Phillips (Aug 12, 2011)

Just measure as normal with the mic about 6-12 inches away from the speaker with only the one speaker going.


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## informel (Jun 21, 2011)

I just do not know what to say
I took some other measurement this morning at low level because everybody are sleeping and the FR looks OK.

I only took left channel but I have a rsponse now that goes all the way to 20Khz


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## informel (Jun 21, 2011)

informel said:


> I just do not know what to say
> I took some other measurement this morning at low level because everybody are sleeping and the FR looks OK.
> 
> I only took left channel but I have a rsponse now that goes all the way to 20Khz


I can only say that I setup my receiver as pure audio ( it was set to stereo before which enable left
+right+sub) so only the 2 front sepaker are active and I physically disconnected the right speaker, looks like I will have to more testing before I can continue with room response


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## Phillips (Aug 12, 2011)

Measure the Right speaker the same way to confirm.

Measurements that are useful for one measurement session:
At listening position
Left speaker only (no sub)
Right speaker only (no sub) 
Both speakers (no sub)
Sub 1 only (crossover disabled)
Sub 2 only (crossover disabled)
Sub 1 & 2 (crossover disabled)
Both speakers + Sub 1 & 2 (crossover enabled)

This will give you a good idea what your speakers/subs are doing e.g. in room, integration etc.


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## informel (Jun 21, 2011)

I took some more measurement at different power level, it seems like the response is OK at low volume but degrade at higher volume
I have inclided the mdat files

last file is from this morning and it does look better


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## informel (Jun 21, 2011)

Phillips said:


> Measure the Right speaker the same way to confirm.
> 
> Measurements that are useful for one measurement session:
> At listening position
> ...


OOOPs, sorry I skipped over this post, will do fater dinner, the wife is calling


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## informel (Jun 21, 2011)

Phillips said:


> Measure the Right speaker the same way to confirm.
> 
> Measurements that are useful for one measurement session:
> At listening position
> ...


Here are the result, I am sending you the files, I also took some near field mesurement


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## spicerr (Jan 1, 2014)

I where is the REW programme to download ?

Thank


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## Phillips (Aug 12, 2011)

spicerr said:


> I where is the REW programme to download ?
> 
> Thank


Follow this link post 6 for the program and post 7 for the manual PDF http://www.hometheatershack.com/for...1-beta-downloads-asio-support.html#post637472


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## spicerr (Jan 1, 2014)

Thank but im not able to download with my iPad ????


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## Phillips (Aug 12, 2011)

informel said:


> Here are the result, I am sending you the files, I also took some near field mesurement


Do you have this line below on your calibration file?
"Sens Factor =-7.442dB, SERNO: 7002286"

The volume you are measuring is excessive, about 70-80db is good.
At the volume you are measuring will be very loud?

I would suggest when looking at 0 - 250hz use no smoothing, don't chase the sharp dips they are not audible.

Re-do the nearfield like you did for the Left tweeter and compare Left & Right to see if they are similar.
If they are that's good.	

With your provided Left & Right measurements done a bit of a exercise and the timing looks ok for the high frequencies that might have related to your problem.

I would suggest trying different positions for your sub or/and LP. You might be able to get a flatter response.

To clear things up please re-do the following, all at listening position:
Please put into one file

Left speaker only with crossover activated
Right speaker only with crossover activated
Sub only with crossover activated
Sub only with crossover not activated
Both speakers and Sub with crossover activated


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## Phillips (Aug 12, 2011)

spicerr said:


> Thank but im not able to download with my iPad ????


Not sure, might pay to post a separate thread.

You might be able to use the Mac download?


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## informel (Jun 21, 2011)

spicerr said:


> Thank but im not able to download with my iPad ????


those files are ment to be loaded from REW, is there a version for IPAD?


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## informel (Jun 21, 2011)

Phillips said:


> Do you have this line below on your calibration file?
> "Sens Factor =-7.442dB, SERNO: 7002286"


That is exactly what I have on the first line





Phillips said:


> The volume you are measuring is excessive, about 70-80db is good.
> At the volume you are measuring will be very loud?


Hitting over 120DB should be painfull right?, I am wondering if I am recording the real value, I have to set the 
volume very low in order to record around 70-80DB


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## Phillips (Aug 12, 2011)

> That is exactly what I have on the first line


Good



> Hitting over 120DB should be painfull right?,


Its very loud



> I am wondering if I am recording the real value, I have to set the
> volume very low in order to record around 70-80DB


If you are running Windows OS check
Control Panel > Sound > Mic Input and make sure it is set to 33% (windows default setting)

I haven't used HDMI, i use headphone out.


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## pacogun (Sep 21, 2013)

I am with Phillip, if you have other computer for measurement comparison. It does happen to me, i have different measurement with different computer. One particular laptop gives me dip on 8khz, where it doesn't happen with other laptop and the desktop. So, I don't use that particular laptop for REW measurement.
Make sure you adjust and tick the appropriate options on REW preferences window before doing measurement.


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## Glyptoron (Apr 20, 2006)

_Hitting over 120DB should be painfull right?_

Hi all,
Not only painful but also dangerous.
In France, the High Council for Public Health says :
Dangerous thresholds for the ear depend on the noise level in dB (A) (which weights frequencies according to the fragility of the ear) and duration of exposure.
Thus, hearing risks are limited if exposure to 85 dBA lasts less than 8 hours, or 4 hours for 88 dBA, or 91 dBA for 2 hours, or 15 minutes at 100 dBA, etc..
So, at 120 dBA, continuous exposure should be limited to 9 seconds.
Do you hear me ? :unbelievable:
When I make acoustic measurements I wear hearing protection. This may seem ridiculous in a house but it is much less tiring in the long run !


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## informel (Jun 21, 2011)

Glyptoron said:


> _Hitting over 120DB should be painfull right?_
> 
> Hi all,
> Not only painful but also dangerous.
> ...


I am still not shure if the level is acurate, it is loud but not sure it is over 120DB, I will use a different laptop and desktop and compare the result and probably tell my wife to go shopping :spend:


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## informel (Jun 21, 2011)

informel said:


> I am still not shure if the level is acurate, it is loud but not sure it is over 120DB, I will use a different laptop and desktop and compare the result and probably tell my wife to go shopping :spend:


WOW, I was going over some of my test and I see that some meseasurement are over 130DB, if those level are true, then my old speakers are efficient


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## Phillips (Aug 12, 2011)

Make sure you have the latest REW version.
If you can use the headphone output and Java drivers, just as matter of interest.
Check your settings in REW > Preferences
Post your calibration file.
Change laptop like you are going to do. 
If this does make a difference you can then hook up the other laptop and adjust the SPL meter to allow for the the difference.


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## informel (Jun 21, 2011)

Sorry for not following up, but looks like everything started to leak in my house,
It started with my water tank, the it was the dishwaher and then it the toilet that was leaking in the basement, if fixed that but then it started to leak between the tank and the bowl:hissyfit:

I should be OK for now and will try to make some mesurement tonight


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## informel (Jun 21, 2011)

I had some time to do some test

Only the sub was connected, no EQ, I also disable the EQ from the sub

first I took the sub near field response


then sub at the original position (left side of seating position)

check at the front btw the main speaker

and tested it at the right side of the seating position


After those test, I decided to move my sub at the front of the room between the front speaker


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## informel (Jun 21, 2011)

I would like to add that when I purchase my sub, I just put it in the corner without testing, I red that corner loading was best, doing some test prove that it was not the best in my case.

I am also fortunate that my wife:bigsmile: never say anyting bad when I play with audio gear, She even help me to put the sub on the couch at the listening position, so I can find the best available position for the sub


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## Phillips (Aug 12, 2011)

Sub only front position between main is the best out of the three although it rolls of early 55hz.
Wayne s house curve is well recognized and used.
Have you tried mid wall?

Corner placement can be beneficial, not with me either other than my RELs, they run really well but different system.

Disable the crossover so it is running to its limits e.g. 120hz.

If you can try other positions as you now have a reference to try and beat.

What EQ do you have?


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## informel (Jun 21, 2011)

Phillips said:


> Sub only front position between main is the best out of the three although it rolls of early 55hz.


considering that EQ was off both on sub and receiver, it is fairly good.
I will post some more graph, this time with main and sub; it looks better



Phillips said:


> Wayne s house curve is well recognized and used.
> Have you tried mid wall?


Not sure what you mean by that.




Phillips said:


> Disable the crossover so it is running to its limits e.g. 120hz.


I did some experiment, I will post later



Phillips said:


> If you can try other positions as you now have a reference to try and beat.


The 3 positions I tested are the only possible positions



Phillips said:


> What EQ do you have?


Audeyssey was off and EQ from sub was also off


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## informel (Jun 21, 2011)

thanks for your avise and comment

here are some more test I did with main and sub, I played with the LFE and crossover setting.

not much of a difference except when LFE and crossover are at 120hz


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## informel (Jun 21, 2011)

Phillips said:


> Wayne s house curve is well recognized and used.
> Have you tried mid wall?


I red Wayne's house curve article, I remembered reading it a while back and probably did not finish the article because I did not agree with that (my backgroung is electronic and used to work with instrument, so for me the response had be flat).

But a stubborn mind never learn anything, so I red his article completely this morning and understand the theory behind it.

the sub is indded midwall btw the main.


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## informel (Jun 21, 2011)

Ine's recommanadtion, I changed the scale to 20-130DB and applied 1/6 octave smoothing.
Things look good.
now, how do I make that target line to appear?
I do not see anything to turn it on or off and the setup to change the value from 75 to 90.

I do see a reference when I click on the EQ button, but I do not see any apply button


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## informel (Jun 21, 2011)

If I understood the theory correctly, the only area you can EQ is where you have minimum phase.
Minimum phase is found by looking at the excess phase, where the graph is horizontal, this is where you have minimum phase.

Well looking at the graph, that would be above 60hz, that mean I cannot EQ lower frequency?


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## Phillips (Aug 12, 2011)

Your scaling was correct in the earlier posts -45 - 105 this is the standard for posting, you can read this on the REW Forum page.

Can you change the listening position you said there was only three positions for the sub. This could result in better results, doesn't take much sometimes few inches.

When using the receivers crossovers disable the subs crossover.

Please measure and post the mdat file, you can post them all as one instead of individual. All this is done after you have optimized the LP.
Also no eq included like you have been doing:

Left speaker full range
Left speaker with best crossover, take some with different and determine which is best for both Left and Right 
Right speaker full range
Right speaker with best crossover, take some with different and determine which is best for both Left and Right 
Sub full range with crossover disabled
Sub with receivers best crossover applied
Left and Right speaker combined full range
Left and Right speaker combined with best crossover, take some with different and determine which is best for both 
Left and Right speaker combined with sub included with optimized crossover


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## informel (Jun 21, 2011)

Phillips said:


> Your scaling was correct in the earlier posts -45 - 105 this is the standard for posting, you can read this on the REW Forum page.


correction done



Phillips said:


> Can you change the listening position you said there was only three positions for the sub. This could result in better results, doesn't take much sometimes few inches.


In fact I have 2 positions on a couch and cannot move the couch or not much.




Phillips said:


> When using the receivers crossovers disable the subs crossover.


done



Phillips said:


> Please measure and post the mdat file, you can post them all as one instead of individual. All this is done after you have optimized the LP.


will do



Phillips said:


> Also no eq included like you have been doing:
> Left speaker full range
> Left speaker with best crossover, take some with different and determine which is best for both Left and Right
> Right speaker full range
> Right speaker with best crossover, take some with different and determine which is best for both Left and Right


Done but not sure I can determine the best one



Phillips said:


> Sub full range with crossover disabled


done



Phillips said:


> Sub with receivers best crossover applied


need to find best crossover first, need help on this one



Phillips said:


> Left and Right speaker combined full range


done



Phillips said:


> Left and Right speaker combined with best crossover, take some with different and determine which is best for both
> Left and Right speaker combined with sub included with optimized crossover


Again, need to find best crossover first, need help on this one


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## Phillips (Aug 12, 2011)

Ok here we go

1. Take the mic calibration file out of the soundcard calibration
2. If you are very restricted to these only for placement and LP then I would use the Measurement 18 position 2 as my first preference then number 19 position 3 as long as we only talking about main LP
3. The sub has good extension but drops of at 50hz, have you still got the receivers or sub crossover set or something like that. 
4. Polarity between the Sub and mains is ok. 

I normally set the speakers/subs position / LP for optimal full range, best as you can then let the EQ tidy up.

What you could do is run measurements with position 2 with the 40,60,80hz range. Personally i wouldn't go above 80hz crossover, though that depends on the size of the speakers.
Remember that crossovers aren't brick walls, that why i said start with full range.


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## informel (Jun 21, 2011)

Sorry for not replying before, but I got very busy at work



Phillips said:


> Ok here we go
> 
> 1. Take the mic calibration file out of the soundcard calibration


Why do you want me to take the calibration file out?



Phillips said:


> 3. The sub has good extension but drops of at 50hz, have you still got the receivers or sub crossover set or something like that.


I tought I had it remove, but I will check again




Phillips said:


> I normally set the speakers/subs position / LP for optimal full range, best as you can then let the EQ tidy up.
> 
> What you could do is run measurements with position 2 with the 40,60,80hz range. Personally i wouldn't go above 80hz crossover, though that depends on the size of the speakers.
> Remember that crossovers aren't brick walls, that why i said start with full range.


Will do


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## Phillips (Aug 12, 2011)

> Sorry for not replying before, but I got very busy at work


No need to be sorry.



> Why do you want me to take the calibration file out?


Because you are using a USB mic no need for soundcard calibration other wise you would be doubling up. The calibration file is a correction file for a particular unit mic, soundcard etc.
The soundcard calibration entry is basically only required if you are using a XLR balanced mic + Pre / Soundcard.
I have used the soundcard calibration entry for a correction that i required at the time but no longer required.

If you had a XLR mic that required a Pre/Soundcard then the soundcard calibration file would be entered + the mics calibration file.


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## informel (Jun 21, 2011)

QUOTEBecause you are using a USB mic no need for soundcard calibration other wise you would be doubling up. The calibration file is a correction file for a particular unit mic, soundcard etc.
The soundcard calibrat UNQUOTE

Sorry I di not notice that the sound card was check.


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## informel (Jun 21, 2011)

Phillips said:


> Ok here we go
> 
> 3. The sub has good extension but drops of at 50hz, have you still got the receivers or sub crossover set or something like that.
> 
> ...


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## informel (Jun 21, 2011)

The first graph is the sub near field reponse, it is nearly flat from 15 to 100 Hz
I tried 3 different Xo at 40, 60 and 80HZ and response are very similar


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## Phillips (Aug 12, 2011)

The mdat file had the mic calibration file in the soundcard calibration box, remove it.

I have a DD15 as well great sub.

If you leave the sub on setting 6 that is fine, but you must disable the subs crossover.

Set the receiver to small for bass management, then max crossover or disable this will give max frequency range to the sub only. Then turn of speaker A (which is your mains) and then set to 2 channel mode.

What you can do is plug into the sub instead of the receiver for the sub measurement only. I don't do this myself.

Take the measurement at your listening position then see if you can get the flattest response either by shifting the listening position or preferably the sub position.

Then continue with the measurements i suggested above.

Post the mdat file and i will give you the filters to apply to the DD15.


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