Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How To Interpret Graphs - Page 509 - AVS Forum | Home Theater Discussions And Reviews
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post #15241 of 15262 Old 06-19-2015, 05:32 PM
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Thanks. I figure one of the tools of REW is seeing something obvious like that, center being low most of the way.
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post #15242 of 15262 Old 06-24-2015, 11:09 AM
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Hey guys, I just today got REW up & running on my iMac. I'm using a UMIK-1 mic for measurements. Ok, so I have absolutely no idea what I'm doing lol!!! I tried reading thru the getting started portion of the REW manual but seem to be having difficulties understanding the "check levels" section. I have my iMac connected HDMI to my Outlaw Model 975 & was trying to verify that my levels were set to an acceptable level for measuring. I can not get anywhere near 75db to show up on the Input portion of the level meter. The output portion shows my defaulted setting of -12dbfs & I raised the volume on my 975 processor to a "decently" loud volume & about as high as I get on the Input side is about -48db. Obviously I'm not grasping something here or I have an incorrect setting that I'm hoping someone can help me sort out. I did not want to go any higher on my processor because with Soundflower on the iMac there is an occasional "static" sound when checking levels & the last thing that I want to do is fry one of my speakers. I hope you guys wouldn't mind helping me out a bit as I'm really interested in jumping into measuring my room. Thanks so much guys!!! Carmine.
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post #15243 of 15262 Old 06-24-2015, 11:20 AM
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Originally Posted by carminepesce View Post
The output portion shows my defaulted setting of -12dbfs & I raised the volume on my 975 processor to a "decently" loud volume & about as high as I get on the Input side is about -48db.
REW has a sound meter portion. I think that's what you want to use to do the sound level check.

BTW, one of the better ways to proceed is to read the guide all the way through. Maybe twice or thrice. Then try to work your way through it.
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post #15244 of 15262 Old 06-27-2015, 11:23 AM
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After calibration (using Dirac), I'm getting a dip around 80-60. But when I boost the bass, I for the most part get rid of it. Wanted to know if its actually removed or I need to start moving stuff around to get rid of the dip. Cross-over is set to 80.
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7.1 Dirac, L+R+C: RA CX-15, SL,SR: RA-CX-8, Subs: Dual Gamma 218. For Sale: dual XV-15: http://www.avsforum.com/forum/209-au...15-1050-a.html
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post #15245 of 15262 Old 06-27-2015, 01:01 PM
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Quote:
Originally Posted by SherazNJ View Post
After calibration (using Dirac), I'm getting a dip around 80-60. But when I boost the bass, I for the most part get rid of it. Wanted to know if its actually removed or I need to start moving stuff around to get rid of the dip. Cross-over is set to 80.
That is kind of weird. I would not think that increasing the sub volume would reduce a dip, by that much, at about 62 hz especially when you have set your cross over at 80 hz. Many people like to run their subs 5db hot so maybe just keep it hot. Looks better and should sound better.

Just our of curiosity maybe try to measure just your sub and see if you get the same results.
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post #15246 of 15262 Old 06-27-2015, 01:55 PM
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Originally Posted by Frank D View Post
That is kind of weird. I would not think that increasing the sub volume would reduce a dip, by that much, at about 62 hz especially when you have set your cross over at 80 hz. Many people like to run their subs 5db hot so maybe just keep it hot. Looks better and should sound better.

Just our of curiosity maybe try to measure just your sub and see if you get the same results.
I"m getting the dip due to the interaction with main. Taking reading of only the sub, I get a perfect graph. Here are all the comparisons.
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7.1 Dirac, L+R+C: RA CX-15, SL,SR: RA-CX-8, Subs: Dual Gamma 218. For Sale: dual XV-15: http://www.avsforum.com/forum/209-au...15-1050-a.html

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post #15247 of 15262 Old 06-27-2015, 02:26 PM
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Quote:
Originally Posted by SherazNJ View Post
I"m getting the dip due to the interaction with main. Taking reading of only the sub, I get a perfect graph. Here are all the comparisons.
Maybe keep the x-over at 80 hz and use a steeper x-over slope (if you can choose the slope) and see if that changes anything?
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post #15248 of 15262 Old 06-29-2015, 08:18 AM
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Quote:
Originally Posted by SherazNJ View Post
After calibration (using Dirac), I'm getting a dip around 80-60. But when I boost the bass, I for the most part get rid of it. Wanted to know if its actually removed or I need to start moving stuff around to get rid of the dip. Cross-over is set to 80.
Sub distance tweak.
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post #15249 of 15262 Old Yesterday, 04:56 PM
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OK, I finally had time to play some with sub placement, measurements, HDMI cable finally worked along with UMIK.
I use Antimode 8033-IIS, both of these graph are with flat response through antimode. these are combined LCR with subs crossed over at 100 Hz.
What is interesting thing is that my response below 130 Hz was much better WITHOUT Audyssey ( Blue) then with it (red). It is debatable is there a huge difference in higher frequencies.

Any thoughts on what happened?

I am going to do some listening today and tomorrow to try to figure out if anything audible comes at me.
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Change is the only constant.

My HT: http://www.avsforum.com/forum/19-ded...l#post32691273
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post #15250 of 15262 Old Today, 07:31 AM
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Originally Posted by sinisanav View Post
OK, I finally had time to play some with sub placement, measurements, HDMI cable finally worked along with UMIK.
I use Antimode 8033-IIS, both of these graph are with flat response through antimode. these are combined LCR with subs crossed over at 100 Hz.
What is interesting thing is that my response below 130 Hz was much better WITHOUT Audyssey ( Blue) then with it (red). It is debatable is there a huge difference in higher frequencies.

Any thoughts on what happened?

I am going to do some listening today and tomorrow to try to figure out if anything audible comes at me.
1) You say these measurements are "combined LCR with subs" - however, there is no way to measure 3 speakers+subs in REW when using HDMI.
2) You're "No Audyssey" response definitely does look better in the lower bass region....but your mid-bass (80-300hz) is kind of all over the place. Did you follow the recommended Audyssey mic placement guidelines, and did you use a tripod or mic boom?
3) Did you run the Antimode before or after Audyssey?
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post #15251 of 15262 Old Today, 08:21 AM
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Quote:
Originally Posted by Alan P View Post
1) You say these measurements are "combined LCR with subs" - however, there is no way to measure 3 speakers+subs in REW when using HDMI.
2) You're "No Audyssey" response definitely does look better in the lower bass region....but your mid-bass (80-300hz) is kind of all over the place. Did you follow the recommended Audyssey mic placement guidelines, and did you use a tripod or mic boom?
3) Did you run the Antimode before or after Audyssey?
Alan, that kind of confused me as well, I didn't want to say anything as I'm a novice with REW.
I know you can measure two speakers and subs with the Timing Reference output, correct me if I'm wrong? I found this out when Jerry says to measure L+R+Subs, at first I didn't know how to do this? Thanks to all and you Alan for all that you guys do.

Cheers Jeffrey
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post #15252 of 15262 Old Today, 09:03 AM
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Alan, that kind of confused me as well, I didn't want to say anything as I'm a novice with REW.
I know you can measure two speakers and subs with the Timing Reference output, correct me if I'm wrong? I found this out when Jerry says to measure L+R+Subs, at first I didn't know how to do this? Thanks to all and you Alan for all that you guys do.

Cheers Jeffrey
Correct, the OP should be measuring L+R+Subs. Something is very wrong with his measurements. No way that Audyssey on should be significantly worse than Audyssey off without some other contributing factor. Unfortunately, as with many new posters, we didn't get enough information to assist in the trouble-shooting. The Antimode and how it is used is the big unknown.
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post #15253 of 15262 Old Today, 09:22 AM
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Originally Posted by AustinJerry View Post
Correct, the OP should be measuring L+R+Subs. Something is very wrong with his measurements. No way that Audyssey on should be significantly worse than Audyssey off without some other contributing factor. Unfortunately, as with many new posters, we didn't get enough information to assist in the trouble-shooting. The Antimode and how it is used is the big unknown.
I have to agree with that assumption.

As you mentioned to me Jerry the suite of measurements should be as follows, please correct me if I'm wrong:

L+R+Subs, 15-300Hz, no smoothing
Subs only, 15-300Hz, no smoothing
Left + Subs, 15-20,000Hz (with 1/6th or 1/24th smoothing)
Right + Subs, 15-20,000, same smoothing
Center + Subs 15-20,000Hz same smoothing.

As a side note, do not average responses, as this masks individual issues that might be present in one or the other channels.
Cheers Jeffrey
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post #15254 of 15262 Old Today, 09:57 AM
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Originally Posted by Alan P View Post
1) You say these measurements are "combined LCR with subs" - however, there is no way to measure 3 speakers+subs in REW when using HDMI.
2) You're "No Audyssey" response definitely does look better in the lower bass region....but your mid-bass (80-300hz) is kind of all over the place. Did you follow the recommended Audyssey mic placement guidelines, and did you use a tripod or mic boom?
3) Did you run the Antimode before or after Audyssey?
1) Yep there is no way to do it, so what I did was took separate L,C,R full range sweeps, no smoothing, then averaged them to get overall signal at MLP, is that right way to do it?
Measurement for C had dip at about 80-90 range while L and R had a bump at same same freq, so smoothed that part.

2) I don't like the 100-400 Hz range either. BTW crossovers set to 100 Hz for LCR. I have followed the audyssey tutorial, I have Audy XT, so I used, as always 8 measurements, using the tripod, if you follow link to my HT, you can see how my seating is set, I have two rows, so position 1 is at MLP( first row seat second from right) then 2 and 3 are on adjoining seats in first row, 4,5,6 are the back row seats, then 7 and 8 are in space between rows, mic about 5 inches above the 1st row headrests ( not sure if maybe those last two spots were too low and got some bouncing off the seats??), should I do 7,8 positions maybe in first row?

3) I ran Antimode before Audyssey, and it did smooth the response compared to the no EQ at all. Subs are equidistant to MLP and Antimode running in flat response curve, no boost added. I know your preference is do it after Audyssey.

I hope I mentioned all the needed details

Change is the only constant.

My HT: http://www.avsforum.com/forum/19-ded...l#post32691273
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post #15255 of 15262 Old Today, 10:00 AM
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As a side note, do not average responses, as this masks individual issues that might be present in one or the other channels.
Cheers Jeffrey
Good catch Jeff, I just noticed after going back and looking that his measurements say "average" in the legend. He is also using variable smoothing on the sub graphs (not that it would make that much difference).
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1) Yep there is no way to do it, so what I did was took separate L,C,R full range sweeps, no smoothing, then averaged them to get overall signal at MLP, is that right way to do it?
No, it is not the correct way. The averaged response provides little insight as to what is going on in your room. If you have a chance, post the measurements Jeffrey suggested, using no averages.

And have you read the REW Guide linked in my sig?
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post #15257 of 15262 Old Today, 11:37 AM
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Originally Posted by ahblaza View Post
I have to agree with that assumption.

As you mentioned to me Jerry the suite of measurements should be as follows, please correct me if I'm wrong:

L+R+Subs, 15-300Hz, no smoothing
Subs only, 15-300Hz, no smoothing
Left + Subs, 15-20,000Hz (with 1/6th or 1/24th smoothing)
Right + Subs, 15-20,000, same smoothing
Center + Subs 15-20,000Hz same smoothing.

As a side note, do not average responses, as this masks individual issues that might be present in one or the other channels.
Cheers Jeffrey
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Good catch Jeff,
At the rate you are progressing, Jeff, you will be the expert in no time!
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post #15258 of 15262 Old Today, 11:50 AM
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At the rate you are progressing, Jeff, you will be the expert in no time!
Thank you Jerry, your guide and comments have helped me to progress to the point where I am no longer intimidated by all of this. The part with me being an expert in no time is correct, I won't be an expert in any time............ Thanks for the compliment though.

@Alan , thank you as well.

Jeffrey
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post #15259 of 15262 Old Today, 12:15 PM
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Originally Posted by AustinJerry View Post
No, it is not the correct way. The averaged response provides little insight as to what is going on in your room. If you have a chance, post the measurements Jeffrey suggested, using no averages.

And have you read the REW Guide linked in my sig?
I am planning to go back to the lab ( aka my HT ) this afternoon and do more measuring. So, with use of HDMI, how does one get measurement for L+R with subs, do I change output from multichannel HDMI to stereo on my Mac?

But, that will not answer the question about the effect of Audyssey, any thoughts on mic positions, would proximity to first row chairs ( positions 7,8) change the response to allows those big swings compared to smoother response without Audyssey.

Yes, I have read the REW guide( minus the windows part as I have Mac), initially was using the RCA cables, now I finally got 30ft USB to work with UMIK so I am able to do HDMI.

So, general question, what would you use averaging for ( measurements of the one particular sweep?, like avearge of 5 sweeps for L+sub), or do you use averaging option in REW at all?

I understand the reason for evaluating each speaker and it's interaction with sub in separate sweep to see how it particularly interacts with room, but when we watch a movie or listen to a concert, we listen to the whole system where all speakers and subs are contributing simultaneously. That is why I averaged the LCR, athough I presume that if I want a true "real measure of how does the LCR response is woudl be to play a sweep through all three speakers+subs simultaneously?

Change is the only constant.

My HT: http://www.avsforum.com/forum/19-ded...l#post32691273

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post #15260 of 15262 Old Today, 12:37 PM
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Originally Posted by sinisanav View Post
I am planning to go back to the lab ( aka my HT ) this afternoon and do more measuring. So, with use of HDMI, how does one get measurement for L+R with subs, do I change output from multichannel HDMI to stereo on my Mac?

But, that will not answer the question about the effect of Audyssey, any thoughts on mic positions, would proximity to first row chairs ( positions 7,8) change the response to allows those big swings compared to smoother response without Audyssey.

Yes, I have read the REW guide( minus the windows part as I have Mac), initially was using the RCA cables, now I finally got 30ft USB to work with UMIK so I am able to do HDMI.

So, general question, what would you use averaging for ( measurements of the one particular sweep?, like avearge of 5 sweeps for L+sub), or do you use averaging option in REW at all?

I understand the reason for evaluating each speaker and it's interaction with sub in separate sweep to see how it particularly interacts with room, but when we watch a movie or listen to a concert, we listen to the whole system where all speakers and subs are contributing simultaneously. That is why I averaged the LCR, athough I presume that if I want a true "real measure of how does the LCR response is woudl be to play a sweep through all three speakers+subs simultaneously?
To measure L+R+Subs, output the REW test signal to both the left and right channels simultaneously, with L and R speakers set to "small". The subs receive the signal by virtue of redirected bass below the crossover point.

The reason an average is an inappropriate measurement is that it masks the underlying causes of poor response. No offense meant, but the measurements you posted are not very good. If you provide the proper measurements, we may be able to get a better idea of what is going on.

Once you have optimized the responses of individual speakers, an average may make more sense, but not as the first measurement presented. We hardly ever see average responses presented here, because of their limited value in troubleshooting, which is why we are here (I think).
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post #15261 of 15262 Old Today, 01:38 PM
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Just to add to Jerry's reply a bit:

To output to 2 channels simultaneously (i.e. FR+FL) you will use the "Timing Reference Output" drop down for the second channel. The only reason I mention it is because it's not really labeled in way that you would intuitively know that is where you select the 2nd channel.

If your system is mainly used for movies, you want to concentrate on the CC+sub(s) measurements the most.

But first, let's just concentrate on the subs....use output channel 4 (LFE) and show us a measurement of the subs only. Then choose output channel 3 (CC+subs) and let us see that.

Both measurements with Audyssey + Antimode on, Dynamic EQ and Dynamic Volume off. Try to get an average sweep level around 85-90db.
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Correct me if I'm wrong but I thought the maximum length of a USB cable is 15', longer may not give an accurate measurement. I've never tried anything longer than 10' so I really can't say for sure how detrimental a 30' length would be.

As far as measuring subs only I found the easiest method for me was to set my LPF of the LFE to off or bypass and select HDMI 4.

Jeffrey
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