# Upper Frequencies



## Phillips (Aug 12, 2011)

Hi can someone please comment on these graphs and questions.

I have noticed that the upper frequencies are lacking and wondering which calibration file to use.

The 90% file graphs don't look as bad.

1. With the upper frequencies especially 3khz > between the Left & Right and Both graphs the Both graph drops off before 10khz. Why does this happen when the Left & Right seperate doesn't have as much drop off?

2. Which calibration file (0 vs 90 degrees)/mic position(horizontal vs vertical) should i use when there is a difference?

Thanks in advance


























Green trace = Left
Purple = Right
Red = Both

































Purple = Left
Green = Right
Tan = Both


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## jtalden (Mar 12, 2009)

Phillips said:


> 1. With the upper frequencies especially 3khz > between the Left & Right and Both graphs the Both graph drops off before 10khz. Why does this happen when the Left & Right seperate doesn't have as much drop off?


This happens when the mic is not exactly equidistant from both the speakers. The phase difference at the high frequencies reduces the combined SPL as the frequency rises. An 8.6 mm distance difference is a 180° phase difference at 20 kHz (a null). Your distance difference was probably nearer half that, i.e, 4.3 mm or 90° at 20 kHz as the combined SPL level was near the individual levels. 

You can prove this to yourself if you like. With loopback on, adjust the mic position slightly until the FL and FR IR peaks is exactly aligned. Then try the measurements again. The SPL reinforcement will now occur all the way to 20 kHz. You can also do this experiment by manually offsetting the individual IR peaks and then using A + B math to add them together to see the impact. 



> 2. Which calibration file (0 vs 90 degrees)/mic position(horizontal vs vertical) should i use when there is a difference?


It theoretically wouldn't make a difference if you had a a free field condition.

For measuring high frequencies in a room though, it is best to use the 0° cal file with mic pointed toward the speakers. 

The mic is more sensitive to 0° signals for the high frequencies so if you point it up at 90° and use the 90° cal file the mic will emphasize the ceiling reflections a little more possibly making the 90° HF readings appear higher that the 0° readings. The 0° on axis approach deemphasizes the floor and ceiling reflections a little.

Also a 20° error pointing a mic on axis has almost no affect on the reading while a 20° error on a 90° mic setup will provide significantly more SPL error at high frequencies. Check out the typical polar plots of a mic. The story is shown there.


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## Phillips (Aug 12, 2011)

> You can prove this to yourself if you like. With loopback on, adjust the mic position slightly until the FL and FR IR peaks is exactly aligned. Then try the measurements again. The SPL reinforcement will now occur all the way to 20 kHz. You can also do this experiment by manually offsetting the individual IR peaks and then using A + B math to add them together to see the impact.


Thank you 

I use a USB mic. 

Can i still use the manually offsetting the individual IR peaks?

The head is 20cm wide so how do i fix this?





> It theoretically wouldn't make a difference if you had a a free field condition.
> 
> For measuring high frequencies in a room though, it is best to use the 0° cal file with mic pointed toward the speakers.
> 
> ...


Doesn't the difference in files compensate for this?

Thanks again


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## Phillips (Aug 12, 2011)

Have done a bit of reading and it appears:

0 degree file for measuring speakers directly and subwoofers.
90% degree file for measuring rooms/speakers with the mic pointed 75-80% slightly pointed towards the speaker, so not quite 90%.

Bit confused


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## jtalden (Mar 12, 2009)

Phillips said:


> I use a USB mic.
> 
> Can i still use the manually offsetting the individual IR peaks?


You cannot align the IR peaks experimentally by moving the mic unless you have loopback capability.

We can still manually move the IR peaks using the offset box in the Impulse controls. With the individual IRs exactly aligned the HF is reinforced. If we find the exact very small IR offset that you actually measured at then the A + B math combination will result in the same trace that you physically measured. 



> The head is 20cm wide so how do i fix this?


?? I don't understand what you are asking here. 

The width of the tip of the mic does impact the frequency and rate of the HF directional characteristics of the mic. 

The width does not impact how far we can move it however, so we can still move it 4.3 mm if we want.



> Doesn't the difference in files compensate for this?


All measuring mics are somewhat directional at HF and changing the calibration file does not change this physical characteristic in any way. It just compensates for the SPL sensitivity in the specified direction. 

Our omnidirectional mics are only omnidirectional below about 2 kHz and above that they are progressively become directional. The mic gives more voltage out (SPL) for an on axis vs an off angle HF signal of equal magnitude.

Calibration files will properly compensate the SPL for a signal from the designated direction only in a *free field *condition. A room is not free field as room boundaries allow reflections from different directions that are also measured by the mic. The calibration files cannot compensate for this as all rooms and setups are different.


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## jtalden (Mar 12, 2009)

Phillips said:


> Have done a bit of reading and it appears:
> 
> 0 degree file for measuring speakers directly and subwoofers.
> 90% degree file for measuring rooms/speakers with the mic pointed 75-80% slightly pointed towards the speaker, so not quite 90%.
> ...


I remember Wayne recommending pointing the mic at the speaker (on axis) and then tilting it upward 20° for measurements of a speaker/room if you are interested in the HF response. 

If you are measuring LF he notes that it does not make a difference (the mic is omnidirectional in the bass range).

If you use 0° and 90° calibration files the difference between 0° and 90° mic orientations measurements is minimized. In my room I still see a clear difference.

In the end, I am not sure if there is a practical impact between these two options. If we EQ the HF, we are still going to tilt our house curve to suit our taste given our specific setup. If we aren't going to EQ the HF, then there cannot be a practical impact. I just prefer to point the mic generally toward the speaker under test as the repeatability is improved and there is slightly less emphasis given to the room reflections.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Phillips said:


> Hi can someone please comment on these graphs and questions.
> 
> I have noticed that the upper frequencies are lacking and wondering which calibration file to use.
> 
> The 90% file graphs don't look as bad.


You forgot to tell us what mic orientation you were using for these measurements.

That said, do any of the graphs represent what you’re actually hearing? IOW, do the highs sound “right,” or do they sound soft, like the first three graphs show?




Phillips said:


> Have done a bit of reading and it appears:
> 
> 90% degree file for measuring rooms/speakers with the mic pointed 75-80% slightly pointed towards the speaker, so not quite 90%.


I assume you got that from the Downloads page? It’s bad information, especially since our stock calibration file is 0-degree.

Regards,
Wayne A. Pflughaupt


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## Phillips (Aug 12, 2011)

> We can still manually move the IR peaks using the offset box in the Impulse controls. With the individual IRs exactly aligned the HF is reinforced. If we find the exact very small IR offset that you actually measured at then the A + B math combination will result in the same trace that you physically measured.


Ok will give it a try.



> ?? I don't understand what you are asking here.


The difference in moving the mic might be 4.3mm but we measure in the middle (between our ears so to speak). We don't measure at each ear. 


Thank you


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## Phillips (Aug 12, 2011)

jtalden said:


> I remember Wayne recommending pointing the mic at the speaker (on axis) and then tilting it upward 20° for measurements of a speaker/room if you are interested in the HF response.
> 
> If you are measuring LF he notes that it does not make a difference (the mic is omnidirectional in the bass range).
> 
> ...



Actually got it from the site below, Googled it.

http://www.hifizine.com/2012/09/day...microphone-calibrated-by-cross-spectrum-labs/

Thanks


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## Phillips (Aug 12, 2011)

> You forgot to tell us what mic orientation you were using for these measurements


.

For the 0 degrees the mic was pointed horizontal with slight upwards.
For the 90 degrees the mic was pointed vertical.



> That said, do any of the graphs represent what you’re actually hearing? IOW, do the highs sound “right,” or do they sound soft, like the first three graphs show?


Depending on my hearing the top three represent more what i am hearing, soft.



> I assume you got that from the Downloads page? It’s bad information, especially since our stock calibration file is 0-degree.


Got it from the site below.

http://www.hifizine.com/2012/09/day...microphone-calibrated-by-cross-spectrum-labs/


Thank you


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## jtalden (Mar 12, 2009)

Phillips said:


> ...
> 
> The difference in moving the mic might be 4.3mm but we measure in the middle (between our ears so to speak). We don't measure at each ear.


You questioned why the FL+FR measurement fell off at HF while the lower freqs showed the expected SPL reinforcement. I explained why this happens. It is a measurement system characteristic. It is also why I don't measure 2 or more main speakers at a time. The interference among them makes the measurement of the HF suspect.

Your comment on the mic position vs. the 2 ears is a good one. We also hear through our nose and mouth and even skull vibration is heard. We also sense the LF over our entire body. With a single mic position the range from maybe 100-600 Hz or so varies a lot in my room with small changes of mic position. After significant experimentation, I settled on taking an average of a small window around my LP. That way my results are basically identical for repeated measurement runs even though the initial mic LP changes a little. That way I reason that I am not chasing my tail when I adjust my house curve and redo the EQ. These are personal choices that work very well in my room to meet my requirements. Other choices may work well for you depending on you room, system and requirements.


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## HifiZine (Feb 7, 2013)

Edit: I think it's important to note that the 70-80 degree orientation requires the use of a 90-degree cal file. My understanding is that using the 90-degree cal file gives the mic a response (in three dimensions) that somewhat resembles a diffuse-field microphone; the 70-80 degree orientation is Herb's recommendation for these inexpensive mics in the case where you have a "halfway" situation between free field (direct sound) and diffuse field (all directions). Again, as I understand it.

I'm assuming that Wayne's "bad information" dismissal is referring only to the use of an on-axis cal file with this orientation. Or...?

Curiously, some of these mics measure almost flat at 90 degrees (with no cal file), up to 12-14 kHz.


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## Phillips (Aug 12, 2011)

> We can still manually move the IR peaks using the offset box in the Impulse controls. With the individual IRs exactly aligned the HF is reinforced. If we find the exact very small IR offset that you actually measured at then the A + B math combination will result in the same trace that you physically measured.



I must be missing something here.

Please can you explain how to do this?

Thank you


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## Phillips (Aug 12, 2011)

jtalden said:


> You questioned why the FL+FR measurement fell off at HF while the lower freqs showed the expected SPL reinforcement. I explained why this happens. It is a measurement system characteristic. It is also why I don't measure 2 or more main speakers at a time. The interference among them makes the measurement of the HF suspect.
> 
> Your comment on the mic position vs. the 2 ears is a good one. We also hear through our nose and mouth and even skull vibration is heard. We also sense the LF over our entire body. With a single mic position the range from maybe 100-600 Hz or so varies a lot in my room with small changes of mic position. After significant experimentation, I settled on taking an average of a small window around my LP. That way my results are basically identical for repeated measurement runs even though the initial mic LP changes a little. That way I reason that I am not chasing my tail when I adjust my house curve and redo the EQ. These are personal choices that work very well in my room to meet my requirements. Other choices may work well for you depending on you room, system and requirements.


Maybe take two measurements where my ears would be (leave my ears there and move away)  and take a average?

Thank you


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## Phillips (Aug 12, 2011)

> I think it's important to note that the 70-80 degree orientation requires the use of a 90-degree cal file. My understanding is that using the 90-degree cal file gives the mic a response (in three dimensions) that somewhat resembles a diffuse-field microphone; the 70-80 degree orientation is Herb's recommendation for these inexpensive mics in the case where you have a "halfway" situation between free field (direct sound) and diffuse field (all directions). Again, as I understand it.


What i will do is redo the 90 degrees measurement with the mic & 70-80 degrees and post them.

In your opinion and experience as a general room/speaker measurement which would you use/or use?

I suppose it also depends on the mic, e.g. Dayton EMM-6 or Behringer ECM8000 vs DSP UMIK or Dayton UMM-6 or Omnimic? 

Thanks again


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## jtalden (Mar 12, 2009)

Phillips said:


> I must be missing something here.
> 
> Please can you explain how to do this?


> Measure FL, FR and FL+FR (all 3 with the mic at exactly the the same LP position).
[REW will align the peak of the IR at 0 ms for all 3 measurements since you don't have loopback engaged.]
> Check the overlay of the FL and FR IRs. If they are not exactly aligned with each other then offset one of them manually as needed. 
> Do the math operation A + B using the FL and FR measurements for "A" and "B"
> Now compare the overlay of the SPL for the 4 traces. 

The A + B trace should have the SPL reinforced all the way to 20 kHz. the FL+FR trace may or may not fall off below the A + B trace depending whether there is an actual distance differential of the 2 speakers relative to the actual mic position you chose. To see (experiment with) the impact of a slight distance difference we just manually offset one of the IRs by the distance we want and again perform the math A + B operation. With small offsets the HF will start to drop off as your original chart showed. With larger offsets we start seeing the impact of comb filtering throughout the HF range. If we play around enough we may be able to find the exact distance offset that results in the FL+FR trace that you measured. That is going to take some work however!


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## jtalden (Mar 12, 2009)

Phillips said:


> Maybe take two measurements where my ears would be (leave my ears there and move away)  and take a average?
> 
> Thank you


Most people posting here don't average and I find it is not really needed for LF and HF EQ. I only am only pointing out that averaging provides much more repeatability between measuring sessions to the mid frequency range and this has a significant impact if we are intending to apply any EQ to that range.

The level of repeatability increases with sample size (N). It starts to converge rapidly as N increases. Sampling practice in statistics often suggests N = 30 is a good sample size and N = 10 is a small, but reasonable sample to use when necessary. N = 6 is not too bad in my experience. N = 2 is probably marginally helpful, but will not be nearly as repeatable as the larger sample sizes.

I just use the RTA with the "forever" averaging option. I start the measurement, rush to the mic stand pull the mic off the holder and move it in zig zag fashion over maybe an 18"h x 40"w vertical window centered on the LP. I slowly move up and down 8 times on each side of the LP going out and then back to the LP. I then put the mic back into the holder and rush back to stop the RTA. The process takes maybe about 25 s and acquires around 160 averages over the window. 

I have compared this process to averaging 9 sweep samples using the same window. They compared very closely, but the RTA method was more repeatable, much faster and only requires one measurement storage location. In my room the RTA method provides a slight emphasis to bass range starting about 80 Hz and slowly increasing to maybe 1-3 dB at 20 Hz (I would have to review this again to be confident in the values). I believe this is a known common occurrence using RTA for low frequencies, but don't know how much this varies in different rooms. I just account for this in my house curve.

This is likely much more info than you wanted, but maybe someone reading this is interested in trying something different to improve measurement repeatability. Again, It's not needed to achieve good results, but some of us (me at least) is bothered by the large variability with small mic position changes.


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## HifiZine (Feb 7, 2013)

Phillips said:


> In your opinion and experience as a general room/speaker measurement which would you use/or use?


I use both  I compared a) mic pointed between speakers with 0 deg cal file and b) mic pointed at 80 degrees with the 90 degree cal file, and they were basically identical. However with different speaker / speaker setup / room there may be more of a difference. Since I generally do speaker measurements more than room measurements, I tend to use (a) because forgetting to swap the cal file back from the 90 to the 0 deg is a real pain... however I keep the recommendation in mind for future "room only" efforts. I don't have any particular conclusion at this point.



> I suppose it also depends on the mic, e.g. Dayton EMM-6 or Behringer ECM8000 vs DSP UMIK or Dayton UMM-6 or Omnimic?


As long as the mic comes with a 90 deg cal file, I wouldn't think there would be much difference, all of those have similar polar responses.

HTH 

PS you may want to have a read through the Mellor and Hedback Acoustical Measurement whitepaper, it gives a whole series of things to measure and will save some guesswork. Link is... 

http://www.acousticfrontiers.com/wh...-standards-for-stereo-listening-rooms-pu.html


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## Phillips (Aug 12, 2011)

jtalden said:


> > Measure FL, FR and FL+FR (all 3 with the mic at exactly the the same LP position).
> [REW will align the peak of the IR at 0 ms for all 3 measurements since you don't have loopback engaged.]
> > Check the overlay of the FL and FR IRs. If they are not exactly aligned with each other then offset one of them manually as needed.
> > Do the math operation A + B using the FL and FR measurements for "A" and "B"
> ...




Thank you, i will give it ago.


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## Phillips (Aug 12, 2011)

> I use both  I compared a) mic pointed between speakers with 0 deg cal file and b) mic pointed at 80 degrees with the 90 degree cal file, and they were basically identical. However with different speaker / speaker setup / room there may be more of a difference. Since I generally do speaker measurements more than room measurements, I tend to use (a) because forgetting to swap the cal file back from the 90 to the 0 deg is a real pain... however I keep the recommendation in mind for future "room only" efforts. I don't have any particular conclusion at this point.


Please let me posted with any findings.




> PS you may want to have a read through the Mellor and Hedback Acoustical Measurement whitepaper, it gives a whole series of things to measure and will save some guesswork. Link is...
> 
> http://www.acousticfrontiers.com/wh...or the link, i will download this.
> Thank you


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## AudiocRaver (Jun 6, 2012)

I have read through this thread with interest, and will venture a few suggestions.

1. *Measuring with FL+FR together using a phase-coherent (mono) test signal:* Forgive me if I am missing something obvious, but I fail to see any real value in this measurement. As has been stated, phase cancellations cause dramatically different HF measurement results with small mic movement, and equidistant placing of the mic with precision and repeatability is extremely tedious and time consuming, and if accomplished it tells you no more than you could tell at a glance at the overlayed FL and FR plots, or by averaging them (which for all practical purposes is the same as summing them).

If my head was the size of a pin (my wife has said this to be the case, but my own measurements indicate otherwise) and my LP was repeatable to a fraction of an inch, it might be useful. As it is, this measurement is low bang for the buck (a lot of tedious trouble and little if any usefulness), a whole lot of data but almost zero useable information. Averaging reduces the potential for error and eases the necessity of precision placement, but it is still a final measurement that tells you nothing you can not get with a lot less trouble.

Under the conditions, there are an infinite number of potential measurement points in space and every one will give a different measurement plot. Of course the same applies to the location of a single isolated ear drum in any listening room under the same conditions - move it slightly and phase cancellations give a different frequency response curve. If that was the way we actually heard, it might be a problem when listen to mono sound through our stereo speakers, and the LP might include a cranial halo to lock that single ear drum into precise position for the duration of the listening session. But as previously stated, we hear through both ears, the skull, the sinuses, the entire upper body, and plenty of averaging is taking place all the time. Plus, as soon as a stereo signal is played, the problem goes away anyway.

If your goal is to see how the two speakers work together, and you are not satisfied to overlay the FL and FR plots and eyeball it - a method that has satisfied even the pickiest perfectionists for decades - then the solution is simple: stereo pink noise measured in RTA mode (with long averaging time to reduce the "noisiness" of the plot). It is the *phase-coherent (mono) test signal* that is causing all the trouble. With stereo pink noise, the FL and FR signals are completely random relative to each other, no phase cancellations due to variations in mic placement.

Many of us are perfectionists when we get into measuring and EQing our rooms/speakers, self included, and I realize it is easy for person A to dismiss something that person B finds critically important. In this case I am not seeing any real value, only an academic curiosity that has no bearing on the human listening experience.

2. *Measurement mic orientation:* A lot is said about the significance of it. If your goal is to be as precise as possible about every aspect of your measurement process because you enjoy doing that, then by all means do so. If your goal is to get a good-sounding result with minimum time and fuss, then mic orientation is not an area to get too wrapped up in. How much difference it makes depends on the mic and the room. As was stated in an earlier post:



jtalden said:


> In the end, I am not sure if there is a practical impact between these two options. If we EQ the HF, we are still going to tilt our house curve to suit our taste given our specific setup. If we aren't going to EQ the HF, then there cannot be a practical impact.


In other words, the difference in measurement results due to mic orientation is small and in many cases ends up being overwhelmed by some other part of the process: use of a house curve, tweaking to personal preference, and so on. If you are concerned that it will throw your results way off by not being super careful about it, be assured that with most quality measurement mics with small head diameter, the _overall measurement differences_ below 10 KHz, where you can do anything about it anyway, are probably in the range of a fraction of a dB. If you use the standard calibration file and point the mic toward the speaker and tilt it up 20 degrees (no protractor or laser surveying equipment needed, just eyeball it) as recommended, you will get excellent, easily repeatable results as far as they will be affected by mic orientation. Putting any effort into it beyond that is for your own satisfaction and will contribute nothing toward a better sounding room.

3. *Averaging numerous mic positions:* I agree with jtalden's statements about averaging...



jtalden said:


> Most people posting here don't average and I find it is not really needed for LF and HF EQ.


... it reduces measurement repeatability error but adds little practical value to the measurement/EQ process. One thing to watch out for if you do get into averaging measurements: do not include "outliers" in the average. When looking at a number of curves taken through/around the listening area, when one sees one or two curves that look significantly different from the rest, there is often a temptation to include them for the sake of thoroughness. In reality, they are indications of problematic areas where the sound will be significantly different from ideal, and including them in measurement averaging simply makes the hoped-for ideal worse than it need be. Averaging a number of curves that are very similar with minor variations does help ensure a good sounding sweet spot area. Those outliers that differ significantly show you the limits of the sweet spot area and can point toward needed room treatment to reduce specific reflections or eliminate standing waves (which could ultimately end up widening the sweet spot further).

====================

Hope you get great results.


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## HifiZine (Feb 7, 2013)

AudiocRaver said:


> If you use the standard calibration file and point the mic toward the speaker and tilt it up 20 degrees


What is the reason for tilting the mic upwards 20 degrees?


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## AudiocRaver (Jun 6, 2012)

The commonly-stated reason is to get a better mix of direct and reflected sound. Actually, I think it makes no significant difference (probably no _measurable_ difference), but I see no harm in it either, so I usually say "go with the recommendation" rather than argue about it. But since you asked.....

I have done calculations and measurements with typical mics of the type we all talk about here, and up to about 90 degrees off-axis, the actual affect on measured results below 10 KHz is a fraction of a dB.

Again, I don't want to be argumentative about it, I am simply answering your question with the facts the way I see them. If someone has data that shows otherwise, I will gladly reconsider my position.


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## HifiZine (Feb 7, 2013)

No, I wasn't being argumentative, just asking what the reason is.


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## AudiocRaver (Jun 6, 2012)

HifiZine said:


> No, I wasn't being argumentative, just asking what the reason is.


Beg pardon, I did not mean you at all, you asked a reasonable question. There are others who seem to feel strongly about the topic, and I am trying not to ruffle any feathers.


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## HifiZine (Feb 7, 2013)

Oh OK


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## jtalden (Mar 12, 2009)

I don't bother with the 20° upward tilt in my room either as testing shows no difference. Possibly it would if my floor was not carpeted? I inferred the reason for the 20 degree tilt is just to minimize the impact of ceiling and floor reflections. The polar plots show the mics are about 6-7 dB hotter at 0° vs 90° at 20 kHz. The floor is closer that the ceiling, hence the tilt to balance the impact of any HF reflections? 

I also just point the mic forward toward the CC main and use that same orientation for all 3 front speakers so the FL and FR are about 25° off axis. This also makes no difference in my room. The polar plots shows the mic response is pretty flat 0°±30° even at 20 kHz. 

Regarding the practice of recommending that mic to be oriented vertically (up or down) with a 15° forward tilt: I finally decided (right or wrong) that this advice is left over from older practice. It hasn't been that may years that calibration curves can be automatically added into measurements to compensate for the inherent mic response characteristics. Computers are a great convenience! A 75-90° orientation of the mic helps offset the typical 6 dB rise at 13 kHz and thus makes a comparatively flat response in a free field. An 75-90° mic orientation to the source is therefore a way to minimize the free field SPL error when using an omnidirectional measurement mic without any calibration curve being applied. With our current capability to automatically apply calibration curves to the measurements, I see no reason not to point the mic generally toward the source being measured.

I still fully agree that this probably makes no practical difference. It does help to try to make some sense of it however considering that it causes so much confusion, so that's my personal rational. I'm sticking to it until I hear a better one. :devil:


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## AudiocRaver (Jun 6, 2012)

jtalden said:


> A 75-90° orientation of the mic helps offset the typical 6 dB rise at 13 kHz and thus makes a comparatively flat response in a free field. An 75-90° mic orientation to the source is therefore a way to minimize the free field SPL error when using an omnidirectional measurement mic without any calibration curve being applied.


The best reason I have heard yet for any kind of mic angle, and is actually the recommended orientation for my Beyerdynamic MM-1 - without a calibration file in use (the HF rise for that mic is about 1 to 2 dB, being nicely cancelled by the 90 degree tilt).


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## Phillips (Aug 12, 2011)

Interesting

Which sound do we hear so to speak, e.g. 0 degrees mic orientation, 45 degrees mic orientation or 90 degrees mic orientation?

I wonder if the 45 degrees mic orientation would be a option as a average?

Applying tilt curves (tone controls) up in the high frequency range (measuring individual speakers) is probaly the best option?

Thank you


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## HifiZine (Feb 7, 2013)

Good question, but bear in mind that when you display an amplitude plot it isn't really showing "what we hear" anyway, as it doesn't account for arrival time of reflections. To take an extreme example, suppose there was nothing but the direct signal and an echo arriving a few hundred ms later. What you would hear is an echo; what the amplitude plot would show is some serious comb filtering.

I've wondered for a while if it's possible to gate out the direct signal and measure just the reflections. Another thing to add to the list of experiments


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## Wayne A. Pflughaupt (Apr 13, 2006)

Phillips said:


> Wayne A. Pflughaupt said:
> 
> 
> > That said, do any of the graphs represent what you’re actually hearing? IOW, do the highs sound “right,” or do they sound soft, like the first three graphs show?
> ...


Well, that’s all you need to know. As I've been saying (elsewhere - not on this thread), if you get different measurements from your 0-degree vs. 90-degree measurements, go with the 0-degrees results. Stick with that measurement technique and trust your ears. When it sounds right, you’ll see flatter response in the higher frequencies.

Interesting that your 90-degee measurements show increased high frequency response. I speculated in this post that this could happen, but this is the first time I’ve actually seen it.



















BTW, I agree with John and AudiocrRaver about the validity of L+R measurements. They’re fine as a “FYI” measurement, but I sure wouldn’t do any equalizing based on one, other than perhaps a broad shelving filter to adjust the overall high end up or down.

Regards,
Wayne


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## Phillips (Aug 12, 2011)

Thanks

From 1khz up EQ flat for *individual *speakers?

Does the difference between my 0 degrees and 90 degrees mesurements tell me something about my room?

Thanks again


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## HifiZine (Feb 7, 2013)

Hm... are you sure you didn't move the mic when changing its orientation?


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## AudiocRaver (Jun 6, 2012)

Phillips said:


> Which sound do we hear so to speak, e.g. 0 degrees mic orientation, 45 degrees mic orientation or 90 degrees mic orientation?


It is difficult to equate human hearing to a microphone. We are not omnidirectional, our frequency response changes dramatically with direction, which gives us cues that help us determine sound source direction. And, as has been pointed out, there are unconscious and conscious perception processes at work all the time.

For what we are trying to accomplish when measuring a room, a truly omnidirectional mic would be ideal. Since no measurement mic is perfect, we are left to decide a) is it imperfect enough to even be concerned about? and b) if so, what do we do about it? For me, the answer to a) is "no," I point the mic on axis. If there is a hearing bias, it is probably slightly upward in a room because we tend to have more sound absorption on our floors and because most of the action is in front of us, not at our feet. And the ceiling is usually the closest reflective surface. What mic angle? Twenty to forty-five degrees? Purely a guess. If it was really significant, it would be different in every room. Twenty degrees is just someone's rule of thumb. I am not trying to be difficult, it just seems like making something out of nothing to me. And measurements taken to satisfy my curiosity have confirmed it.



> I wonder if the 45 degrees mic orientation would be a option as a average?


Sounds perfectly reasonably.



> Applying tilt curves (tone controls) up in the high frequency range (measuring individual speakers) is probaly the best option?


To compensate for the HF droop, that is an option. If the room is very live, that could sound harsh. If it is a low RT60 room, below 0.3 sec above 1 KHz, then it would probably sound alright.


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## AudiocRaver (Jun 6, 2012)

The two curves in post 31 are difficult to equate and draw conclusion from, as their conditions are different other than the cal file. Plus one is for L & R running combined, difficult to trust at all by its nature.


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## Wayne A. Pflughaupt (Apr 13, 2006)

You’re right, I meant to show both of the L+R measurements, not one L+R and one L-only; I’ve fixed it. Comparing the L+R measurements is just as valid for the point I’m making as comparing say, the two left-only graphs, because all the 90-degree graphs show a high-end boost compared to the 0-degree graphs.


Regards,
Wayne


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## Wayne A. Pflughaupt (Apr 13, 2006)

Phillips said:


> Thanks
> 
> From 1khz up EQ flat for *individual *speakers?


Yes. I’d shoot for flat, but if it ends up sounding too bright you could go with declining high-end response.




> Does the difference between my 0 degrees and 90 degrees mesurements tell me something about my room?


I expect it’s a “perfect storm” where a lot of factors come into play all at once, in a negative way, that involves the speakers in use, the room’s ceiling, and the distance of the listening position from the speakers. 

The issue as I see it is the sound bouncing off the ceiling more-or-less directly into the upright mic with little or no attenuation of the highs, as described and shown in the picture from the post I linked in Post #31: The upright mic is using a 90-degree calibration file that boosts the high end, to compensate for the droop in high end response the mic would naturally show being off-axis from the sound source. If the reflected signal from the ceiling does not have sufficient high frequency attenuation, the signal arriving at the mic – again, _virtually on axis_ – is essentially the same as if the mic were pointed directly at the speaker. So then the graph generated will include the high end boost like your graphs show. 

If all this doesn’t make sense, it’s essentially the same as the result you’d get by using a 0-degree mic orientation with a 90-degree calibration file.










There are quite a few things that could alter this undesired outcome. For one, a cathedral ceiling would deflect the signal away from the mic. Even with the low flat ceiling that’s probably more problematic in this situation, one that’s fairly smooth would readily reflect the signal relatively unaltered, while a heavily-textured “popcorn” ceiling would significantly diffuse the high frequency energy. 

I expect the distance between the speakers and listening position plays a significant part as well, especially with a low reflective ceiling. For instance Phillips, I expect that if you moved the mic 10-15 ft. further back you’d see response measured upright that looks more like the 0-degree measurement from your normal listening position. This would be because the mic is no longer in range for the reflected signal to arrive on-axis.

Then you have the speaker itself. Naturally, this situation is aggravated by speakers with a wide dispersion pattern. At the other extreme, THX-certified speakers have controlled vertical dispersion, so I expect they would give virtually identical 0- vs. 90-degree measurements, even with a low reflective ceiling.

Bottom line, you can see why upright measurements are a roll of the dice. Depending on your room and your speakers, there’s a chance such a measurement will have no bearing on what you’re actually hearing, as you’ve seen. By contrast, you can’t wrong with a 0-degree mic orientation. In the end, even an optimal a 90-degree measurement (i.e. one taken in a room where “all the stars are in alignment”) won’t tell you anything that you can’t get from a 0-degree measurement. So why bother?

Regards,
Wayne A. Pflughaupt


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## Wayne A. Pflughaupt (Apr 13, 2006)

Sorry for the slow response; I've been working out of town this week so I'm just now seeing some of these posts.




HifiZine said:


> I'm assuming that Wayne's "bad information" dismissal is referring only to the use of an on-axis cal file with this [90-degree] orientation.


Correct.




> Edit: I think it's important to note that the 70-80 degree orientation requires the use of a 90-degree cal file. My understanding is that using the 90-degree cal file gives the mic a response (in three dimensions) that somewhat resembles a diffuse-field microphone; the 70-80 degree orientation is Herb's recommendation for these inexpensive mics in the case where you have a "halfway" situation between free field (direct sound) and diffuse field (all directions). Again, as I understand it.


The terms “diffuse field” and “free field” are used pretty loosely on these forums. Free field essentially means an open space, free of reflections. Diffuse field (aka “random incident”) has traditionally referred to an environment where the sound arrives from all directions more or less simultaneously, with equal probability and level. In other words, an exceedingly reverberant environment where it would be difficult to pin-point the sound source. There’s a church in my neighborhood with an auditorium that fits that description: It is so reverberant that if someone brought you in blindfolded and spun you around a few times, you would not be able to point to the speaker on the stage. Frankly, I don’t understand why someone would want to utilize a measurement technique (90-degree mic orientation) that’s intended for the most abysmal of acoustical environments.

The million-dollar question is, which acoustical environment does the typical home theater more closely resemble? If a room is dampened enough so that you are able to localize the speakers, then it is not a diffuse-field environment, despite the fact that in most rooms everything below ~500 Hz is omnidirectional.




HifiZine said:


> What is the reason for tilting the mic upwards 20 degrees?


I believe I was the first to make that recommendation on this Forum. It’s something I dug up a number of years ago from the manuals of vintage pro-audio hardware RTAs from manufacturers like Gold Line, Klark Teknik, etc. It’s highly possible the recommendation had something to do with the measurement mics that came with these units, which actually _were_ measurement mics and not something hijacked for the purpose like we’ve done with the ECM8000, EMM6 et. al. Or, perhaps the manufacturers recommended a 20-degree tilt because their RTAs were normally being used to measure the response of speakers in public auditoriums, which typically hang from the ceiling. But I’ll agree with John and AudiocRaver that the 20-degree tilt probably won’t make a measurable difference in our REW measurements. Documents I’ve recently discovered from B&K tend to support this; on Page 13 of their “Measurement Microphones” publication, it says that if you change the orientation of a free-field mic from horizontal, it’s 0-degree incidence calibration is no longer valid.

Regards, 
Wayne


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## Phillips (Aug 12, 2011)

HifiZine said:


> Hm... are you sure you didn't move the mic when changing its orientation?



The mic wasn't in exactly the same position maybe 1 inch.


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## Phillips (Aug 12, 2011)

> I wonder if the 45 degrees mic orientation would be a option as a average?





> Sounds perfectly reasonably.



Sorry i didn't add about the 45 degree cal file. 
To use the 45 degrees mic orientation with the *45 degree calibration file *would be a good average?




> To compensate for the HF droop, that is an option. If the room is very live, that could sound harsh. If it is a low RT60 room, below 0.3 sec above 1 KHz, then it would probably sound alright.


The room has about 0.35 sec above 1 khz.


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## Phillips (Aug 12, 2011)

> Phillips wrote:
> Thanks
> 
> From 1khz up EQ flat for individual speakers?





Wayne A. Pflughaupt said:


> Yes. I’d shoot for flat, but if it ends up sounding too bright you could go with declining high-end respons



Thank you

Any particuliar frequencies that i should deal with?

Would those peaks at 900hz-2khz (Left) and 600hz - 3khz (Right) on those speakers have a influence on the softness i am hearing in the treble?

Does speaker toe in - out effect high frequencies?


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## AudiocRaver (Jun 6, 2012)

Phillips said:


> The room has about 0.35 sec above 1 khz.


With that in mind, I would not hesitate to try some EQ. Your existing curves appear quite easy to work with. The hinge point is 2 KHz and the slope is even beyond that, so minimal filtering should be needed to pull that curve up, especially if you have HF tilt settings available. The maximum boost I would look for in the HF range would be about 6 dB, just so you don't overwork your tweeters.

Then a single *broad* filter centered at 200 Hz could boost that drooping region between 100 and 400 Hz, max boost about 6 dB. I would leave the rest of the finer variations alone.

Start by applying the same EQ to both sides, then minimal additional individual EQ per side to match them up.

I'll bet the result will sound really nice.


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## Phillips (Aug 12, 2011)

> With that in mind, I would not hesitate to try some EQ. Your existing curves appear quite easy to work with. The hinge point is 2 KHz and the slope is even beyond that, so minimal filtering should be needed to pull that curve up, especially if you have HF tilt settings available. The maximum boost I would look for in the HF range would be about 6 dB, just so you don't overwork your tweeters.
> 
> Start by applying the same EQ to both sides, then minimal additional individual EQ per side to match them up.
> 
> I'll bet the result will sound really nice.


Thank you

Since owning the Antimode running the mains full range with 2 x REL Strata 5 is know possible without the boom. The RELS have had to be woken up now.

I have just purchased a DSpeaker Antimode Dual Core 2.0 and finding it versitile. I looked at the Yamaha 2006 but was going to need most likely two and then more than likely need the power supply changed then the freight cost extremely high just for one. All up the cost for one only was going to exceed $700 + tax through customs.

The Dual Core has tilt filters (high and low). High are 1.5hz, 3khz, 5khz, 7khz and 10khz.
Those graphs are Auto EQ from the 500hz down (options 80hz, 150hz, 250hz, 350hz and 500hz, i think i might have missed 1 or 2). 
PEQ includes 17 filters per side (left and right) after the AUTO EQ. One filter can be used for both at once (they call it Stereo) which only takes up one filter.
Also you have 4 profiles (preset options). You can do 100% manual PEQ or copy the AUTO EQ over to the preset then work on that with manual PEQ etc. Not that i will use that many but nice to know there are more than normal.

From 500hz to 2khz seems to be the main PEQ starting point.

The way i see it would be for the: 
Left = Around the 500hz broad one filter, then maybe two filters 1-2khz then with the high tilt either 1.5hz or 3khz?
Right = Two filters from 600hz - 2khz with the high tilt?

Distance settings would make a difference or not worth it?

The Dual Core uses a BW for PEQ so with a Center Frequency = 200 Q = 4.3, the BW would be Center Frequency = 200hz BW = 46.5. Bit of a learning curve.
With REW eq filters (generic, etc) which would you use knowing the above, not easy to do the RTA have to save first before the filter takes effect, then go back into the menu.

Thanks again


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## HifiZine (Feb 7, 2013)

Wayne A. Pflughaupt said:


> Frankly, I don’t understand why someone would want to utilize a measurement technique (90-degree mic orientation) that’s intended for the most abysmal of acoustical environments.




At the risk of re-raising an issue that was dealt with here in the past, the reasoning for a vertical mic orientation seems quite straightforward and sound to me. And that is, that the direct source and the reflections are treated equally. At the least, lateral reflections are treated equally, and the rising response in front of the mic is somewhat compensated by the falling response at the rear of the mic.

I get the impression from some posts in this thread that there is a notion that mic orientation at listening position is somehow related to measuring the speakers (and not the room). If that is the case, then the technique being used is not correct, and (at high frequencies) a gated measurement with suitable speaker and mic placement should be used.



> The million-dollar question is, which acoustical environment does the typical home theater more closely resemble? If a room is dampened enough so that you are able to localize the speakers, then it is not a diffuse-field environment, despite the fact that in most rooms everything below ~500 Hz is omnidirectional.


If you are saying that it's close enough to free field, then it makes no difference which orientation is used, provided that the matching calibration file is used. That does tend to argue in favour of the vertical orientation, in fact.


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## jtalden (Mar 12, 2009)

HifiZine said:


> At the risk of re-raising an issue that was dealt with here in the past, the reasoning for a vertical mic orientation seems quite straightforward and sound to me. And that is, that the direct source and the reflections are treated equally. At the least, lateral reflections are treated equally, and the rising response in front of the mic is somewhat compensated by the falling response at the rear of the mic.


This comment is difficult for me to agree with. It may be we disagree in our understanding, but it's also possible we are assuming a different set of circumstances? The following is an attempt to clarify my thought process.

My frame of reference:
> We are discussing MF and HF EQ in a room with mic at the LP. We are not discussing design of the speaker itself to an anecdotic response curve as a speaker manufacturer must do. 
> There is benefit to EQ a speaker to a particular room setup or there would not be Audyssey and numerous other commercial and professional automated setup systems which use averaged measurements to EQ the MF and HF. 
> We are assuming we have mic calibration files for both 0 and 90° available and can select the appropriate one and the decision is what basic orientation makes the most sense for our measurements.
> The measurement mics are all direction by about +6 dB on axis compared to 90° off axis at 20 kHz. This is true regardless of whether a calibration file is in use. It is a basic physical characteristic of all measurement mics. This means the direction it is pointed is weighted greater than off axis directions.
> The mic polar charts also show that directional sensitivity becomes increasingly greater the as the angle increases from 0°. A 20 or 30° offset from a 0° orientation has little effect on the HF response. Conversely, a 5-10° offset from a 90° orientation has a more significant impact on HF response. 
> Any room is neither free field nor diffuse field, but somewhere in between.
> We are aware of many references/recommendations that it is more important to EQ a room with emphasis on the direct signal rather than emphasis on the reflected signal. 
> There are also warnings not to over EQ the MF and HF to a single LP measurement as it's easy for a hobbyist to overcorrect with EQ and actually make the situation worse.

The intent of my comments in the earlier posts was to point out that:
> If the mic is pointed at the source there is less sensitivity to mic directional error.
> If the mic is pointed at the source there is more weight on the direct signal than the reflections and this situation is often regarded as advantageous.
> If high accuracy is desired then averaging is a very good idea as small changes in mic location will significantly change the measurement. In my room this is true more at MF than at HF, but I am not sure if this is true in all or most rooms.

I also pointed out that:
> Many people use 75 or 90° mic orientations with good success and as a practical matter it may not be significant because we tend to adjust our House Curve accordingly.

I just reran my experiments from several years ago as I could not locate the original data. [The following graphs are all of my CC speaker. The LP is 13 ft from the CC and the dropped ceiling is 8'-5" high.]

Repeatability of RTA average measurements over approximately a 16"H x 36"W window:
[6 Separate RTA measurements of the same window area. Included is also my House Curve target that I determined experimentally (adjusted to suit my preference).]








7 Sweeps (LP and border positions of the window):
[This shows the extremes of the window variability more than a random sampling would have. It emphasizes the scatter somewhat.]








The LP position sweep (red) Vs an RTA window average (green):








Avg of all 7 Sweeps Vs RTA over same window:
[If the sweep positions had been random over the window the average would have been closer to the RTA average. I've done it that way in the past with good correlation using only 9 sweeps.] 








Mic Orientation: The 3 overlapping traces are; On axis, +4°V (horizontal in my setup), and +4°V with +25°R (horizontal and pointed at the FR speaker) The highest trace is with the mic at 75° from horizontal and the one between is the mic pointed at 90° from horizontal. Those 2 used a 90° calibration file. The first 3 used a 0° calibration file.








I remain more comfortable using mic pointed generally at the speaker under test and using an average over a window so that the large variability of small LP position differences is eliminated. I also suspect it better correlates to what is perceived.

I have been unable to find any advantages to orienting a mic vertically with the exception that Audyssey and possibly other automated systems do this because it would be too complicated to ask someone reposition a mic for each speaker. The fronts and Sub would be okay with the mic facing basically forward, but the HF of the Surround and Rear Mains would EQ very differently. The HF would be way too hot. The vertical orientation is a good compromise solution in that case. That my guess as to the reason. I have not heard that from Audyssey.


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## HifiZine (Feb 7, 2013)

Hi John, thank you for replying and for those measurements. I would have thought that moving the mic while measuring would result in handling noise, but that doesn't seem to be the case at all from your RTA measurement.



jtalden said:


> > If the mic is pointed at the source there is less sensitivity to mic directional error.


That is an interesting point.



> > If the mic is pointed at the source there is more weight on the direct signal than the reflections...


Yes, at higher frequencies, no disagreement there. Where I think the crux of the matter comes in is:



> and this situation is often regarded as advantageous.


I don't understand why this would be so. For an in-room measurement, shouldn't all sound sources be weighted equally? You are saying that is not the case... I would be interested to know more about why.

Also, even if it is better to weight the direct signal, mic orientation will do this over only a part of the spectrum. So you're relying on the characteristics of a particular microphone to get your measurements and do corrections.


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## stevekale (Jan 19, 2013)

So in summary...

Don't measure both speakers (L+R) at once

Even with a calibrated microphone with both 0 degree and 90 degree calibration files, use the 0 degree calibration fine and 0 degree orientation

Point the mic at the speaker being tested (i.e. swing it around to point left, right respectively)

Average if you can be bothered

???


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## jtalden (Mar 12, 2009)

HifiZine said:


> I would have thought that moving the mic while measuring would result in handling noise, but that doesn't seem to be the case at all from your RTA measurement.


I have also have seen the often cited advice that we can't handle the mic, or be near the LP when measuring. My experiments with 3 different mics do not support this when RTA averaging as described. 



> I don't understand why this would be so. For an in-room measurement, shouldn't all sound sources be weighted equally? You are saying that is not the case... I would be interested to know more about why.


Possibly. I only know what I have commonly seen on forums and blogs that refer to studies on sound field perception. My take on the matter is that we perceive the SPL smoothness primarily by the direct sound and late arriving reflections have more impact to the perception of ambiance. Early arriving reflects do impact the perception of smoothness and should be avoided if possible. Unlike some of the other advice, I have no way to easily test this matter and have just accepted that it is correct. 



> Also, even if it is better to weight the direct signal, mic orientation will do this over only a part of the spectrum. So you're relying on the characteristics of a particular microphone to get your measurements and do corrections.


It is not so much that I want to weight the HF direct field in some particular way, but more just a recognition that any measurement mic will weight the HF on axis whether I want it to, or not. Given the decision as to which direction to weight, I chose the direct signal for the reasons offered above. I also indicated that possibly the difference is not significant. I put more emphasis into the fact that we can be less careful with the exact angle the mic is pointed. The results are unchanged with the mic pointed in the general direction of the source. It all gets back to the repeatability issue. It's difficult to EQ and confirm the results if we cannot easily repeat the measurements from session to session.


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## HifiZine (Feb 7, 2013)

Hi John, it is not (to my mind) a question of which direction to weight, but which direction to point the microphone so as not to weight. If that is the goal...


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## Phillips (Aug 12, 2011)

It would be interesting to see what Herbs reasoning behind mic orientation and corresponding calibration files.


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## Wayne A. Pflughaupt (Apr 13, 2006)

HifiZine said:


> At the risk of re-raising an issue that was dealt with here in the past, the reasoning for a vertical mic orientation seems quite straightforward and sound to me. And that is, that the direct source and the reflections are treated equally.


There’s really no good reason to make sure that the source and reflections are treated equally, as the ear tends to ignore the reflections and localizes the sound source. Here’s a good read on that topic that quotes Toole and Olive. Besides, as we’ve seen in Phillips’ case, with an upright orientation the lateral reflections are not necessarily treated equally by the measurement mic.




> I get the impression from some posts in this thread that there is a notion that mic orientation at listening position is somehow related to measuring the speakers (and not the room). that is the case, then the technique being used is not correct, and (at high frequencies) a gated measurement with suitable speaker and mic placement should be used.


 Gated measurements have their place, but they don’t give an accurate “picture” of what you’re hearing at the listening position, which is the purpose of in-room measurements to begin with. Zero-degree measurements taken at the listening position has been the accepted professional standard for room measurements as long as RTAs have been available. See Figures 10, 13 and 15 in this white paper from B&K that dates back to 1974. Also note the measurement mic in the picture on the front page. 




> If you are saying that [the typical residential room is] close enough to free field, then it makes no difference which orientation is used, provided that the matching calibration file is used. That does tend to argue in favour of the vertical orientation, in fact.


I have no idea how you could have arrived at either conclusion. It’s true that most rooms don’t meet the rigid definition of a free-field environment, but the free-field, 0-degree measurement protocol has always been the accepted standard for in-room measurements, AFAIK. When I see a situation like Phillips’, where 0- vs. 90-degree measurements delivered drastically different results, that’s enough to convince me that the latter is not the way to go. In some rooms it’s just not going to work well.

I posed the question about mic orientation at the Pro Sound Web Forum a few years ago, which you can review here. These are people who do this stuff for a living. While there were some curious recommendations floated (ground plane?), you can see that no one claimed they used the upright mic orientation.

Regards, 
Wayne


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## Wayne A. Pflughaupt (Apr 13, 2006)

stevekale said:


> So in summary...
> 
> Don't measure both speakers (L+R) at once
> 
> ...


That about sums it up, Steve. :T Combined L+R measurements are fine as “FYI”, but if you want to manually equalize the speakers, you should use separate L and R measurements.

Regards,
Wayne


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## Wayne A. Pflughaupt (Apr 13, 2006)

Phillips said:


> It would be interesting to see what Herbs reasoning behind mic orientation and corresponding calibration files.


 Here you go. 

Regards,
Wayne


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## Phillips (Aug 12, 2011)

Phillips said:


> It would be interesting to see what Herbs reasoning behind mic orientation and corresponding calibration files.


Thought i would post on Herbs thread.

http://www.hometheatershack.com/for...um-microphone-calibration-service-usa-26.html


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## Wayne A. Pflughaupt (Apr 13, 2006)

Here’s the post Phillips is talking about.




Anechoic said:


> Phillips said:
> 
> 
> > For Cross - Spectrum Calibrated Dayton EMM-6 and Behringer ECM8000 microphones with:
> ...


_Loudspeaker measurements_ = frequency response measurements.
_Room acoustics_ = ETC, RT60, etc.
_Calibration measurements_ = DRC.


Regards, 
Wayne


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## Phillips (Aug 12, 2011)

Wayne A. Pflughaupt said:


> Here’s the post Phillips is talking about.
> 
> 
> 
> ...



Thanks Wayne

DRC stand for


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## Wayne A. Pflughaupt (Apr 13, 2006)

Digital room correction, e.g. the auto calibration systems built into receivers these days.

Regards, 
Wayne


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## Phillips (Aug 12, 2011)

Wayne A. Pflughaupt said:


> Digital room correction, e.g. the auto calibration systems built into receivers these days.
> 
> Regards,
> Wayne



Thanks Wayne

This would be for Eqing in general, manual Eq as well?


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## Wayne A. Pflughaupt (Apr 13, 2006)

Not sure I get the question? REW doesn’t perform DRC.

Regards, 
Wayne


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## Phillips (Aug 12, 2011)

Wayne A. Pflughaupt said:


> Not sure I get the question? REW doesn’t perform DRC.
> 
> Regards,
> Wayne


Thanks Wayne
Use this file/mic orientation for measuring, when EQing in general.


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## Wayne A. Pflughaupt (Apr 13, 2006)

For frequency response measurements, and any equalizing from the same, use 0-degree mic orientation and 0-dgree calibration file. :T

Regards, 
Wayne


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## Scubasteve2365 (Mar 15, 2013)

Wayne A. Pflughaupt said:


> Not sure I get the question? REW doesn’t perform DRC.
> 
> Regards,
> Wayne


I think he may be referring to DRC setting (On/Off) as turning on or off the manual EQ settings in an AVR.


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## Phillips (Aug 12, 2011)

Thank you


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## Phillips (Aug 12, 2011)

For EQing high frequencies:

What would be the most boost?
Broad or sharp filters?

Thanks in advance


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## Wayne A. Pflughaupt (Apr 13, 2006)

Either type of filter – broad or sharp – can be boosted as much as you want or have headroom for. However, broader filters are usually better. I wouldn’t be inclined to use a filter tighter than about 1/4-octave for the upper frequencies.

Regards, 
Wayne


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## Phillips (Aug 12, 2011)

Wayne A. Pflughaupt said:


> Either type of filter – broad or sharp – can be boosted as much as you want or have headroom for. However, broader filters are usually better. I wouldn’t be inclined to use a filter tighter than about 1/4-octave for the upper frequencies.
> 
> Regards,
> Wayne


Hi Wayne thank you

Can you please look at my other thread to do with "noise at end of sweep".

Threre are 3 presets available.

On the two mentioned in the thread one has this noise. The graphs look resonably close in frequency resposne but as John said profile c has a alot of distortion from 1khz up (20%) causing the noise. 

Could sharp boosts cause this do you think?

Thanks again


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