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-   -   Microphone stand for measurements at ear height ? (https://www.hometheatershack.com/forums/spl-meters-mic-s-calibration-sound-cards/68358-microphone-stand-measurements-ear-height.html)

Sonic Icons 07-04-13 04:00 PM

Microphone stand for measurements at ear height ?
 

Has anyone else had difficulty finding a stand to place their microphone, vertically oriented, at seated listener ear height, which I estimate to be 39 inches? (Of course, ear height will very depending on the listener and type of seating, but 39 inches is my best estimate for my situation.)

I currently have a Behringer ECM8000 microphone, and an adjustable height microphone stand. The minimum height of the microphone top with this gear is
31 inches (stand) + 1.5 inches (base) + 10 inches (microphone and clip) = 42.5 inches, just a bit high.

I looked extensively at microphone stand listings on Amazon, and a specialty store Musician's Friend (http://www.musiciansfriend.com/microphone-stands). I can't find a shorter stand, except for "desktop" or "low-profile" stands that are much shorter and don't reach high enough.

BTW, I just ordered a Dayton EMM-6 from Cross-Spectrum Labs, because my old Behringer ECM8000 is not calibrated and appears to have a steep response fall-off at high frequencies. I'll report back if the Dayton EMM-6 is a different length than the Behringer - some of you may know that already.

JohnM 07-04-13 05:37 PM

Re: Microphone stand for measurements at ear height ?
 

Just orient the mic horizontally, orientation makes no difference for low frequency measurement and for full range measurements best pointing the mic at the speaker (and using the 0 degree cal file).

Wayne A. Pflughaupt 07-04-13 08:16 PM

Re: Microphone stand for measurements at ear height ?
 


Quote:

Sonic Icons wrote: (Post 621778)
I looked extensively at microphone stand listings on Amazon, and a specialty store Musician's Friend (http://www.musiciansfriend.com/microphone-stands). I can't find a shorter stand, except for "desktop" or "low-profile" stands that are much shorter and don't reach high enough.

You can adjust a stand with a boom to any height you need.

Regards,
Wayne

AudiocRaver 07-06-13 07:01 AM

Re: Microphone stand for measurements at ear height ?
 

291 Attachment(s)
I like the DR Pro DR Pro DR256 MS1500BK Low Profile Mic Boom Stand, got it on a 1/2 price sale for $30. Very well built. Hercules has one similar, the Hercules Stands MS540B Low-Profile Tripod Microphone Boom Stand. It is also handy to have a full-size stand with boom.

Dwight Angus 08-09-13 10:04 AM

Re: Microphone stand for measurements at ear height ?
 

I use a mic and boom stand but with High back theater seats difficult to position mic at ear height from behind the seat. If I position too close to seat I will pickup seat reflections.

jtalden 08-11-13 12:58 PM

Re: Microphone stand for measurements at ear height ?
 

Yes, I would expect any one mic location to be affected by a close boundary and that impact will be very much dependent upon the direction/distance/size of the boundary.

My experimentation experience has shown:
> It doesn't matter at the bass frequencies.
> It does matter at mid frequencies and somewhat at high frequencies.
> There is lots of variation due to the room response with small mic location changes around the LP. Using any one location to EQ the mid and high frequencies is not the best approach. It is better to take an average of several positions around the LP and EQ to that average response.
> My chair is only about ear height but using averaging I get the same result whether the chair is left in position or moved out of the way. (I thus decided to just slide out of the way for convenience of measuring.)
> I get a similar result whether I use averages of sweeps or RTA (except the RTA results in a slight boost of the very low bass). The RTA is a much easier and faster method of averaging.
> I get a very similar results whether I use a vertical window or a horizontal window or a spiral pattern for the averaging.
> I get a similar result using a vertical window size as small as 1'h x 2'w or as large as 2'h x 6'w.
> While these results are only with my room, I have also noted that most all automated room EQ systems (including Audyssey) use spatial averaging. It is interesting to see the large differences that exist between any one measurement and the average.
> When I used a spatial average for manual EQ and target the Audyssey house curve Audyssey XT did not make any significant additional corrections.
> When Audyssey XT was run first my measurements of the average of the same mic positions suggested that additional manual EQ would be of questionable value unless it is to change the house curve.

So my summary thoughts would be that:
> It is better to just let Audyssey do it job. (or just use manual EQ as I do)
> If you want a different house curve that needs to be applied after Audyssey.
> Using spatial averaging the seat back will probably not be a significant.
> Manual EQ to one mic location before Audyssey will just result in Audyssey overriding that setting.

AudiocRaver 08-14-13 07:04 AM

Re: Microphone stand for measurements at ear height ?
 

291 Attachment(s)
Quote:

jtalden wrote: (Post 630189)
> I get a similar result whether I use averages of sweeps or RTA (except the RTA results in a slight boost of the very low bass). The RTA is a much easier and faster method of averaging.

John,

Just curious what you mean in the above statement. Do you mean using the RTA averaging to a) average several readings of the same mic location or b) average several different mic locations? If b, how do you do that?

Dwight Angus 08-14-13 09:45 AM

Re: Microphone stand for measurements at ear height ?
 

Quote:

jtalden wrote: (Post 630189)
Yes, I would expect any one mic location to be affected by a close boundary and that impact will be very much dependent upon the direction/distance/size of the boundary.

My experimentation experience has shown:
> It doesn't matter at the bass frequencies.
> It does matter at mid frequencies and somewhat at high frequencies.
> There is lots of variation due to the room response with small mic location changes around the LP. Using any one location to EQ the mid and high frequencies is not the best approach. It is better to take an average of several positions around the LP and EQ to that average response.
> My chair is only about ear height but using averaging I get the same result whether the chair is left in position or moved out of the way. (I thus decided to just slide out of the way for convenience of measuring.)
> I get a similar result whether I use averages of sweeps or RTA (except the RTA results in a slight boost of the very low bass). The RTA is a much easier and faster method of averaging.
> I get a very similar results whether I use a vertical window or a horizontal window or a spiral pattern for the averaging.
> I get a similar result using a vertical window size as small as 1'h x 2'w or as large as 2'h x 6'w.
> While these results are only with my room, I have also noted that most all automated room EQ systems (including Audyssey) use spatial averaging. It is interesting to see the large differences that exist between any one measurement and the average.
> When I used a spatial average for manual EQ and target the Audyssey house curve Audyssey XT did not make any significant additional corrections.
> When Audyssey XT was run first my measurements of the average of the same mic positions suggested that additional manual EQ would be of questionable value unless it is to change the house curve.

So my summary thoughts would be that:
> It is better to just let Audyssey do it job. (or just use manual EQ as I do)
> If you want a different house curve that needs to be applied after Audyssey.
> Using spatial averaging the seat back will probably not be a significant.
> Manual EQ to one mic location before Audyssey will just result in Audyssey overriding that setting.

John
My Xilica xp4080 PEQ is to arrive in a week and I was going to use an REW average of my HT front row 3 seats for pre eq. Middle seat is MLP. I was going to take only 1 measurement per seat and then average that and then base EQ on that average of 3 measurements. However after reading your post it makes more sense to take several readings around each LP to arrive at an overall stable average. This will help when I then run Audyssey XT32 afterwards. If I did a good job on averaging measurements then REW/XT32 should not be materially different.

I contacted Audyssey and they recommended running MULTEQ after the PRE EQ. So I want to make sure MULTEQ doesn't override PRE EQ filters. I will certainly follow the REW multi measurement average approach that you outlined above. Cheers

jtalden 08-14-13 10:32 AM

Re: Microphone stand for measurements at ear height ?
 

I mean "b".

In my case, I:
> Set the RTA to "Forever Averaging".
> Place mic on stand at LP.
> Start Signal generator then RTA.
> Move quickly to mic, remove it from the stand and slowly sweep around the listening window chosen.
[I use a vertical zigzag pattern moving up and down out to the right and back to the center and then out to the left and back to the center but any pattern covering the window reasonably uniformly will work.]
> Replace the mic in the stand at the LP and return to stop the RTA and then the signal generator.
> I usually end up with maybe around 160 - 180 averages and the process takes maybe 30 sec.

This process is not noticeably sensitive to mic handling, body position, or to mic LP starting/ending positions or from one setup to another on different days. It is very repeatable. I get very similar result in my room whether I use a vertical window or a horizontal window or a spirial pattern incorporating both.

I have verified that this process results in a similar result to averaging many sweep measurements over the same window area and it is much quicker an easier to do.

I posted several charts Here that help to show some the experimentation that was done.

I don't want to over sell this method though. I am sure that reasonable results can be obtained using only the LP mic sweep using judicious EQ application. This method just accounts for the excessive SPL variability when using very small mic capsule and helps to assure that EQ is not overly applied.

In the context of this OP's question, it is a method to minimize or avert the issue of a close boundary on the measurement. It may be easier than moving a large chair and should provide a better result than any one mic location with or without the chair in place.

AudiocRaver 08-16-13 03:27 AM

Re: Microphone stand for measurements at ear height ?
 

291 Attachment(s)
Quote:

jtalden wrote: (Post 630790)
I mean "b".

In my case, I:
> Set the RTA to "Forever Averaging".
> Place mic on stand at LP.
> Start Signal generator then RTA.
> Move quickly to mic, remove it from the stand and slowly sweep around the listening window chosen.
[I use a vertical zigzag pattern moving up and down out to the right and back to the center and then out to the left and back to the center but any pattern covering the window reasonably uniformly will work.]
> Replace the mic in the stand at the LP and return to stop the RTA and then the signal generator.
> I usually end up with maybe around 160 - 180 averages and the process takes maybe 30 sec.

This process is not noticeably sensitive to mic handling, body position, or to mic LP starting/ending positions or from one setup to another on different days. It is very repeatable. I get very similar result in my room whether I use a vertical window or a horizontal window or a spirial pattern incorporating both.

I have verified that this process results in a similar result to averaging many sweep measurements over the same window area and it is much quicker an easier to do.

I posted several charts Here that help to show some the experimentation that was done.

I don't want to over sell this method though. I am sure that reasonable results can be obtained using only the LP mic sweep using judicious EQ application. This method just accounts for the excessive SPL variability when using very small mic capsule and helps to assure that EQ is not overly applied.

In the context of this OP's question, it is a method to minimize or avert the issue of a close boundary on the measurement. It may be easier than moving a large chair and should provide a better result than any one mic location with or without the chair in place.

Very nice, and of course once you think of it, makes perfect sense. I have been giving thought to averaging averaging measurements at the LP when hand tuning, as you have mentioned in other posts, will give it a try next time I am in that mode.

Thanks.


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