Comparison of ten room testing microphones

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Ethan Winer

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youngho

Re: Comparison of ten room testing microphones
« Reply #21 on: 27 Jul 2008, 06:24 pm »
Hi Steve, a few brief points:

Thank you for posting the link to the Radio Shack website. If you download and look at the owner's manual, you'll see on page 22 the manufacturer's specification "+/2 dB@114 SPL" that the TNT reviewer quoted, so you did indeed miss the data given there.

So, to sum up on the "fast asleep and snoring":
http://forum.stereophile.com/forum/showflat.php?Cat=0&Board=tuning&Number=44568&Searchpage=1&Main=43592&Words=+sasaudio&topic=&Search=true#Post44568
http://forum.stereophile.com/forum/showflat.php?Cat=0&Board=TheEntryLevel&Number=44582&Searchpage=1&Main=43995&Words=+sasaudio&topic=&Search=true#Post44582
http://forum.stereophile.com/forum/showflat.php?Cat=0&Board=TheEntryLevel&Number=44618&Searchpage=1&Main=43995&Words=+sasaudio&topic=&Search=true#Post44618
http://forum.stereophile.com/forum/showflat.php?Cat=0&Board=TheEntryLevel&Number=44621&Searchpage=1&Main=43995&Words=+sasaudio&topic=&Search=true#Post44621

I did find the multiple use of this phrase to be weird. I haven't been obsessively combing through the threads and forums to understand the context. Sorry. But I still find it a little weird.

I simply quoted the Michael Sims post that you had referred to. No tricks. Ethan himself acknowledges above that the RS meter tracks very well down to about 40 Hz, and all the correction tables show an increasing need for compensation below that. So we're all in agreement on that, right? You say it, Ethan says it, the correction tables say it. RIP.

Ethan claims that the RS meter is reasonably accurate up to 1000 Hz, but his website does show steep roll-off above ~7 kHz when the meters aren't aimed at the signal, but that's not too surprising, right, given the directionality of the signal and the non-omnidirectional RS SPL meter? When the non-omnidirectional meter was not pointing at the loudspeaker, then it performed quite poorly compared to a omnidirectional microphone not pointing at the loudspeaker (I think this is where you are pulling the numbers from). When the meter was pointing at the loudspeaker, the variation was much less (-16 dB or so from the two mics at 20 KHz). Also, he acknowledges the effects of his room on the measurements, so, for example, he's not claiming that all microphones have a dip at 180 Hz and 1 KHz. These are in-room measurements, so the graph cannot be used to refer directly to the correction tables or anechoic performance of the meter.

Radio Shack itself only rates the meter up to 10 KHz. One of the correction tables suggests the need to add compensation starting at 0.8 dB 2.5 KHz increasing to 11 dB at 20 KHz, suggesting that there may be roll-off at the higher frequencies with the digital meter.

Sure, the XPress article isn't great, but the laughable setup and testing methods are better than doing none and instead simply quoting the manufacturer's specs, no? Interestingly, the graphs from figure 2 look rather similar to Ethan's, though less in magnitude. This was why I said "3. Objective measurements of the RS meters suggest that they may be worse than you say, though perhaps not as bad as Ethan says." However, because Ethan's measurements were done differently, it's hard to directly compare the results.

Steve

Re: Comparison of ten room testing microphones
« Reply #22 on: 28 Jul 2008, 02:04 am »
Quote
Trying to get a straight answer out of him is a moving target, and I have asked Steve directly exactly what he feels is in error in my posts.


Interesting since it seems Ethan has others to answer my posts. And I have made myself very clear at

http://forum.stereophile.com/forum/showflat.php?Cat=0&Board=TheEntryLevel&Number=43995&page=0&fpart=1
and here.

 
Quote
Hi Steve, a few brief points:
Thank you for posting the link to the Radio Shack website. If you download and look at the owner's manual, you'll see on page 22 the manufacturer's specification "+/2 dB@114 SPL" that the TNT reviewer quoted, so you did indeed miss the data given there.

Found it. No biggy as the spec of +/- 2db is rated at 114db. The other links I presented are at normal levels.

Quote
So, to sum up on the "fast asleep and snoring":

http://forum.stereophile.com/forum/showflat.php?Cat=0&Board=tuning&Number=44568&Searchpage=1&Main=43592&Words=+sasaudio&topic=&Search=true#Post44568
http://forum.stereophile.com/forum/showflat.php?Cat=0&Board=TheEntryLevel&Number=44582&Searchpage=1&Main=43995&Words=+sasaudio&topic=&Search=true#Post44582
http://forum.stereophile.com/forum/showflat.php?Cat=0&Board=TheEntryLevel&Number=44618&Searchpage=1&Main=43995&Words=+sasaudio&topic=&Search=true#Post44618
http://forum.stereophile.com/forum/showflat.php?Cat=0&Board=TheEntryLevel&Number=44621&Searchpage=1&Main=43995&Words=+sasaudio&topic=&Search=true#Post44621
I did find the multiple use of this phrase to be weird. I haven't been obsessively combing through the threads and forums to understand the context. Sorry. But I still find it a little weird.

The same page and simply means I was out of there, I was not going to post anymore. It certainly was not dirty in any sense like some posts. I do not know what the big deal is.

So why the character assassination instead of dealing with the issues?
 
Quote
Ethan claims that the RS meter is reasonably accurate up to 1000 Hz, but his website does show steep roll-off above ~7 kHz when the meters aren't aimed at the signal, but that's not too surprising, right, given the directionality of the signal and the non-omnidirectional RS SPL meter? When the non-omnidirectional meter was not pointing at the loudspeaker, then it performed quite poorly compared to a omnidirectional microphone not pointing at the loudspeaker (I think this is where you are pulling the numbers from).

34db on axis total deviation. Approx 51db off axis total deviation. 40db absolute peak to minimum.

 
Quote
When the meter was pointing at the loudspeaker, the variation was much less (-16 dB or so from the two mics at 20 KHz). Also, he acknowledges the effects of his room on the measurements, so, for example, he's not claiming that all microphones have a dip at 180 Hz and 1 KHz. These are in-room measurements, so the graph cannot be used to refer directly to the correction tables or anechoic performance of the meter.

Unfortunately, there are several problems with your assessment.

1) We are not concerned compared to the two mics. The reference is absolute accuracy, not what the two other mics measure and their inaccuracies.

2) We are not concerned with minor dips, so your explanation about 180hz and 1khz does not apply.

3) The room has little to no bearing 7khz on up averaging measurements.
 
4) The approx 12db roll off above 7khz was explained in an earlier post. That is essentially free fall, but the RS meter has correction circuits. So the graphs is simply not accurate unless you wish to defy physics.

5) Ethan cannot explain the descrepancies between the two graphs, one at Stereophile I will call "B", and the other on his webpage I will call "C". Yet he claims both graphs are from the same microphone. I will address this later.

Quote
Radio Shack itself only rates the meter up to 10 KHz. One of the correction tables suggests the need to add compensation starting at 0.8 dB 2.5 KHz increasing to 11 dB at 20 KHz, suggesting that there may be roll-off at the higher frequencies with the digital meter.

Doesn't mean anything as my links provided demonstrate.

Even 11db does not account for the huge db dropoff in the stereophile graph from 7khz to 20khz.

Quote
Sure, the XPress article isn't great, but the laughable setup and testing methods are better than doing none and instead simply quoting the manufacturer's specs, no?

Not necessarily.
 
Quote
Interestingly, the graphs from figure 2 look rather similar to Ethan's, though less in magnitude. This was why I said "3. Objective measurements of the RS meters suggest that they may be worse than you say, though perhaps not as bad as Ethan says." However, because Ethan's measurements were done differently, it's hard to directly compare the results.

Not true. Although there is a peak at 5khz, the 20khz response is right above 0 deviation from midband, not well below like Ethan's measurement.
 
What is interesting is that his graph B posted in Stereophile does not come close to matching the graph C on his website. Same room, speakers, and supposively the same mic. However, Ethan did not use the RS mic for graph B like he is claiming in Stereophile and here.

This is easily demonstrated by the fact that the direct on axis average response of the RS spl meter in graph C cannot be made even close to that of graph B.
 
However, my initial post in "Accuracy" / Entry level forums explains how one can mimick the graph B measurement, using a different mic.

http://forum.stereophile.com/forum/showflat.php?Cat=0&Board=TheEntryLevel&Number=43995&page=0&fpart=1

Let's let the public see graph B and C for comparison.
 
Ethan's Graph B from Stereophile post



Graph C from Ethan's website



Ethan's Graph A from Stereophile post, 20-200



Pretty easy to see the graphs do not match from 20 to 200hz (comb filtering different, mic position. Young will complain if I don't post graph A). 200 to 20khz average also quite different. The average has to match, it all has to match, not just portions. So Ethan could not have used the same mic for both measurements as he has been claiming for the past 3 weeks.

And let's not forget that Ethan tried to change the test setup from two speakers to one speaker, as well as changing the mic used.

I don't think I need to post anymore.
 
« Last Edit: 28 Jul 2008, 12:15 pm by Steve »

Ethan Winer

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Re: Comparison of ten room testing microphones
« Reply #23 on: 28 Jul 2008, 03:13 pm »
Pretty easy to see the graphs do not match from 20 to 200hz

Uh Steve, those are totally different rooms. One is 16 by 11 by 8, the other is 33 by 18 with a ceiling that ranges from 8 feet in the front and rear to 12 feet at the center peak.

Quote
I don't think I need to post anymore.

No kidding. :duh:

--Ethan

Steve

Re: Comparison of ten room testing microphones
« Reply #24 on: 28 Jul 2008, 08:51 pm »
Pretty easy to see the graphs do not match from 20 to 200hz

Uh Steve, those are totally different rooms. One is 16 by 11 by 8, the other is 33 by 18 with a ceiling that ranges from 8 feet in the front and rear to 12 feet at the center peak.

Quote
I don't think I need to post anymore.

No kidding. :duh:

--Ethan


Interesting that you conveniently forgot to post the words right after your quote that were in ().

Quote
(comb filtering different, mic position. Young will complain if I don't post graph A).

I posted graph A because Young would make a scene, and I clearly stated that comb filtering and mic position would make the graphs look different between 20-200hz.

By the way, whether graph A is from another room is of little importance as we shall see.

Ok, remember this. Ethan states graphs A and C were made in different rooms, because graph B does not cover 20-200hz while graphs A and C do.

Ethan still has the problem of between 200 and 20khz, graph B does not match graph C on the average and using the same mic and speakers. So he did not use the RS spl meter in graph B, as he suddenly "remembered" after my initial post in the "accuracy" string.

Want to try another smoke screen again?

Evidently so. Here Ethan states this on Stereophile

Me:
Quote
You cannot explain the differences between the two graphs, A and B

Same graphs A and B here. A from 20-200hz, B from 200-20khz.

Ethan
Quote
they are from totally different rooms.

So  on Stereophile Ethan claims, after nearly 4 weeks, that graphs A and B were made in different rooms.

Yet here on Audio Circle Ethan states the measurements/graphs A and C were made in different rooms.

So what, three rooms now Ethan, or are graphs B and C made in the same room?

Oh, by the way, this is what you stated on Stereophile when graph B was posted (graph A had just been posted just earlier).

Quote
This next graph shows the very same measurement data expressed as 1/3 and 1/12 octaves:

just above graph B. Graph A was using gate time: 100ms

I guess it was a different room though. Hmmmm. Still does not make any difference
since the evidence I presented on Stereophile concerns above 200hz, which after a month
you still have not refuted.

http://forum.stereophile.com/forum/showflat.php?Cat=0&Board=TheEntryLevel&Number=43995&page=0&fpart=1

I did not need to post anymore, last post, since you could not refute my evidence.

Any more convenient stories?

By the way, a good article to read is "Truth be Told"

http://www.boundforsound.com/reviews.htm#Truth




« Last Edit: 29 Jul 2008, 12:07 am by Steve »

Ethan Winer

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Re: Comparison of ten room testing microphones
« Reply #25 on: 29 Jul 2008, 02:46 pm »
Steve,

For the 40th time, if you have a specific question please just ask and I'll do my best to explain. But stop the accusations, okay? All of my data is valid as measured. If you're not clear as to what a particular graph shows, or what microphone was used, or whether the room was empty or full of bass traps etc, please ask. But cut the insults, okay? If you find that everyone in a forum disagrees with you (Clifton, YoungHo, many others) , maybe that should tell you something. :roll:

--Ethan

Steve

Re: Comparison of ten room testing microphones
« Reply #26 on: 29 Jul 2008, 04:21 pm »
Steve,

For the 40th time, if you have a specific question please just ask and I'll do my best to explain. But stop the accusations, okay? All of my data is valid as measured. If you're not clear as to what a particular graph shows, or what microphone was used, or whether the room was empty or full of bass traps etc, please ask. But cut the insults, okay? If you find that everyone in a forum disagrees with you (Clifton, YoungHo, many others) , maybe that should tell you something. :roll:

--Ethan

 I have been concise and after 4 weeks you have yet to refute any evidence I presented. It is right there to refute, clear and concise. All I see is an attempt to change the setup, change mics, attack me, weird mic graphs, and now changing rooms. Just refute the evidence I presented 3 weeks + ago at

http://forum.stereophile.com/forum/showflat.php?Cat=0&Board=TheEntryLevel&Number=43995&page=0&fpart=1

and be done with it. It is right there.

By the way, you want to show us where Clifton disagrees with me concerning the graphs and mics etc?

I do, however see Cifton disagreeing with you and your "typical room" that is completely bare, with no carpet/hardwood floor, no furniture of any kind, no window with shades/curtains etc, no nothing, to produce graph A and B.

And you never notified any of us that your graphs were in-accurate until I asked questions and presented the evidence. So you would have left the public believing your graphs were accurate forever.

Please list, by name, the "many others" that have posted and disagree with me and agree with you on this issue. YoungHo and JeffB are hardly credible when one sees their posts and my replies on this string. I mean physics is physics unless you and they can circumvent it.

Rob Babcock

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Re: Comparison of ten room testing microphones
« Reply #27 on: 29 Jul 2008, 05:50 pm »
This is starting to get out of hand.  I'm locking this for the time being.