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Author Topic: real sound lab Coneq ?  (Read 38500 times)

theo mack

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real sound lab Coneq ?
« on: October 11, 2007, 12:37:14 AM »

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Andy Peters

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Re: real sound lab Coneq ?
« Reply #1 on: October 11, 2007, 12:54:49 AM »

theo mack wrote on Wed, 10 October 2007 21:37

Anyone check this out at AES?

http://www.realsoundlab.com/for-professionals.html


The following graph is quite interesting.  The green line is the measured actual frequency response and the yellow line is the synthesized correction that gets applied so that one gets the blue result.
http://www.realsoundlab.com/images/graph.gif

Once, before I knew any better, I tried to apply such a "corrective EQ" to the HF of a PA, and it didn't work.  I mean, I was able to get the transfer function amplitude to flatten out but the drivers were so inefficient up high that the amp clipped at even moderate SPLs.

The moral of the story, of course, is that if the HF driver rolls off above, say, 8 kHz, no amount of corrective EQ boosting will help.

-a
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Bennett Prescott

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Re: real sound lab Coneq ?
« Reply #2 on: October 11, 2007, 07:19:53 AM »

Theo,

I happened to be having a conversation with Bruce Olson when I first saw an ad for this. He's a very well respected consultant, and heavily involved with EASERA, an excellent measurement piece on its way up in the world.

Bruce asked me what I thought and I looked at him and said "Come on, Bruce, you and I both know there's no possible way for that to be any good, no matter how many measurement points and fancy math they use." He and I both did know, he just likes to keep a more open mind than I do, even though he certainly knows far more about it than I.

Long story short, except with a single source in a non-reverberant field (i.e. one loudspeaker in an anechoic chamber) this is just as worthless as an Auto RTA. Even given those requirements, it will still require human interaction as it has NO IDEA of the physical capabilities of the drivers it's measuring and it has NO IDEA of time/phase relationships. So why bother dicking around when to do it right you're going to have to do it "manually" anyway?
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Pascal Pincosy

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Re: real sound lab Coneq ?
« Reply #3 on: October 11, 2007, 07:48:42 AM »

I spoke a bit with Bruce Collins of JK Sound who used this box at Burning Man this year. It was installed in center camp. Advantages are this: 1) The box has 4096 EQ points, far more than any parametric and 2) you shoot the room by waving a measurement mic around the room, a several minute process. To do this with SMAART, you would need to take dozens (hundreds?) of measurements all through the room, average them all, and come up with a useable EQ curve.

Does it work? He said yes, it works great. Note that you do interface with a computer, and I'm sure you still need to make important decisions about how high and low to go with your EQ-ing, as well as deal with interactions between drivers where phase cancellation is an issue.

Here's an article about ConEQ at Burning Man. Checkout what Bruce has to say at the bottom of the article: http://www.prosoundnews.com/publish/news/CONEQ-ting_At_Burni ng_Man.shtml I'd certainly love to get my hands on one of these units.
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Ivan Beaver

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Re: real sound lab Coneq ?
« Reply #4 on: October 11, 2007, 07:58:57 AM »

As you pointed out, there is a lot more involved than just freq response.  If you push a driver beyond what it is capable of, the amplitude response may look fine, but it will probably sound like crap.

But for people that are satisfied with just freq response Very Happy

As usual a single number or graph cannot what performance a device has.
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Don Boomer

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Re: real sound lab Coneq ?
« Reply #5 on: October 11, 2007, 11:19:24 AM »

[quote title=Andy Peters wrote on Wed, 10 October 2007 23:54]
theo mack wrote on Wed, 10 October 2007 21:37



The moral of the story, of course, is that if the HF driver rolls off above, say, 8 kHz, no amount of corrective EQ boosting will help.



You can however cut the other side, bringing it down so that the HF driver keeps up (or maybe split the difference and keeps up better)
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mel taylor

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Re: real sound lab Coneq ?
« Reply #6 on: October 11, 2007, 01:32:18 PM »

Anyone that thinks this won't be useful needs to study more before working on a system that requires any optimization techniques or measurements by the user.  

Equalizing via power response with hundreds of measurement points, instead of frequency response with a few points is obviously a better platform, many professional engineers agree (not sound guys, but the leading designer minds in the industry).  Couple that measurement platform with the fine resolution of FIR filters, then yes, you can optimize a system to be nearly absent of all electrical and acoustical distortions (yes, lots of circumstances surrounding, but best-case-scenario).

Everyone can disregard it now, but it will be eminent in some form or another.  Maybe not in this amateur user form, but I'd bet the philosophy will become a standard of measurement.
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Mac Kerr

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Re: real sound lab Coneq ?
« Reply #7 on: October 11, 2007, 03:33:24 PM »

theo mack wrote on Thu, 11 October 2007 00:37

Anyone check this out at AES?

http://www.realsoundlab.com/for-professionals.html
I did. I went to the demo as a skeptic, and came away as someone who thinks it is an interesting product that does not have much utility in the live sound industry. The first thing that live sound people notice is that it is a "time blind" system, and therefore not much more than an auto eq with RTA. The key is that the system has a more limited application. It is not a sound system optimization tool like Smaart or SIM, or any of the other dual FFT transfer function systems we have come to know and love. It is a speaker equalization system that at least partially overcomes its time blindness by taking thousands of measurements in thousands of locations so that the time errors become statistically insignificant. Each measurement location has a unique time error, but it is only in that single measurement out of thousands. This is an equalization system only, it is not trying to make any corrections for phase response. It assumes that is already correct, and it the demo that compared a Tannoy Reveal to a Genelec, those issues had already been addressed with some degree of success. In the demo, a piece of music was played through the Tannoy, which sounded pretty good. It was then played through the Genelec, which also sounded pretty good, but completely different. After applying the ConEq system, the monitors sounded virtually identical, although with the short cuts it was hard to evaluate which of the 4 sounds may have been best.

The second part of the demo was a live performance by a trio of piano, bass, and sax, interspersed with a playback of the same music, that had been recorded in the demo room a couple of days before. Each of the musicians had a different speaker system for playback of their track, and they alternated between live and playback every couple of bars. With the bass and piano it was very hard to tell when it was live without watching the musicians. The sax was out front, and there was a timbre change between the live and playback, although it was quite close.

An interesting idea that may not apply to us, but what it does may be useful to someone.

Mac
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Bob McCarthy

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Re: real sound lab Coneq ?
« Reply #8 on: October 13, 2007, 11:09:05 AM »

I also attended the demo and have a few comments:

Disclosure of bias: I have been involved in the development of a competing acoustic measurement platform for decades.

1) The end product of this new technology is a computer generated EQ curve. EQ is the most subjective of all sound system optimization results. So often in life we find we can be replaced by a computer. Here the computer can be replaced by an opinion.
2) The unique feature here is that the EQ curve is derived by a measurement of acoustic power radiating over the space, rather than SPL at a given location. At first glance the replacement of a single  point with a field of data would seem like an important breakthrough, but the following considerations apply:

A) Does the treatment(EQ) match the diagnosis (frequency response as an average over a spread sound field)?  Consider the fact that EQ affects all of the speaker's pattern, and does nothing to modify its directional character. Moving the mic all over the field statistically randomizes three items that are not at all random: the speaker's polar response, the reflections and the interactions with other speakers. Should Side lobes/down lobes be given equal treatment to front lobes? How does one feel about comb filter interaction between speakers and the room being statistically (although not audibly) eliminated?

For studio applications, the area of primary interest is the mix engineer's head. All others are secondary and can only be solved by uniformity of pattern in the speaker and well behaved room acoustics. To give the off axis producer's desk equal statistical value could result in excessive HF at the mix position. (This was evident in the extreme HF boosting at the demo and in the curves supplied in this thread).

B) For reinforcement work it is important to bear in mind that EQ is the least objective task of the optimization process. Speaker positioning, array angles, spectral crossover alignment, polarity verification, delay setting, relative level and acoustical treatment are the major players and have objectively defensible conclusions. Any analyzers that dismiss phase (as do CONEX, RTAs etc.) are knocked out of the main optimization events. An approach that can not tell where a speaker is pointed (because of its lack of single points of data) will be of limited use.

So in CONEX we have a tool that can do one thing: EQ (that the other analyzers can do, and that is subject to whims and opinions) and we will need to have a second analyzer at the ready if we want to do the remaining work of system tuning.

There may indeed by some interesting practical applications for CONEX's ability to measure the acoustic power field. At first glance this would seem promising in the field of noise analysis, where random sound fields are generated by machinery etc. In such cases single points of data are poor representatives of a stable event and a spread field of measurement would enhance the statistical significance of the result. I will leave that, however, for experts in that field to consider.

6o6
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Mac Kerr

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Re: real sound lab Coneq ?
« Reply #9 on: October 13, 2007, 11:25:59 AM »

Bob McCarthy wrote on Sat, 13 October 2007 11:09

Consider the fact that EQ affects all of the speaker's pattern, and does nothing to modify its directional character. Moving the mic all over the field statistically randomizes three items that are not at all random: the speaker's polar response, the reflections and the interactions with other speakers. Should Side lobes/down lobes be given equal treatment to front lobes? How does one feel about comb filter interaction between speakers and the room being statistically (although not audibly) eliminated?
Well said. I think 2 of those 3 things were minimized, and must be for there to be any utility as a speaker equalization tool, those being interaction with the room, which was draped with heavy velour with fullness, and interaction with other speaker systems, as one system at a time was treated. Your point about equalizing for response out of the useful coverage of the speaker was not at all addressed, as it was clear the mic was scanned through a very wide area around the speaker. They also tossed around the description "thousands of measurements" in regard to how much data was being analyzed, yet there were no more than "hundreds" of frequency sweeps, and as the mic was moving constantly, every sweep was integrated over some change in position.

To me it remains an interesting concept, but one I don't see a use for in my line of work.

Mac
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Re: real sound lab Coneq ?
« Reply #9 on: October 13, 2007, 11:25:59 AM »


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