Floyd Toole Anti-DSP?

dallasjustice

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Apr 12, 2011
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Here is a paper Dr. Toole wrote recently.
http://www.aes.org/tmpFiles/elib/20150911/17839.pdf


I just skimmed it. It looks like a summary of past research. It also offers some conclusions about places he thinks the research should go. My take-away here is that Dr. Toole believes that in room measurements below the Schroeder frequency are needed and DSP to correct minimum phase bass issues below the Schroeder frequency are very helpful. However, Dr. Toole seems to dismiss the notion that a rolled-off HF target curve is needed. That's not been my experience but that's what his paper says. Dr. Toole is also very critical of any attempt to apply DSP above the Schroeder frequency. He doesn't think time windowing techniques work well above Schroeder. My experience having used several different softwares is that this varies greatly from setup to setup. So, there may not be a universal answer. But I believe that smart DSP above Schroeder can be very effective.

I don't think Dr. Toole anti-DSP. IME, the best target based DSP I've used is very careful to treat measurement above the Schroeder frequency differently from measurement below. Of course, windowing is the special sauce in all fancy DSP softwares. This is where the debate rages. What is the appropriate, if any, windowing which should be applied to get the best psychoacoustic response from the listening position?
 

Phelonious Ponk

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Jun 30, 2010
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I think Dr. Toole, and Linkwitz for that matter, believe the best psychoacoustics are a result of good, natural room acoustics. That belief would pretty naturally lead you to be skeptical of using DSP or even extensive physical treatments in the critical midrange. Now, I just put words in the mouths of a couple of guys who probably know more about audio reproduction than the rest of us combined; presumptuous, I know.

Tim
 

amirm

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Apr 2, 2010
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You should not interpret the paper that way. There is a subtext known in the industry that for the sake of politeness is not front and center in that paper. But that is its entire purpose. Namely to push SMPTE to coming with a new standard for *cinema sound* that is based on latest science and not some made up notions from decades back called the X-curve. See this article I wrote: http://www.madronadigital.com/Library/Room Equalization/Room Equalization.html. I have a second installment that I will put online soon which adds more context.

For now, what the X-curve says to do, is to subject the audio system to a DSP with a canned target curve looking like this:



When shown the faults of such a target curve, people then futz with it saying if the room is this big, make the tilt X, or if it is that size, make it Y. In other words, all random made up tortures of the audio system to a response curve that makes no sense. So when Dr. Toole says DSP is bad, he means subjecting your room to that curve using 1/3 octave response even in low frequencies! It is that audience that he is talking to.

That said, in my book, the ideal system would allow you to defeat the high frequency correction and see if you like it better that way. I have been playing with Dirac Live and I wished it had that option. I am not quite sure of what it is going to high frequencies being proper.
 

dallasjustice

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Apr 12, 2011
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I have been playing with Dirac Live and I wished it had that option. I am not quite sure of what it is going to high frequencies being proper.

You can do that no problem in DIRAC Live. Which version are you using? Is it just the trial version?

You can just drag the edge of the measurement from right to left until you find the spot you want the correction to stop.

I've done this myself and found the default curve sounds best.
 

Yuri Korzunov

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Jul 30, 2015
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My take-away here is that Dr. Toole believes that in room measurements below the Schroeder frequency are needed and DSP to correct minimum phase bass issues below the Schroeder frequency are very helpful. However, Dr. Toole seems to dismiss the notion that a rolled-off HF target curve is needed. That's not been my experience but that's what his paper says. Dr. Toole is also very critical of any attempt to apply DSP above the Schroeder frequency. He doesn't think time windowing techniques work well above Schroeder. My experience having used several different softwares is that this varies greatly from setup to setup. So, there may not be a universal answer. But I believe that smart DSP above Schroeder can be very effective.

I don't think Dr. Toole anti-DSP. IME, the best target based DSP I've used is very careful to treat measurement above the Schroeder frequency differently from measurement below. Of course, windowing is the special sauce in all fancy DSP softwares. This is where the debate rages. What is the appropriate, if any, windowing which should be applied to get the best psychoacoustic response from the listening position?

Me seems, no bad in applying correction DSP for full range [0...20000 Hz].

If it will do ideally - as minimum, no harm.

However, some practital implementations may be give some distortions. As example, if use IIR filters without time delay that have non-ideal phase response.
 

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