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Timbre matching a dubious feature?

post #1 of 27
4/11/10 at 9:21am
Thread Starter 
I was reading Dr. Toole's paper Direction and Space - the Final Frontiers and was surprised to read:

Quote:


Timbre matching of the surround to the L,C.R (front) channels. In my view, this is a dubious feature. Sounds arriving from the sides, or from random incidences will have timbres that differ from sounds arriving from the front because of the head and external ears - see HRTF explanation, p. 16. It is nature at work, and it needs no correction.

And yet from the Paradigm Signature Reference catalog I find:

Quote:


Extreme Timbre Matching
The final frontier in achieving seamless multi-channel music and home theatre performance is timbre matchingthe identical sonic signature passing smoothly from speaker to speaker, Timbre matching has a profound and fundamental impact on the sound we hear. For true state-of-the-art multi-channel performance, sound must flow from speaker to speaker with dead-on accuracy.

Timbre matching the center-channel and rear/surround speakers with front speakers is perhaps the ultimate challenge for a speaker designer. How do you make sound from a horizontal center channel blend seamlessly with that from vertically configured front speakers? The mere differences in horizontal and vertical orientation will cause changes in timbre. And to compound the challenge, with their large reverberant soundfield, Paradigm's ADP surround/rear speakers have an altogether different driver orientationone which enables them to accurately disperse sound towards the front and back of the room.

Building on Signatures countless advanced design features, Paradigm engineers set to work measuring, listening, testing and re-testing yet again. Their goal was to achieve vastly superior timbre matching. Two critical components lie behind our successthe precision and accuracy of our remarkable unified drive assembly and sophisticated crossover design itself.

The result is unique to Paradigm Reference SignatureExtreme Timbre Matching. Properly set up in a good neutral listening room, the fundamental timbre of each Signature speaker is not just closely matchedit is virtually identical.

Who is correct?
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post #2 of 27
4/11/10 at 9:28am
Suggesting that voice matching in surround speakers is not important is just dumb. It's easily the single most important factor.
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post #3 of 27
4/11/10 at 10:18am
Most surround speakers aren't matched anyway. Different cabinet sizes will give a completely different and easily localizable 'voice' that is different from the fronts. Even if the midbass woofers are the same. The speaker being positioned in a different point in space will cause it to sound different. Take my past and present speakers for instance.

12 years ago I had a matching 5 speaker setup of Technics 3-way speakers. Despite having completely matching speakers all around I STILL had to extensively equalize the rears and fronts to sound similar. Even when panning pink noise, the speakers sounded different. I now have BIC DV62CLRS fronts but an Optimus LX-5 II pair of surrounds. I extensively equalized this setup and got the same results. They sound 'matched' when playing music and surround material but when you play pink noise, they sound different. Even when you match all the speakers. But when you have a a properly EQ'd set of rears, the panning of sounds gives off a very similar front to rear character. I was able to successfully duplicate front to rear thru painstaking calibration. I can run 2-channel stereo music on any combination of 2-speakers in my system and they sound like a matching pair with music and movies but NOT with pink noise. If I connect the front-right and left-rear, they sound like a matching pair of stereo speakers due to my manual calibration. The MCACC auto-tune, while decent, did NOT match the tonal character. Only my manual adjustments pulled this off.
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post #4 of 27
4/11/10 at 10:22am
Quote:
Originally Posted by rdgrimes View Post

Suggesting that voice matching in surround speakers is not important is just dumb. It's easily the single most important factor.

Maybe for multi-channel music (those 7 titles that are available in the U.S), but surround information in movie soundtracks is of a diffuse nature, and for most practical purposes the timbre is not that critical. Is it ideal? Sure, but I would argue the "single most important factor".
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post #5 of 27
4/11/10 at 10:24am
I've found that most any surrounds that are "in the ballpark" sonically will work well. You just don't want such a glaring mismatch that it becomes sonically distracting, like using Klipsch surrounds with laid-back, inefficient fronts.
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post #6 of 27
4/11/10 at 10:29am
Quote:
Originally Posted by mbfleming View Post

I was reading Dr. Toole's paper Direction and Space - the Final Frontiers and was surprised to read:

Quote:


Timbre matching of the surround to the L,C.R (front) channels. In my view, this is a dubious feature. Sounds arriving from the sides, or from random incidences will have timbres that differ from sounds arriving from the front because of the head and external ears - see HRTF explanation, p. 16. It is nature at work, and it needs no correction.

I don't doubt that this may technically be correct. However the human brain is probably used to tracking sounds and automatically compensates for the timbre changes due to your ears.

Also, stop in your local Consumer Electronics store. Sit down in the demo room and choose a center speaker that is very different from the left and right. When something moves left to right you will easily be able to tell: "ok the sound is coming from the left speaker, now the center, now the right". Repeat the exercise with matched speakers and the transisions if noticiable will at least be much smoother.
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post #7 of 27
4/11/10 at 10:34am
Quote:
Originally Posted by gravi View Post

...but surround information in movie soundtracks is of a diffuse nature, and for most practical purposes the timbre is not that critical.

It is becoming more and more discrete and directional, especially in action movies. It was meant to be diffused in the days of Dolby Pro Logic

It may not be critical, but I would argue that those that have experienced it, would want to have it. I know that that those that have it, do not want to give it up.
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post #8 of 27
4/11/10 at 10:40am
Quote:
Originally Posted by mbfleming View Post

I was reading Dr. Toole's paper Direction and Space - the Final Frontiers and was surprised to read:



And yet from the Paradigm Signature Reference catalog I find:



Who is correct?

If you read Floyd Toole's quoted statement very closely, you will see that he is referring to a different situation and different issue entirely from that of the Paradigm quote. Paradigm is referring to the likeness of sound between speakers of different form factors and implementations. I'm pretty sure Toole is referring to a post-processing effort found in some THX processing functions, where they were attempting to apply compensation for the different spectral sensitivity we have to side and rear oriented sounds.

If you look at the last comment by Toole of "It is nature at work, and it needs no correction." he is affirming that you merely need to keep the behavior of the speakers/sources the same, where we will naturally correlate and expect the same speaker placed behind us to sound slightly different until we turn around to face it.
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post #9 of 27
4/11/10 at 2:30pm
Quote:
Originally Posted by rdgrimes View Post

Suggesting that voice matching in surround speakers is not important is just dumb. It's easily the single most important factor.

What are your credentials in relation to studying this phenomenon? You'll easily find Dr. Toole's, but how about yours?

Quote:
Originally Posted by DaveHCYJ View Post

Also, stop in your local Consumer Electronics store. Sit down in the demo room and choose a center speaker that is very different from the left and right. When something moves left to right you will easily be able to tell: "ok the sound is coming from the left speaker, now the center, now the right". Repeat the exercise with matched speakers and the transisions if noticiable will at least be much smoother.

This is true, but we're talking the surround channels, not the front three.

Getting back to the OP: considering Floyd Toole's credentials, I wouldn't argue against what he said. He has nothing to gain by stating his findings, and I simply don't have the experience to argue them (most of us probably don't). Plus, to my ears, the rears are not nearly as important as the fronts. YMMV.
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post #10 of 27
4/11/10 at 4:09pm
For home theater, the nature of the sound coming from the surround speakers is really quite different than that coming from the front. Go stand next to your surrounds and listen to them during a movie. A knock on a door..... a gunshot.... the sound of wind or rain.... a car horn... IMO, sounds like these don't need to be timbre matched to the dialog or music coming from the fronts. Sure, there are occasional exceptions where a voice or sound pans all the way around, but this does not happen frequently. Timbre matching with dipoles is even more dubious- since they depend on reflected sound, any benefit from timbre matching would be seriously compromised. Ideally, I would go with timbre matched speakers all the way around, but I wouldn't lose any sleep over it if they were not. For multichannel music, I would certainly want timbre matched direct radiating speakers all the way around, or better yet- identical speakers all around.
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post #11 of 27
4/11/10 at 7:05pm
I can't stress enough that when you pan pink noise around all channels with MATCHING speakers all-around, the rears still sound different than the fronts. I would invite anyone to try the experiment. When you know matching speakers won't sound the same when aimed from a surround position, it becomes clear that you can use a mismatch speaker with careful equalization and come away with a perfect result.
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post #12 of 27
4/11/10 at 7:25pm
Quote:
Originally Posted by Timothy91 View Post

I can't stress enough that when you pan pink noise around all channels with MATCHING speakers all-around, the rears still sound different than the fronts. I would invite anyone to try the experiment. When you know matching speakers won't sound the same when aimed from a surround position, it becomes clear that you can use a mismatch speaker with careful equalization and come away with a perfect result.

They sound different because of the room interaction...something that happens naturally. IMO, better to start with the same timbre, and let that act happen, just as if you were to speak to someone from different points in a room...same person talking, just from a different area.

As illustrated in Toole's quote that Mark pointed out"
"It is nature at work, and it needs no correction."
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post #13 of 27
4/11/10 at 8:31pm
Quote:
Originally Posted by cschang View Post

They sound different because of the room interaction...something that happens naturally. IMO, better to start with the same timbre, and let that act happen, just as if you were to speak to someone from different points in a room...same person talking, just from a different area.

As illustrated in Toole's quote that Mark pointed out"
"It is nature at work, and it needs no correction."

I've pretty much convinced myself that absolutely identical speakers are not necessary. Not even identical drivers. I would probably try to stay with similar driver material (ie, if the front woofers are carbon fiber, then if you mismatch the brand, try and keep the driver materials similar). I kept the materials matching by making sure all drivers used polypropylene. Although the sound didn't seem to match at first, with EQ the results were fantastic.
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post #14 of 27
4/11/10 at 8:36pm
Quote:
Originally Posted by Timothy91 View Post

I've pretty much convinced myself that absolutely identical speakers are not necessary.

Apparently that process did not involve actually trying identical speakers all around with appropriate setup. Just because a particular surround speaker is claimed to be "matching" doesn't mean it is. Nothing is "necessary", but once experienced you won't want to go back. It's all about trade-offs. Anything other than identical speakers is a trade-off. "Matching" models are not presumed to be identical in voice, but it's usually a good starting point.
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post #15 of 27
4/11/10 at 8:44pm
Thread Starter 
Quote:
Originally Posted by rdgrimes View Post

Nothing is "necessary", but once experienced you won't want to go back.

This is how I feel about the Paradigm ADP3 surrounds after watching several movies with them. They blend very well with the front channels; it is something you have to experience yourself. I don't see how you can develop an opinion if you have never tried it personally.

If the rear speakers are not important, I could have used Bose speakers.
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post #16 of 27
4/11/10 at 9:23pm
Quote:
Originally Posted by mbfleming View Post

I don't see how you can develop an opinion if you have never tried it personally.

Agreed, but it happens all the time around here.
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post #17 of 27
4/11/10 at 9:30pm
Quote:
Originally Posted by cschang View Post

Agreed, but it happens all the time around here.

LMAO! I nominate this for best statement of the week!
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post #18 of 27
4/12/10 at 10:06am
Here is a good explanation of why Toole says what he says in the quote from the OP:

"In a home theater, if broadband pink noise (not the common band-limited multichannel calibration signal) is switched to each of five identical loudspeakers, a listener facing forward will hear obvious changes in timbre. In jumping from the center to the left front or right front loudspeaker, a high frequency boost may be heard. From there to either of the side surround loudspeakers, there are more timbral changes. This is as it should be. To confirm that all five loudspeakers in a system are similar in timbre, it is necessary to face each of the loudspeakers as they play the same test signal. Then, and only then, can identical loudspeakers have identical perceived timbres. This is the timbre matching important to sound reproduction, not what is heard while facing forward. If a five-channel system reproduced a quintet of identical musical instruments, one would want each reproduced identically, even though we know that, depending on incident angle, the sound from each one will be distinctively modified on the way to our ear drums After all, that is what would happen in a live situation."

Copyright 2008, Floyd E. Toole - Sound Reproduction, chapter 3, page 38.

So in short, in order for the human ears and brain to perceive the exact same timbre, you'd have to be listening to the exact same signal, one speaker at a time, while facing said speaker. Obviously this is not how we listen to music or movies, hence why I believe Dr. Toole said what he said.
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post #19 of 27
4/12/10 at 10:42am
Quote:
Originally Posted by rdgrimes View Post

Suggesting that voice matching in surround speakers is not important is just dumb. It's easily the single most important factor.

You really want to call out Dr. Toole and say he is being dumb?

The quote is taking out of context. There is a specific need in that discussion.

I think all of Toole's research should become required reading for anyone that calls themself an audiophile!
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post #20 of 27
4/12/10 at 10:44am
Quote:
Originally Posted by cschang View Post

Quote:
Originally Posted by gravi View Post

...but surround information in movie soundtracks is of a diffuse nature, and for most practical purposes the timbre is not that critical.

It is becoming more and more discrete and directional, especially in action movies. It was meant to be diffused in the days of Dolby Pro Logic.

Agreed, surround content is 'becoming more and more discrete'. Nonetheless, there remains a fundamental difference between L/C/R pans, and front-to-back pans . . . and timbre matching is most critical in making an audio source pan believable. An L/C/R pan is designed to pull the viewer's focus across the screen from left to right, whereas a front to back pan is not intended to make the viewer (listener?) turn around. Although surround contents are now 'discrete', the primary use of surrounds is still to provide cues rather than to function as the principal audio source.
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post #21 of 27
4/12/10 at 10:51am
Thanks 'Chex....and I agree.
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post #22 of 27
4/12/10 at 12:49pm
Guys, many of you seem to have missed Mark Seaton's post. He correctly pointed out that Toole's comment was about THX post-processing "Timbre-Matching". THX post-processing involves Re-EQ, Boundary Gain Compensation, Adaptive Decorrelation, Adaptive Speaker Array, and... Timbre-Matching. This is an function of the electronic processing performed in a THX processor. This is completely and essentially different than attempting to timbre-match your loudspeakers.

Quote:


Timbre Matching

Your ears hear different tonal qualities in sounds coming from different directions. Timbre Matching restores the frequency balance between your front and surround speakersensuring seamless and smooth panning between the front to back of the room.

http://www.thx.com/consumer/thx-tech...iver-features/


Toole's comment was in a discussion about THX processing. In that context he stated that THX "timbre-matching" post processing is a dubious feature. He was not in any way addressing using identical speakers in all positions, or ensuring that the surrounds are "timbre-matched" to the mains. Here is the entire discussion from which Toole's comment was taken out of context:

Quote:


In a natural succession to their THX program for certifying cinema sound systems, Lucasfilm established a licensing scheme for features intended to help in reproducing a cinema experience in home theater systems. Home THX, as it was called, added features to a Dolby ProLogic processor and to the loudspeakers used in home theater systems. It also set some minimum performance standards for the electronics and loudspeakers. At a time when the market was inundated with cheap and cheerful add-on center and surround speakers and amplifiers, THX made a clear statement that all channels had to meet a similar standard. This amalgam of existing and novel features was a useful stimulus for consumer home theater in the early days. The THX embellishments in the original specification were:

1. High- and low-pass filters to help achieve a proper crossover between the subwoofer and satellite loudspeakers. This was a serious omission in early surround-sound systems, leading to lots of bad bass. Now, with even more flexibility, it is common in processors and receivers. In-room measurement and equalization is what is really needed.

2. Electronic decorrelation between the left and right surround channels. Reducing the number of surround speakers to two, and putting them in a small room, eliminated much of the acoustical decorrelation (randomization of the sounds arriving at the listeners' left and right ears) that multiple speakers in a large cinema accomplished automatically. As I recall, it was first introduced in the Shure HTS systems. Now that surround channels are discrete, the current adaptive version is activated only when a monophonic surround signal is detected, as in Dolby Surround sound tracks.

3. Timbre matching of the surround to the L,C.R (front) channels. In my view, this is a dubious feature. Sounds arriving from the sides, or from random incidences will have timbres that differ from sounds arriving from the front because of the head and external ears - see HRTF explanation, p. 16. It is nature at work, and it needs no correction.

4. Re-equalization of the sound track to compensate for excessive treble that is sometimes built into film tracks to compensate for sound systems in large cinemas. THX used a single correction curve but it needed to be adjustable since sound tracks vary in treble balance. Now, movie and music concert DVD's are often mastered in circumstances resembling home theaters, so the problem goes away. It is a tone control, and off' is a useful setting.

In loudspeakers, THX required some control of the vertical dispersion from the L, C, R (front) units. To keep costs in line, the simple driver configurations that were sometimes used resulted in off-axis performance that no self-respecting loudspeaker engineer would be proud of. The requirement has been relaxed in recent years. Directivity control can be useful if it is done well, as it can be with horns or complex arrays of drivers, especially when combined with digital processing.

The recommended bi-directional dipole surround loudspeakers increased the proportion of reflected sound that is generated by the surround speakers, making it appear that there are more than two of them. Success is highly dependent on the specific acoustics of the listening room, since most of the sound is reflected. This was a persuasive argument in the days of Dolby ProLogic, with its single surround channel. Now, discrete left and right surround channels allow for acoustical and electronic decorrelation between the left and right surrounds in the program itself. The additional surround channels in 6.1 and 7.1 systems are more reasons to consider alternatives.

If you guys want to argue about the necessity of timbre-matching all your speakers, that's fine, but it is unrelated to the original question.

To the OP:
The two comments you are attempting to compare are essentially different. Toole's comment was about THX post-processing, and Paradigm's marketing fluff is about speaker design. Paradigm is attempting to convince you that they have figured out how to design a vertical speaker, a horizontal speaker and a multi-polar speaker and make all these different designs sound the same. This is as dubious a claim as is THX timbre-matching post processing.

Craig
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post #23 of 27
4/12/10 at 1:20pm
Thread Starter 
Got it. I didn't understand that when I read the paper. There was no need to post further after Mark Seaton clarified that point.
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post #24 of 27
4/12/10 at 1:27pm
Quote:


Paradigm is attempting to convince you that they have figured out how to design a vertical speaker, a horizontal speaker and a multi-polar speaker and make all these different designs sound the same. This is as dubious a claim

Good call, All this focus on Toole's comment and we forgot about the marketing BS from Paradigm
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post #25 of 27
4/12/10 at 1:34pm
Thread Starter 
Quote:
Originally Posted by craig john View Post

Paradigm is attempting to convince you that they have figured out how to design a vertical speaker, a horizontal speaker and a multi-polar speaker and make all these different designs sound the same. This is as dubious a claim as is THX timbre-matching post processing.

Craig

The BS must have worked, because at the same time I ordered their C5 center channel and ADP3 surrounds, I also ordered the world's loudest subwoofer.

On that note, I'm going stop posting in this thread before I get accused of being a troll.
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post #26 of 27
4/12/10 at 3:33pm
Quote:
Originally Posted by penngray View Post

Good call, All this focus on Toole's comment and we forgot about the marketing BS from Paradigm

+1. Thanks, craig john!
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post #27 of 27
5/27/10 at 9:20pm
Quote:
Originally Posted by craig john View Post

Guys, many of you seem to have missed Mark Seaton's post. He correctly pointed out that Toole's comment was about THX post-processing "Timbre-Matching". THX post-processing involves Re-EQ, Boundary Gain Compensation, Adaptive Decorrelation, Adaptive Speaker Array, and... Timbre-Matching. This is an function of the electronic processing performed in a THX processor. This is completely and essentially different than attempting to timbre-match your loudspeakers.



http://www.thx.com/consumer/thx-tech...iver-features/


Toole's comment was in a discussion about THX processing. In that context he stated that THX "timbre-matching" post processing is a dubious feature. He was not in any way addressing using identical speakers in all positions, or ensuring that the surrounds are "timbre-matched" to the mains. Here is the entire discussion from which Toole's comment was taken out of context:



If you guys want to argue about the necessity of timbre-matching all your speakers, that's fine, but it is unrelated to the original question.

To the OP:
The two comments you are attempting to compare are essentially different. Toole's comment was about THX post-processing, and Paradigm's marketing fluff is about speaker design. Paradigm is attempting to convince you that they have figured out how to design a vertical speaker, a horizontal speaker and a multi-polar speaker and make all these different designs sound the same. This is as dubious a claim as is THX timbre-matching post processing.

Craig


He is talking about THX, but what difference does it make if it's done by the receiver or by having matching speakers? He is still saying there would be differences in timbre depending on where the person was sitting regardless. The question is, even if this is correct, which I am sure it is, wouldn't having identical speakers be compared to as one poster put it, walking around the room and talking to someone from different parts of the room, as opposed to mismatched speakers being the equivalent of having 2 different people walking around the room that "kind of" sound like each other?
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