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Topic: What *does* make a difference? (Read 16855 times) previous topic - next topic
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What *does* make a difference?

I've been reluctant to post this because they seem like stupid questions, but my beliefs have been turned upside down so much this week i donno what's "stupid" anymore.  So, here i go, even though i'd bet that all three comparisons below would be detectable.

Note that none of this is about perceived quality. It's about not being able to tell appreciable differences via ABXing.

I've been reading up on ABX tests all week and i just give up.  I don't get it. There seem to be a few stand-outs such as cables, and devices with D/A converters that don't make any difference, but i'm about ready to throw up my hands in frustration. I just don't get it.

Speakers can be so physically different. I've got the Anthony Gallo Acoustic Reference 3.1's.  They are about 3' tall, have rounded "cabinets" around the cones, a cylindrical tweeter and a 10" side firing driver.  How can they sound the same as a speaker built around a single fostex driver, or an 8' tall 3' wide Sound Labs panel speaker or a Wilson Audio Maxx ( http://www.wilsonaudio.com/product_images/...groom_large.jpg ).

It is the consensus of the forum that tube amps, class t/d and class A/AB of the same relative power sound the same for the most part?  What about different tubes in tube amps? Is tube rolling pointless from a sonic perspective? I mean again, tube amps. and the other types are working in a very different physical manner so how can they not be detectable from one another?

I saw some snickering at room treatments.  Is the forum suggesting that room treatments and digital room correction make little to no difference in sound quality? I mean hard/absorbent surfaces do effect what frequencies reach your ears at what times (or at all), so my mind says that logically has to make a difference.  Digitally flattening out a response curve has to effect the sound, right?  Now, i'm not talking about the *value* of such treatments. Most of the time i see an expensive bass trap or a pricey colorful audiophile pillow that i'm supposed to put on my wall i think "I bet my mate who's a quilter could make me something that would do that same thing or i could just hang a blanket on the wall" Regardless of whether or not you use the $2k room treatment, change your curtains or move the couch for the same effect, the effect wouldn't likely be a placebo would it? Why would recording studios and concert halls work so hard at it?

Bearcat
Music lover and recovering high end audiophile

What *does* make a difference?

Reply #1
Speakers can be so physically different. I've got the Anthony Gallo Acoustic Reference 3.1's.  They are about 3' tall, have rounded "cabinets" around the cones, a cylindrical tweeter and a 10" side firing driver.  How can they sound the same as a speaker built around a single fostex driver, or an 8' tall 3' wide Sound Labs panel speaker or a Wilson Audio Maxx ( http://www.wilsonaudio.com/product_images/...groom_large.jpg ).


Different speakers sound different.  You don't need ABX to realize that. 

It is the consensus of the forum that tube amps, class t/d and class A/AB of the same relative power sound the same for the most part?


No.

I saw some snickering at room treatments.  Is the forum suggesting that room treatments and digital room correction make little to no difference in sound quality?


I don't know what a room treatment is, but acoustic properties of a room are generally considered to be one of the most important factors in determining what acoustic field can be placed into the room. 

What *does* make a difference?

Reply #2
Different speakers sound different.  You don't need ABX to realize that.

Agreed, but you do need to perform double-blind tests in order to reliably determine which sounds better to you and this is true for my following answers as well, although conducting such tests might be difficult.

It is the consensus of the forum that tube amps, class t/d and class A/AB of the same relative power sound the same for the most part?

I realize this is going to be overly-simplistic, but it's commonly accepted here that tube amps often add coloration, and some even consider this euphonic, whereas most solid state amplifiers typically don't.  There are other considerations that need to be taken into account such as whether the amplifiers are running within specification and what that is exactly.

I saw some snickering at room treatments.  Is the forum suggesting that room treatments and digital room correction make little to no difference in sound quality?

I don't think so, no.  Reflections and resonances can absolutely have an impact on sound quality.

What *does* make a difference?

Reply #3
Speakers can be so physically different. I've got the Anthony Gallo Acoustic Reference 3.1's.  They are about 3' tall, have rounded "cabinets" around the cones, a cylindrical tweeter and a 10" side firing driver.  How can they sound the same as a speaker built around a single fostex driver, or an 8' tall 3' wide Sound Labs panel speaker or a Wilson Audio Maxx .


Not a chance that people can fail to detect the differences between different speakers in an ABX test. Just move the speaker a few inches. Twist it a few degrees. The same speaker will then sound different in an ABX test.

Quote
It is the consensus of the forum that tube amps, class t/d and class A/AB of the same relative power sound the same for the most part?  What about different tubes in tube amps? Is tube rolling pointless from a sonic perspective? I mean again, tube amps. and the other types are working in a very different physical manner so how can they not be detectable from one another?


Not at all. The debate is over amplifiers that all perform to a fairly high standard, not amps in general.  For decades people have been claiming that their magic amp disentangles the vacuum matrix of its frammus or some such, and therefore is mind-blowingly better sounding.

Quote
I saw some snickering at room treatments.


Depends which room treatments you are talking about. There are room treatments the size of a quarter, wooden bricks, microchips, etc.,  for which incredible claims are made. If someone is snickering, it is about them.

Quote
Is the forum suggesting that room treatments and digital room correction make little to no difference in sound quality? I mean hard/absorbent surfaces do effect what frequencies reach your ears at what times (or at all), so my mind says that logically has to make a difference.  Digitally flattening out a response curve has to effect the sound, right?  Now, i'm not talking about the *value* of such treatments. Most of the time i see an expensive bass trap or a pricey colorful audiophile pillow that i'm supposed to put on my wall i think "I bet my mate who's a quilter could make me something that would do that same thing or i could just hang a blanket on the wall" Regardless of whether or not you use the $2k room treatment, change your curtains or move the couch for the same effect, the effect wouldn't likely be a placebo would it? Why would recording studios and concert halls work so hard at it?


Nobody is seriouisly suggesting that those things don't make an audible difference.

What *does* make a difference?

Reply #4
Thanks for the replies folks. That does make me feel better. Perhaps you aren't all *quite* as crazy as i thought. 
Music lover and recovering high end audiophile

What *does* make a difference?

Reply #5
Most of the time i see an expensive bass trap or a pricey colorful audiophile pillow that i'm supposed to put on my wall i think "I bet my mate who's a quilter could make me something that would do that same thing or i could just hang a blanket on the wall" Regardless of whether or not you use the $2k room treatment, change your curtains or move the couch for the same effect, the effect wouldn't likely be a placebo would it? Why would recording studios and concert halls work so hard at it?

Bearcat


I agree with the previous answerers so I won't repeat what they said. I just wanted to point out that a blanket or quilt isn't a substitute for a bass trap. You can in fact get many of the benefits of acoustical room treatment using common furnishings -- CD and bookcases for diffusion, curtains for high frequency absorption, etc. Bass modes, unfortunately, are less amenable to that sort of treatment, but can be reduced with careful placement of speakers and listener, the use of multiple subwoofers, and equalization, or changes to the room envelope.

Anyway, the differences in bass response are easily measurable and should be measured, not so much because of the placebo effect (although it could potentially affect a listener's judgment) as the sheer difficulty of juggling loudspeaker position, listener position, acoustical treatments, and equalization to get the best bass response. You can still use the old techniques if you have to -- listening to walking bass, swapping speaker and listener positions, using rules of thumb -- but I don't think you'll get the best results flying blind.

What *does* make a difference?

Reply #6
I agree with the previous answerers so I won't repeat what they said. I just wanted to point out that a blanket or quilt isn't a substitute for a bass trap. You can in fact get many of the benefits of acoustical room treatment using common furnishings -- CD and bookcases for diffusion, curtains for high frequency absorption, etc. Bass modes, unfortunately, are less amenable to that sort of treatment, but can be reduced with careful placement of speakers and listener, the use of multiple subwoofers, and equalization, or changes to the room envelope.

Anyway, the differences in bass response are easily measurable and should be measured, not so much because of the placebo effect (although it could potentially affect a listener's judgment) as the sheer difficulty of juggling loudspeaker position, listener position, acoustical treatments, and equalization to get the best bass response. You can still use the old techniques if you have to -- listening to walking bass, swapping speaker and listener positions, using rules of thumb -- but I don't think you'll get the best results flying blind.

When discussing an Ambisonics setup that i want to do, it was advised that i set up a subwoofer in each corner of the room to 'pressurize the room' and provide some cancellation of standing bass waves. Does that follow with your knowledge?

Also, i still wonder if one couldn't just make ones own bass traps. It's just material placed in the room some where in a particular shape. Sure, they may advertise it as a space-aged patented mix of calcified nymph blood and gremlin brains, but i'm skeptical of such things.

Music lover and recovering high end audiophile

What *does* make a difference?

Reply #7
When discussing an Ambisonics setup that i want to do, it was advised that i set up a subwoofer in each corner of the room to 'pressurize the room' and provide some cancellation of standing bass waves. Does that follow with your knowledge?


Pushing more energy into a room to alleviate a bass cancellation null is close to mission impossible.  Remember that a 20 dB null takes 100 times more energy to "fill". So if you need a 100 watt amp to drive your sub woofer so that it is loud enough outside the nulls, it might take 10,000 watts to fill the nulls. Actually finding that sort of amp is not nearly as hard as finding a sub woofer that could actually translate its power into acoustic energy to fill the nulls.

Quote
Also, i still wonder if one couldn't just make ones own bass traps. It's just material placed in the room some where in a particular shape. Sure, they may advertise it as a space-aged patented mix of calcified nymph blood and gremlin brains, but i'm skeptical of such things.


Here is a reliable source of information about acoustical traps:
RealTraps Web Article Archive

If I were going to build my own traps, I'd read up there and then search the web for articles about building traps that were consistent with its wisdom.

What *does* make a difference?

Reply #8
Thanks for the info Arnold. I'm still new at all this sciency thinking stuff :")  I'll read up on that page tonight. *bookmarks it*
Music lover and recovering high end audiophile

What *does* make a difference?

Reply #9
Thanks for the info Arnold. I'm still new at all this sciency thinking stuff :")  I'll read up on that page tonight. *bookmarks it*


Afraid I've been slow on the draw again. In any case, I agree with Arnold. You can build your own bass traps, tube and otherwise, and there are various web sites with DIY projects, though of course there are no performance guarantees. But there is a science to it, as there is to most of audio. Not everything is a scam!

If you're interested in the topic, I recommend Everest's Master Handbook of Acoustics. Also Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms, by Floyd Toole. Not that you should feel guilty if you don't choose to delve that deeply.

BTW, what I suspect the Ambisonics recommendation was about was running two subs monophonically at opposite walls in a symmetrical room. That's a recognized means of smoothing bass modes. And corner placement increases bass level, though in most real-world cases uniform bass response is more important than gain (since it's harder to achieve smooth bass than it is to get high bass output). You can achieve marginally more with four subwoofers than with two. Beyond that, adding subs doesn't improve bass uniformity.

So, very broadly --

- If your main interest is in smoothing bass for one listener in the "stereo sweet spot," you might as well just get things as smooth as you can by changing speaker and listener positions and then use low frequency room correction.

- If you want to smooth bass for multiple listening positions, as in a home theater environment, you'll have to start worrying about multiple subs and/or room treatment, since EQ alone can't optimize bass response in a large area of the room.

The one thing I'd caution you about, if I haven't already, is not to get so carried away by room treatment that you overdo it. The trick is to identify your biggest problem, treat it, then measure and listen. One step at a time. Excessive treatment can have side effects that have been demonstrated to have a detrimental effect on perceived sound quality, not to mention your budget and your decor.

What *does* make a difference?

Reply #10
Thanks very much for all that Josh. I will look in to those books and probably get them. I've been eyeing the one by Toole.  Right now i'm reading a series called Musimathics by Gary Loy. It's written for those who operate at about a high-school math level, which is just about perfect for me. :") The two volumes cover all the important stuff but from the stand-point of someone who also stuggled with math.  It uses a lot of visual examples which are prefect for me. I think in visions not words or symbols, hence math was very difficult for me. At 38 i've only just taken off in math by actually starting over and imagining 4 stones in my head to add 2+2. I can do basic algebra now that way.


Musicmathics: http://goo.gl/NWjFL

Looking back over it, the person was in fact talking about smoothing bass modes, with a sub in each corner. i don't know that the term 'monophonic' applies when were talking about ambisonics. In fact i'm probably gonna beg Fons for his help in making the proper set ups for this in his awesome ambisonic decoder as a 8 channel + 4 sub system sounds very complicated to get all the phase stuff right.

For those interested: http://www.kokkinizita.net/linuxaudio/  ambdec about halfway down the page.
Music lover and recovering high end audiophile

What *does* make a difference?

Reply #11
Thanks very much for all that Josh. I will look in to those books and probably get them. I've been eyeing the one by Toole.  Right now i'm reading a series called Musimathics by Gary Loy. It's written for those who operate at about a high-school math level, which is just about perfect for me. :")

The Toole-book hardly contains a formula. Anyone with the interest of good-sounding music playback at home could (and probably should) read it.

-k

What *does* make a difference?

Reply #12
When discussing an Ambisonics setup that i want to do, it was advised that i set up a subwoofer in each corner of the room to 'pressurize the room' and provide some cancellation of standing bass waves. Does that follow with your knowledge?


Pushing more energy into a room to alleviate a bass cancellation null is close to mission impossible.  Remember that a 20 dB null takes 100 times more energy to "fill". So if you need a 100 watt amp to drive your sub woofer so that it is loud enough outside the nulls, it might take 10,000 watts to fill the nulls. Actually finding that sort of amp is not nearly as hard as finding a sub woofer that could actually translate its power into acoustic energy to fill the nulls.

But using more than one sub and positioning/EQ-ing them wisely is not necessarily a waste of time and resources.

-k

What *does* make a difference?

Reply #13
This is the email that contains the information on multiple subs in corners that was posted on the public list in response to my question about Ambisonics and "full range" speakers..

http://lists.linuxaudio.org/pipermail/linu...uly/028991.html

The "it makes your room effectively infinite volume" makes my mouth water.

Music lover and recovering high end audiophile

What *does* make a difference?

Reply #14
This is the email that contains the information on multiple subs in corners that was posted on the public list in response to my question about Ambisonics and "full range" speakers..

http://lists.linuxaudio.org/pipermail/linu...uly/028991.html

The "it makes your room effectively infinite volume" makes my mouth water.


Looks to me like a candidate for the "What's the craziest thing you've ever been told by an audio salesman" thread.

A room with effectively infinite volume may be sitting in your back yard, if your back yard is big enough.  There's no way to simulate that with just a few woofers. Furthermore, if you've ever tried to obtain deep bass outdoors, you know that it is a very difficult path to go down.

Some well-chosen room treatments seems like the more profitable path to go down. It is in fact where just about everybody who is serious goes.

What *does* make a difference?

Reply #15
Subwoofers: Optimum Number and Locations
by Todd Welti, Research Acoustician, Harman International Industries, Inc.
http://www.wghwoodworking.com/audio/multsubs.pdf
"Intuition tells us that putting a large number of subwoofers at different locations in a room is likely to excite room modes in a more “balanced” manner, as compared to a single subwoofer. This idea has potential where there is not a single listening location, but rather a listening area."


Low-Frequency Optimization Using Multiple Subwoofers*
by Todd Welti and Allan Devantier
http://www.wghwoodworking.com/audio/low-fr..._subwoofers.pdf
At low frequencies the listening environment has a significant impact on the sound quality of an audio system. Standing waves within the room cause large frequency-response variations at the listening locations. Furthermore, the frequency response changes significantly from one listening location to another; therefore the system cannot be equalized effectively. However, through the use of multiple subwoofers the seat-to-seat variation in the frequency response can be reduced significantly, allowing subsequent equalization to be more effective.


What *does* make a difference?

Reply #16
Thanks very much for all that Josh. I will look in to those books and probably get them. I've been eyeing the one by Toole.  Right now i'm reading a series called Musimathics by Gary Loy. It's written for those who operate at about a high-school math level, which is just about perfect for me. :") The two volumes cover all the important stuff but from the stand-point of someone who also stuggled with math.  It uses a lot of visual examples which are prefect for me. I think in visions not words or symbols, hence math was very difficult for me. At 38 i've only just taken off in math by actually starting over and imagining 4 stones in my head to add 2+2. I can do basic algebra now that way.


Musicmathics: http://goo.gl/NWjFL

Looking back over it, the person was in fact talking about smoothing bass modes, with a sub in each corner. i don't know that the term 'monophonic' applies when were talking about ambisonics. In fact i'm probably gonna beg Fons for his help in making the proper set ups for this in his awesome ambisonic decoder as a 8 channel + 4 sub system sounds very complicated to get all the phase stuff right.

For those interested: http://www.kokkinizita.net/linuxaudio/  ambdec about halfway down the page.


As usual, I'm late to the party! Agree that Toole's book has very little math. And it has some excellent illustrations and measurements that I think will give you a good intuitive feel for what can and can't be accomplished with a multiple subwoofer setup, as well as other sound field management tools.

By "mono" I meant that the multiple subs have to be run in mono below about 80 Hz if they're to reduce the effect of room modes and make the frequency response more uniform. That's generally considered OK, because the ear isn't very good at detecting the location of loudspeakers that are crossed over at 80 Hz or lower.

I'm not sure what he's getting at in the Ambisonics thread . . .

What *does* make a difference?

Reply #17
I've been reluctant to post this because they seem like stupid questions, but my beliefs have been turned upside down so much this week i donno what's "stupid" anymore.  So, here i go, even though i'd bet that all three comparisons below would be detectable.

Note that none of this is about perceived quality. It's about not being able to tell appreciable differences via ABXing.

I've been reading up on ABX tests all week and i just give up.  I don't get it. There seem to be a few stand-outs such as cables, and devices with D/A converters that don't make any difference, but i'm about ready to throw up my hands in frustration. I just don't get it.


The consistent and universal takeaway from all DBTs is that during such tests, apparently gross differences (ie speakers) shrink to modest differences; apparently modest differences shrink to barely perceptible differences, and small differences appear to vanish.

It's simple to formulate from this general prediction how an individual might perform on such a test when factoring in their acuity and experience, and - perhaps most crucially - the quality of the listening environment. A bad space is a good leveler - which is why recording and performance venues go to such lengths to construct good rooms.

What *does* make a difference?

Reply #18
Not only is that overly-simplistic, it is simply not true.

A very obvious example as to where this "universally" applicable generalization falls flat on its face is with perceptual coding where problems with speakers and listening environments can actually break masking.

If this thread was resurrected in order to argue the merits of double-blind testing it will be closed since the poster already has another open discussion on the topic.

What *does* make a difference?

Reply #19
Not only is that overly-simplistic, it is simply not true.

A very obvious example as to where this "universally" applicable generalization falls flat on its face is with perceptual coding where problems with speakers and listening environments can actually break masking.

If this thread was resurrected in order to argue the merits of double-blind testing it will be closed since the poster already has another open discussion on the topic.


Of course, under specific alignments of random circumstances, multiple imperfections may act to multiply differences usefully. But imperfections and deviations more likely act as a leveler during analytical testing. It's all distortion - noise screwing up accurate results.

What *does* make a difference?

Reply #20
Of course, under specific alignments of random circumstances, multiple imperfections may act to multiply differences usefully. But imperfections and deviations more likely act as a leveler during analytical testing. It's all distortion - noise screwing up accurate results.


I'm pretty sure the generic term for what you're doing is "trolling".

What *does* make a difference?

Reply #21
Of course, under specific alignments of random circumstances, multiple imperfections may act to multiply differences usefully. But imperfections and deviations more likely act as a leveler during analytical testing. It's all distortion - noise screwing up accurate results.


I'm pretty sure the generic term for what you're doing is "trolling".


Trolls provoke insincerely for sport. Or mock/hate for kicks. None of the above apply.

What *does* make a difference?

Reply #22
If not trolling it does demonstrate a gross lack of understanding of the subject of of perceptual coding at the very least.

Anyhow, the OPs questions have been asked and answered with replies that are hardly controversial as well as in keeping with the rules of the site.

This thread will now close.