My wife has a PhD in marketing. I get to enjoy conversations in the acedemic setting so I 100% understand that POV.
The discussion about someone like Toole or even Geddes qualifications beyond having a PhD. There documented and published findings have helped many individuals go far beyond what was possible before them. To post calling Toole's books mediocre is jealousy at best when the proof is in the improvements all over the audio world because of their input. They have had a great impact and have improved the audio world to argue against that is just foolish IMO.
Thread closed while we take the trash out. You guys need a rest, go somewhere else for a while.
A number of posts deleted, but i only went back a day or 2. Some yellow cards handed out. Thread will remain closed to allow for tempers to cool down.
dave
dave
We should remember to all talk like we are face to face with one another. I think there would be less posturing as I've never seen anyone act like this at an audio event.
Sorry, carry on with measurement discussions. I'd really like to see some real data on CBTs. This is something I believe SUM has done a bit of work on. I know there's a thread going on the topic, but it's pretty light reading so far.
Dan
Sorry, carry on with measurement discussions. I'd really like to see some real data on CBTs. This is something I believe SUM has done a bit of work on. I know there's a thread going on the topic, but it's pretty light reading so far.
Dan
Dan, have you read about the pro-10s that tweak City Audio has just finished and are selling?
THE Pro-10 Information thread - Tweak City Audio
I can not find measurements yet but Im reading through it. The waveguide looks small and its matched with a 10" woofer.
THE Pro-10 Information thread - Tweak City Audio
I can not find measurements yet but Im reading through it. The waveguide looks small and its matched with a 10" woofer.
The fixed version- to long but lots covered
Yes sir. Back in the school days we did A LOT of CBTs using music students. Seemed we convinced some professors to make it a requirement for music students to participate to earn their degrees. Such blatant abuse of power, haha- hahaha. Phase and changes in phase was most of the focus because of the early results. Plenty of custom equipment and extensive used of Fourier synthesizers. In the end given a pitch center near 692Hz and a reasonably flat response loudspeaker phase response was the most easily recognized change in a experienced sound. Even when the bandwidth was limited to a telephone like of 200-2000Hz phase was still the most audible effect. It took a phase change of nay but 75 degrees (as I recall- tossed all the research after discovery of politics) of the 2nd harmonic of a fundamental near 400Hz to have all students say the timbre had changed. This lead to the obvious design goal.
So this begs the question of why not publish? Every paper submitted was rejected with very weak reasons such as "everyone knows this" or " no one cares about this" and so on. The writing was on the wall. Peer review was about politics and not about science.
Since then there have been a lot of laboratory testing and a good fortune to work with some people who built full experience flight simulators among other things. You know, the military budget kind? Still have not swallowed all there was to know from that and am still confused about the exact nature of many spacial effects. Wish I knew what the one giant I stand on knows.
There are 3D audio experience theaters using headphone like devices and users sit in something akin to the old dentist chair (headlock) with the ear speaker mounted to the chair. They regularly get people jumping from their seats. 3D vision in the same theater. Never been, always wanted. Circle vision at Disney anyone? Hand rails to keep people from falling over, haha again.
But the CBTs on moving sources and moving lobes. One must have a "viable" source which does not misbehave in the first place. Much easier to say than to do. Statistically, moving sources and moving lobes are only heard by about 80% of the listeners. The other 20% don't. The testing of such proved to be quite difficult and I truly believe the source is still the main limit to that kind of testing. Careful selection of content, careful band limiting, and again, plenty of other stuff and still the source was the main limiting factor for testing. On the other hand, if you ever have a chance to hear a speaker (there are a very few) that has this pretty well under control it may be difficult to go back. Studio engineers really like it because it makes everything so effortless to hear and hence my work continues.
Since those days have been working on "phase correct" non-moving lobe/apparent source" loudspeakers and then adding controlled directivity. Phase correct took 25 years of trying. Controlled directivity was a lot easier! Almost off the shelf and today it is off the shelf, SEAS tweeter (Madisound H1499 ?) with the wrong or to much ferro-fluid can be used. A 6.5" with 1.25 inch/32mm voice coil can get you close but there is still one very pesky problem, crossover. If I get the patent then I will share how to OR use that (((acourate)))® - Room Correction, Speaker Optimization and Sound Improvement software and FIR filters. That works really well or any other good FIR filter and delays to mix the drivers perfectly. Try it, it really does work! If you hear image, then you will hear real image like nothing else before.
Moderators- thanks for the cleaning!
And bringing the thread back. Lots of good stuff in this thread.
😀=SUM
Yes sir. Back in the school days we did A LOT of CBTs using music students. Seemed we convinced some professors to make it a requirement for music students to participate to earn their degrees. Such blatant abuse of power, haha- hahaha. Phase and changes in phase was most of the focus because of the early results. Plenty of custom equipment and extensive used of Fourier synthesizers. In the end given a pitch center near 692Hz and a reasonably flat response loudspeaker phase response was the most easily recognized change in a experienced sound. Even when the bandwidth was limited to a telephone like of 200-2000Hz phase was still the most audible effect. It took a phase change of nay but 75 degrees (as I recall- tossed all the research after discovery of politics) of the 2nd harmonic of a fundamental near 400Hz to have all students say the timbre had changed. This lead to the obvious design goal.
So this begs the question of why not publish? Every paper submitted was rejected with very weak reasons such as "everyone knows this" or " no one cares about this" and so on. The writing was on the wall. Peer review was about politics and not about science.
Since then there have been a lot of laboratory testing and a good fortune to work with some people who built full experience flight simulators among other things. You know, the military budget kind? Still have not swallowed all there was to know from that and am still confused about the exact nature of many spacial effects. Wish I knew what the one giant I stand on knows.
There are 3D audio experience theaters using headphone like devices and users sit in something akin to the old dentist chair (headlock) with the ear speaker mounted to the chair. They regularly get people jumping from their seats. 3D vision in the same theater. Never been, always wanted. Circle vision at Disney anyone? Hand rails to keep people from falling over, haha again.
But the CBTs on moving sources and moving lobes. One must have a "viable" source which does not misbehave in the first place. Much easier to say than to do. Statistically, moving sources and moving lobes are only heard by about 80% of the listeners. The other 20% don't. The testing of such proved to be quite difficult and I truly believe the source is still the main limit to that kind of testing. Careful selection of content, careful band limiting, and again, plenty of other stuff and still the source was the main limiting factor for testing. On the other hand, if you ever have a chance to hear a speaker (there are a very few) that has this pretty well under control it may be difficult to go back. Studio engineers really like it because it makes everything so effortless to hear and hence my work continues.
Since those days have been working on "phase correct" non-moving lobe/apparent source" loudspeakers and then adding controlled directivity. Phase correct took 25 years of trying. Controlled directivity was a lot easier! Almost off the shelf and today it is off the shelf, SEAS tweeter (Madisound H1499 ?) with the wrong or to much ferro-fluid can be used. A 6.5" with 1.25 inch/32mm voice coil can get you close but there is still one very pesky problem, crossover. If I get the patent then I will share how to OR use that (((acourate)))® - Room Correction, Speaker Optimization and Sound Improvement software and FIR filters. That works really well or any other good FIR filter and delays to mix the drivers perfectly. Try it, it really does work! If you hear image, then you will hear real image like nothing else before.
Moderators- thanks for the cleaning!
And bringing the thread back. Lots of good stuff in this thread.😀=SUM
Since this thread started as a look a loudspeaker measurements, here is a list I put into a discussion at the "Classic Speakers" forum about the attributes of the ideal loudspeaker.
Others may have different opinions.
Note that most of these items are very easy to measure with standard test gear.
An Ideal speaker has:
Very flat on-axis response
Very smooth on axis response
Very flat and smooth response through any likely listening window
Smooth and resonance free power response, but of no particular curve
Holes in the power response are acceptable but peaks are not
Generally rising directivity (non flat d.i.)
Generally wide dispersion
Wide bandwidth with a -10dB cutoff below 35 Hz
Interfaces well with the room, gives a smooth in-room curve below 200Hz
Adequately low distortion. Low AM distortion with high woofer excursion
“Ideals” that haven’t been proven to be beneficial:
Flat phase response
Response extended beyond the audible range
Extremely low distortion
Low order or particularly high order crossovers
Any particular in-room curve, above 200 Hz
Any particular spectral response of reflections
High tech. materials
Exotic transducer types
Exotic cabinet types
Overly high or overly low directivity
Things that have been proven to be detrimental:
Flat power response
David Smith
Others may have different opinions.
Note that most of these items are very easy to measure with standard test gear.
An Ideal speaker has:
Very flat on-axis response
Very smooth on axis response
Very flat and smooth response through any likely listening window
Smooth and resonance free power response, but of no particular curve
Holes in the power response are acceptable but peaks are not
Generally rising directivity (non flat d.i.)
Generally wide dispersion
Wide bandwidth with a -10dB cutoff below 35 Hz
Interfaces well with the room, gives a smooth in-room curve below 200Hz
Adequately low distortion. Low AM distortion with high woofer excursion
“Ideals” that haven’t been proven to be beneficial:
Flat phase response
Response extended beyond the audible range
Extremely low distortion
Low order or particularly high order crossovers
Any particular in-room curve, above 200 Hz
Any particular spectral response of reflections
High tech. materials
Exotic transducer types
Exotic cabinet types
Overly high or overly low directivity
Things that have been proven to be detrimental:
Flat power response
David Smith
The first item in the ideal leaves me puzzled. How can an "ideal" speaker have no particular power response, even when satisfying the other specified criteria? The leaves a lot of "ideal" power response curves. 🙂 A good thing, I suppose.
Generally wide response, generally rising D.I. with the other characteristics satisfied. How wide, what rise? Those are the two unanswered fundamental questions that leave me in a quandary. There seems to be more than one position on these. Then there's the followup question, what is the best method to address this? Waveguides, dipoles, cardioids? Are multiple driver systems adequate enough for many in-room situations? So far my efforts have been on the last one with dipoles now planned. My last speaker purchase was a hybrid ribbon dipole system that I wish I still had for comparisons.
I follow the discussions, some rather closely, but I've got to say that I have not found any of the positions to be completely convincing.
Dave
Because there is not final answer, there isnt any one superior position. There are just too many variables outside of speaker science for someone believe any one conclusion is superior over others.
All anyone can do is build or buy speakers following their own guidelines. Those guidelines for some are built on years of listening and guidelines for others are built on spec requirements and measurement data.
We never are forced to listen to someone elses speakers and the debate about the idea speaker/perfect speaker has lasted since the hobby started.
I think that depends on with whom one is debating. Some would disagree with you.
I design/build based on both. That doesn't prevent me from trying to further understand what influences my perceptions. The only way for me to accept any proposition is to see objective measurements that can be shown to directly correlate to perception and not just from individual experience and anecdotes. Some form their entire basis on the latter and use it in an attempt to advance their positions.
This issues extend to those on the professional side as well to varying degrees. It's not strictly a DIY issue. This brings us back to my previous post on power response.
Dave
I, of course, disagree with a lot to most of these comments. We have learned a lot over the last few decades and the "ideal" is becoming much clearer as a result. It's not completely fixed in stone as yet, but its getting there.
Dave:
Your comments were pretty general, and in that form its hard to disagree, but here are some comments:
I think that the there is a need for controlled directivity beyond the listening window as well because of the early reflections. Your statement does not preclude this, it just isn't as explicitly stated as I would suggest.
I think that the power response requirement is not arbitrary if one considers the polar response beyond the listener window - it becomes dictated by these requirements. Olive shows data that refutes your claim to "holes" being (more on this below) inaudible.
To me the problem below 200 Hz is a room problem and not a loudspeaker problem, and so we should seperate those two regions in these kinds of discussions. There is no single loudspeaker solution to the room problem in the modal region so you cannot talk about what any single loudspeaker should do down this low.
I often say the nonlinear distortion is irrelavent, but thats simply because I believe the same thing that you state here. It needs to be "adequite" but more than that is meaningless.
I agree with all of your "non-proven" as well as your "detrimental'. I might go further to your "non-proven" list to say that some have been "proven to not" - a much stronger claim, but I won't get into all that.
So it seems like we only disagree on the how wide the controlled directivity should be and the need for a "narrowing" directivity.
I would trade off a "narrowing directivity" for a shallow falling HF response and a fairly flat DI along the listener axis. If you think about it this is not much different than what you recommend because the net result is a lower total HF response as heard by the listener. Our disagreements lie mostly in how strong the reverberant field influences the perception. Again, I point to Olive's recent work on room EQ and how he shows that a flatter reverberant field was "prefered". This is in stark contrast to you position on dips in the power response.
Our disagreements may be a direct result of the "room" since I know that I find the "standard" listening room to be too dead. This puts more emphasis on a wider directivity and stronger emphases on the "listener window". All of the rooms that I build are designed to be as reverberant as possible above the modal region. This puts more emphasis on narrower directivity and much more importance on the total polar response because of the increase in the early reflections. I have heard both situations, but I suggest that you may not have heard my approach. You should, since it may change your mind as it has so many others who have heard it. You (and anyone else) are more than welcome to visit and hear for yourself.
Dave:
Your comments were pretty general, and in that form its hard to disagree, but here are some comments:
I think that the there is a need for controlled directivity beyond the listening window as well because of the early reflections. Your statement does not preclude this, it just isn't as explicitly stated as I would suggest.
I think that the power response requirement is not arbitrary if one considers the polar response beyond the listener window - it becomes dictated by these requirements. Olive shows data that refutes your claim to "holes" being (more on this below) inaudible.
These are the two that I completely disagree with and wonder what "data" you have on which to make such a claim. Floyd believe this as well, but his data is rather sparse. This is the one area where Floyd and I disagree.
To me the problem below 200 Hz is a room problem and not a loudspeaker problem, and so we should seperate those two regions in these kinds of discussions. There is no single loudspeaker solution to the room problem in the modal region so you cannot talk about what any single loudspeaker should do down this low.
I often say the nonlinear distortion is irrelavent, but thats simply because I believe the same thing that you state here. It needs to be "adequite" but more than that is meaningless.
I agree with all of your "non-proven" as well as your "detrimental'. I might go further to your "non-proven" list to say that some have been "proven to not" - a much stronger claim, but I won't get into all that.
So it seems like we only disagree on the how wide the controlled directivity should be and the need for a "narrowing" directivity.
I would trade off a "narrowing directivity" for a shallow falling HF response and a fairly flat DI along the listener axis. If you think about it this is not much different than what you recommend because the net result is a lower total HF response as heard by the listener. Our disagreements lie mostly in how strong the reverberant field influences the perception. Again, I point to Olive's recent work on room EQ and how he shows that a flatter reverberant field was "prefered". This is in stark contrast to you position on dips in the power response.
Our disagreements may be a direct result of the "room" since I know that I find the "standard" listening room to be too dead. This puts more emphasis on a wider directivity and stronger emphases on the "listener window". All of the rooms that I build are designed to be as reverberant as possible above the modal region. This puts more emphasis on narrower directivity and much more importance on the total polar response because of the increase in the early reflections. I have heard both situations, but I suggest that you may not have heard my approach. You should, since it may change your mind as it has so many others who have heard it. You (and anyone else) are more than welcome to visit and hear for yourself.
Dave - we are in complete agreement on this point. But, as Markus points out "directly correlate to perception" is almost nil. We have only some peripheral data in many cases and one has to use some form of logical deduction to arrive at useful design objectives.
I think that the data that I showed shows that the dipole has advantages in the 200-500 Hz frequency region, but I see no advantages above that point.
Interesting. My room may be too dead at the higher frequencies, but it's difficult to measure.
Is there a good software that will do room impulse, e.g. a pistol shot? ARTA maybe?
Is there a good software that will do room impulse, e.g. a pistol shot? ARTA maybe?
I love the discussion of perspectives of what is important and how to measure it. Am not really looking for agreement among posters'. Am more looking for viewpoints not previously considered. Certainly there is some of that for every one. Increased perspective is always good.
There is evidence for "response beyond the audible range" to be beneficial:
Inaudible High-Frequency Sounds Affect Brain Activity: Hypersonic Effect -- Oohashi et al. 83 (6): 3548 -- Journal of Neurophysiology
Of course there are a few that says it isn't, but they weren't looking at it this way.
Dan
Inaudible High-Frequency Sounds Affect Brain Activity: Hypersonic Effect -- Oohashi et al. 83 (6): 3548 -- Journal of Neurophysiology
Of course there are a few that says it isn't, but they weren't looking at it this way.
Dan
OK, how about someone who simply cannot use flat graphs to judge his speakers and must voice them completely by ear as the effect of a flat response speaker is an unpleasant result to that person. How about that person not giving much of a hoot about the effect that sound has on other persons because it is he who designed, built and ultimately listens to that speaker? How about someone who realized that perhaps it was not the ineptitude of the studio engineers and that maybe, just maybe his ears are different enough from others, the acceptance of which allowed him to break away from the "rules" and simply build something that sounds good to him?
Is that different enough fer ya? 🙂
I guess "voicing completely by ear" is a redundancy but what the heck, I've been known to say things again and again and again...
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