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  • Heresy or....

    Earl Geddes has some strongly held beliefs with not just a little bit of research into most of his positions. This latest seems to be a culmination of the aspect of non-linear distortion in drivers. It's antithetical to much current thought and direction of drivers. I have to say that I have been on the fence and still haven't come down on one side or the other yet, more because I really haven't tried to make enough concerted comparisons for what I think is audible to me.

    Geddes comment on driver non-linear distortion audibility

    The prominent comment:
    This makes the nonlinear distortion in a loudspeaker very nearly inaudible.
    Let the fur fly!

    dlr
    WinPCD - Windows .NET Passive Crossover Designer

    Dave's Speaker Pages

  • #2
    Re: Heresy or....

    Haha, that's just silly. Anyone can hear a bad speaker. Everyone has. I bet it had pretty close to flat frequency response, too.
    I am trolling you.

    Comment


    • #3
      Re: Heresy or....

      Originally posted by MSaturn View Post
      Haha, that's just silly. Anyone can hear a bad speaker. Everyone has. I bet it had pretty close to flat frequency response, too.
      Don't be so quick to dismiss Geddes. He also references some of the most prominent researchers in audibility and preference studies in the industry. It has nothing to do with a bad speaker. He doesn't come to his conclusions lightly.

      dlr
      WinPCD - Windows .NET Passive Crossover Designer

      Dave's Speaker Pages

      Comment


      • #4
        Re: Heresy or....

        Originally posted by MSaturn View Post
        Haha, that's just silly. Anyone can hear a bad speaker. Everyone has. I bet it had pretty close to flat frequency response, too.
        Silly indeed.

        He completely justifies never having to spend money on his high quality drivers!!!! Just line up the Goldwood's and digital EQ and you've got Geddes quality HT!!!
        R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
        Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

        95% of Climate Models Agree: The Observations Must be Wrong
        "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

        Comment


        • #5
          Re: Heresy or....

          Originally posted by dlr View Post
          Don't be so quick to dismiss Geddes. He also references some of the most prominent researchers in audibility and preference studies in the industry. It has nothing to do with a bad speaker. He doesn't come to his conclusions lightly.

          dlr
          We're not dismissing Geddes, but man, a dumb statement is a dumb statement.

          Jeff B painstakingly built two small monitors, with nearly identical frequency responses, and put them next to each other for evaluation. One used a high quality, low distortion midwoofer and tweeter, the other much lesser quality construction. There were quite audible differences, which can ONLY be due to the distortion spectra.
          R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
          Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

          95% of Climate Models Agree: The Observations Must be Wrong
          "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

          Comment


          • #6
            Re: Heresy or....

            We're not dismissing Geddes, but man, a dumb statement is a dumb statement.

            Jeff B painstakingly built two small monitors, with nearly identical frequency responses, and put them next to each other for evaluation. One used a high quality, low distortion midwoofer and tweeter, the other much lesser quality construction. There were quite audible differences, which can ONLY be due to the distortion spectra.
            With all due respect to Jeff, I've never heard two systems for which there was a single difference in the resultant sound. I'm not saying that there weren't easily identifiable differences, but to attribute it to distortion explicitly is not something I can accept yet. Considering that Geddes is not relying solely on his perceptions and not even his more considered research (e.g. Toole, Olive, etc.), it gives me further pause in my thinking on the importance of distortion.

            Dismissing it out-of-hand (MSaturn's response can't be characterised any other way) is short-sighted and misplaced. It merits more consideration than that. I'll be looking to see if he retracts his "dumb statement".

            dlr
            WinPCD - Windows .NET Passive Crossover Designer

            Dave's Speaker Pages

            Comment


            • #7
              Re: Heresy or....

              Well . . . I certainly agree with him regarding harmonic distortion below a percent or two, which is masked by natural harmonics in any real music signal. IM is a different beast, and whether one can hear it in synthetic tests depends very much on the nature of the test. I'm convinced I can hear it in music . . . as "something there" that shouldn't be, that results either in "grunge" or "harshness" (much llike the sound of aliasing in early digital recordings) or a general "muddiness" in the sound.

              Of course IM products are generated whenever there is gain nonlinearity (compression or limiting, suspension non-linearity, many kinds of cone breakup), and harmonics are also. Testing to determine the audibility of harmonics by adding clean harmonic components to a clean fundamental will give different results from testing using complex signals on a non-linear device that generates a broad spectrum of distortion components. Any claim about the audibility of distortion must be specific about how the test signals were generated and how the distortion products were measured and characterized.

              I'm just not buying it that critical listeners, Dr. Geddes included, cannot hear the distortion generated by many common loudspeakers . . .
              "It suggests that there is something that is happening in the real system that is not quite captured in the models."

              Comment


              • #8
                Re: Heresy or....

                Originally posted by dlr View Post
                Earl Geddes has some strongly held beliefs with not just a little bit of research into most of his positions. This latest seems to be a culmination of the aspect of non-linear distortion in drivers. It's antithetical to much current thought and direction of drivers. I have to say that I have been on the fence and still haven't come down on one side or the other yet, more because I really haven't tried to make enough concerted comparisons for what I think is audible to me.

                Geddes comment on driver non-linear distortion audibility

                The prominent comment:


                Let the fur fly!

                dlr
                http://www.audiosignal.co.uk/freeware.html

                At the above link, Kieth Howard provides a program that will add user-definable nonlinear distortion products to a sound file.



                .
                "Our Nation’s interests are best served by fostering a peaceful global system comprised
                of interdependent networks of trade, finance, information, law, people and governance."
                - from the October 2007 U.S. Naval capstone doctrine
                A Cooperative Strategy for 21st Century Seapower
                (a lofty notion since removed in the March 2015 revision)

                Comment


                • #9
                  Re: Heresy or....

                  I mean, when you throw around a word like that - distortion products - you really are saying that a $15 POS speaker sounds exactly like any speaker with a similar frequency response. It simply ISN'T TRUE. You can measure frequency response all the live long day, but I definitely built speakers with flat response that sounded like crap when I first started doing this. That simply has to be a gaffe.
                  I am trolling you.

                  Comment


                  • #10
                    Re: Heresy or....

                    Originally posted by Deward Hastings View Post
                    Well . . . I certainly agree with him regarding harmonic distortion below a percent or two, which is masked by natural harmonics in any real music signal. IM is a different beast, and whether one can hear it in synthetic tests depends very much on the nature of the test. I'm convinced I can hear it in music . . . as "something there" that shouldn't be, that results either in "grunge" or "harshness" (much llike the sound of aliasing in early digital recordings) or a general "muddiness" in the sound.

                    Of course IM products are generated whenever there is gain nonlinearity (compression or limiting, suspension non-linearity, many kinds of cone breakup), and harmonics are also. Testing to determine the audibility of harmonics by adding clean harmonic components to a clean fundamental will give different results from testing using complex signals on a non-linear device that generates a broad spectrum of distortion components. Any claim about the audibility of distortion must be specific about how the test signals were generated and how the distortion products were measured and characterized.

                    I'm just not buying it that critical listeners, Dr. Geddes included, cannot hear the distortion generated by many common loudspeakers . . .
                    How about that? Here is one post where I agree with everything you have to say. Reducing IM distortion from all kinds of sources is one of the things that has driven me for years. That is a good portion of what my filtration products are about.

                    Dave
                    "A man with an experience is never at the mercy of a man with an argument." - Hilmar von Campe

                    www.piaudiogroup.com

                    http://www.avguide.com/blog/tas-rmaf...w-technologies
                    http://positive-feedback.com/Issue47/ramblings.htm
                    http://positive-feedback.com/Issue47/uber_buss.htm

                    Comment


                    • #11
                      Re: Heresy or....

                      In fact, easily experienced proof exists in small speakers "making bass". happens all the time in cars. you're hearing mostly 2nd and 3rd order distortion.
                      I am trolling you.

                      Comment


                      • #12
                        Re: Heresy or....

                        Hi Dave,

                        This really is not anything Dr. Geddes hasn't been saying for a while.

                        And, frankly I agree with him, sort of...

                        To summarize what Geddes is saying.

                        Lower order distortion is the dominant distortion in loudspeakers

                        For speakers, the dominant component of THD and IMD would be 2,3 order products.

                        Ergo, THD and IMD are meaningless.


                        I think I goaded him one time, asking why he didn't just use a 4-6" and a 1" dome...

                        But I think his reasoning, in as much as he carefully chooses his words, is correct. Lower order distortion does tend to dominate in loudspeaker units. I've listened to a lot of distortion patterns over the years. And I have difficulty distinguishing sound based on looking at the magnitude of 2 and 3 order HD/IMD products.

                        However, higher order distortion and the absolute number of products is fairly audible on test tones and I'm leery of dismissing their audibility in more complex music.

                        Distortion testing seems quite useful, say, in picking a lower limit for tweeters. For example, distortion testing does allow one to pick a good tweeter for crossing low. I have no doubt that, in a two way, the RS28F can be crossed at 1.2k without any discernable strain. I can also say that there are other tweeters, that, crossed at 1.2k would give lots of 5-10k distortion products that would be fairly audible.

                        On the flip side, I would have a great deal of trouble distinguishing modest differences in sound on the basis of small differences in 2nd and 3rd order products.

                        Then there is the issue of accurate sound versus what is obvious distortion. An old experiment of mine was to play a 50 Hz fundamental at a certain level on two separate boxed woofers, an M130 and an SS8554, both with ML TL loading





                        Neither sounds like distortion, but one is clearly more accurate to the original and they do sound different.

                        So there are cases where distortion testing is helpful, and some where it's very inconclusive.

                        But on theoretical grounds, I think Dr. Geddes' position doesn't stand up in one very important way. In general, linearity is scientifically desireable. Yes, certain degrees of linear and nonlinear distortion may be inaudible, nonetheless using linearity as a surrogate for quality is reasonable.
                        audioheuristics isn't around right now...

                        Comment


                        • #13
                          Re: Heresy or....

                          Originally posted by MSaturn View Post
                          I mean, when you throw around a word like that - distortion products - you really are saying that a $15 POS speaker sounds exactly like any speaker with a similar frequency response. It simply ISN'T TRUE. You can measure frequency response all the live long day, but I definitely built speakers with flat response that sounded like crap when I first started doing this. That simply has to be a gaffe.
                          I said nothing of the sort, made no such claim that a $15 POS sounds the same as a more linear item. I merely pointed out some free software that allows you to add nonlinear distortion products of your choosing, allowing you to keep all else similar. Make your own subjective judgements.




                          .
                          "Our Nation’s interests are best served by fostering a peaceful global system comprised
                          of interdependent networks of trade, finance, information, law, people and governance."
                          - from the October 2007 U.S. Naval capstone doctrine
                          A Cooperative Strategy for 21st Century Seapower
                          (a lofty notion since removed in the March 2015 revision)

                          Comment


                          • #14
                            Re: Heresy or....

                            Well the important thing to note is that Earl has said a lot in other posts beyond that one single statement.

                            He isn't talking (for example) about running a 6" woofer with 5 mm of xmax and rated at 50 watts with 300 watts annd hitting double that excursion or listening to a woofer with a nasty breakup without filtering the breakup and again hitting huge levels of distortion. Neither is he talking about crossing a tweeter over way too low. He dohas said multiple times that if a driver has high distortion above or below a certain frequency, don't use it there.


                            What he is saying is that if you take a decent driver with some level of non linear distortion driven sensibly in it's appropriate passband and compare it to another driver with higher but still reasonable levels of distortion again driven sensibly, then other sonic difference such as frequency response including polar reponse will swamp out any differences in distortion.

                            Also in regards to his advocating cheap drivers, all his speakers use high quality pro drivers (usually B&C) always with faraday rings in them. Now you can debate pro vs. hifi drivers for good sound, but the ones he uses are not cheap.

                            Again, you can discount Earl's statements and research, but there are a number of other heavyweights in the industry such as Floyd Tool who agree with him. But it is important to read his research to put such statements in context.

                            Regards,

                            Dennis

                            Comment


                            • #15
                              Re: Heresy or....

                              Originally posted by djarchow View Post
                              Well the important thing to note is that Earl has said a lot in other posts beyond that one single statement.

                              He isn't talking (for example) about running a 6" woofer with 5 mm of xmax and rated at 50 watts with 300 watts annd hitting double that excursion or listening to a woofer with a nasty breakup without filtering the breakup and again hitting huge levels of distortion. Neither is he talking about crossing a tweeter over way too low. He dohas said multiple times that if a driver has high distortion above or below a certain frequency, don't use it there.


                              What he is saying is that if you take a decent driver with some level of non linear distortion driven sensibly in it's appropriate passband and compare it to another driver with higher but still reasonable levels of distortion again driven sensibly, then other sonic difference such as frequency response including polar reponse will swamp out any differences in distortion.

                              Also in regards to his advocating cheap drivers, all his speakers use high quality pro drivers (usually B&C) always with faraday rings in them. Now you can debate pro vs. hifi drivers for good sound, but the ones he uses are not cheap.

                              Again, you can discount Earl's statements and research, but there are a number of other heavyweights in the industry such as Floyd Tool who agree with him. But it is important to read his research to put such statements in context.

                              Regards,

                              Dennis
                              If distortion is unimportant, then why does Earl use Faraday shielded components when you can accomplish the same response without the added cost?
                              R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
                              Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

                              95% of Climate Models Agree: The Observations Must be Wrong
                              "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

                              Comment

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