prodj101 Posted July 1, 2003 Share Posted July 1, 2003 ok, take a quick look at any time alligned speakers you know, try the meadowlark shearwater. the baffle set up sets the tweeter back about 3-4 inches from the woofers, so they will reach the listeners ears at exactly the same time, as to avoid any sound "smear".than, take a look at your klipsch ref series speakers, or any klipsch for that matter (though the throats of some heritage are much too long). notice that the horn sets the midrange/tweeter back almost the same as it would on a "time aligned" baffle. now I know klipsch didn't intend this, but is it possible? even if it's not, this certainly should be an idea to keep in mind, since they could easily make some minor horn length adjusts ment to accomplish it, and they wouldn't even have to make a baffle with strange angles! Quote Link to comment Share on other sites More sharing options...
jdm56 Posted July 2, 2003 Share Posted July 2, 2003 Virually all speakers that actually achieve time alignment only do so at very specific distances and angles relative to the speaker baffle. And to maintain time alignment through the crossover range, the crossover must be specially designed for that purpose, which usually requires a 1st order (6db/octave) slope. Not so good for horns. The audibility of time alignment is questionable at any rate. But to your point, yes, many klipsch designs do have the tweeter driver on nearly the same vertical plane as the woofer. Quote Link to comment Share on other sites More sharing options...
prodj101 Posted July 2, 2003 Author Share Posted July 2, 2003 yeah, I'd really like to hear a time aligned speaker with the same drivers put in a standard baffle enclosure. I don't think the human ear could detect a difference. from a listening position of 15 feet, it would take the sound from the speakers roughly 13 thousandths of a second. I think anyone would be hard pressed to notice a difference. maybe one of those things that they put on paper to sound cool eh? Quote Link to comment Share on other sites More sharing options...
lynnm Posted July 2, 2003 Share Posted July 2, 2003 I find it puzzling when I see posts that imply that Klipsch just builds speakers and further imply that little thought goes into the physics of the thing. I am sure that time-alignment is an issue that Klipsch has studied to death and has not ignored. FWIW I see the whole time alignment thing as being just so much theoretical Fairy poop. As Joan Rivers says "I have taken so many Philosophy courses that I can prove that diapers don't exist ! " The fact that something can be demonstrated logically does not necessarily imply that that concept is of any practical relevance. Quote Link to comment Share on other sites More sharing options...
Randy Bey Posted July 2, 2003 Share Posted July 2, 2003 In fact, PWK thought and wrote about time alignment in the "Dope from Hope" papers. Time alignment is practical only outside, or where there are no room reflections of the sound. Inside, like in a concert hall, or a listening room, there will be all kinds of differing time alignments for differing frequencies. It is alleged to be inaudible to 2ms, which is several feet, and to have little impact until it goes much longer. Quote Link to comment Share on other sites More sharing options...
Parrot Posted July 2, 2003 Share Posted July 2, 2003 Paul W. Klipsch in Dope from Hope, July 1977, excerpts: ***There have been several technical presentations on this subject and the audiences could well have been misled by them. One author claimed superior performance by "phasing" woofer-squawker-tweeter arrays to a fraction of a centimeter, and I wanted to ask him which ear he listened: certainly if the array was phased within 3mm for one ear, it must certainly have been 200mm "out of phase" for the other ear!*** ***Time delay effects in loudspeakers are discussed in a paper I published in October 1972. Several experiments of my own and several described by others lead to the conclusion that time delays of up to 2 or 3 or even 4 milliseconds are inaudible for all forms of audio program material, provided DISTORTION is adequately low.*** Quote Link to comment Share on other sites More sharing options...
artto Posted July 2, 2003 Share Posted July 2, 2003 Klipsch is quite aware of time delay effects and was studying delay effects in multi-driver loudspeaker systems as early as 1950. In the Klipsch Audio Papers, Delay Effects in Loudspeakers published in the Journal of the Audio Engineering Society, 1972, PWK describes a number of experiments & observations on the subject. Whether any time delay effects are audible appears to be dependent on program material, the listening room, crossover points & crossover slope, etc. As a trade off it is our opinion that most listeners would accept an inaudible time delay in preference to a high contamination of frequencies not originally present - in other words, high distortion. This paper also explains the relationship between frequency response (amplitude) variations and time delay effects. Frequency and time are related. Just different ways of describing the same thing. This can be described mathematically through Fourier Transformations. It was concluded that It is thus an amplitude, rather than a phase anomaly that is audible, and if the speaker system is rendered reasonably flat, phase errors as such are not audible. In the Dope From Hope newsletter, July 1977 (response to a Sound Advice Khorn review), One author claimed superior performance by phasing woofer-squawker-tweeter arrays to a fraction of a centimeter, and I wanted to ask him which ear he listened: certainly if the array was phased within 5mm for one ear, it must certainly have been 200mm out of phase for the other ear! In this same paper PWK states that, in order of importance are 1) distortion at 2) adequate power output, and 3) polar response 4) frequency response. PWK goes on to say Choosing low distortion is not a trade-off. It is just good judgement. Richard Heyser (a former NASA aerospace engineer) also did a lot of work on the subject. And PWK references this material as well as personal correspondence with Mr. Heyser in his papers. A number of years later Mr. Heyser also did a very in depth technical review of the Klipschorn in Audio Magazine which also covers this topic. Quote Link to comment Share on other sites More sharing options...
sunnysal Posted July 2, 2003 Share Posted July 2, 2003 as much as I love klipsch speakers and pwk was obviously a genius, he is famous for denying totally the idea of time alignment. this has been discussed over and over again in the industry and there are, as always, two main camps. the time alginment/phase issue is b*llsh*t camp (which included PWK) and the camp that says it has real, audible effect. there are credible people on both sides of the argument, scientists and engineers. you guys will not be able to decide it here, nor are you capable of proving or disproving it given the complexity. suffice it to say believe what you want and enjoy the music. tony Quote Link to comment Share on other sites More sharing options...
Deang Posted July 2, 2003 Share Posted July 2, 2003 Anyone that says it doesn't work hasn't sat in front of a pair of DQ-10's for any extended period of time. Now that I have another amp in the house more appropriate for pushing them -- the effect is as stunning to me as the first time I heard them. Quote Link to comment Share on other sites More sharing options...
Ray Garrison Posted July 2, 2003 Share Posted July 2, 2003 One thing I believe - Designing speakers that are truly time coherent (and exactly what the definition of "truly time coherent" means might be open to discussion) forces the designer to do a lot of *OTHER* things correctly. Speakers that are time coherent (QUAD ESL's, Thiel, Beveridge (and they're back, by the way... see their website for some really cool ideas on sound propogation, time alignment, stuff like that...) anyway, speakers that are time coherent tend to have really good amplitude / frequency responses, well designed and engineered crossovers (though they may be complex, or, at the other extreme, extremely simple {Lowther}), and perform well by standards *OTHER* than time coherence. How much of the sound quality you perceive is do to the time coherence property, and how much to other factors, I don't know how to quantify. Quote Link to comment Share on other sites More sharing options...
formica Posted July 2, 2003 Share Posted July 2, 2003 I think one of the reasons it is still considered an "audio mystery" is that it is very difficult to do ABX tests with the only variable being the alignment of the drivers. My understanding is, as mentioned, moving the drivers will change their dispersion/reflection patterns and require modifying both the drivers and crossovers. Now an ABX test will involve many factors other than the alignment. As full-heartily that both camps will present their argument, we are often comparing two entirely different speakers rather than comparing the simple effects of time alignment. I guess I'm undecided on this one... Rob Quote Link to comment Share on other sites More sharing options...
TBrennan Posted July 2, 2003 Share Posted July 2, 2003 There's no doubt that time delay between drivers can be heard, just refer back to the famous "double tap" incident at MGM in the 1930s and John Hilliard's investigation of it and Hilliard's subsequent development of the Shearer Horn and then later the VOT to deal with the problem. The question really should be how much does it effect the sound with a given design and are other qualities more worthwhile. PWK took the view that the low distortion of his folded horn speakers outweighed the time delay problem. That was a reasonable point of view. It was also a point of view he was stuck with as his speakers had a great deal of delay by their nature. Quote Link to comment Share on other sites More sharing options...
artto Posted July 2, 2003 Share Posted July 2, 2003 DQ10's SUCK. Quote Link to comment Share on other sites More sharing options...
sunnysal Posted July 2, 2003 Share Posted July 2, 2003 what prompted that post from artto? DQ10s can sound great...I have heard them only once, but they sounded goo din that system/room. I cretianly agree that timealigment/phase issues may be less important that distortion (as PWK said) AND that the many variables mentioned (x-overs for example) play a more important role that time alginment. beveridge is a great example of attention to the many issues brought up and the resulting sound is quite amazing. I still love the sound from my k-horns even if it is not timealigned and phase coherent! It doesn't mean that we should negate the validity of speakers that address those issues. I think it would be fun to figure out how to optimize a k-horn re: time and phase (driver placment and x-over)...tony Quote Link to comment Share on other sites More sharing options...
Parrot Posted July 2, 2003 Share Posted July 2, 2003 Tom, What was the double tap incident? Quote Link to comment Share on other sites More sharing options...
rtaylor Posted July 2, 2003 Share Posted July 2, 2003 Do your speakers being time aligned neccessarily make them sound good to you or in spite of?? Quote Link to comment Share on other sites More sharing options...
Deang Posted July 2, 2003 Share Posted July 2, 2003 Artto, you are a wiener. That's O.K., I think K-horns suck. It takes more than just aligning the drivers. Also, the drivers should be aligned so that it is the voice coils that are aligned, not the surface of the drivers. Like someone above said, you need 6db/octave crossovers and much work. Quote Link to comment Share on other sites More sharing options...
ben. Posted July 2, 2003 Share Posted July 2, 2003 I'm certainly not going to get in the middle of time-alignment brouhaha in the context of speaker design, but everyone on this board can hear the effect of a 1ms delay - it would sound like a chorus effect. .1-7ms are fun delay times to play with in recording because they change the tone of the sound without a disrete slap echo being audible. They mess with the phase charactaristics of sound in the range of human hearing. 7-27ms will change the percieved tone as well, without the brain processing them as seperate events. These are fun to play with as hard-panned stereo effects-ala The Beatles. We only process sounds as being seperate events above about 30ms (this makes sense from an evolutionary biology standpoint, too). This would translate to a source distance of roughly 30ft. This is why taming early reflections effect the tone of a space, but longer reflection times are more relevant to ambience. What the world needs is a coaxial point source Khorn!(Which would require a repeal of certain laws of physics) Quote Link to comment Share on other sites More sharing options...
dodger Posted July 2, 2003 Share Posted July 2, 2003 ---------------- On 7/2/2003 12:55:57 AM prodj101 wrote: yeah, I'd really like to hear a time aligned speaker with the same drivers put in a standard baffle enclosure. I don't think the human ear could detect a difference. from a listening position of 15 feet, it would take the sound from the speakers roughly 13 thousandths of a second. I think anyone would be hard pressed to notice a difference. maybe one of those things that they put on paper to sound cool eh? ---------------- Greetings: I have had that pleasure. It was done with 5 people present and custom cabinets to allow proper mounting on the board were made. Between a Cornwall II and the "Custom mega-buck time aligned," no-one noticed a difference. Take care, be safe, and don't play with fireworks! dodger Quote Link to comment Share on other sites More sharing options...
Deang Posted July 2, 2003 Share Posted July 2, 2003 The main diffraction problem for the DQ-10 is the metal grill. 9% of all generated sound is deflected back into the soundfield. Remove the grill (as well as the one on the rear). The midrange driver is somewhat recessed into the baffle, there is diffraction here. I lined this part of the baffle with soft foam weather stripping. The tweeter sitting on top of the midrange baffle is offset, and there is diffraction from the top of the midrange board from the tweeter. I also line this. I increase rigidity by pitching the masonite baffles and replacing them with Baltic Birch plywood. I then screw/bolt everything together with enough torque to drop a ********. The tweeter is out of phase with the Motorola piezo and the Philips dome midrange. This phase reversal is actually on the crossover -- not the drivers. Not well known is the fact that several thousand of these left the factory wired incorrectly at the drivers. No one ever knew until DQ DIY'ers started tearing them down and rebuilding them. Finally, each baffle is sized for the frequencies coming off of it. A few tweaks here and there, good positioning, and they do very good. Put one or two good subs in the room and they are killer. Quote Link to comment Share on other sites More sharing options...
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