The sloped baffle is to align the voice coils.... perfect voice coil alignment is the big draw of a point source driver. (proper coax mount)
Tim
Tim
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Psag, I don't think the last couple of comments posted before your comment (mine included) deviated from the OP's question about sloped baffles. I say that because sloped baffled may be used to address (in whole or part) issues relating to using multiple speakers and electronic crossovers. Bombaywalla and others have provided us with a cornucopia of information about time and phase coherance -- sloped baffles just being a subset of the larger issue. Quite honestly, I didn't realize that the time and phase alignment problem was so difficult to solve. Having said that, admittedly, I do not fully appreciate to what extent a speaker's sonic performance is compromised by time and/or phase errors. Perhaps, as Sounds_Real_Audio just posted, the issue may be more hype than real. I just don't know. Al and Ralph .... where are you??? :) |
Sometimes sloped baffles are cosmetic only. My understanding for 1st order crossover speakers is the broad frequency overlap between drivers, requires a sloped baffle to keep the drivers on a single axis. When off axis the shared frequencies between drivers will cause cancellations/nulls depending on the distance. |
Getting back to the original question concerning sloped baffles and time alignment, Mofimadness commented: "It is used to time align the drivers. Some manufacturers do this physically, (with the cabinet) and some do it electronically (in the crossover)." No knowing a whole lot about speaker design, my guess is that it is more difficult and expensive to design and produce a speaker with a sloped baffle. Wouldn't that imply that there is some perceived advantage to doing so? |
Thanks Tim. I'm listening to a HD CD of Dave Brubeck's, "Time Out." Perhaps I'm just used to listening to sonic swill, but the imaging is more than satisfactory and the music is quite enjoyable. My fronts are Paradigm S8s (v3), with beryllium tweeters. Btw, I think the original recording was made in 1959. Maybe that was the Golden Age of music recording, maybe not. But the HD CD redo sounds great. As an Fyi, I bought the CD from the Acoustic Sounds web site. AS is located in Kansas. Very good source of music in all formats. BIF |
Hi guys, I don't want to pretend to be The Expert on this subject, but I've built hundreds of speakers and have worked and designed along side some of the best back in my Marcof/SpeakerCraft days... so, "but only if in combination with 1st order crossovers as used by Thiel and Vandersteen, revealing a coherent time-aligned step response" 1st order helps, but there is no speaker that is in complete phase at all frequencies... When you roll a speaker hard, it throws the driver out of phase just by the nature of steep slopes... Remember a speaker rolls in and out of phase up and down the frequency ladder, once you choose your initial crossover point, you need to remeasure the drivers phasing up and down the scale with your first crossover in place , then choose another point that gets absolute phase at the crossover point. You may see a speaker that has a 350 & 3750 crossover point and you know that the tweeter can easily be crossed at 2500 or so, as long as the mid is smooth out to a given frequency, the designer may choose to take the frequency where absolute phase comes back into place. Also Impedance compensation helps control phasing a also. For that reason, I prefer impedance compensation, normally a driver sounds better when it needs compensation and compensation is used. "I recall reading that Focal, Harman and Paradigm have anechoic testing chambers, staffs of engineers and physical facilities that presumably enables these companies to make rational and informed choices when designing and building speakers. I also recall reading that these companies manufacture in-house their own drivers". Anechoic chambers help tremendously in measuring driver frequency and the effects that driver modifications have on a drivers frequency response, but Impedance & phasing are measurements that can be done without having a critical listening environment, I'm not trying to say that a great listening environment is not important, only that impedance and phasing can be handled without an anechoic chamber. Again, time alignment & correct phasing are keys to an imaging champ. I've kept it as simple as possible, I hope this helps, Tim |
Bombaywalla, I have a follow up question. How are small speaker manufacturers able to design speakers without the benefit of the R&D budget, engineers, and testing facilities that some of the larger manufacturers have at their disposal. For example, I recall reading that Focal, Harman and Paradigm have anechoic testing chambers, staffs of engineers and physical facilities that presumably enables these companies to make rational and informed choices when designing and building speakers. I also recall reading that these companies manufacture in-house their own drivers. That is a question ... not a statement. Bruce |
Bombaywalla ... I read as much of the discussions as I could before falling asleep at 1:30am in the morning. No surprise ... the physical science is way over my head. But I do have some take-a-ways that I would like to share. As a threshold matter, I ask whether we are "polishing a turd" as a practical matter. As a warm up, there was some discussion which addressed whether using mics to record a musical presentation accurately captured the complex sound wave information that emanated from the multiple performers and instruments. One poster said that all a mic could do was sample a point in 3-D space, thereby missing a considerable amount of sonic/acoustical information. Even using multiple mics, while an improvement, still left much sonic information "on the floor," figuratively speaking. Next ... the mastering process. So called sound engineers manipulate the sonic information that was imperfectly recorded at the live performance. The result is more sonic contortion and distortion. Let's skip the next steps relating to the reproduction and transmission of source material via the various media used today (e.g., LP, CD, SACD, internet downloads, etc) and the electronics used to decode the information back into analogue electrical signals that are fed into the speakers. Suffice to say that additional contortions and distortions are infused into the analogue signal before it even reaches the speakers. Ok, we're now at the speakers and a whole new set of issues present themselves. The bottom line challenge is that our speakers have to reproduce, more like reconstruct, the complex electrical analogue signals back into sound waves that are in phase through the whole harmonic spectrum. And here the engineering problems and challenges are almost insurmountable: designing a system using multiple drivers that are mounted on a baffle (sloped or not sloped) to reproduce a point complex source sonic wave front that is the same as the original signal, even as modified by the sound engineers at the studio. My take-a-way is that the speaker designer can solve one problem, but create 5 more. I don't want to embarrass myself by trying to faithfully restate what was said in the various posts. Suffice to say there are physical science challenges presented with every electrical and mechanical component that makes up a complete speaker system. At best ... what reaches our ears is the product of price point driven compromises that are ultimately limited by the laws of physical science. My bottom line take-a-way is if "it" sounds good, "it" is good. Sure, we can and should audition speakers. Some will sound better than others. But to think any one speaker has perfectly solved all the engineering challenges and is able to faithfully reproduce a point source complex sound wave at the listening point is a pipe dream ... more like shear nonsense. Perhaps that may be the reason many audiophiles and reviewers say that while specs and stats are informative ... in the end, what counts the most is how a speaker **subjectively** sounds to THAT listener, plugged into THAT listener's rig, positioned in THAT listener's sound room, and so forth. And to me, that is what makes our hobby fun. Right now, I am listening to Eugene Ormandy, conducting the Philly Orchestra, performing a suite of various Saint-Saens selections. I am still enjoying the music even though it is being imperfectly reproduced by my imperfect rig. Cheers, Bruce |
IMHO, the first link is perhaps the best thread ever to appear on audiogon, Roy Johnson of Green Mountain Audio was especially generous in sharing his thoughts. I've come to believe that some are more sensitive and/or prioritize these specific attributes more than others. Quite by accident, I've come to accept that these design principles are very important |
I think there is a lot of hype around this issue. A lot. If you have floor standing speakers and simply adjust the spikes so the front is slightly higher to accommodate your sitting position the you may have it. Is this just all a bunch of hype? Are there other more serious considerations? Cabinet construction, drive quality? Probably |
Bifwynne, welcome. I figured that these links would NOT be wasted on you. :-) indeed, speaker design is a complicated affair. Fully understanding what's going on takes skill, knowledge & experience as speaker design involves the mechanical aspect of actually building the speaker but also understanding what the electrical effect of the x-over is to the mechanical aspect. It's an inter-disciplinary expertise. In those links, there's a lot of chatter by members who don't know what they are talking about & by those who are airing their thoughts & experiences. You can skip over that which will shorten the reading time. Pay closer attention to the speaker manuf posts. Those are revealing in info. Well, now that you have the amp-speaker interface licked :-) it's time to go a bit downstream & understand what that electrical-to-sound transducer is all about... |
Bombaywalla, ... that;s for the links. I started reading into the threads. This is very complicated stuff. And I thought getting my arms around amp and speaker compatibility was tough. Speaker design is a beast. I will return to these threads over the weekend. In the end, as it seems to be the case with end end electronic gear, we're talking about design compromises. No perfect solutions ... just trade-offs that hopefully result in a product that sounds good. Thanks |
Bifwynne, your entire post is a LOADED question! :-) we have discussed this way back in 2002. Here is the link to that thread (many very good & informative & technical posts by Roy Johnson of Green Mtn Audio speakers): http://forum.audiogon.com/cgi-bin/fr.pl?cspkr&1032037028 And here is a thread that Gmood1 started on Time & Phase as related to speaker operation: http://forum.audiogon.com/cgi-bin/fr.pl?cspkr&1060123575 And, finally, member Rbischoff (who started the 1st thread, above, that I provided the link) started another thread on First Order Cross-overs: Pros & Cons: http://forum.audiogon.com/cgi-bin/fr.pl?cspkr&1113252618 There is a great deal of really good info on this subject of phase & time coherency. Happy reading.... ;-) |
Mofimadness answered correctly About time alignment.As far as phasing... it is simply having your individual drivers operating In unison at all frequencies... As you change crossover points and slopes, phasing changes between drivers.... Correct time and phase alignment is what seperates many ok speakers From world class speakers... These factors are why so many audiophiles like sigle drivers or point source.... I hope this helps, Tim |
I recall seeing the terms "time coherent" and "phase coherent." Do these terms mean the same thing or are they different? Since this thread speaks to speaker alignment, perhaps someone could explain in layman's terms what causes speaker to operate out of phase. Does it have something to do with the use of caps and chokes in the x-over? Or perhaps the attribute of a dynamic speaker creating its own back EMF by reason of the voice coil moving in a magnetic field?? Incidentally, do all these electrical dynamics operating in tandem cause the electrical phase shifting that gives most amps a headache? Thanks |