Sloped baffle


Some great speakers have it, some don't. Is it an important feature?
psag
06-21-14: Bifwynne
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.
Bifwynne, as Timlub wrote earlier, I don't think it's necessary to have an extensive R&D budget, scores of engineers, anechoic chambers & mutli-million $ machines to make a good sounding speaker *iffffff* the manuf really knows how to design a speaker.
The companies that you stated need this to make-up for their lack of knowledge of speaker design. Focal has gotten better over the years. when I 1st heard their Electra series speakers, they sounded like sh**. Their ultra-expensive speakers have a big wow factor but nothing more. Those R&D budget, scores of engineers, anechoic chambers & mutli-million $ machines are good marketing hype items that sells. ;-) of course, my opinion based on listening to many of the cited manuf's speakers.

If one really knows what one is doing then it is possible to select & buy speaker drivers made by OEM speaker driver manuf that are superlative in their specs & performance. The next thing to do is to design a speaker integrating those drivers into a cabinet such that sum of the two is greater than each part.

Al and Ralph .... where are you??? :)
Bifwynne
You know Bifwynne, it is entirely possible that Al & Ralph cannot help us here. Raplh is an amplifier expert & the fine points of speaker design might not be in his 'quiver of arrows'. Same for Al.
Unlike explaining electronics, one cannot explain way speaker design unless one has dealt with this complex task.

Yeah, everything is a compromise - engineering is an applied science. By its definition it is supposed to make compromises to bring about a solution. The key is: which engineer makes the best compromise?

I believe that the 3rd link I stated clarified your earlier question re. the difference between time coherent & phase coherent.
The sloped baffle gives you a time alignment of drivers but does not tell anything about the time or phase coherence of the speaker.
Another thing I learnt was that just because a speaker has a 1st-order x-over does not mean that the speaker is time or phase coherent. I found that a lot of speaker manuf hide behind their using a 1st order x-over. I found that many such speakers used a 1st order x-over but their drivers were some higher order (such a 2nd or 3rd) which means that the driver performance rolled off with a higher order well before the 1st-order x-over kicked in. So, in effect, such a speaker is a 2nd-order or 3rd-order speaker & not a 1st-order speaker.
To be truly a 1st-order speaker the speaker has to be electrically & mechanically a 1st order speaker meaning to say that the driver's performance needs to extend beyond the x-over point so that the roll-off is being done only by the electrical x-over network.

it's complex material that cannot be absorbed in 1 reading. I've those threads printed off & re-read them from time to time to refresh my understanding. Each time I extract new info from them. Like Unsound wrote earlier the 1st thread & I think the other 2 as well are some of the very best threads to have appeared on A'gon.
I'll be off the net for a couple of days, so I'll end my part of this thread here. Simple 6 db slopes do not tell the story at all, Most would be amazed that when you put a simple cap on a tweeter expecting a 6db slope, many times you might find 9 or 10 db slopes.... There is a difference between electrical vs acoustic slopes... On my MTM speakers that I referenced... I may be using 12/18 slopes, but the finished acoustic slopes are 24db per octave. Speaker design with new drivers from scratch requires measurements, you can get amazingly close with some of the better software however... Then lastly to throw another wrench in the fire... you can easily get time alignment between a tweeter & woofer without being phase aligned, but you can never achieve TRUE phase alignment between a tweeter & woofer without time alignment. I haven't read either of the threads referenced above, but hopefully a quality speaker manufacturer out there has explain it better.
I was only trying to help, Tim
Ok ... if Tim or Bombaywalla catch this, here the ultimate Q. How can one tell whether a speaker is time and phase coherent? Critical listening? Reviewer comments? Bench test?

If critical listening is that important, the real challenge for us is, as many have written, that it is not easy to meaningfully audition speakers. So what's a person to do?

I'll ask again, how important is time and phase coherence? FWIW, ... really more as an FYI, ... Paradigm's web site states that its "speakers have phase coherent crossovers designed so that the summed output of the drivers is completely and accurately rejoined." Is that hype? It is true at all frequencies? Dunno

Thanks again.
^Again good step and square wave response are indications of wave form fidelity (time and phase). Again, as to it's importance, well that's up to debate, with opposing opinions prevalent on both sides. I will say when I first began seriously auditioning speakers and without any real technical knowledge I was consistently drawn to those speakers that unbeknownst to me at the time shared those design properties, and those speakers designs continue to favorably impress. Others don't always seem to share the same sensitivity and/or priorities that speakers with these design priorities share. Only by listening to them yourself will you know for sure if it's important to you. Oh, btw, they usually share the similar quality of steady impedance loads, a subject of which I'm confident you will recall being discussed previously here on Audiogon.
Hi Bif, I've found that time alignment is certainly worthwhile, but let me just say that all you may need is a way to visualize how and why it would be important. I'm not technically as well versed on the subject as some, but I do have some direct user experience with it. I'm in the process of triamping my rig. Each amp I have (and will be adding) will have a suite of (digital) tools which include a pair of xovers, EQ and time delay. Each pair of tweeters, mids and woofers will have their own amp...and each of those frequency bands can be delayed the appropriate amount - dialing in by ear alone, at the lp, is sufficient. I can tell you that in practice that process is far from complicated and can be done in a couple minutes by anyone. It just may seem impossible to grasp for you at the moment because (understandably) you don't have any way to vary the control over your time alignment one way or the other so there is no way for you to realize its effects at this point. But, try to visualize it in terms of what you may already have some ordinary experience with. Try this: turn on a TV in one room of your home and then turn on another TV in a different room, but turn that one up loud enough to hear it while you're in the other room listening to the 1rst TV. Make sure they are both on the same channel. You can't help but notice the substantial time delay - like a rather serious echo, but in a nutshell, that's really all there is to time alignment. You've likely heard this effect countless times before without thinking about it at places like car dealerships, fire halls, etc...places where a PA system is using more than one loudspeaker in different places outside (usually on the other side of the building), creating the very noticeable amount of delay. Now, the big difference (apart from the sheer amount of time in the delay) is the fact that, like with the TV example, all of the frequencies overlap...hence the echo effect, naturally. But, with HiFi speakers (except to a degree at the xover regions, which we'll ignore here) the frequency groups are largely separated in their delay. What this means is that (with any conventional, flat baffle arrangement, anyway) the highs reach your ears first, then the mids and then the bass. Basically it means that the highs are simply being projected out into the room and are imaged a little closer to you (in soundstage distance) than the mids, which are in turn projected a little farther into the room than the bass...it simply becomes apparent to you that the higher frequency band seems physically imaged a little closer to you. Time alignment resets this effect, moving the imaging of the higher band back into place with the frequency band below and gets all the instruments and voices that much more correctly positioned from top to bottom in the frequency range...a very nice and more realistic or natural presentation - definitely worthwhile. Once you've ever heard the effect for yourself it takes all of about 5 seconds to solve the mystery as to how and why it might be useful, but, with speakers if you visualize the difference in terms of the distance of the soundstage image from you with each driver's operating range, then you just may at some point be able to recognize just how most speakers have somewhat less than ideal time alignment. And some will seem a little worse or better than others. If you use subs, however, it is always recommendable to take time alignment into consideration along with the other factors concerning placement, but I don't believe perfect time and phase alignment has ever been done in any speaker and I may never see it in my lifetime. But, triamping in this way for me is giving me the opportunity to pretty much 'fix' the time-alignment problem, which won't hurt me at all. Apart from building your own speakers though, it seems there are not too many designs that have actually tackled the problem, as near as I can tell. Until more makers become convinced there is a market for time-aligned cabinets (expensive because it's so labor intensive), then there may be only a handful of alternatives for us. Other problems for manufacturers include that in designing cabinets for true time alignment (meaning driver offset at something close to the correct distance) they start getting into a world of cabinet diffractions and reflections - not easy enough to successfully solve, particularly in any aesthetic sense. It's not horribly critical to get the distance precisely right, but the closer the better up to a point...like trying to position both your speakers the same - it might be quite good to get them within, say, a 1/4" of each other, but under an eighth of an inch??..at some point there ceases to be an improvement, but then again, with time alignment you would notice generally a better sense of scale and improvements in the macro areas of the soundstage...while the soundstage details would remain largely unchanged. Hope this helps.