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time-aligned speakers: stepped fronts vs. sloping fronts

Let me first say my understanding of these things is rudimentary.

But I was thinking about manufacturers who used stepped back fronts (several vertical planes) to achieve so-called time-alignment, vs. those who slope back the whole front baffle at a certain angle/rake.

Thinking about, for instance, the tweeter driver mounted on a sloped baffle, won't its axis of radiation be shooting at a corresponding angle upward, meaning that a listener located directly in front of the speaker and with ears at tweeter height would already be listening off-axis?  Or am I missing something?  Or is that the point?

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Showing 2 responses by andy2

andy2
1,534 posts
 
There are two ways to time align the drivers - sloping the baffle or stepped baffle : both achieve the same thing.  The advantage of sloping is to minimize diffraction caused by the stepped baffle.

Sloping baffle is also used in first order/time-phase coherence design to further adjust the phase of the tweeter and mid (among other things).  

As for listening off axis on a slope baffle, that is true but it gets complicated beyond this as there are other variables that come to play besides sloping baffle.  And everything besides sloping has to be considered on a case by case basis and difficult to make a general conclusion.  
andy2
1,534 posts
 
if not, you'll be hearing the tweeters doubly off-axis
Although I know what you meant, I don't think the word "doubly off-axis" is a proper characterization.  It's either exactly on-axis or off-axis at certain degree angle in a 3-dimensional space.  The tweeter may be angled upward and the listening position at a lateral angle, overall it's still just off-axis at some angle in a 3D environment.  

The difference with angled baffle is probably more about aligning the phase of the tweeter and the mid driver.  


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