Question for Dave about 3-way speaker driver configurations

[j0nnyfive]

I guess the reason I'm asking is because I'm trying to understand the benefits of putting the tweeter between the woofer and the midrange. I looked for the old post where you spoke about this, but I can't find it. I think I remember you saying something about acoustic center being closer to the woofer? I don't know. Ideas I'm coming up with in my mind are:

1. Gives the cabinet certain amount of volume while keeping tweeter at desired height (ear level?).

2. Allows for a certain cabinet volume, and a sealed midwoofer, and ear level tweeter all at once.

3. Makes the interaction between the upper woofer, mid, and tweeter more like an MTM in time alignment? Such that the mid and woofer are time aligned on the tweeter axis? I'm guessing.

What I'm really curious about is whether there is a significant difference in dispersion into the room between a WMT and a WTM design.

No rush, I just wanted to provide more information about my curiosity.

By the way, ANYONE is free to answer this thread. I didn't mean to single out "just Dave only" or anything!

Everyone please be safe.

[j0nnyfive]

I FOUND IT!!! YAY!!!

////////////////////////////////////////////////////////////////////////
Originally Posted by GirgleMirt View Post
Also, any particular reason why the tweeter is between the mids and the woofers and not on top like most usually seen? MTWW vs TMWW? Curtis earlier mentioned it might have to do with OPPIX, but does it really use OPPIX and if so, does orientation of TM really make a difference?
Excellent question!

There are a few reasons for this orientation.

First off, it was important for us to keep the acoustic center of the critical tweeter and mid combination as close to the lower woofers as possible. This type of orientation allows for tighter phase integration between all of the drivers and is closer to acting like a single point source as compared to the more common TMWW. In addition, for most listeners, the acoustic center will be at or very close to ear level.

Another key aspect is that the midrange driver is housed in its own critically damped sealed enclosure, the volume and damping of which is carefully controlled to obtain a specific acoustic rolloff and Q. Assuming the same dimensions for the cabinet, in a TMWW design, if the midrange driver was to have the exact same enclosure volume, it would take up some of the cabinet volume the woofers would require thus we would either have to make the cabinet taller or settle for slightly less bass extension.

And finally, this orientation provides more vertical directivity and a more symmetrical vertical off-axis response than a TMWW design, thus reducing ceiling and floor reflections, but with a considerably wider vertical listening window compared to an MTM design. An MTM design will have greater vertical directivity but will also exhibit off-axis lobing, which is not consistent with mimicking the response of a single point source. The MTWW design was the perfect solution and retains much of the off-axis characteristics of the Sierra-1, thus keeping the speaker in the same family

The imaging of this speaker is remarkable yet it is not at all fussy about placement.

Hope this makes sense!
/////////////////////////////////////////////////////////////////////////////


It sure does!!! Thanks! lol