Inverse mounting a woofer - I never see this

I’m doing research for a possible build but there is no information on this outside of subwoofer use. I’m wondering why no one inverts one of two woofers in their 3way speaker? I’ll attach a rough sketch.

I can see a huge potential drawback being mechanical noise. The only quiet woofer I’ve used is the Acoustic Elegance TD15h.

Another drawback in this drawing is the bottom woofer is not time aligned, although that may be a nonissue in a 3.5 way design?

Is the reduced 2nd harmonic distortion worth it if mechanical noise can be overcome?
09C4BA50-9FE7-4690-AF02-FF6490FEF2DC.jpeg
 
This has been done a lot - search push-pull subwoofers. There are many variants but usually the volume between the two are lot less, and usually one of them is in a separate sealed cabinet and the other on the inside of a bass reflex. In your drawing I don’t think push-pull will work due to the volume. I think you’re better off just investing the phase and let them play push-push but then again what’s the point. The formation of the cone usually have something to say as well in practical terms you’re making a dome subwoofer. Have no idea how that will play in a sealed box. A bass reflex is probably a safer choice.

Example: https://www.audiotag.com.br/web-files/uploads/site/produtos/1245/x-series-push-pull.jpg
 
music soothes the savage beast
Joined 2004
Paid Member
I’m doing research for a possible build but there is no information on this outside of subwoofer use. I’m wondering why no one inverts one of two woofers in their 3way speaker? I’ll attach a rough sketch.

I can see a huge potential drawback being mechanical noise. The only quiet woofer I’ve used is the Acoustic Elegance TD15h.

Another drawback in this drawing is the bottom woofer is not time aligned, although that may be a nonissue in a 3.5 way design?

Is the reduced 2nd harmonic distortion worth it if mechanical noise can be overcome?
View attachment 1212165
 

Attachments

  • image024.jpg
    image024.jpg
    136.4 KB · Views: 50
Other disadvantages include:

  • It sticks out, which is mechanically awkward.
  • Depending on the construction of the woofer, the voice coil may be exposed to contamination.
  • Wires are exposed.
  • The magnet can be quite powerful, so there's a risk of things sticking to it. Ferrite magnets are brittle too, so this could cause damage.
  • It's ugly.

Don't underestimate the importance of the last point.
 
  • Like
Reactions: 1 user
Mounting a woofer on an angle, or even horizontal (or vertical, depending on your frame of reference, anyway 90 degree), will cause additional distortion since the suspension is not symmetrical anymore.
Which not only causes additional distortion in BL, but also in the suspension itself and could also limit cone excursion.

In any case, it's a compromise in my book that I would never take, unless absolutely necessary.
I am surprised certain "high-end" systems use this.
 
diyAudio Moderator
Joined 2008
Paid Member
There are three distortions often mentioned..
1. Electrical distortion
2. Mechanical distortion (such as surround asymmetry)
3. Vibration modes (think of a boxer engine)

The first two can be handled by running one in reversed polarity and mounting one backward into the box. The third can be managed by putting one on the back panel or putting both on the sides.
 
  • Like
Reactions: 1 user
The first two can be handled by running one in reversed polarity and mounting one backward into the box.
To some extend, but never canceled. It just adds up less. (I mentioned that in another post)

It doesn't matter how you're gonna explain it, but in those positions, they always will perform worse.
Unless you very specifically design a speaker for it.
 
Something I always wanted to do.
Especially with drivers with a elaborate frame.
Visually it is just cool looking and different.
large magnet drivers would not remove/
displace as much airspace mounted outside the box.
Far as real world distortion or artifacts. Blah
If crossed at 200 or 80 to 60Hz for a sub.
Dont matter or dont care. be fine.
Doesnt need to be push pull but has been done
of course. Looks cool and saves box space.
Sounds good to me.
If I did it, be a sub crossed around 80 Hz
call it a day.